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Sample records for channel knockout induces

  1. Severe Salt-Losing Syndrome and Hyperkalemia Induced by Adult Nephron-Specific Knockout of the Epithelial Sodium Channel α-Subunit

    DEFF Research Database (Denmark)

    2016-01-01

    Systemic pseudohypoaldosteronism type 1 (PHA-1) is a severe salt-losing syndrome caused by loss-of-function mutations of the amiloride-sensitive epithelial sodium channel (ENaC) and characterized by neonatal life-threatening hypovolemia and hyperkalemia. The very high plasma aldosterone levels...... is neonatally lethal in mice. We generated adult inducible nephron-specific αENaC-knockout mice (Scnn1a(Pax8/LC1)) that exhibit hyperkalemia and body weight loss when kept on a regular-salt diet, thus mimicking PHA-1. Compared with control mice fed a regular-salt diet, knockout mice fed a regular-salt diet...... cannot be compensated for by other sodium channels and/or transporters, only by a high-sodium and reduced-potassium diet. We further conclude that hyperkalemia becomes the determining factor in regulating NCC activity, regardless of sodium loss, in the ENaC-mediated salt-losing PHA-1 phenotype....

  2. Neutrino induced pion production and nucleon knockout within the GiBUU transport model

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, T.; Mosel, U. [Inst. fuer Theoretische Physik, Univ. Giessen (Germany); Alvarez-Ruso, L. [Univ. de Valencia (Spain)

    2007-07-01

    There is an extensive experimental effort aiming at the precise determination of neutrino oscillation parameters. Its success depends critically on a good knowledge of neutrino-nucleus interactions in order to minimize the systematic uncertainties in neutrino fluxes, backgrounds and detector responses. We describe such charged and neutral current neutrino-nucleus interactions at intermediate neutrino energies within the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) coupled-channel transport model. We account for in-medium effects such as Fermi motion, Pauli blocking, nuclear binding, and final-state interactions which allows us to study exclusive channels as pion production and nucleon knockout. We find that final-state interactions modify considerably the distributions through rescattering, charge-exchange and absorption. Side-feeding induced by charge-exchange scattering is important in both cases. In the case of pions, there is a strong absorption associated with the in-medium pionless decay modes of the Delta, while nucleon knockout exhibits a considerable enhancement of low energy nucleons due to rescattering. At neutrino energies above 1 GeV, we also obtain that the contribution to nucleon knockout from Delta excitation is comparable to that from quasielastic scattering. (orig.)

  3. Knockout reaction induced by 6He at 61.2 MeV/u

    Institute of Scientific and Technical Information of China (English)

    LU Lin-Hui; CAO Zhong-Xin; SONG Yu-Shou; XIAO Jun; LI Qi-Te; QIAO Rui; YOU Hai-Bo; CHEN Rui-Jiu; XU Hu-Shan; WANG Jian-Song; GUO Zhong-Yan; YE Yan-Lin; ZHANG Xue-Ying; LI Chen; HU Zheng-Guo; CHEN Ruo-FU; WANG Meng; XU Zhi-Guo; YUE Ke; TANG Bin; ZANG Yong-Dong; ZHANG Xue-Heng; JIANG Dong-Xing; YAO Xiang-Wu; CHEN Jin-Da; BAI Zhen; HUA Hui; ZHENG Tao; LI Zhi-Huan; GE Yu-Cheng; LI Xiang-Qing; LOU Jian-Ling

    2011-01-01

    A knockout reaction induced by 6He at 61.2 MeV/u was carried out at the HIRFL-RIBLL radioactive beam line.The α core fragments at forward angles were detected in coincidence with the recoiled protons at large angles.From this coincident measurement the valence nucleon knockout mechanism and the core knockout mechanism can be separated according to the polar angle correlation between the core fragments and the recoiled protons.It is demonstrated that,when reconstructing the resonant state of a weakly bound nucleus,the contamination resulting from the core knockout mechanism should be eliminated in order to obtain the correct structure information.

  4. Effects of alpha-AMPK knockout on exercise-induced gene activation in mouse skeletal muscle

    DEFF Research Database (Denmark)

    Jørgensen, Sebastian Beck; Wojtaszewski, Jørgen; Viollet, Benoit

    2005-01-01

    We tested the hypothesis that 5'AMP-activated protein kinase (AMPK) plays an important role in regulating the acute, exercise-induced activation of metabolic genes in skeletal muscle, which were dissected from whole-body a2- and a1-AMPK knockout (KO) and wild-type (WT) mice at rest, after treadmi...

  5. Comprehensive behavioral analysis of voltage-gated calcium channel beta-anchoring and -regulatory protein knockout mice

    Directory of Open Access Journals (Sweden)

    Akito eNakao

    2015-06-01

    Full Text Available Calcium (Ca2+ influx through voltage-gated Ca2+ channels (VGCCs induces numerous intracellular events such as neuronal excitability, neurotransmitter release, synaptic plasticity, and gene regulation. It has been shown that genes related to Ca2+ signaling, such as the CACNA1C, CACNB2, and CACNA1I genes that encode VGCC subunits, are associated with schizophrenia and other psychiatric disorders. Recently, VGCC beta-anchoring and -regulatory protein (BARP was identified as a novel regulator of VGCC activity via the interaction of VGCC β subunits. To examine the role of the BARP in higher brain functions, we generated BARP knockout (KO mice and conducted a comprehensive battery of behavioral tests. BARP KO mice exhibited greatly reduced locomotor activity, as evidenced by decreased vertical activity, stereotypic counts in the open field test, and activity level in the home cage, and longer latency to complete a session in spontaneous T-maze alteration test, which reached study-wide significance. Acoustic startle response was also reduced in the mutants. Interestingly, they showed multiple behavioral phenotypes that are seemingly opposite to those seen in the mouse models of schizophrenia and its related disorders, including increased working memory, flexibility, prepulse inhibition, and social interaction, and decreased locomotor activity, though many of these phenotypes are statistically weak and require further replications. These results demonstrate that BARP is involved in the regulation of locomotor activity and, possibly, emotionality. The possibility was also suggested that BARP KO mice may serve as a unique tool for investigating the pathogenesis/pathophysiology of schizophrenia and related disorders. Further evaluation of the molecular and physiological phenotypes of the mutant mice would provide new insights into the role of BARP in higher brain functions.

  6. Adrenaline-induced colonic K+ secretion is mediated by KCa1.1 (BK) channels

    DEFF Research Database (Denmark)

    Sørensen, Mads Vaarby; Sausbier, Matthias; Ruth, Peter

    2010-01-01

    secretory K(+) channel in the apical membrane of the murine distal colon. The BK channel is responsible for both resting and Ca(2+)-activated colonic K(+) secretion and is up-regulated by aldosterone. Agonists (e.g. adrenaline) that elevate cAMP are potent activators of distal colonic K(+) secretion....... However, the secretory K(+) channel responsible for cAMP-induced K(+) secretion remains to be defined. In this study we used the Ussing chamber to identify adrenaline-induced electrogenic K(+) secretion. We found that the adrenaline-induced electrogenic ion secretion is a compound effect dominated...... by anion secretion and a smaller electrically opposing K(+) secretion. Using tissue from (i) BK wildtype (BK(+/+)) and knockout (BK(/)) and (ii) cystic fibrosis transmembrane regulator (CFTR) wildtype (CFTR(+/+)) and knockout (CFTR(/)) mice we were able to isolate the adrenaline-induced K(+) secretion. We...

  7. Characterization of Phototransduction Gene Knockouts Revealed Important Signaling Networks in the Light-Induced Retinal Degeneration

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    Jayalakshmi Krishnan

    2008-01-01

    Full Text Available Understanding the molecular pathways mediating neuronal function in retinas can be greatly facilitated by the identification of genes regulated in the retinas of different mutants under various light conditions. We attempted to conduct a gene chip analysis study on the genes regulated during rhodopsin kinase (Rhok-/- and arrestin (Sag-/- knockout and double knockouts in mice retina. Hence, mice were exposed to constant illumination of 450 lux or 6,000 lux on dilated pupils for indicated periods. The retinas were removed after the exposure and processed for microarray analysis. Double knockout was associated with immense changes in gene expression regulating a number of apoptosis inducing transcription factors. Subsequently, network analysis revealed that during early exposure the transcription factors, p53, c-MYC, c-FOS, JUN, and, in late phase, NF-B, appeared to be essential for the initiation of light-induced retinal rod loss, and some other classical pro- and antipoptotic genes appeared to be significantly important as well.

  8. Cardiac-Specific Knockout of ETA Receptor Mitigates Paraquat-Induced Cardiac Contractile Dysfunction.

    Science.gov (United States)

    Wang, Jiaxing; Lu, Songhe; Zheng, Qijun; Hu, Nan; Yu, Wenjun; Li, Na; Liu, Min; Gao, Beilei; Zhang, Guoyong; Zhang, Yingmei; Wang, Haichang

    2016-07-01

    Paraquat (1,1'-dim ethyl-4-4'-bipyridinium dichloride), a highly toxic quaternary ammonium herbicide widely used in agriculture, exerts potent toxic prooxidant effects resulting in multi-organ failure including the lung and heart although the underlying mechanism remains elusive. Recent evidence suggests possible involvement of endothelin system in paraquat-induced acute lung injury. This study was designed to examine the role of endothelin receptor A (ETA) in paraquat-induced cardiac contractile and mitochondrial injury. Wild-type (WT) and cardiac-specific ETA receptor knockout mice were challenged to paraquat (45 mg/kg, i.p.) for 48 h prior to the assessment of echocardiographic, cardiomyocyte contractile and intracellular Ca(2+) properties, as well as apoptosis and mitochondrial damage. Levels of the mitochondrial proteins for biogenesis and oxidative phosphorylation including UCP2, HSP90 and PGC1α were evaluated. Our results revealed that paraquat elicited cardiac enlargement, mechanical anomalies including compromised echocardiographic parameters (elevated left ventricular end-systolic and end-diastolic diameters as well as reduced factional shortening), suppressed cardiomyocyte contractile function, intracellular Ca(2+) handling, overt apoptosis and mitochondrial damage. ETA receptor knockout itself failed to affect myocardial function, apoptosis, mitochondrial integrity and mitochondrial protein expression. However, ETA receptor knockout ablated or significantly attenuated paraquat-induced cardiac contractile and intracellular Ca(2+) defect, apoptosis and mitochondrial damage. Taken together, these findings revealed that endothelin system in particular the ETA receptor may be involved in paraquat-induced toxic myocardial contractile anomalies possibly related to apoptosis and mitochondrial damage.

  9. Enhanced morphine-induced antinociception in histamine H3 receptor gene knockout mice.

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    Mobarakeh, Jalal Izadi; Takahashi, Kazuhiro; Yanai, Kazuhiko

    2009-09-01

    Previous studies have implicated a potential role for histamine H3 receptor in pain processing. There have been conflicting data, however, on the roles of H3 receptors in pain perception, and little information is available about the role of spinal histamine H3 receptors in morphine-induced antinociception. In the present study we examined the role of histamine H3 receptor in morphine-induced antinociception using histamine H3 receptor knockout mice and a histamine H3 receptor antagonist. Anitinociception was evaluated by assays for four nociceptive stimuli: hot-plate, tail-flick, paw-withdrawal, and formalin tests. Antinociception induced by morphine (0.125 nmol/5 microl, i.t.) was significantly augmented in histamine H3 receptor knockout (-/-) mice compared to the wild-type (+/+) mice in all four assays of pain. Furthermore, the effect of intrathecally administered morphine with thioperamide, a histamine H3 antagonist, was examined in C57BL/6J mice. A low dose of i.t. administered thioperamide (0.125 nmol/5 microl) alone had no significant effect on the nociceptive response. In contrast, the combination of morphine (0.125 nmol/5 microl, i.t.) with the same dose of thioperamide resulted in a significant reduction in the pain-related behaviors in all four nociceptive tests. These results suggest that histamine exerts inhibitory effects on morphine-induced antinociception through H3 receptors at the spinal level.

  10. CXCR2 knockout mice are protected against DSS-colitis-induced acute kidney injury and inflammation.

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    Ranganathan, Punithavathi; Jayakumar, Calpurnia; Manicassamy, Santhakumar; Ramesh, Ganesan

    2013-11-15

    Organ cross talk exists in many diseases of the human and animal models of human diseases. A recent study demonstrated that inflammatory mediators can cause acute kidney injury and neutrophil infiltration in a mouse model of dextran sodium sulfate (DSS)-colitis. However, the chemokines and their receptors that may mediate distant organ effects in colitis are unknown. We hypothesized that keratinocyte chemoattractant (KC)/IL-8 receptor chemokine (C-X-C motif) ligand 2 (CXCL2) mediates DSS-colitis-induced acute kidney injury. Consistent with our hypothesis, wild-type (WT) mice developed severe colitis with DSS treatment, which was associated with inflammatory cytokine and chemokine expression and neutrophil infiltration in the colon. DSS-colitis in WT was accompanied by acute kidney injury and enhanced expression of inflammatory cytokines in the kidney. However, CXCR2 knockout mice were protected against DSS-colitis as well as acute kidney injury. Moreover, the expression of cytokines and chemokines and neutrophil infiltration was blunted in CXCR2 knockout mice in the colon and kidney. Administration of recombinant KC exacerbated DSS-colitis-induced acute kidney injury. Our results suggest that KC/IL-8 and its receptor CXCR2 are critical and major mediators of organ cross talk in DSS colitis and neutralization of CXCR2 will help to reduce the incidence of acute kidney injury due to ulcerative colitis and Crohn's disease in humans.

  11. Knockout of the 15 kDa selenoprotein protects against chemically-induced aberrant crypt formation in mice.

    Directory of Open Access Journals (Sweden)

    Petra A Tsuji

    Full Text Available Evidence suggests that selenium has cancer preventive properties that are largely mediated through selenoproteins. Our previous observations demonstrated that targeted down-regulation of the 15 kDa selenoprotein (Sep15 in murine colon cancer cells resulted in the reversal of the cancer phenotype. The present study investigated the effect of Sep15 knockout in mice using a chemically-induced colon cancer model. Homozygous Sep15 knockout mice, and wild type littermate controls were given four weekly subcutaneous injections of azoxymethane (10 mg/kg. Sep15 knockout mice developed significantly (p<0.001 fewer aberrant crypt foci than controls demonstrating that loss of Sep15 protects against aberrant crypt foci formation. Dietary selenium above adequate levels did not significantly affect aberrant crypt foci formation in Sep15 knockout mice. To investigate molecular targets affected by loss of Sep15, gene expression patterns in colonic mucosal cells of knockout and wild type mice were examined using microarray analysis. Subsequent analyses verified that guanylate binding protein-1 (GBP-1 mRNA and protein expression were strongly upregulated in Sep15 knockout mice. GBP-1, which is expressed in response to interferon-γ, is considered to be an activation marker during inflammatory diseases, and up-regulation of GBP-1 in humans has been associated with a highly significant, increased five-year survival rate in colorectal cancer patients. In agreement with these studies, we observed a higher level of interferon-γ in plasma of Sep15 knockout mice. Overall, our results demonstrate for the first time, that Sep15 knockout mice are protected against chemically-induced aberrant crypt foci formation and that Sep15 appears to have oncogenic properties in colon carcinogenesis in vivo.

  12. Increased susceptibility to diet-induced obesity in GPRC6A receptor knockout mice

    DEFF Research Database (Denmark)

    Clemmensen, Christoffer; Smajilovic, Sanela; Madsen, Andreas N;

    2013-01-01

    complications is still elusive. In the present study, we investigated the impact of GPRC6A deficiency in a murine model of diet-induced obesity (DIO). Male Gprc6a knockout (KO) mice and WT littermates were subjected to a high-fat diet (HFD) for 25 weeks and exposed to comprehensive metabolic phenotyping...... locomotor activity. Moreover, diet-induced obese Gprc6a KO mice had increased circulating insulin and leptin levels relative to WT animals, thereby demonstrating that endocrine abnormalities associate with the reported disturbances in energy balance. The phenotype was further accompanied by disruptions......The recently identified G protein-coupled receptor GPRC6A is activated by dietary amino acids and expressed in multiple tissues. Although the receptor is hypothesised to exert biological impact on metabolic and endocrine-related parameters, the role of the receptor in obesity and metabolic...

  13. Neuronal conditional knockout of NRSF decreases vulnerability to seizures induced by pentylenetetrazol in mice

    Institute of Scientific and Technical Information of China (English)

    Ming Liu; Zhejin Sheng; Lei Cai; Kai Zhao; Yu Tian; Jian Fei

    2012-01-01

    Neuron restrictive silencer factor (NRSF),also known as repressor element-1 silencing transcription factor,has been reported to modulate neuronal excitability and acts as endogenous anticonvulsant in kainic acid-induced or kindling-evoked seizure activity.However,whether NRSF functions in pentylenetetrazol (PTZ)-induced seizure activity has never been studied.To investigate the role of endogenous NRSF in the epileptogenesis induced by PTZ,in our experiment,NRSF neuronal conditional knockout mice (NRSF cKO) were adopted,in which NRSF was specifically deleted in neurons by the Cre-loxP system.Seizure threshold for PTZ,including the dose-response convulsions and the threshold dose,was compared between NRSF cKO and control mice.The threshold dose of PTZ that induced clonic and tonic seizures was significantly higher in NRSF cKO mice compared with the control.Similarly,the median lethal dose (LD50) of PTZ in NRSF cKO mice was also considerably higher than that of the control mice.These results revealed that NRSF cKO mice are of higher resistance to convulsions induced by PTZ.Our work first demonstrated the function of NRSF in PTZ-induced seizure and provided new evidence for differential pathways in diverse types of seizure.

  14. GARP2 accelerates retinal degeneration in rod cGMP-gated cation channel β-subunit knockout mice

    Science.gov (United States)

    DeRamus, Marci L.; Stacks, Delores A.; Zhang, Youwen; Huisingh, Carrie E.; McGwin, Gerald; Pittler, Steven J.

    2017-01-01

    The Cngb1 locus-encoded β-subunit of rod cGMP-gated cation channel and associated glutamic acid rich proteins (GARPs) are required for phototransduction, disk morphogenesis, and rod structural integrity. To probe individual protein structure/function of the GARPs, we have characterized several transgenic mouse lines selectively restoring GARPs on a Cngb1 knockout (X1−/−) mouse background. Optical coherence tomography (OCT), light and transmission electron microscopy (TEM), and electroretinography (ERG) were used to analyze 6 genotypes including WT at three and ten weeks postnatal. Comparison of aligned histology/OCT images demonstrated that GARP2 accelerates the rate of degeneration. ERG results are consistent with the structural analyses showing the greatest attenuation of function when GARP2 is present. Even 100-fold or more overexpression of GARP1 could not accelerate degeneration as rapidly as GARP2, and when co-expressed GARP1 attenuated the structural and functional deficits elicited by GARP2. These results indicate that the GARPs are not fully interchangeable and thus, likely have separate and distinct functions in the photoreceptor. We also present a uniform murine OCT layer naming nomenclature system that is consistent with human retina layer designations to standardize murine OCT, which will facilitate data evaluation across different laboratories. PMID:28198469

  15. Transthyretin knockout mice display decreased susceptibility to AMPA-induced neurodegeneration

    DEFF Research Database (Denmark)

    Nunes, Ana Filipa; Montero, Maria; Franquinho, Filipa;

    2009-01-01

    Transthyretin (TTR) has been regarded as a neuroprotective protein given that TTR knockout (KO) mice display increased susceptibility for amyloid beta deposition and memory deficits during aging. In parallel, TTR KO mice have increased levels of neuropeptide Y (NPY), which promotes neuroprotection...... and neuroproliferation. In this work, we aimed at evaluating TTR neuroprotective effect against an excitotoxic insult that is known to be prevented by NPY action. We show that despite a putative neuroprotective role of TTR, hippocampal slice cultures from TTR KO mice display a decreased susceptibility to AMPA......-induced neurodegeneration. We also suggest that increased NPY levels in TTR KO mice are not associated with increased cell proliferation in the dentate gyrus or subventricular zone. In summary, the alleged neuroprotective role of TTR in the nervous system should be regarded with caution and should not be generalized to all...

  16. IKKε knockout prevents high fat diet induced arterial atherosclerosis and NF-κB signaling in mice.

    Directory of Open Access Journals (Sweden)

    Changchun Cao

    Full Text Available AIMS: Atherosclerosis is a public health concern affecting many worldwide, but its pathogenesis remains unclear. In this study we investigated the role of IKKε during the formation of atherosclerosis and its molecular mechanism in the mouse aortic vessel wall. METHODS AND RESULTS: C57BL/6 wild-type or IKKε knockout mice bred into the ApoE knockout genetic background were divided into 4 groups: (1 wild-type (WT, (2 ApoE knockout (AK, (3 IKKε knockout (IK, (4 or both ApoE and IKKε knockout (DK. Each group of mice were fed with a high fat diet (HFD for 12 weeks from 8 weeks of age. Immunohistochemistry and Western blotting analysis demonstrated obvious increases in the expression of IKKε in the AK group compared with the WT group, especially in the intima. Serum lipid levels were significantly higher in the AK and DK groups than in the other two groups. Staining with hematoxylin-eosin and Oil Red, as well as scanning electron microscopy revealed less severe atherosclerotic lesions in the DK group than in the AK group. Immunofluorescence and Western blot analysis demonstrated obvious increases in the expression of NF-κB pathway components and downstream factors in the AK group, especially in the intima, while these increases were blocked in the DK group. CONCLUSION: The knockout of IKKε prevented significant atherosclerosis lesions in the mouse aorta from in both wild-type and ApoE knockout mice fed a HFD, suggesting that IKKε may play a vital role in HFD-induced atherosclerosis and would be an important target for the treatment of atherosclerosis.

  17. Increased sensitivity of apolipoprotein E knockout mice to copper-induced oxidative injury to the liver.

    Science.gov (United States)

    Chen, Yuan; Li, Bin; Zhao, Ran-ran; Zhang, Hui-feng; Zhen, Chao; Guo, Li

    2015-04-10

    Apolipoprotein E (ApoE) genotypes are related to clinical presentations in patients with Wilson's disease, indicating that ApoE may play an important role in the disease. However, our understanding of the role of ApoE in Wilson's disease is limited. High copper concentration in Wilson's disease induces excessive generation of free oxygen radicals. Meanwhile, ApoE proteins possess antioxidant effects. We therefore determined whether copper-induced oxidative damage differ in the liver of wild-type and ApoE knockout (ApoE(-/-)) mice. Both wild-type and ApoE(-/-) mice were intragastrically administered with 0.2 mL of copper sulfate pentahydrate (200 mg/kg; a total dose of 4 mg/d) or the same volume of saline daily for 12 weeks, respectively. Copper and oxidative stress markers in the liver tissue and in the serum were assessed. Our results showed that, compared with the wild-type mice administered with copper, TBARS as a marker of lipid peroxidation, the expression of oxygenase-1 (HO-1), NAD(P)H dehydrogenase, and quinone 1 (NQO1) significantly increased in the ApoE(-/-) mice administered with copper, meanwhile superoxide dismutase (SOD) activity significantly decreased. Thus, it is concluded that ApoE may protect the liver from copper-induced oxidative damage in Wilson's disease.

  18. NQO1-Knockout Mice Are Highly Sensitive to Clostridium Difficile Toxin A-Induced Enteritis.

    Science.gov (United States)

    Nam, Seung Taek; Hwang, Jung Hwan; Kim, Dae Hong; Lu, Li Fang; Hong, Ji; Zhang, Peng; Yoon, I Na; Hwang, Jae Sam; Chung, Hyo Kyun; Shong, Minho; Lee, Chul-Ho; Kim, Ho

    2016-08-28

    Clostridium difficile toxin A causes acute gut inflammation in animals and humans. It is known to downregulate the tight junctions between colonic epithelial cells, allowing luminal contents to access body tissues and trigger acute immune responses. However, it is not yet known whether this loss of the barrier function is a critical factor in the progression of toxin A-induced pseudomembranous colitis. We previously showed that NADH:quinone oxidoreductase 1 (NQO1) KO (knockout) mice spontaneously display weak gut inflammation and a marked loss of colonic epithelial tight junctions. Moreover, NQO1 KO mice exhibited highly increased inflammatory responses compared with NQO1 WT (wild-type) control mice when subjected to DSS-induced experimental colitis. Here, we tested whether toxin A could also trigger more severe inflammatory responses in NQO1 KO mice compared with NQO1 WT mice. Indeed, our results show that C. difficile toxin A-mediated enteritis is significantly enhanced in NQO1 KO mice compared with NQO1 WT mice. The levels of fluid secretion, villus disruption, and epithelial cell apoptosis were also higher in toxin A-treated NQO1 KO mice compared with WT mice. The previous and present results collectively show that NQO1 is involved in the formation of tight junctions in the small intestine, and that defects in NQO1 enhance C. difficile toxin A-induced acute inflammatory responses, presumably via the loss of epithelial cell tight junctions.

  19. Ghrelin knockout mice show decreased voluntary alcohol consumption and reduced ethanol-induced conditioned place preference.

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    Bahi, Amine; Tolle, Virginie; Fehrentz, Jean-Alain; Brunel, Luc; Martinez, Jean; Tomasetto, Catherine-Laure; Karam, Sherif M

    2013-05-01

    Recent work suggests that stomach-derived hormone ghrelin receptor (GHS-R1A) antagonism may reduce motivational aspects of ethanol intake. In the current study we hypothesized that the endogenous GHS-R1A agonist ghrelin modulates alcohol reward mechanisms. For this purpose ethanol-induced conditioned place preference (CPP), ethanol-induced locomotor stimulation and voluntary ethanol consumption in a two-bottle choice drinking paradigm were examined under conditions where ghrelin and its receptor were blocked, either using ghrelin knockout (KO) mice or the specific ghrelin receptor (GHS-R1A) antagonist "JMV2959". We showed that ghrelin KO mice displayed lower ethanol-induced CPP than their wild-type (WT) littermates. Consistently, when injected during CPP-acquisition, JMV2959 reduced CPP-expression in C57BL/6 mice. In addition, ethanol-induced locomotor stimulation was lower in ghrelin KO mice. Moreover, GHS-R1A blockade, using JMV2959, reduced alcohol-stimulated locomotion only in WT but not in ghrelin KO mice. When alcohol consumption and preference were assessed using the two-bottle choice test, both genetic deletion of ghrelin and pharmacological antagonism of the GHS-R1A (JMV2959) reduced voluntary alcohol consumption and preference. Finally, JMV2959-induced reduction of alcohol intake was only observed in WT but not in ghrelin KO mice. Taken together, these results suggest that ghrelin neurotransmission is necessary for the stimulatory effect of ethanol to occur, whereas lack of ghrelin leads to changes that reduce the voluntary intake as well as conditioned reward by ethanol. Our findings reveal a major, novel role for ghrelin in mediating ethanol behavior, and add to growing evidence that ghrelin is a key mediator of the effects of multiple abused drugs.

  20. alpha7 Nicotinic acetylcholine receptor knockout selectively enhances ethanol-, but not beta-amyloid-induced neurotoxicity.

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    de Fiebre, Nancyellen C; de Fiebre, Christopher M

    2005-01-03

    The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.

  1. Engineering Human Stem Cell Lines with Inducible Gene Knockout using CRISPR/Cas9.

    Science.gov (United States)

    Chen, Yuejun; Cao, Jingyuan; Xiong, Man; Petersen, Andrew J; Dong, Yi; Tao, Yunlong; Huang, Cindy Tzu-Ling; Du, Zhongwei; Zhang, Su-Chun

    2015-08-06

    Precise temporal control of gene expression or deletion is critical for elucidating gene function in biological systems. However, the establishment of human pluripotent stem cell (hPSC) lines with inducible gene knockout (iKO) remains challenging. We explored building iKO hPSC lines by combining CRISPR/Cas9-mediated genome editing with the Flp/FRT and Cre/LoxP system. We found that "dual-sgRNA targeting" is essential for biallelic knockin of FRT sequences to flank the exon. We further developed a strategy to simultaneously insert an activity-controllable recombinase-expressing cassette and remove the drug-resistance gene, thus speeding up the generation of iKO hPSC lines. This two-step strategy was used to establish human embryonic stem cell (hESC) and induced pluripotent stem cell (iPSC) lines with iKO of SOX2, PAX6, OTX2, and AGO2, genes that exhibit diverse structural layout and temporal expression patterns. The availability of iKO hPSC lines will substantially transform the way we examine gene function in human cells.

  2. Iron metabolism in hepcidin1 knockout mice in response to phenylhydrazine-induced hemolysis.

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    Masaratana, Patarabutr; Latunde-Dada, Gladys O; Patel, Neeta; Simpson, Robert J; Vaulont, Sophie; McKie, Andrew T

    2012-08-15

    Hepcidin, an iron regulatory peptide, plays a central role in the maintenance of systemic iron homeostasis by inducing the internalization and degradation of the iron exporter, ferroportin. Hepcidin expression in the liver is regulated in response to several stimuli including iron status, erythropoietic activity, hypoxia and inflammation. Hepcidin expression has been shown to be reduced in phenylhydrazine-treated mice, a mouse model of acute hemolysis. In this mouse model, hepcidin suppression was associated with increased expression of molecules involved in iron transport and recycling. The present study aims to explore whether the response to phenylhydrazine treatment is affected by hepcidin deficiency and/or the subsequently altered iron metabolism. Hepcidin1 knockout (Hamp(-/-)) and wild type mice were treated with phenylhydrazine or saline and parameters of iron homeostasis were determined 3 days after the treatment. In wild type mice, phenylhydrazine administration resulted in significantly reduced serum iron, increased tissue non-heme iron levels and suppressed hepcidin expression. The treatment was also associated with increases in membrane ferroportin protein levels and spleen heme oxygenase 1 mRNA expression. In addition, trends toward increased mRNA expression of duodenal iron transporters were also observed. In contrast, serum iron and tissue non-heme iron levels in Hamp(-/-) mice were unaffected by the treatment. Moreover, the effects of phenylhydrazine on the expression of ferroportin and duodenal iron transporters were not observed in Hamp(-/-) mice. Interestingly, mRNA levels of molecules involved in splenic heme uptake and degradation were significantly induced by Hamp disruption. In summary, our study demonstrates that the response to phenylhydrazine-induced hemolysis differs between wild type and Hamp(-/-) mice. This observation may be caused by the absence of hepcidin per se or the altered iron homeostasis induced by the lack of hepcidin in

  3. Alleviation of high-fat diet-induced fatty liver damage in group IVA phospholipase A2-knockout mice.

    Science.gov (United States)

    Ii, Hiromi; Yokoyama, Naoki; Yoshida, Shintaro; Tsutsumi, Kae; Hatakeyama, Shinji; Sato, Takashi; Ishihara, Keiichi; Akiba, Satoshi

    2009-12-01

    Hepatic fat deposition with hepatocellular damage, a feature of non-alcoholic fatty liver disease, is mediated by several putative factors including prostaglandins. In the present study, we examined whether group IVA phospholipase A(2) (IVA-PLA(2)), which catalyzes the first step in prostanoid biosynthesis, is involved in the development of fatty liver, using IVA-PLA(2)-knockout mice. Male wild-type mice on high-fat diets (20% fat and 1.25% cholesterol) developed hepatocellular vacuolation and liver hypertrophy with an increase in the serum levels of liver damage marker aminotransferases when compared with wild-type mice fed normal diets. These high-fat diet-induced alterations were markedly decreased in IVA-PLA(2)-knockout mice. Hepatic triacylglycerol content was lower in IVA-PLA(2)-knockout mice than in wild-type mice under normal dietary conditions. Although high-fat diets increased hepatic triacylglycerol content in both genotypes, the degree was lower in IVA-PLA(2)-knockout mice than in wild-type mice. Under the high-fat dietary conditions, IVA-PLA(2)-knockout mice had lower epididymal fat pad weight and smaller adipocytes than wild-type mice. The serum level of prostaglandin E(2), which has a fat storage effect, was lower in IVA-PLA(2)-knockout mice than in wild-type mice, irrespective of the kind of diet. In both genotypes, high-fat diets increased serum leptin levels equally between the two groups, but did not affect the serum levels of adiponectin, resistin, free fatty acid, triacylglycerol, glucose, or insulin. Our findings suggest that a deficiency of IVA-PLA(2) alleviates fatty liver damage caused by high-fat diets, probably because of the lower generation of IVA-PLA(2) metabolites, such as prostaglandin E(2). IVA-PLA(2) could be a promising therapeutic target for obesity-related diseases including non-alcoholic fatty liver disease.

  4. Collecting duct-specific knockout of renin attenuates angiotensin II-induced hypertension.

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    Ramkumar, Nirupama; Stuart, Deborah; Rees, Sara; Hoek, Alfred Van; Sigmund, Curt D; Kohan, Donald E

    2014-10-15

    The physiological and pathophysiological significance of collecting duct (CD)-derived renin, particularly as it relates to blood pressure (BP) regulation, is unknown. To address this question, we generated CD-specific renin knockout (KO) mice and examined BP and renal salt and water excretion. Mice containing loxP-flanked exon 1 of the renin gene were crossed with mice transgenic for aquaporin-2-Cre recombinase to achieve CD-specific renin KO. Compared with controls, CD renin KO mice had 70% lower medullary renin mRNA and 90% lower renin mRNA in microdissected cortical CD. Urinary renin levels were significantly lower in KO mice (45% of control levels) while plasma renin concentration was significantly higher in KO mice (63% higher than controls) during normal-Na intake. While no observable differences were noted in BP between the two groups with varying Na intake, infusion of angiotensin II at 400 ng·kg(-1)·min(-1) resulted in an attenuated hypertensive response in the KO mice (mean arterial pressure 111 ± 4 mmHg in KO vs. 128 ± 3 mmHg in controls). Urinary renin excretion and epithelial Na(+) channel (ENaC) remained significantly lower in the KO mice following ANG II infusion compared with controls. Furthermore, membrane-associated ENaC protein levels were significantly lower in KO mice following ANG II infusion. These findings suggest that CD renin modulates BP in ANG II-infused hypertension and these effects are associated with changes in ENaC expression.

  5. Effects of disulfiram and dopamine beta-hydroxylase knockout on cocaine-induced seizures

    Science.gov (United States)

    Gaval-Cruz, Meriem; Schroeder, Jason P.; Liles, L. Cameron; Javors, Martin A.; Weinshenker, David

    2008-01-01

    The antialcoholism drug disulfiram has shown recent promise as a pharmacotherapy for treating cocaine dependence, probably via inhibition of dopamine β-hydroxylase (DBH), the enzyme that catalyzes the conversion of dopamine (DA) to norepinephrine (NE). We previously showed that DBH knockout (Dbh -/-) mice, which lack NE, are susceptible to seizures and are hypersensitive to the psychomotor, rewarding, and aversive effects of cocaine, suggesting that disulfiram might exacerbate cocaine-induced seizures (CIS) by inhibiting DBH. To test this, we examined CIS in wild-type and Dbh -/- mice following administration of disulfiram or the selective DBH inhibitor nepicastat. We found that Dbh genotype had no effect on CIS probability or frequency, whereas disulfiram, but not nepicastat, increased the probability of having CIS in both wild-type and Dbh -/- mice. Both disulfiram and nepicastat increased CIS frequency in wild-type but not Dbh -/- mice. There were no genotype or treatment effects on serum cocaine levels, except for an increase in disulfiram-treated Dbh -/- mice at the highest dose of cocaine. These results suggest that disulfiram enhances CIS via two distinct mechanisms: it both increases CIS frequency by inhibiting DBH and increases CIS frequency in a DBH-independent manner. PMID:18329701

  6. Functional importance of T-type voltage-gated calcium channels in the cardiovascular and renal system: news from the world of knockout mice.

    Science.gov (United States)

    Hansen, Pernille B L

    2015-02-15

    Over the years, it has been discussed whether T-type calcium channels Cav3 play a role in the cardiovascular and renal system. T-type channels have been reported to play an important role in renal hemodynamics, contractility of resistance vessels, and pacemaker activity in the heart. However, the lack of highly specific blockers cast doubt on the conclusions. As new T-type channel antagonists are being designed, the roles of T-type channels in cardiovascular and renal pathology need to be elucidated before T-type blockers can be clinically useful. Two types of T-type channels, Cav3.1 and Cav3.2, are expressed in blood vessels, the kidney, and the heart. Studies with gene-deficient mice have provided a way to investigate the Cav3.1 and Cav3.2 channels and their role in the cardiovascular system. This review discusses the results from these knockout mice. Evaluation of the literature leads to the conclusion that Cav3.1 and Cav3.2 channels have important, but different, functions in mice. T-type Cav3.1 channels affect heart rate, whereas Cav3.2 channels are involved in cardiac hypertrophy. In the vascular system, Cav3.2 activation leads to dilation of blood vessels, whereas Cav3.1 channels are mainly suggested to affect constriction. The Cav3.1 channel is also involved in neointima formation following vascular damage. In the kidney, Cav3.1 regulates plasma flow and Cav3.2 plays a role setting glomerular filtration rate. In conclusion, Cav3.1 and Cav3.2 are new therapeutic targets in several cardiovascular pathologies, but the use of T-type blockers should be specifically directed to the disease and to the channel subtype.

  7. Prevention of elastase-induced emphysema in placenta growth factor knock-out mice

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    Tsao Po

    2009-11-01

    Full Text Available Abstract Background Although both animal and human studies suggested the association between placenta growth factor (PlGF and chronic obstructive pulmonary disease (COPD, especially lung emphysema, the role of PlGF in the pathogenesis of emphysema remains to be clarified. This study hypothesizes that blocking PlGF prevents the development of emphysema. Methods Pulmonary emphysema was induced in PlGF knock-out (KO and wild type (WT mice by intra-tracheal instillation of porcine pancreatic elastase (PPE. A group of KO mice was then treated with exogenous PlGF and WT mice with neutralizing anti-VEGFR1 antibody. Tumor necrosis factor alpha (TNF-α, matrix metalloproteinase-9 (MMP-9, and VEGF were quantified. Apoptosis measurement and immuno-histochemical staining for VEGF R1 and R2 were performed in emphysematous lung tissues. Results After 4 weeks of PPE instillation, lung airspaces enlarged more significantly in WT than in KO mice. The levels of TNF-α and MMP-9, but not VEGF, increased in the lungs of WT compared with those of KO mice. There was also increased in apoptosis of alveolar septal cells in WT mice. Instillation of exogenous PlGF in KO mice restored the emphysematous changes. The expression of both VEGF R1 and R2 decreased in the emphysematous lungs. Conclusion In this animal model, pulmonary emphysema is prevented by depleting PlGF. When exogenous PlGF is administered to PlGF KO mice, emphysema re-develops, implying that PlGF contributes to the pathogenesis of emphysema.

  8. Safrole-2',3'-oxide induces atherosclerotic plaque vulnerability in apolipoprotein E-knockout mice.

    Science.gov (United States)

    Su, Le; Zhang, Haiyan; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

    2013-02-27

    Safrole-2',3'-oxide (SFO) is the major electrophilic metabolite of safrole (4-allyl-1, 2-methylenedioxybenzene), a natural plant constituent found in essential oils of numerous edible herbs and spices and in food containing these herbs, such as pesto sauce, cola beverages and bologna sausages. The effects of SFO in mammalian systems, especially the cardiovascular system, are little known. Disruption of vulnerable atherosclerotic plaques in atherosclerosis, a chronic inflammatory disease, is the main cause of cardiovascular events. In this study, we investigated SFO-induced atherosclerotic plaque vulnerability (possibility of rupture) in apolipoprotein E-knockout (apoE(-/-)) mice. Lipid area in vessel wall reached 59.8% in high dose SFO (SFO-HD) treated group, which is only 31.2% in control group. SFO treatment changed the lesion composition to an unstable phenotype, increased the number of apoptotic cells in plaque and the endothelium in plaques was damaged after SFO treatment. Furthermore, compared with control groups, the plaque endothelium level of p75(NTR) was 3-fold increased and the liver level of p75(NTR) was 17.4-fold increased by SFO-HD. Meanwhile, the serum level of KC (a functional homolog of IL-8 and the main proinflammatory alpha chemokine in mice) in apoE(-/-) mice was up to 357pg/ml in SFO-HD treated group. Thus, SFO contributes to the instability of atherosclerotic plaque in apoE(-/-) mice through activating p75(NTR) and IL-8 and cell apoptosis in plaque.

  9. Histidine decarboxylase knockout mice, a genetic model of Tourette syndrome, show repetitive grooming after induced fear.

    Science.gov (United States)

    Xu, Meiyu; Li, Lina; Ohtsu, Hiroshi; Pittenger, Christopher

    2015-05-19

    Tics, such as are seen in Tourette syndrome (TS), are common and can cause profound morbidity, but they are poorly understood. Tics are potentiated by psychostimulants, stress, and sleep deprivation. Mutations in the gene histidine decarboxylase (Hdc) have been implicated as a rare genetic cause of TS, and Hdc knockout mice have been validated as a genetic model that recapitulates phenomenological and pathophysiological aspects of the disorder. Tic-like stereotypies in this model have not been observed at baseline but emerge after acute challenge with the psychostimulant d-amphetamine. We tested the ability of an acute stressor to stimulate stereotypies in this model, using tone fear conditioning. Hdc knockout mice acquired conditioned fear normally, as manifested by freezing during the presentation of a tone 48h after it had been paired with a shock. During the 30min following tone presentation, knockout mice showed increased grooming. Heterozygotes exhibited normal freezing and intermediate grooming. These data validate a new paradigm for the examination of tic-like stereotypies in animals without pharmacological challenge and enhance the face validity of the Hdc knockout mouse as a pathophysiologically grounded model of tic disorders.

  10. Ras Transformation Overrides a Proliferation Defect Induced by Tpm3.1 Knockout.

    Science.gov (United States)

    Coombes, Jason D; Schevzov, Galina; Kan, Chin-Yi; Petti, Carlotta; Maritz, Michelle F; Whittaker, Shane; Mackenzie, Karen L; Gunning, Peter W

    2015-12-01

    Extensive re-organisation of the actin cytoskeleton and changes in the expression of its binding proteins is a characteristic feature of cancer cells. Previously we have shown that the tropomyosin isoform Tpm3.1, an integral component of the actin cytoskeleton in tumor cells, is required for tumor cell survival. Our objective was to determine whether cancer cells devoid of Tpm3.1 would evade the tumorgenic effects induced by H-Ras transformation. The tropomyosin isoform (Tpm) expression profile of a range of cancer cell lines (21) demonstrates that Tpm3.1 is one of the most broadly expressed Tpm isoform. Consequently, the contribution of Tpm3.1 to the transformation process was functionally evaluated. Primary embryonic fibroblasts isolated from wild type (WT) and Tpm3.1 knockout (KO) mice were transduced with retroviral vectors expressing SV40 large T antigen and an oncogenic allele of the H-Ras gene, H-RasV12, to generate immortalized and transformed WT and KO MEFs respectively. We show that Tpm3.1 is required for growth factor-independent proliferation in the SV40 large T antigen immortalized MEFs, but this requirement is overcome by H-Ras transformation. Consistent with those findings, we found that Tpm3.1 was not required for anchorage independent growth or growth of H-Ras-driven tumors in a mouse model. Finally, we show that pERK and Importin 7 protein interactions are significantly decreased in the SV40 large T antigen immortalized KO MEFs but not in the H-Ras transformed KO cells, relative to control MEFs. The data demonstrate that H-Ras transformation overrides a requirement for Tpm3.1 in growth factor-independent proliferation of immortalized MEFs. We propose that in the SV40 large T antigen immortalized MEFs, Tpm3.1 is partly responsible for the efficient interaction between pERK and Imp7 resulting in cell proliferation, but this is overidden by Ras transformation.

  11. Retinoid-related orphan receptor γ (RORγ) adult induced knockout mice develop lymphoblastic lymphoma.

    Science.gov (United States)

    Liljevald, Maria; Rehnberg, Maria; Söderberg, Magnus; Ramnegård, Marie; Börjesson, Jenny; Luciani, Donatella; Krutrök, Nina; Brändén, Lena; Johansson, Camilla; Xu, Xiufeng; Bjursell, Mikael; Sjögren, Anna-Karin; Hornberg, Jorrit; Andersson, Ulf; Keeling, David; Jirholt, Johan

    2016-11-01

    RORγ is a nuclear hormone receptor which controls polarization of naive CD4(+) T-cells into proinflammatory Th17 cells. Pharmacological antagonism of RORγ has therapeutic potential for autoimmune diseases; however, this mechanism may potentially carry target-related safety risks, as mice deficient in Rorc, the gene encoding RORγ, develop T-cell lymphoma with 50% frequency. Due to the requirement of RORγ during development, the Rorc knockout (KO) animals lack secondary lymphoid organs and have a dysregulation in the generation of CD4+ and CD8+ T cells. We wanted to extend the evaluation of RORγ deficiency to address the question whether lymphomas, similar to those observed in the Rorc KO, would develop in an animal with an otherwise intact adult immune system. Accordingly, we designed a conditional RORγ knockout mouse (Rorc CKO) where the Rorc locus could be deleted in adult animals. Based on these studies we can confirm that these animals also develop lymphoma in a similar time frame as embryonic Rorc knockouts. This study also suggests that in animals where the gene deletion is incomplete, the thymus undergoes a rapid selection process replacing Rorc deficient cells with remnant thymocytes carrying a functional Rorc locus and that subsequently, these animals do not develop lymphoblastic lymphoma.

  12. Toll-like receptor 4 knockout alleviates paraquat-induced cardiomyocyte contractile dysfunction through an autophagy-dependent mechanism.

    Science.gov (United States)

    Wang, Shuyi; Zhu, Xiaoling; Xiong, Lize; Zhang, Yingmei; Ren, Jun

    2016-08-22

    Paraquat, a quarternary nitrogen herbicide, is a toxic prooxidant leading to multi-organ failure including the heart although the underlying mechanism remains poorly understood. This study was designed to examine the role of the innate proinflammatory mediator toll-like receptor 4 (TLR4) in paraquat-induced cardiac contractile anomalies and the underlying mechanisms involved with a focus on autophagy, a conservative machinery governing protein and organelle degradation and recycling for cardiac homeostasis. Wild-type (WT) and TLR4 knockout (TLR4(-/-)) mice were challenged with paraquat (45mg/kg, i.p.) for 48h. Paraquat challenge did not affect mRNA levels of TLR2, TLR4 and TLR9 in WT mice nor did paraquat treatment alter TREM-1 levels. Paraquat challenge elicited cardiac mechanical defects including compromised cardiomyocyte contractile function, intracellular Ca(2+) handling, and overt autophagy as manifested by increased LC3BII-to-LC3BI ratio, Atg5, Atg7 and p62 levels. Interestingly, TLR4 knockout significantly attenuated paraquat-induced cardiac contractile and intracellular Ca(2+) derangement as well as alterations of autophagy markers. Paraquat-elicited changes in cardiac autophagy markers (LC3BII, LC3BII-to-LC3BI ratio and p62) were augmented by lysosomal inhibition using bafilomycin A1 in WT mice. TLR4 knockout significantly attenuated or negated paraquat-elicited increase in LC3BII, LC3BII-to-LC3BI ratio and p62 levels in the presence of lysosomal inhibition. In addition, paraquat challenge promoted phosphorylation of AMPK while suppressing the phosphorylation of mTOR and ULK1 (the autophagy inhibitory Ser(757)), the effects of which were significantly attenuated by TLR4 ablation. In vitro study revealed that AMPK activation using AICAR or mTOR inhibition using rapamycin effectively negated the beneficial cardiomyocyte mechanical effects of TLR4 inhibition (CLI-095) against paraquat toxicity, supporting a permissive role for AMPK-mTOR in TLR4 inhibition

  13. The BSA-induced Ca(2+ influx during sperm capacitation is CATSPER channel-dependent

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    Ren Dejian

    2009-10-01

    Full Text Available Abstract Background Serum albumin is a key component in mammalian sperm capacitation, a functional maturation process by which sperm become competent to fertilize oocytes. Capacitation is accompanied by several cellular and molecular changes including an increased tyrosine phosphorylation of sperm proteins and a development of hyperactivated sperm motility. Both of these processes require extracellular calcium, but how calcium enters sperm during capacitation is not well understood. Methods BSA-induced changes in intracellular calcium concentration were studied using Fluo-4 and Fura-2 calcium imaging with wild-type and Catsper1 knockout mouse sperm. Results We found that the fast phase of the BSA-induced rises in intracellular calcium concentration was absent in the Catsper1 knockout sperm and could be restored by an EGFP-CATSPER1 fusion protein. The calcium concentration increases were independent of G-proteins and phospholipase C but could be partially inhibited when intracellular pH was clamped. The changes started in the principal piece and propagated toward the sperm head. Conclusion We conclude that the initial phase of the increases in intracellular calcium concentration induced by BSA requires the CATSPER channel, but not the voltage-gated calcium channel. Our findings identify the molecular conduit responsible for the calcium entry required for the sperm motility changes that occur during capacitation.

  14. (--Pentazocine induces visceral chemical antinociception, but not thermal, mechanical, or somatic chemical antinociception, in μ-opioid receptor knockout mice

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    Satoh Masamichi

    2011-04-01

    Full Text Available Abstract Background (--Pentazocine has been hypothesized to induce analgesia via the κ-opioid (KOP receptor, although the involvement of other opioid receptor subtypes in the effects of pentazocine remains unknown. In this study, we investigated the role of the μ-opioid (MOP receptor in thermal, mechanical, and chemical antinociception induced by (--pentazocine using MOP receptor knockout (MOP-KO mice. Results (--Pentazocine-induced thermal antinociception, assessed by the hot-plate and tail-flick tests, was significantly reduced in heterozygous and abolished in homozygous MOP-KO mice compared with wildtype mice. The results obtained from the (--pentazocine-induced mechanical and somatic chemical antinociception experiments, which used the hind-paw pressure and formalin tests, were similar to the results obtained from the thermal antinociception experiments in these mice. However, (--pentazocine retained its ability to induce significant visceral chemical antinociception, assessed by the writhing test, in homozygous MOP-KO mice, an effect that was completely blocked by pretreatment with nor-binaltorphimine, a KOP receptor antagonist. In vitro binding and cyclic adenosine monophosphate assays showed that (--pentazocine possessed higher affinity for KOP and MOP receptors than for δ-opioid receptors. Conclusions The present study demonstrated the abolition of the thermal, mechanical, and somatic chemical antinociceptive effects of (--pentazocine and retention of the visceral chemical antinociceptive effects of (--pentazocine in MOP-KO mice. These results suggest that the MOP receptor plays a pivotal role in thermal, mechanical, and somatic chemical antinociception induced by (--pentazocine, whereas the KOP receptor is involved in visceral chemical antinociception induced by (--pentazocine.

  15. Involvement of Na+/Ca2+ exchanger in pentylenetetrazol-induced convulsion by use of Na+/Ca2+ exchanger knockout mice.

    Science.gov (United States)

    Saito, Ryo; Kaneko, Erina; Tanaka, Yusuke; Honda, Kenji; Matsuda, Toshio; Baba, Akemichi; Komuro, Issei; Kita, Satomi; Iwamoto, Takahiro; Takano, Yukio

    2009-11-01

    Involvement of Na+/Ca2+ exchanger (NCX) in pentylenetetrazol (PTZ)-induced convulsion by use of NCX knockout mice and the selective ligand SEA0400 to NCX was examined. In the SEA0400-administered group, the latency to clonic convulsion was extended into 210 s, although the latency to clonic convulsion was observed until 100 s in control group. SEA0400 had little effect on bicuculline-induced clonic seizure nicotine-induced wild running and 4-aminopyridine-induced tonic flexion, respectively. Tonic flexion convulsion was occurred three fifth in the wild type mice group by administration of PTZ, but tonic flexion was not observed in NCX1 knockout mice groups. These results suggest that NCX is involved in inhibitory action in PTZ-induced convulsion.

  16. Urat1-Uox double knockout mice are experimental animal models of renal hypouricemia and exercise-induced acute kidney injury.

    Science.gov (United States)

    Hosoyamada, Makoto; Tsurumi, Yu; Hirano, Hidenori; Tomioka, Naoko H; Sekine, Yuko; Morisaki, Takayuki; Uchida, Shunya

    2016-12-01

    Renal hypouricemia (RHUC) is a hereditary disease characterized by a low level of plasma urate but with normal urinary urate excretion. RHUC type 1 is caused by mutations of the urate transporter URAT1 gene (SLC22A12). However, the plasma urate levels of URAT1 knockout mice are no different from those of wild-type mice. In the present study, a double knockout mouse, in which the URAT1 and uricase (Uox) genes were deleted (Urat1-Uox-DKO), were used as an experimental animal model of RHUC type 1 to investigate RHUC and excise-induced acute kidney injury (EIAKI). Mice were given a variable content of allopurinol for one week followed by HPLC measurement of urate and creatinine concentrations in spot urine and blood from the tail. The urinary excretion of urate in Urat1-Uox-DKO mice was approximately 25 times higher than those of humans. With allopurinol, the plasma urate levels of Urat1-Uox-DKO mice were lower than those of Uox-KO mice. There were no differences in the urinary urate excretions between Urat1-Uox-DKO and Uox-KO mice administered with 9 mg allopurinol /100 g feed. In the absence of allopurinol, plasma creatinine levels of some Urat1-Uox-DKO mice were higher than those of Uox-KO mice. Consequently, hypouricemia and normouricosuria may indicate that the Urat1-Uox-DKO mouse administered with allopurinol may represent a suitable animal model of RHUC type 1. Urat1-Uox-DKO mice without allopurinol exhibited acute kidney injury, thus providing additional benefit as a potential animal model for EIAKI. Finally, our data indicate that allopurinol appears to provide prophylactic effects for EIAKI.

  17. A reduced zinc diet or zinc transporter 3 knockout attenuate light induced zinc accumulation and retinal degeneration.

    Science.gov (United States)

    Bai, Shi; Sheline, Carolyn R; Zhou, Yongdong; Sheline, Christian T

    2013-03-01

    Our previous study on retinal light exposure suggests the involvement of zinc (Zn(2+)) toxicity in the death of RPE and photoreceptors (LD) which could be attenuated by pyruvate and nicotinamide, perhaps through restoration of NAD(+) levels. In the present study, we examined Zn(2+) toxicity, and the effects of NAD(+) restoration in primary retinal cultures. We then reduced Zn(2+) levels in rodents by reducing Zn(2+) levels in the diet, or by genetics and measured LD. Sprague Dawley albino rats were fed 2, or 61 mg Zn(2+)/kg of diet for 3 weeks, and exposed to 18 kLux of white light for 4 h. We light exposed (70 kLux of white light for 50 h) Zn(2+) transporter 3 knockout (ZnT3-KO, no synaptic Zn(2+)), or RPE65 knockout mice (RPE65-KO, lack rhodopsin cycling), or C57/BI6/J controls and determined light damage and Zn(2+) staining. Retinal Zn(2+) staining was examined at 1 h and 4 h after light exposure. Retinas were examined after 7 d by optical coherence tomography and histology. After LD, rats fed the reduced Zn(2+) diet showed less photoreceptor Zn(2+) staining and degeneration compared to a normal Zn(2+) diet. Similarly, ZnT3-KO and RPE65-KO mice showed less Zn(2+) staining, NAD(+) loss, and RPE or photoreceptor death than C57/BI6/J control mice. Dietary or ZnT3-dependent Zn(2+) stores, and intracellular Zn(2+) release from rhodopsin recycling are suggested to be involved in light-induced retinal degeneration. These results implicate novel rhodopsin-mediated mechanisms and therapeutic targets for LD. Our companion manuscript demonstrates that pharmacologic, circadian, or genetic manipulations which maintain NAD(+) levels reduce LD.

  18. Pion-induced nucleon knockout reactions on 16O and 18O

    Science.gov (United States)

    Piasetzky, E.; Altman, A.; Lichtenstadt, J.; Yavin, A. I.; Ashery, D.; Bertl, W.; Felawka, L.; Walter, H. K.; Schlepütz, F. W.; Powers, K. J.; Winter, R. G.; Pluym, J. V. D.

    1982-12-01

    The (π+, π+p), (π-, π-p), and (π-, π-n) reactions on 16O and 18O were studied at 165 MeV by coincidence measurements of the outgoing particles. The cross sections for the (π-, π-n) reaction is larger on 18O than on 16O, whereas those for the (π+, π+p) and the (π-, π-p) reactions are smaller, most likely because of the coupling between the absorption and the scattering channels. NUCLEAR REACTIONS (π+/-, π+/-p) (π-, π-n) coin. Measurements on 16O18O E=165 MeV; deduced coupling between the absorption and the scattering channels.

  19. Cardiac-specific knockout of ETA receptor mitigates low ambient temperature-induced cardiac hypertrophy and contractile dysfunction

    Institute of Scientific and Technical Information of China (English)

    Yingmei Zhang; Linlin Li; Yinan Hua; Jennifer M. Nunn; Feng Dong; Masashi Yanagisawa; Jun Ren

    2012-01-01

    Cold exposure is associated with oxidative stress and cardiac dysfunction.The endothelin (ET) system,which plays a key role in myocardial homeostasis,may participate in cold exposure-induced cardiovascular dysfunction.This study was designed to examine the role of ET-1 in cold stress-induced cardiac geometric and contractile responses.Wild-type (WT) and ETA receptor knockout (ETAKO) mice were assigned to normal or cold exposure (4℃) environment for 2 and 5 weeks prior to evaluation of cardiac geometry,contractile,and intracellular Ca2+ properties.Levels of the temperature sensor transient receptor potential vanlllold (TRPV1),mitochondrlal proteins for biogenesis and oxidative phosphorylatlon,Including UCP2,HSP90,and PGC1α were evaluated.Cold stress triggered cardiac hypertrophy,depressed myocardial contractile capacity,including fractional shortening,peak shortening,and maximal velocity of shortening/relengthening,reduced intracellular Ca2+ release,prolonged intracellular Ca2+ decay and relengthening duration,generation of ROS and superoxide,as well as apoptosls,the effects of which were blunted by ETAKO.Western blotting revealed downregulated TRPV1 and PGC1α as well as upregulated UCP2 and activation of GSK3β,GATA4,and CREB in cold-stressed WT mouse hearts,which were obliterated by ETAKO.Levels of HSP90,an essential regulator for thermotolerance,were unchanged.The TRPV1 agonist SA13353 attenuated whereas TRPV1 antagonist capsazepino mimicked cold stress- or ET-1-induced cardiac anomalies.The GSK3β Inhibitor SB216763 ablated cold stress-induced cardiac contractile (but not remodeling) changes and ET-1-induced TRPV1 downregulation.These data suggest that ETAKO protects against cold exposure-induced cardiac remodeling and dysfunction mediated through TRPV1 and mitochondrlal function.

  20. Transcriptomics and knockout mutant analysis of rhizobacteria-mediated induced systemic resistance in Arabidopsis

    NARCIS (Netherlands)

    Verhagen, B.W.M.

    2004-01-01

    A classic example of induced resistance is triggered after infection by a necrotizing pathogen, rendering uninfected,distal parts more resistant to subsequent pathogen attack, and is often referred to as systemic acquired resistance (SAR). A phenotypically comparable type of induced resistance is tr

  1. Hepatic Gene Expression Profiling in Nrf2 Knockout Mice after Long-Term High-Fat Diet-Induced Obesity

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    Dionysios V. Chartoumpekis

    2013-01-01

    Full Text Available Introduction. The transcription factor NFE2-related factor 2 (Nrf2 is a central regulator of antioxidant and detoxification gene expression in response to electrophilic or oxidative stress. Nrf2 has recently been shown to cross-talk with metabolic pathways, and its gene deletion protected mice from high-fat-diet-(HFD- induced obesity and insulin resistance. This study aimed to identify potential Nrf2-regulated genes of metabolic interest by comparing gene expression profiles of livers of wild-type (WT versus Nrf2 knockout (Nrf2-KO mice after a long-term HFD. Methods. WT and Nrf2-KO mice were fed an HFD for 180 days; total RNA was prepared from liver and used for microarray analysis and quantitative real-time RT-PCR (qRT-PCR. Results. The microarray analysis identified 601 genes that were differentially expressed between WT and Nrf2-KO mice after long-term HFD. Selected genes, including ones known to be involved in metabolic regulation, were prioritized for verification by qRT-PCR: Cyp7a1 and Fabp5 were significantly overexpressed in Nrf2-KO mice; in contrast, Car, Cyp2b10, Lipocalin 13, Aquaporin 8, Cbr3, Me1, and Nqo1 were significantly underexpressed in Nrf2-KO mice. Conclusion. Transcriptome profiling after HFD-induced obesity confirms that Nrf2 is implicated in liver metabolic gene networks. The specific genes identified here may provide insights into Nrf2-dependent mechanisms of metabolic regulation.

  2. Effects of p53 knockout on ochratoxin A-induced genotoxicity in p53-deficient gpt delta mice.

    Science.gov (United States)

    Hibi, Daisuke; Kijima, Aki; Suzuki, Yuta; Ishii, Yuji; Jin, Meilan; Sugita-Konishi, Yoshiko; Yanai, Tokuma; Nishikawa, Akiyoshi; Umemura, Takashi

    2013-02-01

    Ochratoxin A (OTA) is a mycotoxin produced by fungal species and is carcinogenic targeting the S3 segment of the renal proximal tubules in rodents. We previously reported that exposure of gpt delta rats to OTA induced both mutations in the red/gam gene (Spi(-)), suggesting large deletion mutations, and fluctuations in genes transcribed by p53 in the kidneys, which were associated with DNA double-strand break (DSB) repair, particularly homologous recombination (HR) repair. In the present study, to investigate the effects of p53 knockout on OTA-induced mutagenicity, apoptosis, and karyomegaly in renal tubular cells, p53-proficient and p53-deficient gpt delta mice were given 1 and 5mg/kg of OTA for 4 weeks. Significant increases in Spi(-) mutant frequencies (MFs) were observed in the kidneys of p53-deficient gpt delta mice given 5 mg/kg of OTA, but not in the kidneys of p53-proficient gpt delta mice given the same dose. There were no changes in gpt MFs in both genotypes of mice treated with OTA. Western blotting analysis demonstrated that p53 protein levels in the kidneys of p53-proficient mice given OTA were significantly increased compared with the control. Incidences of apoptosis and karyomegaly in not only the outer stripe of outer medulla but also the cortex were significantly higher in p53-deficient at 5mg/kg than in p53-proficient gpt delta mice at same dose, which had no change in the cortex, the inner stripe of outer stripe, and the inner medulla. Given that p53 regulates HR repair in DSBs, these results suggest that OTA may promote large deletion mutations in the process of HR repair for DSBs. Additionally, the lower incidence of karyomegaly and apoptosis found in the p53-proficient gpt delta mice suggests that these phenomena may arise from OTA-induced DNA damage.

  3. On the mechanistic differences of benzene-induced leukemogenesis between wild type and p53 knockout mice

    Energy Technology Data Exchange (ETDEWEB)

    Hirabayashi, Yoko; Yoon, Byung-Il; Kawasaki, Yasushi; Li, Guang-Xun; Kanno, Jun; Inoue, Tohru [National Inst. of Health Sciences, Tokyo (Japan)

    2003-07-01

    Leukemia induction by benzene inhalation was first reported by Le Noire in 1887, described multiple cases of leukemia among Parisian cobblers. However, experimental induction of leukemia by benzene exposure was not succeeded for a hundred years, until Snyder et al. and our group reported it nearly 20 years ago. Nevertheless, the mechanistic background of benzene-induced leukemia was still an enigma until recently a benzene-induced peculiar cell kinetics of the stem/progenitor cells has been elucidated by our study, demonstrated a marked repeated oscillatory decrease in peripheral blood and bone marrow (BM) cellularity during and after benzene exposure, which epigenetically preceded and developed the leukemia more than a year later. We utilized the BUUV (bromodeoxyuridine + UV exposure) method to study stem/progenitor cell kinetics during and/or after benzene exposure. Using these methods, we were able to measure the labeling rate, cycling fraction of clonogenic progenitor cells, and other cell cycle parameters. The cycling fraction of stem/progenitor cells was found not to turn into an active hematopoiesis but to remain low during benzene inhalation and further we found evidence that the cycling fraction depression may be mediated in part by a slowing of stem/progenitor cell cycling perse by up-regulation of p21. The benzene induced leukemogenicity between mice carrying wild-type p53 and mice lacking p53 seem to differ from one another. In the case of p53 knockout mouse, DNA damage such as weak mutagenicity and or chromosomal damages are retained, and those damages participated in the induction of a consequent activation of proto-oncogenes and the like, which led cells to further neoplastic changes. In contrast, in the case of wild type mice, a dramatic oscillational change in the cell cycle of the stem cell compartment seems to be an important factor for mice carrying the p53 gene. (author)

  4. Atorvastatin attenuates p-cresyl sulfate-induced atherogenesis and plaque instability in ApoE knockout mice

    Science.gov (United States)

    Han, Hui; Chen, Yanjia; Zhu, Jinzhou; Ni, Jingwei; Sun, Jiateng; Zhang, Ruiyan

    2016-01-01

    p-cresyl sulfate (PCS) is a protein-bound uremic toxin retained in the blood of patients with chronic kidney disease (CKD) As atherosclerosis is a primary cardiovascular complication for patients with CKD, the aim of the present study was to investigate the mechanisms underlying the aggravation of atherosclerosis by PCS. In addition, the effect of atorvastatin was assessed in reversing the effects of PCS. PCS was revealed to promote the initiation and progression of atherosclerosis. Following treatment with atorvastatin, apolipoprotein E knockout mice demonstrated a reduction in PCS-induced atherogenesis and plaque vulnerability. In addition, atorvastatin decreased the protein expression levels of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1, and the interaction between leukocytes and endothelia. The plasma lipid profiles of mice were not significantly affected by gavage of low-dose atorvastatin. The results of the present study indicate that PCS promotes plaque growth and instability by enhancing leukocyte-endothelium interaction, and that these effects may be attenuated by atorvastatin treatment. PMID:27574007

  5. Identifying the Integrated Neural Networks Involved in Capsaicin-Induced Pain Using fMRI in Awake TRPV1 Knockout and Wild-Type Rats

    Directory of Open Access Journals (Sweden)

    Jason Richard Yee

    2015-02-01

    Full Text Available In the present study, we used functional MRI in awake rats to investigate the pain response that accompanies intradermal injection of capsaicin into the hindpaw. To this end, we used BOLD imaging together with a 3D segmented, annotated rat atlas and computational analysis to identify the integrated neural circuits involved in capsaicin-induced pain. The specificity of the pain response to capsaicin was tested in a transgenic model that contains a biallelic deletion of the gene encoding for the transient receptor potential cation channel subfamily V member 1 (TRPV1. Capsaicin is an exogenous ligand for the TRPV1 receptor, and in wild-type rats, activated the putative pain neural circuit. In addition, capsaicin-treated wild-type rats exhibited activation in brain regions comprising the Papez circuit and habenular system, systems that play important roles in the integration of emotional information, and learning and memory of aversive information, respectively. As expected, capsaicin administration to TRPV1-KO rats failed to elicit the robust BOLD activation pattern observed in wild-type controls. However, the intradermal injection of formalin elicited a significant activation of the putative pain pathway as represented by such areas as the anterior cingulate, somatosensory cortex, parabrachial nucleus, and periaqueductal gray. Notably, comparison of neural responses to capsaicin in wild-type versus knock-out rats uncovered evidence that capsaicin may function in an antinociceptive capacity independent of TRPV1 signaling. Our data suggest that neuroimaging of pain in awake, conscious animals has the potential to inform the neurobiological basis of full and integrated perceptions of pain.

  6. A Comprehensive TALEN-Based Knockout Library for Generating Human Induced Pluripotent Stem Cell-Based Models for Cardiovascular Diseases.

    Science.gov (United States)

    Karakikes, Ioannis; Termglinchan, Vittavat; Cepeda, Diana A; Lee, Jaecheol; Diecke, Sebastian; Hendel, Ayal; Itzhaki, Ilanit; Ameen, Mohamed; Shrestha, Rajani; Wu, Haodi; Ma, Ning; Shao, Ning-Yi; Seeger, Timon; Woo, Nicole A; Wilson, Kitchener D; Matsa, Elena; Porteus, Matthew H; Sebastiano, Vittorio; Wu, Joseph C

    2017-02-28

    Rationale: Targeted genetic engineering using programmable nucleases such as transcription activator-like effector nucleases (TALENs) is a valuable tool for precise, site-specific genetic modification in the human genome. Objective: The emergence of novel technologies such as human induced pluripotent stem cells (iPSCs) and nuclease-mediated genome editing represent a unique opportunity for studying cardiovascular diseases in vitro. Methods and Results: By incorporating extensive literature and database searches, we designed a collection of TALEN constructs to knockout (KO) eighty-eight human genes that are associated with cardiomyopathies and congenital heart diseases. The TALEN pairs were designed to induce double-strand DNA break near the starting codon of each gene that either disrupted the start codon or introduced a frameshift mutation in the early coding region, ensuring faithful gene KO. We observed that all the constructs were active and disrupted the target locus at high frequencies. To illustrate the general utility of the TALEN-mediated KO technique, six individual genes (TNNT2, LMNA/C, TBX5, MYH7, ANKRD1, and NKX2.5) were knocked out with high efficiency and specificity in human iPSCs. By selectively targeting a dilated cardiomyopathy (DCM)-causing mutation (TNNT2 p.R173W) in patient-specific iPSC-derived cardiac myocytes (iPSC-CMs), we demonstrated that the KO strategy ameliorates the DCM phenotype in vitro. In addition, we modeled the Holt-Oram syndrome (HOS) in iPSC-CMs in vitro and uncovered novel pathways regulated by TBX5 in human cardiac myocyte development. Conclusions: Collectively, our study illustrates the powerful combination of iPSCs and genome editing technology for understanding the biological function of genes and the pathological significance of genetic variants in human cardiovascular diseases. The methods, strategies, constructs and iPSC lines developed in this study provide a validated, readily available resource for cardiovascular

  7. Knockout of NMDA-receptors from parvalbumin interneurons sensitizes to schizophrenia-related deficits induced by MK-801.

    Science.gov (United States)

    Bygrave, A M; Masiulis, S; Nicholson, E; Berkemann, M; Barkus, C; Sprengel, R; Harrison, P J; Kullmann, D M; Bannerman, D M; Kätzel, D

    2016-04-12

    It has been suggested that a functional deficit in NMDA-receptors (NMDARs) on parvalbumin (PV)-positive interneurons (PV-NMDARs) is central to the pathophysiology of schizophrenia. Supportive evidence come from examination of genetically modified mice where the obligatory NMDAR-subunit GluN1 (also known as NR1) has been deleted from PV interneurons by Cre-mediated knockout of the corresponding gene Grin1 (Grin1(ΔPV) mice). Notably, such PV-specific GluN1 ablation has been reported to blunt the induction of hyperlocomotion (a surrogate for psychosis) by pharmacological NMDAR blockade with the non-competitive antagonist MK-801. This suggests PV-NMDARs as the site of the psychosis-inducing action of MK-801. In contrast to this hypothesis, we show here that Grin1(ΔPV) mice are not protected against the effects of MK-801, but are in fact sensitized to many of them. Compared with control animals, Grin1(ΔPV)mice injected with MK-801 show increased stereotypy and pronounced catalepsy, which confound the locomotor readout. Furthermore, in Grin1(ΔPV)mice, MK-801 induced medial-prefrontal delta (4 Hz) oscillations, and impaired performance on tests of motor coordination, working memory and sucrose preference, even at lower doses than in wild-type controls. We also found that untreated Grin1(ΔPV)mice are largely normal across a wide range of cognitive functions, including attention, cognitive flexibility and various forms of short-term memory. Taken together these results argue against PV-specific NMDAR hypofunction as a key starting point of schizophrenia pathophysiology, but support a model where NMDAR hypofunction in multiple cell types contribute to the disease.

  8. Fatty Liver and Insulin Resistance in the Liver-Specific Knockout Mice of Mitogen Inducible Gene-6

    Science.gov (United States)

    Park, Byung Kil; Kim, Hee-Youn; Lee, Jun Choul; Kim, Koon Soon; Jeong, Won Hoon; Kim, Ki Young

    2016-01-01

    Mitogen inducible gene-6 (Mig-6) is a feedback inhibitor of epidermal growth factor receptor (EGFR) signaling pathway. The liver-specific knockout mice of the Mig-6 gene (Mig-6d/d) showed hepatomegaly and increased hypercholesterolemia. In this study, the biomarkers of insulin resistance and the effects of high-fat diets in the wild (Mig-6f/f) and Mig-6d/d mice were analyzed. The fasting plasma concentrations of glucose, triglyceride, cholesterols, free fatty acids, and HOMA-IR were measured and the glucose tolerance and insulin resistance tests were performed in the 25-week-old Mig-6f/f and the Mig-6d/d mice. The protein levels of active insulin receptor, glucose 6-phosphatase, and phosphoenolpyruvate carboxykinase were analyzed in the liver and fat. The fasting plasma cholesterol and glucose concentration were higher in the Mig-6d/d mice than the Mig-6f/f mice with increased fat deposition in the liver. But the Mig-6d/d mice had the improved glucose intolerance and insulin resistance without increased amount of phosphoinsulin receptor after insulin infusion in the liver. The hepatic concentration of phosphoenolpyruvate carboxykinase was increased in fasting Mig-6d/d mice. The feeding of high-fat diet accelerated the plasma lipids profiles and HOMA-IR in the Mig-6d/d mice but had no differential effects in oral glucose tolerance test and insulin tolerance test in both genotypes. These results suggest that the activated EGFR signaling might increase the fasting plasma glucose concentration through inducing the hepatic steatosis and the improved whole-body insulin resistance in the KO mice be caused by decreased adipogenesis in fat tissues. PMID:28053990

  9. Orexin gene transfer into the amygdala suppresses both spontaneous and emotion-induced cataplexy in orexin-knockout mice.

    Science.gov (United States)

    Liu, Meng; Blanco-Centurion, Carlos; Konadhode, Roda Rani; Luan, Liju; Shiromani, Priyattam J

    2016-03-01

    Narcolepsy is a chronic sleep disorder linked to the loss of orexin-producing neurons in the hypothalamus. Cataplexy, a sudden loss of muscle tone during waking, is an important distinguishing symptom of narcolepsy and it is often triggered by strong emotions. The neural circuit underlying cataplexy attacks is not known, but is likely to involve the amygdala, a region implicated in regulating emotions. In mice models of narcolepsy, transfer of the orexin gene into surrogate neurons has been successful in ameliorating narcoleptic symptoms. However, it is not known whether this method also blocks cataplexy triggered by strong emotions. To examine this possibility, the gene encoding mouse prepro-orexin was transferred into amygdala neurons of orexin-knockout (KO) mice (rAAV-orexin; n = 8). Orexin-KO mice that did not receive gene transfer (no-rAAV; n = 7) or received only the reporter gene (rAAV-GFP; n = 7) served as controls. Three weeks later, the animal's sleep and behaviour were recorded at night (no-odour control night), followed by another recording at night in the presence of predator odour (odour night). Orexin-KO mice given the orexin gene transfer into surrogate amygdala neurons had significantly less spontaneous bouts of cataplexy, and predator odour did not induce cataplexy compared with control mice. Moreover, the mice with orexin gene transfer were awake more during the odour night. These results demonstrate that orexin gene transfer into amygdala neurons can suppress both spontaneous and emotion-induced cataplexy attacks in narcoleptic mice. It suggests that manipulating amygdala pathways is a potential strategy for treating cataplexy in narcolepsy.

  10. Intractable hyperkalemia due to nicorandil induced potassium channel syndrome

    Directory of Open Access Journals (Sweden)

    Vivek Chowdhry

    2015-01-01

    Full Text Available Nicorandil is a commonly used antianginal agent, which has both nitrate-like and ATP-sensitive potassium (K ATP channel activator properties. Activation of potassium channels by nicorandil causes expulsion of potassium ions into the extracellular space leading to membrane hyperpolarization, closure of voltage-gated calcium channels and finally vasodilatation. However, on the other hand, being an activator of K ATP channel, it can expel K + ions out of the cells and can cause hyperkalemia. Here, we report a case of nicorandil induced hyperkalemia unresponsive to medical treatment in a patient with diabetic nephropathy.

  11. Higher Incidence of Lung Adenocarcinomas Induced by DMBA in Connexin 43 Heterozygous Knockout Mice

    Directory of Open Access Journals (Sweden)

    Krishna Duro de Oliveira

    2013-01-01

    Full Text Available Gap junctions are communicating junctions which are important for tissue homeostasis, and their disruption is involved in carcinogenic processes. This study aimed to verify the influence of deletion of one allele of the Connexin 43 gene on cancer incidence in different organs. The 7, 12-dimethylbenzanthracene (DMBA carcinogenic model, using hebdomadary doses by gavage of 9 mg per animal, was used to induce tumors in Connexin 43 heterozygous or wild-type mice. The experiment began in the eighth week of the mice life, and all of them were euthanized when reaching inadequate physical condition, or at the end of 53 weeks. No statistical differences occurred for weight gain and cancer survival time (P=0.9853 between heterozygous and wild-type mice. Cx43+/− mice presented significantly higher susceptibility to lung cancer (P=0.0200 which was not evidenced for benign neoplasms (P=0.3449. In addition, incidence of ovarian neoplasms was 2.5-fold higher in Cx43+/− mice, although not statistically significant. Other organs showed a very similar cancer occurrence between Cx43 groups. The experiment strengthens the evidence of the relationship between Connexin 43 deficiency and carcinogenesis.

  12. Neonatal periostin knockout mice are protected from hyperoxia-induced alveolar simplication.

    Directory of Open Access Journals (Sweden)

    Paul D Bozyk

    Full Text Available In bronchopulmonary dysplasia (BPD, alveolar septae are thickened with collagen and α-smooth muscle actin, transforming growth factor (TGF-β-positive myofibroblasts. Periostin, a secreted extracellular matrix protein, is involved in TGF-β-mediated fibrosis and myofibroblast differentiation. We hypothesized that periostin expression is required for hypoalveolarization and interstitial fibrosis in hyperoxia-exposed neonatal mice, an animal model for this disease. We also examined periostin expression in neonatal lung mesenchymal stromal cells and lung tissue of hyperoxia-exposed neonatal mice and human infants with BPD. Two-to-three day-old wild-type and periostin null mice were exposed to air or 75% oxygen for 14 days. Mesenchymal stromal cells were isolated from tracheal aspirates of premature infants. Hyperoxic exposure of neonatal mice increased alveolar wall periostin expression, particularly in areas of interstitial thickening. Periostin co-localized with α-smooth muscle actin, suggesting synthesis by myofibroblasts. A similar pattern was found in lung sections of infants dying of BPD. Unlike wild-type mice, hyperoxia-exposed periostin null mice did not show larger air spaces or α-smooth muscle-positive myofibroblasts. Compared to hyperoxia-exposed wild-type mice, hyperoxia-exposed periostin null mice also showed reduced lung mRNA expression of α-smooth muscle actin, elastin, CXCL1, CXCL2 and CCL4. TGF-β treatment increased mesenchymal stromal cell periostin expression, and periostin treatment increased TGF-β-mediated DNA synthesis and myofibroblast differentiation. We conclude that periostin expression is increased in the lungs of hyperoxia-exposed neonatal mice and infants with BPD, and is required for hyperoxia-induced hypoalveolarization and interstitial fibrosis.

  13. CCR2 knockout exacerbates cerulein-induced chronic pancreatitis with hyperglycemia via decreased GLP-1 receptor expression and insulin secretion.

    Science.gov (United States)

    Nakamura, Yuji; Kanai, Takanori; Saeki, Keita; Takabe, Miho; Irie, Junichiro; Miyoshi, Jun; Mikami, Yohei; Teratani, Toshiaki; Suzuki, Takahiro; Miyata, Naoteru; Hisamatsu, Tadakazu; Nakamoto, Nobuhiro; Yamagishi, Yoshiyuki; Higuchi, Hajime; Ebinuma, Hirotoshi; Hozawa, Shigenari; Saito, Hidetsugu; Itoh, Hiroshi; Hibi, Toshifumi

    2013-04-15

    Glucagon-like peptide-1 (GLP-1) promotes insulin release; however, the relationship between the GLP-1 signal and chronic pancreatitis is not well understood. Here we focus on chemokine (C-C motif) ligand 2 (CCL2) and its receptor (CCR2) axis, which regulates various immune cells, including macrophages, to clarify the mechanism of GLP-1-mediated insulin secretion in chronic pancreatitis in mice. One and multiple series of repetitive cerulein administrations were used to induce acute and chronic cerulein pancreatitis, respectively. Acute cerulein-administered CCR2-knockout (KO) mice showed suppressed infiltration of CD11b(+)Gr-1(low) macrophages and pancreatic inflammation and significantly upregulated insulin secretion compared with paired wild-type (WT) mice. However, chronic cerulein-administered CCR2-KO mice showed significantly increased infiltration of CD11b(+)/Gr-1(-) and CD11b(+)/Gr-1(high) cells, but not CD11b(+)/Gr-1(low) cells, in pancreas with severe inflammation and significantly decreased insulin secretion compared with their WT counterparts. Furthermore, although serum GLP-1 levels in chronic cerulein-administered WT and CCR2-KO mice were comparably upregulated after cerulein administrations, GLP-1 receptor levels in pancreases of chronic cerulein-administered CCR2-KO mice were significantly lower than in paired WT mice. Nevertheless, a significantly higher hyperglycemia level in chronic cerulein-administered CCR2-KO mice was markedly restored by treatment with a GLP-1 analog to a level comparable to the paired WT mice. Collectively, the CCR2/CCL2 axis-mediated CD11b(+)-cell migration to the pancreas is critically involved in chronic pancreatitis-mediated hyperglycemia through the modulation of GLP-1 receptor expression and insulin secretion.

  14. Diacylglycerol kinase β knockout mice exhibit attention-deficit behavior and an abnormal response on methylphenidate-induced hyperactivity.

    Directory of Open Access Journals (Sweden)

    Mitsue Ishisaka

    Full Text Available BACKGROUND: Diacylglycerol kinase (DGK is an enzyme that phosphorylates diacylglycerol to produce phosphatidic acid. DGKβ is one of the subtypes of the DGK family and regulates many intracellular signaling pathways in the central nervous system. Previously, we demonstrated that DGKβ knockout (KO mice showed various dysfunctions of higher brain function, such as cognitive impairment (with lower spine density, hyperactivity, reduced anxiety, and careless behavior. In the present study, we conducted further tests on DGKβ KO mice in order to investigate the function of DGKβ in the central nervous system, especially in the pathophysiology of attention deficit hyperactivity disorder (ADHD. METHODOLOGY/PRINCIPAL FINDINGS: DGKβ KO mice showed attention-deficit behavior in the object-based attention test and it was ameliorated by methylphenidate (MPH, 30 mg/kg, i.p.. In the open field test, DGKβ KO mice displayed a decreased response to the locomotor stimulating effects of MPH (30 mg/kg, i.p., but showed a similar response to an N-methyl-d-aspartate (NMDA receptor antagonist, MK-801 (0.3 mg/kg, i.p., when compared to WT mice. Examination of the phosphorylation of extracellular signal-regulated kinase (ERK, which is involved in regulation of locomotor activity, indicated that ERK1/2 activation induced by MPH treatment was defective in the striatum of DGKβ KO mice. CONCLUSIONS/SIGNIFICANCE: These findings suggest that DGKβ KO mice showed attention-deficit and hyperactive phenotype, similar to ADHD. Furthermore, the hyporesponsiveness of DGKβ KO mice to MPH was due to dysregulation of ERK phosphorylation, and that DGKβ has a pivotal involvement in ERK regulation in the striatum.

  15. Regulation of prostaglandin generation in carrageenan-induced pleurisy by inducible nitric oxide synthase in knockout mice.

    NARCIS (Netherlands)

    Rossi, A.; Cuzzocrea, S.; Mazzon, E.; Serraino, I.; Sarro, A. de; Dugo, L.; Felice, M.R.; Loo, F.A.J. van de; Rosa, M. Di; Musci, G.; Caputi, A.P.; Sautebin, L.

    2003-01-01

    In the present study, by comparing the responses in wild-type mice (iNOSWT) and mice lacking (iNOSKO) the inducible (or type 2) nitric oxide synthase (iNOS), we investigated the correlation between endogenous nitric oxide (NO) and prostaglandin (PG) generation in carrageenan-induced pleurisy. The in

  16. TLR4 knockout attenuated high fat diet-induced cardiac dysfunction via NF-κB/JNK-dependent activation of autophagy.

    Science.gov (United States)

    Hu, Nan; Zhang, Yingmei

    2017-01-17

    Obesity is commonly associated with a low grade systemic inflammation, which may contribute to the onset and development of myocardial remodeling and contractile dysfunction. Toll-like receptor 4 (TLR4) plays an important role in innate immunity and inflammation although its role in high fat diet-induced obesity cardiac dysfunction remains elusive. This study was designed to examine the effect of TLR4 ablation on high fat diet intake-induced cardiac anomalies, if any, and underlying mechanism(s) involved. Wild-type (WT) and TLR4 knockout mice were fed normal or high fat (60% calorie from fat) diet for 12weeks prior to assessment of mechanical and intracellular Ca(2+) properties. The inflammatory signaling proteins (TLR4, NF-κB, and JNK) and autophagic markers (Atg5, Atg12, LC3B and p62) were evaluated. Our results revealed that high fat diet intake promoted obesity, marked decrease in fractional shortening, and cardiomyocyte contractile capacity with dampened intracellular Ca(2+) release and clearance, elevated ROS generation and oxidative stress as measured by aconitase activity, the effects of which were significantly attenuated by TLR4 knockout. In addition, high fat intake downregulated levels of Atg5, Atg12 and LC3B, while increasing p62 accumulation. TLR4 knockout itself did not affect Atg5, Atg12, LC3B and p62 levels while it reconciled high fat diet intake-induced changes in autophagy. In addition, TLR4 knockout alleviated high fat diet-induced phosphorylation of IKKβ, JNK and mTOR. In vitro study revealed that palmitic acid suppressed cardiomyocyte contractile function, the effect of which was inhibited the TLR4 inhibitor CLI-095, the JNK inhibitor AS601245 or the NF-κB inhibitor Celastrol. Taken together, these data showed that TLR4 knockout ameliorated high fat diet-induced cardiac contractile and intracellular Ca(2+) anomalies through inhibition of inflammation and ROS, possibly through a NF-κB/JNK-dependent activation of autophagy. This article is

  17. Acoustic Diagnostics of Plasma Channels Induced by Intense Femtosecond Laser Pulses in Air

    Institute of Scientific and Technical Information of China (English)

    HAO Zuo-Qiang; WEI Zhi-Yi; YU Jin; ZHANG Jie; LI Yu-Tong; YUAN Xiao-Hui; ZHENG Zhi-Yuan; WANG Peng; WANG Zhao-Hua; LING Wei-Jun

    2005-01-01

    @@ Long plasma channels induced by femtosecond laser pulses in air are diagnosed using the sonographic method. By detecting the sound signals along the channels, the length and the electron density of the channels are measured.

  18. Hyperinsulinism induced by targeted suppression of beta cell KATP channels.

    Science.gov (United States)

    Koster, J C; Remedi, M S; Flagg, T P; Johnson, J D; Markova, K P; Marshall, B A; Nichols, C G

    2002-12-24

    ATP-sensitive K+ (K(ATP)) channels couple cell metabolism to electrical activity. To probe the role of K(ATP) in glucose-induced insulin secretion, we have generated transgenic mice expressing a dominant-negative, GFP-tagged K(ATP) channel subunit in which residues 132-134 (Gly-Tyr-Gly) in the selectivity filter were replaced by Ala-Ala-Ala, under control of the insulin promoter. Transgene expression was confirmed by both beta cell-specific green fluorescence and complete suppression of channel activity in those cells ( approximately 70%) that did fluoresce. Transgenic mice developed normally with no increased mortality and displayed normal body weight, blood glucose levels, and islet architecture. However, hyperinsulinism was evident in adult mice as (i) a disproportionately high level of circulating serum insulin for a given glucose concentration ( approximately 2-fold increase in blood insulin), (ii) enhanced glucose-induced insulin release from isolated islets, and (iii) mild yet significant enhancement in glucose tolerance. Enhanced glucose-induced insulin secretion results from both increased glucose sensitivity and increased release at saturating glucose concentration. The results suggest that incomplete suppression of K(ATP) channel activity can give rise to a maintained hyperinsulinism.

  19. Excessive novelty-induced c-Fos expression and altered neurogenesis in the hippocampus of GluA1 knockout mice.

    Science.gov (United States)

    Procaccini, Chiara; Aitta-aho, Teemu; Jaako-Movits, Külli; Zharkovsky, Alexander; Panhelainen, Anne; Sprengel, Rolf; Linden, Anni-Maija; Korpi, Esa R

    2011-01-01

    α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluA1 subunit-deficient (GluA1-/-) mice display novelty-induced hyperactivity, cognitive and social defects and may model psychiatric disorders, such as schizophrenia and depression/mania. We used c-Fos expression in GluA1-/- mice to identify brain regions responsible for novelty-induced hyperlocomotion. Exposure to a novel cage for 2 h significantly increased c-Fos expression in many brain regions in both wild-type and knockout mice. Interestingly, the clearest genotype effect was observed in the hippocampus and its main input region, the entorhinal cortex, where the novelty-induced c-Fos expression was more strongly enhanced in GluA1-/- mice. Their novelty-induced hyperlocomotion partly depended on the activity of AMPA receptors, as it was diminished by the AMPA receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulphonamide (NBQX) and unaffected by the AMPA receptor potentiator 2,3-dihydro-1,4-benzodioxin-6-yl-1-piperidinylmethanone (CX546). The hyperlocomotion of GluA1-/- mice was normalised to the level of wild-type mice within 5-6 h, after which their locomotion followed normal circadian rhythm and was not affected by acute or chronic treatments with the selective serotonin reuptake inhibitor escitalopram. We propose that hippocampal dysfunction, as evidenced by the excessive c-Fos response to novelty, is the major contributor to novelty-induced hyperlocomotion in GluA1-/- mice. Hippocampal dysfunction was also indicated by changes in proliferation and survival of adult-born dentate gyrus cells in the knockout mice. These results suggest focusing on the functions of hippocampal formation, such as novelty detection, when using the GluA1-/- mouse line as a model for neuropsychiatric and cognitive disorders.

  20. GDNF-induced leukemia inhibitory factor can mediate differentiation via the MEK/ERK pathway in pheochromocytoma cells derived from nf1-heterozygous knockout mice.

    Science.gov (United States)

    Park, Jong-In; Powers, James F; Tischler, Arthur S; Strock, Christopher J; Ball, Douglas W; Nelkin, Barry D

    2005-02-01

    Glial cell line-derived neurotrophic factor (GDNF) can induce neuron-like differentiation of mouse pheochromocytoma (MPC) cell lines derived from mice with a heterozygous knockout mutation of nf1, the murine counterpart of the human gene mutated in neurofibromatosis type 1 (NF1). Here, we show that GDNF-induced differentiation in the MPC 862L cell line is mediated by the MEK/extracellular signal-regulated kinase (ERK) pathway. Neurite outgrowth, increased expression of growth-associated protein 43, and decreased incorporation of bromodeoxyuridine (BrdU) were induced by treatment with GDNF, H-RasV12, or a constitutively active MEK2. GDNF also induces leukemia inhibitory factor (LIF) via the MEK/ERK pathway, and LIF itself can elicit these differentiative changes via a cell-extrinsic autocrine/paracrine pathway. Treatment with anti-LIF neutralizing antibody depleted the differentiative activity of the conditioned medium from cells stimulated for MEK/ERK signaling, while recombinant LIF could induce differentiation in MPC cells, indicating that LIF is the sole factor with differentiative activity. LIF could activate MEK1/2 and STAT3, but LIF-induced differentiation was blocked only by the MEK1/2-specific inhibitor U0126, indicating that the MEK/ERK pathway is necessary for LIF action in MPC cells. Our findings suggest that LIF may be utilized for signaling mediated by GDNF and may be important in the pathobiology of neuroendocrine tumors.

  1. Increased amphetamine-induced locomotor activity, sensitization, and accumbal dopamine release in M5 muscarinic receptor knockout mice

    DEFF Research Database (Denmark)

    Schmidt, Lene S; Miller, Anthony D; Lester, Deranda B

    2010-01-01

    showed that M(5) receptor knockout (M (5) (-/-) ) mice are less sensitive to the reinforcing properties of addictive drugs. MATERIALS AND METHODS: Here, we investigate the role of M(5) receptors in the effects of amphetamine and cocaine on locomotor activity, locomotor sensitization, and dopamine release...... and locomotor sensitization were enhanced in M (5) (-/-) mice, while the effects of cocaine were similar in M (5) (-/-) and wild-type mice. RESULTS: Consistent with the behavioral results, amphetamine-, but not cocaine, -elicited dopamine release in nucleus accumbens was enhanced in M (5) (-/-) mice. DISCUSSION......: The different effects of amphetamine and cocaine in M (5) (-/-) mice may be due to the divergent pharmacological profile of the two drugs, where amphetamine, but not cocaine, is able to release intracellular stores of dopamine. In conclusion, we show here for the first time that amphetamine...

  2. The mu-opioid receptor gene-dose dependent reductions in G-protein activation in the pons/medulla and antinociception induced by endomorphins in mu-opioid receptor knockout mice.

    Science.gov (United States)

    Mizoguchi, H; Narita, M; Oji, D E; Suganuma, C; Nagase, H; Sora, I; Uhl, G R; Cheng, E Y; Tseng, L F

    1999-01-01

    There appear to be different relationships between mu-opioid receptor densities and the acute and neuroadaptive mu-opioid agonist-induced responses of the multiple opioid neuronal systems, including important pons/medulla circuits. The recent success in creating mu-opioid receptor knockout mice allows studies of mu-opioid agonist-induced pharmacological and physiological effects in animals that express no, one or two copies of the mu-opioid receptor gene. We now report that the binding of mu-opioid receptor ligand, [3H][D-Ala2,NHPhe4,Gly-ol]enkephalin to membrane preparations of the pons/medulla was reduced by half in heterozygous mu-opioid receptor knockout mice and eliminated in homozygous mu-opioid receptor knockout mice. The endogenous mu-opioid agonist peptides endomorphin-1 and -2 activate G-proteins in the pons/medulla from wild-type mice in a concentration-dependent fashion, as assessed using [35S]guanosine-5'-o-(3-thio)triphosphate binding. This stimulation was reduced to half of the wild-type levels in heterozygous mice and eliminated in homozygous knockout mice. The intracerebroventricular injection of either endomorphin-1 or endomorphin-2 produced marked antinociception in the hot-plate and tail-flick tests in wild-type mice. These antinociceptive actions were significantly reduced in heterozygous mu-opioid receptor knockout mice, and virtually abolished in homozygous knockout mice. The mu-opioid receptors are the principal molecular targets for endomorphin-induced G-protein activation in the pons/medulla and the antinociception caused by the intracerebroventricular administration of mu-opioid agonists. These data support the notion that there are limited physiological mu-opioid receptor reserves for inducing G-protein activation in the pons/medulla and for the nociceptive modulation induced by the central administration of endomorphin-1 and -2.

  3. The Knockout Mouse Project

    OpenAIRE

    Austin, Christopher P.; Battey, James F.; Bradley, Allan; Bucan, Maja; Capecchi, Mario; Collins, Francis S; Dove, William F.; Duyk, Geoffrey; Dymecki, Susan; Eppig, Janan T.; Grieder, Franziska B.; Heintz, Nathaniel; Hicks, Geoff; Insel, Thomas R; Joyner, Alexandra

    2004-01-01

    Mouse knockout technology provides a powerful means of elucidating gene function in vivo, and a publicly available genome-wide collection of mouse knockouts would be significantly enabling for biomedical discovery. To date, published knockouts exist for only about 10% of mouse genes. Furthermore, many of these are limited in utility because they have not been made or phenotyped in standardized ways, and many are not freely available to researchers. It is time to harness new technologies and e...

  4. Prostaglandin metabolite induces inhibition of TRPA1 and channel-dependent nociception

    Directory of Open Access Journals (Sweden)

    Weng Yingqi

    2012-09-01

    Full Text Available Abstract Background The Transient Receptor Potential (TRP ion channel TRPA1 is a key player in pain pathways. Irritant chemicals activate ion channel TRPA1 via covalent modification of N-terminal cysteines. We and others have shown that 15-Deoxy-Δ12, 14-prostaglandin J2 (15d-PGJ2 similarly activates TRPA1 and causes channel-dependent nociception. Paradoxically, 15d-PGJ2 can also be anti-nociceptive in several pain models. Here we hypothesized that activation and subsequent desensitization of TRPA1 in dorsal root ganglion (DRG neurons underlies the anti-nociceptive property of 15d-PGJ2. To investigate this, we utilized a battery of behavioral assays and intracellular Ca2+ imaging in DRG neurons to test if pre-treatment with 15d-PGJ2 inhibited TRPA1 to subsequent stimulation. Results Intraplantar pre-injection of 15d-PGJ2, in contrast to mustard oil (AITC, attenuated acute nocifensive responses to subsequent injections of 15d-PGJ2 and AITC, but not capsaicin (CAP. Intraplantar 15d-PGJ2—administered after the induction of inflammation—reduced mechanical hypersensitivity in the Complete Freund’s Adjuvant (CFA model for up to 2 h post-injection. The 15d-PGJ2-mediated reduction in mechanical hypersensitivity is dependent on TRPA1, as this effect was absent in TRPA1 knockout mice. Ca2+ imaging studies of DRG neurons demonstrated that 15d-PGJ2 pre-exposure reduced the magnitude and number of neuronal responses to AITC, but not CAP. AITC responses were not reduced when neurons were pre-exposed to 15d-PGJ2 combined with HC-030031 (TRPA1 antagonist, demonstrating that inhibitory effects of 15d-PGJ2 depend on TRPA1 activation. Single daily doses of 15d-PGJ2, administered during the course of 4 days in the CFA model, effectively reversed mechanical hypersensitivity without apparent tolerance or toxicity. Conclusions Taken together, our data support the hypothesis that 15d-PGJ2 induces activation followed by persistent inhibition of TRPA1 channels

  5. Mechanisms underlying probucol-induced hERG-channel deficiency

    Directory of Open Access Journals (Sweden)

    Shi YQ

    2015-07-01

    Full Text Available Yuan-Qi Shi,1,* Cai-Chuan Yan,1,* Xiao Zhang,1 Meng Yan,1 Li-Rong Liu,1 Huai-Ze Geng,1 Lin Lv,1 Bao-Xin Li1,21Department of Pharmacology, Harbin Medical University, 2State-Province Key Laboratory of Biopharmaceutical Engineering, Harbin, Heilongjiang, People’s Republic of China*These authors contributed equally to this workAbstract: The hERG gene encodes the pore-forming α-subunit of the rapidly activating delayed rectifier potassium channel (IKr, which is important for cardiac repolarization. Reduction of IhERG due to genetic mutations or drug interferences causes long QT syndrome, leading to life-threatening cardiac arrhythmias (torsades de pointes or sudden death. Probucol is a cholesterol-lowering drug that could reduce hERG current by decreasing plasma membrane hERG protein expression and eventually cause long QT syndrome. Here, we investigated the mechanisms of probucol effects on IhERG and hERG-channel expression. Our data demonstrated that probucol reduces SGK1 expression, known as SGK isoform, in a concentration-dependent manner, resulting in downregulation of phosphorylated E3 ubiquitin ligase Nedd4-2 expression, but not the total level of Nedd4-2. As a result, the hERG protein reduces, due to the enhanced ubiquitination level. On the contrary, carbachol could enhance the phosphorylation level of Nedd4-2 as an alternative to SGK1, and thus rescue the ubiquitin-mediated degradation of hERG channels caused by probucol. These discoveries provide a novel mechanism of probucol-induced hERG-channel deficiency, and imply that carbachol or its analog may serve as potential therapeutic compounds for the handling of probucol cardiotoxicity.Keywords: long QT, hERG potassium channels, probucol, SGK1, Nedd4-2

  6. Knockout of the TauT gene predisposes C57BL/6 mice to streptozotocin-induced diabetic nephropathy.

    Directory of Open Access Journals (Sweden)

    Xiaobin Han

    Full Text Available Diabetic nephropathy is the leading cause of end stage renal disease in the world. Although tremendous efforts have been made, scientists have yet to identify an ideal animal model that can reproduce the characteristics of human diabetic nephropathy. In this study, we hypothesize that taurine insufficiency is a critical risk factor for development of diabetic nephropathy associated with diabetes mellitus. This hypothesis was tested in vivo in TauT heterozygous (TauT+/- and homozygous (TauT-/- knockout in C57BL/6 background mice. We have shown that alteration of the TauT gene (also known as SLC6A6 has a substantial effect on the susceptibility to development of extensive diabetic kidney disease in both TauT+/- and TauT-/-mouse models of diabetes. These animals developed histological changes characteristic of human diabetic nephropathy that included glomerulosclerosis, nodular lesions, arteriosclerosis, arteriolar dilation, and tubulointerstitial fibrosis. Immunohistochemical staining of molecular markers of smooth muscle actin, CD34, Ki67 and collagen IV further confirmed these observations. Our results demonstrated that both homozygous and heterozygous TauT gene deletion predispose C57BL/6 mice to develop end-stage diabetic kidney disease, which closely replicates the pathological features of diabetic nephropathy in human diabetic patients.

  7. Morphodynamics structures induced by variations of the channel width

    Science.gov (United States)

    Duro, Gonzalo; Crosato, Alessandra; Tassi, Pablo

    2014-05-01

    In alluvial channels, forcing effects, such as a longitudinally varying width, can induce the formation of steady bars (Olesen, 1984). The type of bars that form, such as alternate, central or multiple, will mainly depend on the local flow width-to-depth ratio and on upstream conditions (Struiksma et al., 1985). The effects on bar formation of varying the channel width received attention only recently and investigations, based on flume experiments and mathematical modelling, are mostly restricted to small longitudinal sinusoidal variations of the channel width (e.g. Repetto et al., 2002; Wu and Yeh, 2005, Zolezzi et al., 2012; Frascati and Lanzoni, 2013). In this work, we analyze the variations in equilibrium bed topography in a longitudinal width-varying channel with characteristic scales of the Waal River (The Netherlands) using two different 2D depth-averaged morphodynamic models, one based on the Delft3D code and one on Telemac-Mascaret system. In particular, we explore the effects of changing the wavelength of sinusoidal width variations in a straight channel, focusing on the effects of the spatial lag between bar formation and forcing that is observed in numerical models and laboratory experiments (e.g. Crosato et al, 2011). We extend the investigations to finite width variations in which longitudinal changes of the width-to-depth ratio are such that they may affect the type of bars that become unstable (alternate, central or multiple bars). Numerical results are qualitatively validated with field observations and the resulting morphodynamic pattern is compared with the physics-based predictor of river bar modes by Crosato and Mosselman (2009). The numerical models are finally used to analyse the experimental conditions of Wu and Yeh (2005). The study should be seen as merely exploratory. The aim is to investigate possible approaches for future research aiming at assessing the effects of artificial river widening and narrowing to control bar formation in

  8. Asbestos-Induced Peribronchiolar Cell Proliferation and Cytokine Production Are Attenuated in Lungs of Protein Kinase C-δ Knockout Mice

    Science.gov (United States)

    Shukla, Arti; Lounsbury, Karen M.; Barrett, Trisha F.; Gell, Joanna; Rincon, Mercedes; Butnor, Kelly J.; Taatjes, Douglas J.; Davis, Gerald S.; Vacek, Pamela; Nakayama, Keiichi I.; Nakayama, Keiko; Steele, Chad; Mossman, Brooke T.

    2007-01-01

    The signaling pathways leading to the development of asbestos-associated diseases are poorly understood. Here we used normal and protein kinase C (PKC)-δ knockout (PKCδ−/−) mice to demonstrate multiple roles of PKC-δ in the development of cell proliferation and inflammation after inhalation of chrysotile asbestos. At 3 days, asbestos-induced peribronchiolar cell proliferation in wild-type mice was attenuated in PKCδ−/− mice. Cytokine profiles in bronchoalveolar lavage fluids showed increases in interleukin (IL)-1β, IL-4, IL-6, and IL-13 that were decreased in PKCδ−/− mice. At 9 days, microarray and quantitative reverse transcriptase-polymerase chain reaction analysis of lung tissues revealed increased mRNA levels of the profibrotic cytokine, IL-4, in asbestos-exposed wild-type mice but not PKCδ−/− mice. PKCδ−/− mice also exhibited decreased lung infiltration of polymorphonuclear cells, natural killer cells, and macrophages in bronchoalveolar lavage fluid and lung, as well as increased numbers of B lymphocytes and plasma cells. These changes were accompanied by elevated mRNA levels of immunoglobulin chains. These data show that modulation of PKC-δ has multiple effects on peribronchiolar cell proliferation, proinflammatory and profibrotic cytokine expression, and immune cell profiles in lung. These results also implicate targeted interruption of PKC-δ as a potential therapeutic option in asbestos-induced lung diseases. PMID:17200189

  9. B cell antigen receptor-induced activation of an IRAK4-dependent signaling pathway revealed by a MALT1-IRAK4 double knockout mouse model

    Directory of Open Access Journals (Sweden)

    Dufner Almut

    2011-03-01

    Full Text Available Abstract Background The B cell antigen receptor (BCR and pathogen recognition receptors, such as Toll-like receptor 4 (TLR4, act in concert to control adaptive B cell responses. However, little is known about the signaling pathways that integrate BCR activation with intrinsic TLR4 stimulation. Antigen receptors initialize activation of the inducible transcription factor nuclear factor-κB (NF-κB via recruitment of the membrane-associated guanylate kinase caspase recruitment domain protein 11 (CARD11, the adapter molecule B cell CLL/lymphoma 10 (BCL10, and the "paracaspase" mucosa-associated lymphoid tissue lymphoma translocation gene 1 (MALT1 into lipid rafts. Upon BCR triggering, this activation strictly depends on BCL10, but not on MALT1, leading to the hypothesis that a MALT1-independent NF-κB activation pathway contributes to BCR-induced NF-κB activation downstream of BCL10. The identity of this pathway has remained elusive. Results Using genetic and biochemical approaches, we demonstrate that the IRAK4- and IRAK1-dependent TLR signaling branch is activated upon BCR triggering to induce partial NF-κB activation. BCR-induced MALT1-independent IκB degradation and B cell proliferation were inhibited in MALT1/IRAK4 double knockout B cells. Moreover, IRAK1 was recruited into lipid rafts upon BCR stimulation and activated following transient recruitment of IRAK4. Conclusion We propose that the observed crosstalk between BCR and TLR signaling components may contribute to the discrimination of signals that emanate from single and dual receptor engagement to control adaptive B cell responses.

  10. Microfluidic Induced Controllable Microdroplets Assembly in Confined Channels

    Directory of Open Access Journals (Sweden)

    Juan Wang

    2015-09-01

    Full Text Available We report on the microfluidic induced monodispersed microdroplet generation and assembly in confined microchannels. Two and three dimensional close-packed droplet lattices were obtained in microfluidic devices by adjusting the channel geometry, the fluidic flow rates and the monodispersed droplet size. The droplet packing was mainly caused by the volumetric effect and capillarity in confined microchannels. Polymerizable fluids were also investigated to demonstrate the effect of fluidic properties on the microdroplet generation and assembly, which could find interesting applications in the future. This approach would be helpful to fundamentally understand the mechanism of self-assembly process of particles in confined microstructures, and practically be applied in sensing and energy storage devices.

  11. Leukemogenesis in heterozygous PU.1 knockout mice.

    Science.gov (United States)

    Genik, Paula C; Vyazunova, Irina; Steffen, Leta S; Bacher, Jeffery W; Bielefeldt-Ohmann, Helle; McKercher, Scott; Ullrich, Robert L; Fallgren, Christina M; Weil, Michael M; Ray, F Andrew

    2014-09-01

    Most murine radiation-induced acute myeloid leukemias involve biallelic inactivation of the PU.1 gene, with one allele being lost through a radiation-induced chromosomal deletion and the other allele affected by a recurrent point mutation in codon 235 that is likely to be spontaneous. The short latencies of acute myeloid leukemias occurring in nonirradiated mice engineered with PU.1 conditional knockout or knockdown alleles suggest that once both copies of PU.1 have been lost any other steps involved in leukemogenesis occur rapidly. Yet, spontaneous acute myeloid leukemias have not been reported in mice heterozygous for a PU.1 knockout allele, an observation that conflicts with the understanding that the PU.1 codon 235 mutation is spontaneous. Here we describe experiments that show that the lack of spontaneous leukemia in PU.1 heterozygous knockout mice is not due to insufficient monitoring times or mouse numbers or the genetic background of the knockout mice. The results reveal that spontaneous leukemias that develop in mice of the mixed 129S2/SvPas and C57BL/6 background of knockout mice arise by a pathway that does not involve biallelic PU.1 mutation. In addition, the latency of radiation-induced leukemia in PU.1 heterozygous mice on a genetic background susceptible to radiation-induced leukemia indicates that the codon 235 mutation is not a rate-limiting step in radiation leukemogenesis driven by PU.1 loss.

  12. Mu opioid receptors on primary afferent nav1.8 neurons contribute to opiate-induced analgesia: insight from conditional knockout mice.

    Directory of Open Access Journals (Sweden)

    Raphaël Weibel

    Full Text Available Opiates are powerful drugs to treat severe pain, and act via mu opioid receptors distributed throughout the nervous system. Their clinical use is hampered by centrally-mediated adverse effects, including nausea or respiratory depression. Here we used a genetic approach to investigate the potential of peripheral mu opioid receptors as targets for pain treatment. We generated conditional knockout (cKO mice in which mu opioid receptors are deleted specifically in primary afferent Nav1.8-positive neurons. Mutant animals were compared to controls for acute nociception, inflammatory pain, opiate-induced analgesia and constipation. There was a 76% decrease of mu receptor-positive neurons and a 60% reduction of mu-receptor mRNA in dorsal root ganglia of cKO mice. Mutant mice showed normal responses to heat, mechanical, visceral and chemical stimuli, as well as unchanged morphine antinociception and tolerance to antinociception in models of acute pain. Inflammatory pain developed similarly in cKO and controls mice after Complete Freund's Adjuvant. In the inflammation model, however, opiate-induced (morphine, fentanyl and loperamide analgesia was reduced in mutant mice as compared to controls, and abolished at low doses. Morphine-induced constipation remained intact in cKO mice. We therefore genetically demonstrate for the first time that mu opioid receptors partly mediate opiate analgesia at the level of Nav1.8-positive sensory neurons. In our study, this mechanism operates under conditions of inflammatory pain, but not nociception. Previous pharmacology suggests that peripheral opiates may be clinically useful, and our data further demonstrate that Nav1.8 neuron-associated mu opioid receptors are feasible targets to alleviate some forms of persistent pain.

  13. Mu opioid receptors on primary afferent nav1.8 neurons contribute to opiate-induced analgesia: insight from conditional knockout mice.

    Science.gov (United States)

    Weibel, Raphaël; Reiss, David; Karchewski, Laurie; Gardon, Olivier; Matifas, Audrey; Filliol, Dominique; Becker, Jérôme A J; Wood, John N; Kieffer, Brigitte L; Gaveriaux-Ruff, Claire

    2013-01-01

    Opiates are powerful drugs to treat severe pain, and act via mu opioid receptors distributed throughout the nervous system. Their clinical use is hampered by centrally-mediated adverse effects, including nausea or respiratory depression. Here we used a genetic approach to investigate the potential of peripheral mu opioid receptors as targets for pain treatment. We generated conditional knockout (cKO) mice in which mu opioid receptors are deleted specifically in primary afferent Nav1.8-positive neurons. Mutant animals were compared to controls for acute nociception, inflammatory pain, opiate-induced analgesia and constipation. There was a 76% decrease of mu receptor-positive neurons and a 60% reduction of mu-receptor mRNA in dorsal root ganglia of cKO mice. Mutant mice showed normal responses to heat, mechanical, visceral and chemical stimuli, as well as unchanged morphine antinociception and tolerance to antinociception in models of acute pain. Inflammatory pain developed similarly in cKO and controls mice after Complete Freund's Adjuvant. In the inflammation model, however, opiate-induced (morphine, fentanyl and loperamide) analgesia was reduced in mutant mice as compared to controls, and abolished at low doses. Morphine-induced constipation remained intact in cKO mice. We therefore genetically demonstrate for the first time that mu opioid receptors partly mediate opiate analgesia at the level of Nav1.8-positive sensory neurons. In our study, this mechanism operates under conditions of inflammatory pain, but not nociception. Previous pharmacology suggests that peripheral opiates may be clinically useful, and our data further demonstrate that Nav1.8 neuron-associated mu opioid receptors are feasible targets to alleviate some forms of persistent pain.

  14. XPM-induced degradation of multilevel phase modulated channel caused by neighboring NRZ modulated channels

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Schiellerup, G.; Peucheret, Christophe

    2008-01-01

    The impact of XPM from NRZ modulated channels on an 8-level phase modulated channel in a WDM system was investigated. Requirements on launch power are found. 400 km transmission was achieved with negligible penalty.......The impact of XPM from NRZ modulated channels on an 8-level phase modulated channel in a WDM system was investigated. Requirements on launch power are found. 400 km transmission was achieved with negligible penalty....

  15. Villin promoter-mediated transgenic expression of transient receptor potential cation channel, subfamily V, member 6 (TRPV6) increases intestinal calcium absorption in wild-type and vitamin D receptor knockout mice.

    Science.gov (United States)

    Cui, Min; Li, Qiang; Johnson, Robert; Fleet, James C

    2012-10-01

    Transient receptor potential cation channel, subfamily V, member 6 (TRPV6) is an apical membrane calcium (Ca) channel in the small intestine proposed to be essential for vitamin D-regulated intestinal Ca absorption. Recent studies have challenged the proposed role for TRPV6 in Ca absorption. We directly tested intestinal TRPV6 function in Ca and bone metabolism in wild-type (WT) and vitamin D receptor knockout (VDRKO) mice. TRPV6 transgenic mice (TG) were made with intestinal epithelium-specific expression of a 3X Flag-tagged human TRPV6 protein. TG and VDRKO mice were crossed to make TG-VDRKO mice. Ca and bone metabolism was examined in WT, TG, VDRKO, and TG-VDRKO mice. TG mice developed hypercalcemia and soft tissue calcification on a chow diet. In TG mice fed a 0.25% Ca diet, Ca absorption was more than three-fold higher and femur bone mineral density (BMD) was 26% higher than WT. Renal 1α hydroxylase (CYP27B1) mRNA and intestinal expression of the natural mouse TRPV6 gene were reduced to intestine calbindin-D(9k) expression was elevated >15 times in TG mice. TG-VDRKO mice had high Ca absorption that prevented the low serum Ca, high renal CYP27B1 mRNA, low BMD, and abnormal bone microarchitecture seen in VDRKO mice. In addition, small intestinal calbindin D(9K) mRNA and protein levels were elevated in TG-VDRKO. Transgenic TRPV6 expression in intestine is sufficient to increase Ca absorption and bone density, even in VDRKO mice. VDR-independent upregulation of intestinal calbindin D(9k) in TG-VDRKO suggests this protein may buffer intracellular Ca during Ca absorption. © 2012 American Society for Bone and Mineral Research.

  16. Recoiled Proton Tagged Knockout Reaction for 8He

    Institute of Scientific and Technical Information of China (English)

    曹中鑫; 叶沿林; 江栋兴; 郑涛; 李智焕; 华辉; 葛榆成; 李湘庆; 楼建玲; 肖军; 李奇特; 吕林辉; 李阔昂; 王赫; 乔锐; 游海波; 陈瑞九

    2012-01-01

    An experiment for knockout reaction induced by SHe beam at 82.5 MeV/nucleon on CH2 and C targets was carried out. The 6He and 4He core fragments at forward angles and the recoiled protons at large angles were detected coincidently. From this exclusive measurement the valence nucleon knockout mechanism and the core knockout mechanism are separated, which can be applied to the exclusive spectroscopic study on the structure of exotic nuclei.

  17. Characterization of partial ligation-induced carotid atherosclerosis model using dual-modality molecular imaging in ApoE knock-out mice.

    Directory of Open Access Journals (Sweden)

    Ik Jae Shin

    Full Text Available BACKGROUND: Recently, partial ligation of the common carotid artery (CCA was reported to induce carotid atheromata rapidly in apolipoprotein-E knockout (ApoE(-/- mice. We investigated this new atherosclerosis model by using combined matrix-metalloproteinase (MMP near-infrared fluorescent (NIRF imaging and macrophage-tracking luciferase imaging. METHODOLOGY AND PRINCIPAL FINDINGS: Partial ligation of the left CCA was performed in 10-week-old ApoE(-/- mice on a high fat diet (n=33; the internal and external carotid arteries and occipital artery were ligated, while the superior thyroid artery was left intact. Two thirds of the animals were treated with either LiCl or atorvastatin. At 1-week, Raw264.7 macrophages modified to express the enhanced firefly-luciferase reporter gene (10(7 Raw-luc cells were injected intravenously. At 2-week, NIRF molecular imaging visualized strong MMP-2/9 activity in the ligated area of the left CCA as well as in the aortic arch. Left-to-right ratios of the NIRF signal intensities in the CCA had a decreasing gradient from the highest value in the upper-most ligated area to the lowest value in the lower-most region adjacent to the aortic arch. Luciferase imaging showed that most Raw-luc macrophages were recruited to the ligated area of the CCA rather than to the aortic arch, despite similarly strong MMP-2/9-related NIRF signal intensities in both areas. In addition, LiCl or atorvastatin could reduce MMP-2/9 activity in the aortic arch but not in the ligated area of the CCA. CONCLUSIONS/SIGNIFICANCE: This is the first molecular imaging study to characterize the partial ligation-induced carotid atherosclerosis model. Molecularly divergent types of atherosclerosis were identified: conventional lipogenic atherosclerosis in the aorta vs. flow-related mechanical atherosclerosis in the partially ligated left system.

  18. High glucose-induced oxidative stress increases transient receptor potential channel expression in human monocytes

    DEFF Research Database (Denmark)

    Wuensch, Tilo; Thilo, Florian; Krueger, Katharina;

    2010-01-01

    Transient receptor potential (TRP) channel-induced cation influx activates human monocytes, which play an important role in the pathogenesis of atherosclerosis. In the present study, we investigated the effects of high glucose-induced oxidative stress on TRP channel expression in human monocytes....

  19. Increased plasma cholesterol esterification by LCAT reduces diet-induced atherosclerosis in SR-BI knockout mice.

    Science.gov (United States)

    Thacker, Seth G; Rousset, Xavier; Esmail, Safiya; Zarzour, Abdalrahman; Jin, Xueting; Collins, Heidi L; Sampson, Maureen; Stonik, John; Demosky, Stephen; Malide, Daniela A; Freeman, Lita; Vaisman, Boris L; Kruth, Howard S; Adelman, Steven J; Remaley, Alan T

    2015-07-01

    LCAT, a plasma enzyme that esterifies cholesterol, has been proposed to play an antiatherogenic role, but animal and epidemiologic studies have yielded conflicting results. To gain insight into LCAT and the role of free cholesterol (FC) in atherosclerosis, we examined the effect of LCAT over- and underexpression in diet-induced atherosclerosis in scavenger receptor class B member I-deficient [Scarab(-/-)] mice, which have a secondary defect in cholesterol esterification. Scarab(-/-)×LCAT-null [Lcat(-/-)] mice had a decrease in HDL-cholesterol and a high plasma ratio of FC/total cholesterol (TC) (0.88 ± 0.033) and a marked increase in VLDL-cholesterol (VLDL-C) on a high-fat diet. Scarab(-/-)×LCAT-transgenic (Tg) mice had lower levels of VLDL-C and a normal plasma FC/TC ratio (0.28 ± 0.005). Plasma from Scarab(-/-)×LCAT-Tg mice also showed an increase in cholesterol esterification during in vitro cholesterol efflux, but increased esterification did not appear to affect the overall rate of cholesterol efflux or hepatic uptake of cholesterol. Scarab(-/-)×LCAT-Tg mice also displayed a 51% decrease in aortic sinus atherosclerosis compared with Scarab(-/-) mice (P esterification by LCAT is atheroprotective, most likely through its ability to increase HDL levels and decrease pro-atherogenic apoB-containing lipoprotein particles.

  20. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)

    2007-07-01

    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  1. δ-opioid Receptor Induced Inhibition of Sodium Channel Function

    Institute of Scientific and Technical Information of China (English)

    康学智; 顾全保; 丁光宏; 晁东满; 王英伟; G Balboni; LH Lazarus; 夏萤

    2008-01-01

    Objective: To study the precise role of DOR in the regulation of sodium channels at present. Methods: With Xenopus oocytes co-expressing sodium channel subtype 2 (Nav1.2) and DOR. Results: 1) Nav1.2 expression induced tetrodotoxin-sensitive inward currents; 2) DOR expression reduced the inward currents; 3) activation of DOR reduced the amplitude of the current and rightly shifted the activation curve of the current in the oocytes with both Nav1.2 and DOR, but not in ones with Nav1.2 alone; 4) the DOR agonist-induced inhibition of Nav1.2 currents was in a dose-dependent manner and saturable; 5) the DOR agonist had no effect on naive oocytes. Conclusion: These data represent the first demonstration that activation of DOR inhibits Na+ channel function by decreasing the amplitude of sodium currents and increasing its threshold of activation. This novel finding has far-reaching impacts on novel solutions of certain neurological disorders such as hypoxic/ischemic injury, epilepsy and pain. Also, our data may improve the understanding of the mechanisms underlying acupuncture since acupuncture is known to activate the brain opioid system.%目的:研究δ-阿片受体表达和激活对钠通道1.2亚型的电流特性的影响.方法:用双电极电压钳技术,在δ-阿片受体和钠通道亚型1.2共表达的非洲爪蟾第V期卵母细胞上,观察δ-阿片受体表达和/或激活后,钠通道1.2亚型电流特性的变化.结果:1)钠通道1.2亚型的表达产生河豚毒素(tetrodotoxin,TTX)敏感的内向电流;2)δ-阿片受体的表达减少钠通道激活电流的幅度;3)δ-阿片受体和钠通道1.2亚型共表达的卵母细胞中,δ-阿片受体激动剂可以抑制钠通道激活电流的幅度和电导,而只有钠通道1.2亚型表达的卵母细胞则无此现象;4)δ-阿片受体激动剂抑制钠电流的作用具有剂量依赖关系,并能达到饱和状态;5)δ-阿片受体激动剂对未表达外派陛蛋白的卵母细胞无影响.结论:本结

  2. Effects of calcium channel on 3-morpholinosydnonimine-induced rat hippocampal neuronal apoptosis

    Institute of Scientific and Technical Information of China (English)

    Quanzhong Chang; Shuling Zhang; Yuanyin Zheng; Lijuan Xu; Jinbao Yin; Shining Cai

    2011-01-01

    Previous studies have demonstrated that increased chloride channel activity plays a role in nitric oxide-induced neuronal apoptosis in the rat hippocampus.The present study investigated the effects of the broad-spectrum calcium channel blocker CdC12 on survival rate, percentage of apoptosis, and morphological changes in hippocampal neurons cultured in vitro, as well as the effects of calcium channels on neuronal apoptosis.The chloride channel blockers 4-acetamido-4'-isothiocyanatostilbene-2, 2'-disulfonic acid (SITS) or 4, 4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) increased the survival rate of 3-morpholinosydnonimine (SIN-1)-treated neurons and suppressed SIN-1-induced neuronal apoptosis.The calcium channel blocker CdC12 did not increase the survival rate of neurons and did not affect SIN-1-induced apoptosis or SITS- or DIDS-suppressed neuronal apoptosis.Results demonstrated that calcium channels did not significantly affect neuronal apoptosis.

  3. Radiation-Induced Short Channel (RISCE) and Narrow Channel (RINCE) Effects in 65 and 130 nm MOSFETs

    CERN Document Server

    Faccio, F; Cornale, D; Paccagnella, A; Gerardin, S

    2015-01-01

    The behavior of transistors in commercial-grade complementary metal-oxide semiconductor technologies in the 65 and 130 nm nodes has been explored up to a total ionizing dose of 1 Grad. The large dose tolerance of the thin gate oxide is confirmed, but defects in the spacer and STI oxides have a strong effect on the performance of the transistors. A radiation-induced short channel effect is traced to charge trapping in the spacers used for drain engineering, while a radiation-induced narrow channel effect is due to defect generation in the lateral isolation oxide (STI). These strongly degrade the electrical characteristics of short and narrow channel transistors at high doses, and their magnitude depends on the applied bias and temperature during irradiation in a complex way.

  4. CCR5 knockout prevents neuronal injury and behavioral impairment induced in a transgenic mouse model by a CXCR4-using HIV-1 glycoprotein 120.

    Science.gov (United States)

    Maung, Ricky; Hoefer, Melanie M; Sanchez, Ana B; Sejbuk, Natalia E; Medders, Kathryn E; Desai, Maya K; Catalan, Irene C; Dowling, Cari C; de Rozieres, Cyrus M; Garden, Gwenn A; Russo, Rossella; Roberts, Amanda J; Williams, Roy; Kaul, Marcus

    2014-08-15

    The innate immune system has been implicated in several neurodegenerative diseases, including HIV-1-associated dementia. In this study, we show that genetic ablation of CCR5 prevents microglial activation and neuronal damage in a transgenic model of HIV-associated brain injury induced by a CXCR4-using viral envelope gp120. The CCR5 knockout (KO) also rescues spatial learning and memory in gp120-transgenic mice. However, the CCR5KO does not abrogate astrocytosis, indicating it can occur independently from neuronal injury and behavioral impairment. To characterize further the neuroprotective effect of CCR5 deficiency we performed a genome-wide gene expression analysis of brains from HIVgp120tg mice expressing or lacking CCR5 and nontransgenic controls. A comparison with a human brain microarray study reveals that brains of HIVgp120tg mice and HIV patients with neurocognitive impairment share numerous differentially regulated genes. Furthermore, brains of CCR5 wild-type and CCR5KO gp120tg mice express markers of an innate immune response. One of the most significantly upregulated factors is the acute phase protein lipocalin-2 (LCN2). Using cerebrocortical cell cultures, we find that LCN2 is neurotoxic in a CCR5-dependent fashion, whereas inhibition of CCR5 alone is not sufficient to abrogate neurotoxicity of a CXCR4-using gp120. However, the combination of pharmacologic CCR5 blockade and LCN2 protects neurons from toxicity of a CXCR4-using gp120, thus recapitulating the finding in CCR5-deficient gp120tg mouse brain. Our study provides evidence for an indirect pathologic role of CCR5 and a novel protective effect of LCN2 in combination with inhibition of CCR5 in HIV-associated brain injury.

  5. KnockoutJS blueprints

    CERN Document Server

    Russo, Carlo

    2015-01-01

    If you are a JavaScript developer and already know the basics of KnockoutJS and you want to get the most out of it, then this book is for you. This book will help in your transition from a small site to a large web application that is easily maintainable.

  6. Observation of the induced pressure in a hybrid micro/nano-channel

    Institute of Scientific and Technical Information of China (English)

    KONG Gao-pan; ZHENG Xu; SILBER-LI Zhan-hua; XU Zheng

    2013-01-01

    This paper studies the flow characteristics in micro/nano-channels subjected to an applied electric field.The nano-channel flow was observed by means of the fluorescence Calcein.A Fluorescence Concentration Gradient Interface (FCGI) was observed across the nano-channel array.The front of the FCGI was shown to have an analogous parabolic shape.The propagation of this interface reflects indirectly the induced pressure at the micro/nano-channel junction,where the enrichment-depletion processes are known to take place.This induced pressure was predicted by numerical simulations,and this paper gives the first experimental evidence.

  7. The coupling of acetylcholine-induced BK channel and calcium channel in guinea pig saccular type II vestibular hair cells.

    Science.gov (United States)

    Kong, Wei-Jia; Guo, Chang-Kai; Zhang, Xiao-Wen; Chen, Xiong; Zhang, Song; Li, Guan-Qiao; Li, Zhi-Wang; Van Cauwenberge, Paul

    2007-01-19

    Molecular biological studies and electrophysiological data have demonstrated that acetylcholine (ACh) is the principal cochlear and vestibular efferent neurotransmitter among mammalians. However, the functional roles of ACh in type II vestibular hair cells (VHCs II) among mammalians are still unclear, with the exception of the well-known alpha9-containing nicotinic ACh receptor (alpha9-containing nAChR)-activated small conductance, calcium-dependent potassium current (SK) in cochlear hair cells and frog saccular hair cells. The activation of SK current was necessary for the calcium influx through the alpha9-containing nAChR. Recently, we have demonstrated that ACh-induced big conductance, calcium-dependent potassium current (BK) was present in VHCs II of the vestibular end-organ of guinea pig. In this study, the nature of calcium influx for the activation of ACh-induced BK current in saccular VHCs II of guinea pig was investigated. Following extracellular perfusion of ACh, saccular VHCs II displayed a sustained outward current, which was sensitive to iberiotoxin (IBTX). High concentration of apamin failed to inhibit the current amplitude of ACh-induced outward current. Intracellular application of Cs(+) completely abolished the current evoked by ACh. ACh-induced current was potently inhibited by nifedipine, nimodipine, Cd(2+) and Ni(2+), respectively. The inhibition potency of these four calcium channel antagonists was nimodipine>nifedipine>cadmium>nickel. The L-type Ca(2+) channels agonist, (-)-Bay-K 8644 mimicked the effect of ACh and activated an IBTX-sensitive current. In addition, partial VHCs II displayed a biphasic waveform. In conclusion, the present data showed that in the guinea pig saccular VHCs II, ACh-induced BK channel was coupled with the calcium channel, but not the receptor. The perfusion of ACh will drive the opening of calcium channels; the influx of calcium ions will then activate the BK current.

  8. Vascular remodeling and mobilization of bone marrow-derived cells in cuff-induced vascular injury in LDL receptor knockout muce

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Background Vascular remodeling is an important pathologic process in vascular injury for various vascular disorders such as atherosclerosis,postangioplasty restenosis and transplant arteriopathy.Recently,pathologic change and the role of bone marrow derived cells were wildly studied in atherosclerosis and restenosis.But the manner of lesion formation in neointima and cell recruitment in vascular remodeling lesion in the present of hypercholesterolemia is not Vet fully understood. Methods Double-transgenic mice knockout of LDL receptor gene (LDL-/-) and expressing ubiquitously green fluorescent protein (GFP) were obtained by cross-breeding LDL-/-mice with the GFP-expressing transgenic mice. LDL-/- mice (22-24 weeks of age) fed high fat diet containing 1.25% (w/w) cholesterol were subjected to 9Gy irradiation and received bone marrow (BM) cells from the double-transgenic mice.Four weeks later,a nonconstrictive cuff was Dlaced around the right femoral artery.After another 2 weeks,both right and left femoral arteries were harvested and subjected to histochemical analysis.Apoptosis was analyzed in situ using TUNEL assay.Resuits Two weeks after cuff placement,atherosclerotic lesions developed in the intima consisting of a massive accumulation of foam cells, The tissue stained with anti-α smooth muscle actin (SMA) antibody,showed a number of SMA-positive cells in the intimal lesion area.They were also positive for GFP,indicating that BM-derived cells can differentiate to SMCs in the intima in cuff-induced vascular remodeling lesions.Numerous small vessels in the adventitia as well as the endothelial lining of the intima were positive both for CD31 and GFP.The intima and media showed a larae number of TUNEL-positive signals after 2 weeks cuff injury,indicating the presence of apoptosis in vascular remodelina.Conclusions Atherosclerotic lesions in mice can be developed in the intima after 2 weeks of cuff-induced vascular inJury under the hypercholesterolemic conditions

  9. Acrolein-induced oxidative stress in NAD(P)H Oxidase Subunit gp91phox knock-out mice and its modulation of NFκB and CD36.

    Science.gov (United States)

    Yousefipour, Zivar; Zhang, Chelsea; Monfareed, Mahdieh; Walker, James; Newaz, Mohammad

    2013-11-01

    An essential component of NAD(P)H, gp91phox, maintains the functionality of the enzyme in producing oxygen radicals. NAD(P)H oxidase plays an important role in oxidative stress but its precise contribution in acrolein-induced toxicity was not explored. We examined the involvement of NAD(P)H oxidase and other oxidant system in acrolein toxicity using gp91phox knockout mice. Male gp91phox knockout (KO) mice (20-25 gm) or wild type (WT) controls were treated with acrolein (0.5 μg/kg; 1 week). Animals were sacrificed and the liver was used to determine biochemical parameters. Knockout mice generated low (1.43 ±.02 pg/μg protein) free radicals as evident in 8-Isoprostane compared with the WT mice (2.19 ± 0.1). Acrolein increased 8-Isoprostane in WT (PAcrolein increased XO in KO mice, but significantly increased it only in WT. Cycloxygenase (COX) activity was not different between WT and KO mice, although acroelin increased COX in WT. Knockout mice exhibited a significantly low (2.1 ± 0.2 μmol/mg protein) total antioxidant status (TAS) compared with the WT (3.5 ± 0.3). Acrolein reduced TAS in both WT and KO mice equally. Baseline NFκB was significantly higher in KO mice, although acrolein increased NFκB in WT but not in KO. CD36 was higher (pacrolein increased (pacrolein-induced oxidative stress. We also suggests that in the absence of NAD(P)H oxidase XO plays a definitive role together with reduced antioxidant ability to compound the toxic effects of acrolein. We propose that in absence of NAD(P)H oxidase a different signaling process may involve that utilizes CD36 besides NFκB.

  10. Wave-induced flow and its influence on ridge erosion and channel deposition in Lanshayang channel of radial sand ridges

    Institute of Scientific and Technical Information of China (English)

    陈可峰; 安翔; 陆培东; 张玮; 徐卓

    2014-01-01

    Very limited modeling studies were available of the wave-induced current under the complex hydrodynamic conditions in the South Yellow Sea Radial Sand Ridge area (SYSRSR). Partly it is due to the difficulties in estimating the influence of the wave-induced current in this area. In this study, a coupled 3-D storm-surge-wave model is built. In this model, the time-dependent varying Collins coefficient with the water level method (TCL) are used. The wave-flow environment in the Lanshayang Channel (LSYC) during the “Winnie” typhoon is successfully represented by this model. According to the modelling results, at a high water level (HWL), the wave-induced current similar to the long-shore current will emerge in the shallow area of the ridges, and has two different motion trends correlated with the morphological characteristics of the ridges. The wave-induced current velocity could be as strong as 1 m/s, which is at the same magnitude as the tidal current. This result is verified by the bathymetric changes in the LSYC during the “Matsa” typhoon. Thus, the wave-induced current may be one of the driven force of the ridge erosion and channel deposition in the SYSRSR. These conclusions will help to further study the mechanism of the ridge erosion and channel deposition in the SYSRSR.

  11. Inducible 70 kDa Heat Shock Proteins Protect Embryos from Teratogen-Induced Exencephaly: Analysis using Hspa1a/a1b Knockout Mice

    Science.gov (United States)

    Background: It is well known that a variety of teratogens induce neural tube defects in animals; however, less is known about proteins that play a role in protecting embryos from teratogen-induced neural tube defects. Previously, our lab has shown that embryos over-expressing th...

  12. Crimean-Congo Hemorrhagic Fever Virus Subunit Vaccines Induce High Levels of Neutralizing Antibodies But No Protection in STAT1 Knockout Mice

    NARCIS (Netherlands)

    Kortekaas, Jeroen; Vloet, Rianka P M; McAuley, Alexander J; Shen, Xiaoli; Bosch, Berend Jan|info:eu-repo/dai/nl/273306049; de Vries, Laura; Moormann, Rob J M|info:eu-repo/dai/nl/069850550; Bente, Dennis A

    2015-01-01

    Crimean-Congo hemorrhagic fever virus is a tick-borne bunyavirus of the Nairovirus genus that causes hemorrhagic fever in humans with high case fatality. Here, we report the development of subunit vaccines and their efficacy in signal transducer and activator of transcription 1 (STAT1) knockout mice

  13. Hormone-Sensitive Lipase Knockouts

    Directory of Open Access Journals (Sweden)

    Shen Wen-Jun

    2006-02-01

    Full Text Available Abstract All treatments for obesity, including dietary restriction of carbohydrates, have a goal of reducing the storage of fat in adipocytes. The chief enzyme responsible for the mobilization of FFA from adipose tissue, i.e., lipolysis, is thought to be hormone-sensitive lipase (HSL. Studies of HSL knockouts have provided important insights into the functional significance of HSL and into adipose metabolism in general. Studies have provided evidence that HSL, though possessing triacylglycerol lipase activity, appears to be the rate-limiting enzyme for cholesteryl ester and diacylglycerol hydrolysis in adipose tissue and is essential for complete hormone stimulated lipolysis, but other triacylglycerol lipases are important in mediating triacylglycerol hydrolysis in lipolysis. HSL knockouts are resistant to both high fat diet-induced and genetic obesity, displaying reduced quantities of white with increased amounts of brown adipose tissue, increased numbers of adipose macrophages, and have multiple alterations in the expression of genes involved in adipose differentiation, including transcription factors, markers of adipocyte differentiation, and enzymes of fatty acid and triglyceride synthesis. With disruption of lipolysis by removal of HSL, there is a drastic reduction in lipogenesis and alteration in adipose metabolism.

  14. ANALYSIS OF NANO CHANNEL FORMATION IN QUARTZ CUBES BY LASER-INDUCED PROCESS

    Institute of Scientific and Technical Information of China (English)

    QIN S.J.; Li Wen J.

    2004-01-01

    A novel laser processing technique was developed for making channels in the nano regime in this paper. A Nd:YAG laser was used to dry fabricate micro channels (25μm~100μm diameter) in a 1 cm3 fused silica substrate by thermal-induced processing. By controlling the locations of these initiating micro channels on a silica cube, 1D-controllable self-connecting nano fractures can be formed as rectangular channels. These nano channels are smooth and with extremely high aspect ratio (~104 depth to width ratio). A possible mechanism is proposed to explain the formation of the nano channels. This laser-based nano channel fabrication technique is fast and inexpensive, and with potential applications in capillary electrophoresis and electro-osmosis driven nano-filtration.

  15. KnockoutJS essentials

    CERN Document Server

    Ferrando, Jorge

    2015-01-01

    If you are a JavaScript developer who has been using DOM manipulation libraries such as Mootools or Scriptaculous, and you want go further in modern JavaScript development with a simple and well-documented library, then this book is for you. Learning how to use Knockout will be perfect as your next step towards building JavaScript applications that respond to user interaction.

  16. Targeted mutagenesis in Atlantic salmon (Salmo salar L. using the CRISPR/Cas9 system induces complete knockout individuals in the F0 generation.

    Directory of Open Access Journals (Sweden)

    Rolf B Edvardsen

    Full Text Available Understanding the biological function behind key proteins is of great concern in Atlantic salmon, both due to a high commercial importance and an interesting life history. Until recently, functional studies in salmonids appeared to be difficult. However, the recent discovery of targeted mutagenesis using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated system enables performing functional studies in Atlantic salmon to a great extent. We used the CRISPR/Cas9 system to target two genes involved in pigmentation, tyrosinase (tyr and solute carrier family 45, member 2 (slc45a2. Embryos were assayed for mutation rates at the 17 somite stage, where 40 and 22% of all injected embryos showed a high degree of mutation induction for slc45a2 and tyr, respectively. At hatching this mutation frequency was also visible for both targeted genes, displaying a graded phenotype ranging from complete lack of pigmentation to partial loss and normal pigmentation. CRISPRslc45a2/Cas9 injected embryos showing a complete lack of pigmentation or just a few spots of pigments also lacked wild type sequences when assaying more than 80 (slc45a2 sequence clones from whole embryos. This indicates that CRISPR/Cas9 can induce double-allelic knockout in the F0 generation. However, types and frequency of indels might affect the phenotype. Therefore, the variation of indels was assayed in the graded pigmentation phenotypes produced by CRISPR/Cas9-slc45a2. The results show a tendency for fewer types of indels formed in juveniles completely lacking pigmentation compared to juveniles displaying partial pigmentation. Another interesting observation was a high degree of the same indel type in different juveniles. This study shows for the first time successful use of the CRISPR/Cas9 technology in a marine cold water species. Targeted double-allelic mutations were obtained and, though the level of mosaicism has to be considered, we demonstrate that F0

  17. Targeted mutagenesis in Atlantic salmon (Salmo salar L.) using the CRISPR/Cas9 system induces complete knockout individuals in the F0 generation.

    Science.gov (United States)

    Edvardsen, Rolf B; Leininger, Sven; Kleppe, Lene; Skaftnesmo, Kai Ove; Wargelius, Anna

    2014-01-01

    Understanding the biological function behind key proteins is of great concern in Atlantic salmon, both due to a high commercial importance and an interesting life history. Until recently, functional studies in salmonids appeared to be difficult. However, the recent discovery of targeted mutagenesis using the CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) system enables performing functional studies in Atlantic salmon to a great extent. We used the CRISPR/Cas9 system to target two genes involved in pigmentation, tyrosinase (tyr) and solute carrier family 45, member 2 (slc45a2). Embryos were assayed for mutation rates at the 17 somite stage, where 40 and 22% of all injected embryos showed a high degree of mutation induction for slc45a2 and tyr, respectively. At hatching this mutation frequency was also visible for both targeted genes, displaying a graded phenotype ranging from complete lack of pigmentation to partial loss and normal pigmentation. CRISPRslc45a2/Cas9 injected embryos showing a complete lack of pigmentation or just a few spots of pigments also lacked wild type sequences when assaying more than 80 (slc45a2) sequence clones from whole embryos. This indicates that CRISPR/Cas9 can induce double-allelic knockout in the F0 generation. However, types and frequency of indels might affect the phenotype. Therefore, the variation of indels was assayed in the graded pigmentation phenotypes produced by CRISPR/Cas9-slc45a2. The results show a tendency for fewer types of indels formed in juveniles completely lacking pigmentation compared to juveniles displaying partial pigmentation. Another interesting observation was a high degree of the same indel type in different juveniles. This study shows for the first time successful use of the CRISPR/Cas9 technology in a marine cold water species. Targeted double-allelic mutations were obtained and, though the level of mosaicism has to be considered, we demonstrate that F0 fish can be used

  18. Ingestion of TRP channel agonists attenuates exercise-induced muscle cramps.

    Science.gov (United States)

    Craighead, Daniel H; Shank, Sean W; Gottschall, Jinger S; Passe, Dennis H; Murray, Bob; Alexander, Lacy M; Kenney, W Larry

    2017-02-13

    Exercise associated muscle cramping (EAMC) is a poorly understood problem that is neuromuscular in origin. Ingestion of transient receptor potential (TRP) channel agonists has been efficacious in attenuating electrically-induced muscle cramps.

  19. Global Nav1.7 knockout mice recapitulate the phenotype of human congenital indifference to pain.

    Directory of Open Access Journals (Sweden)

    Jacinthe Gingras

    Full Text Available Clinical genetic studies have shown that loss of Nav1.7 function leads to the complete loss of acute pain perception. The global deletion is reported lethal in mice, however, and studies of mice with promoter-specific deletions of Nav1.7 have suggested that the role of Nav1.7 in pain transduction depends on the precise form of pain. We developed genetic and animal husbandry strategies that overcame the neonatal-lethal phenotype and enabled construction of a global Nav1.7 knockout mouse. Knockouts were anatomically normal, reached adulthood, and had phenotype wholly analogous to human congenital indifference to pain (CIP: compared to littermates, knockouts showed no defects in mechanical sensitivity or overall movement yet were completely insensitive to painful tactile, thermal, and chemical stimuli and were anosmic. Knockouts also showed no painful behaviors resulting from peripheral injection of nonselective sodium channel activators, did not develop complete Freund's adjuvant-induced thermal hyperalgesia, and were insensitive to intra-dermal histamine injection. Tetrodotoxin-sensitive sodium current recorded from cell bodies of isolated sensory neurons and the mechanically-evoked spiking of C-fibers in a skin-nerve preparation each were reduced but not eliminated in tissue from knockouts compared to littermates. Results support a role for Nav1.7 that is conserved between rodents and humans and suggest several possibly translatable biomarkers for the study of Nav1.7-targeted therapeutics. Results further suggest that Nav1.7 may retain its key role in persistent as well as acute forms of pain.

  20. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias.

    Science.gov (United States)

    Cubeddu, Luigi X

    2016-01-01

    Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.

  1. Scorpion Toxin, BmP01, Induces Pain by Targeting TRPV1 Channel.

    Science.gov (United States)

    Hakim, Md Abdul; Jiang, Wenbin; Luo, Lei; Li, Bowen; Yang, Shilong; Song, Yuzhu; Lai, Ren

    2015-09-14

    The intense pain induced by scorpion sting is a frequent clinical manifestation. To date, there is no established protocol with significant efficacy to alleviate the pain induced by scorpion envenomation. One of the important reasons is that, little information on pain-inducing compound from scorpion venoms is available. Here, a pain-inducing peptide (BmP01) has been identified and characterized from the venoms of scorpion (Mesobuthus martensii). In an animal model, intraplantar injection of BmP01 in mouse hind paw showed significant acute pain in wild type (WT) mice but not in TRPV1 knock-out (TRPV1 KO) mice during 30 min recording. BmP01 evoked currents in WT dorsal root ganglion (DRG) neurons but had no effect on DRG neurons of TRPV1 KO mice. Furthermore, OPEN ACCESS Toxins 2015, 7 3672 BmP01 evoked currents on TRPV1-expressed HEK293T cells, but not on HEK293T cells without TRPV1. These results suggest that (1) BmP01 is one of the pain-inducing agents in scorpion venoms; and (2) BmP01 induces pain by acting on TRPV1. To our knowledge, this is the first report about a scorpion toxin that produces pain by targeting TRPV1. Identification of a pain-inducing compound may facilitate treating pain induced by scorpion envenomation.

  2. Cluster knockout reactions

    Indian Academy of Sciences (India)

    Arun K Jain; B N Joshi

    2014-04-01

    Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile–cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (, 2) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.

  3. Highly Selective Artificial K(+) Channels: An Example of Selectivity-Induced Transmembrane Potential.

    Science.gov (United States)

    Gilles, Arnaud; Barboiu, Mihail

    2016-01-13

    Natural KcsA K(+) channels conduct at high rates with an extraordinary selectivity for K(+) cations, excluding the Na(+) or other cations. Biomimetic artificial channels have been designed in order to mimick the ionic activity of KcSA channels, but simple artificial systems presenting high K(+)/Na(+) selectivity are rare. Here we report an artificial ion channel of H-bonded hexyl-benzoureido-15-crown-5-ether, where K(+) cations are highly preferred to Na(+) cations. The K(+)-channel conductance is interpreted as arising in the formation of oligomeric highly cooperative channels, resulting in the cation-induced membrane polarization and enhanced transport rates without or under pH-active gradient. These channels are selectively responsive to the presence of K(+) cations, even in the presence of a large excess of Na(+). From the conceptual point of view, these channels express a synergistic adaptive behavior: the addition of the K(+) cation drives the selection and the construction of constitutional polarized ion channels toward the selective conduction of the K(+) cation that promotes their generation in the first place.

  4. Non-selective cation channels mediate chloroquine-induced relaxation in precontracted mouse airway smooth muscle.

    Directory of Open Access Journals (Sweden)

    Ting Zhang

    Full Text Available Bitter tastants can induce relaxation in precontracted airway smooth muscle by activating big-conductance potassium channels (BKs or by inactivating voltage-dependent L-type Ca2+ channels (VDLCCs. In this study, a new pathway for bitter tastant-induced relaxation was defined and investigated. We found nifedipine-insensitive and bitter tastant chloroquine-sensitive relaxation in epithelium-denuded mouse tracheal rings (TRs precontracted with acetylcholine (ACH. In the presence of nifedipine (10 µM, ACH induced cytosolic Ca2+ elevation and cell shortening in single airway smooth muscle cells (ASMCs, and these changes were inhibited by chloroquine. In TRs, ACH triggered a transient contraction under Ca2+-free conditions, and, following a restoration of Ca2+, a strong contraction occurred, which was inhibited by chloroquine. Moreover, the ACH-activated whole-cell and single channel currents of non-selective cation channels (NSCCs were blocked by chloroquine. Pyrazole 3 (Pyr3, an inhibitor of transient receptor potential C3 (TRPC3 channels, partially inhibited ACH-induced contraction, intracellular Ca2+ elevation, and NSCC currents. These results demonstrate that NSCCs play a role in bitter tastant-induced relaxation in precontracted airway smooth muscle.

  5. Involvement of anion channels in mediating elicitor-induced ATP efflux in Salvia miltiorrhiza hairy roots.

    Science.gov (United States)

    Wu, Shu-Jing; Siu, Ka-Chai; Wu, Jian-Yong

    2011-01-15

    This study examines the roles of anion channels and ATP binding cassette (ABC) protein transporters in mediating elicitor-induced ATP release in Salvia miltiorrhiza hairy root cultures. The elicitor-induced ATP release was effectively blocked by two putative membrane anion channel blockers, niflumic acid and Zn(2+), but not by a specific Cl(-) channel blocker, phenylanthranilic acid. The elicitor-induced ATP release was also significantly suppressed by two ABC inhibitors, glibenclamide and ethacrynic acid. Notable ATP release from the hairy roots was also induced by verapamil (2mM), an ABC activator in animal cells. The verapamil-induced ATP release was effectively blocked by niflumic acid, but only slightly inhibited by the ABC inhibitors. Another notable effect of verapamil was the induction of exocytosis, the secretion of vesicle-like particles to the root surface. The verapamil-induced exocytosis was not inhibited by nifulumic acid and YE did not induce the exocytosis. Overall, the results suggest a significant role of anion channels, a possible involvement of ABC proteins and no significant involvement of exocytosis in mediating the ATP efflux in hairy root cells.

  6. Activation of TRPC6 Channels Is Essential for Lung Ischaemia–Reperfusion Induced Oedema in Mice

    OpenAIRE

    Weissmann, Norbert; Sydykov, Akylbek; Kalwa, Hermann; Storch, Ursula; Fuchs, Beate; Mederos y Schnitzler, Michael; Ralf P Brandes; Grimminger, Friedrich; Meissner, Marcel; Freichel, Marc; Offermanns, Stefan; Veit, Florian; Pak, Oleg; Krause, Karl-Heinz; Schermuly, Ralph T.

    2012-01-01

    Lung ischaemia–reperfusion-induced oedema (LIRE) is a life-threatening condition that causes pulmonary oedema induced by endothelial dysfunction. Here we show that lungs from mice lacking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2\\(^{y/−}\\)) or the classical transient receptor potential channel 6 TRPC6\\(^{−/-}\\) are protected from LIR-induced oedema (LIRE). Generation of chimeric mice by bone marrow cell transplantation and endothelial-specific Nox2 deletion showed that...

  7. Opposing Shear-Induced Forces Dominate Inertial Focusing in Curved Channels and High Reynolds Numbers

    CERN Document Server

    Keinan, Eliezer; Nahmias, Yaakov

    2015-01-01

    Inertial focusing is the migration of particles in fluid toward equilibrium, where current theory predicts that shear-induced and wall-induced lift forces are balanced. First reported in 1961, this Segre-Silberberg effect is particularly useful for microfluidic isolation of cells and particles. Interestingly, recent work demonstrated particle focusing at high Reynolds numbers that cannot be explained by current theory. In this work, we show that non-monotonous velocity profiles, such as those developed in curved channels, create peripheral velocity maxima around which opposing shear-induced forces dominate over wall effects. Similarly, entry effects amplified in high Reynolds flow produce an equivalent trapping mechanism in short, straight channels. This new focusing mechanism in the developing flow regime enables a 10-fold miniaturization of inertial focusing devices, while our model corrects long-standing misconceptions about the nature of mechanical forces governing inertial focusing in curved channels.

  8. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    Science.gov (United States)

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-05

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel.

  9. Open channel flows of magnetic fluid induced by traveling magnetic field

    Science.gov (United States)

    Kuwahara, Takuya; Okubo, Masaaki; Yamane, Ryuichiro

    A theoretical analysis is made on laminar open channel flows of magnetic fluid induced by a non uniform traveling magnetic field which is applied with a stator of a single-sided linear induction motor. The induced flows are mainly in the direction opposite to the traveling direction of the magnetic field and in proportion to the phase velocity of the magnetic field. The velocity profiles are greatly affected by dimensionless wave number of the magnetic field. Near the bottom of the channel, the theoretical velocity distributions agree well with experimental ones which are measured with a laser optical fiber velocity sensor. However, the experimental velocity distributions become larger near the free surface.

  10. Stretch-activated channels in stretch-induced muscle damage: role in muscular dystrophy.

    Science.gov (United States)

    Yeung, Ella W; Allen, David G

    2004-08-01

    1. Stretch-induced muscle injury results in the damage that causes reduced force and increased membrane permeability. This muscle damage is caused, in part, by ionic entry through stretch-activated channels and blocking these channels with Gd3+ or streptomycin reduces the force deficit associated with damage. 2. Dystrophin-deficient muscles are more susceptible to stretch-induced muscle injury and the recovery from injury can be incomplete. We have found that Na+ entry associated with stretch-induced injury is enhanced in dystrophin-deficient muscles and that blockers of stretch-activated channels are capable of preventing ionic entry and reducing muscle damage. 3. A model is presented that proposes links between stretch-induced injury, opening of stretch-activated channels, increased levels of intracellular ions and various forms of muscle damage. Although changes in Na+ accompany stretch-induced muscle injury, we believe that changes in Ca2+ probably have a more central role in the damage process.

  11. Lack of transient receptor potential vanilloid 1 channel modulates the development of neurogenic bladder dysfunction induced by cross-sensitization in afferent pathways

    Directory of Open Access Journals (Sweden)

    Lei Qi

    2013-01-01

    Full Text Available Abstract Background Bladder pain of unknown etiology has been associated with co-morbid conditions and functional abnormalities in neighboring pelvic organs. Mechanisms underlying pain co-morbidities include cross-sensitization, which occurs predominantly via convergent neural pathways connecting distinct pelvic organs. Our previous results showed that colonic inflammation caused detrusor instability via activation of transient receptor potential vanilloid 1 (TRPV1 signaling pathways, therefore, we aimed to determine whether neurogenic bladder dysfunction can develop in the absence of TRPV1 receptors. Methods Adult male C57BL/6 wild-type (WT and TRPV1−/− (knockout mice were used in this study. Colonic inflammation was induced by intracolonic trinitrobenzene sulfonic acid (TNBS. The effects of transient colitis on abdominal sensitivity and function of the urinary bladder were evaluated by cystometry, contractility and relaxation of detrusor smooth muscle (DSM in vitro to various stimuli, gene and protein expression of voltage-gated sodium channels in bladder sensory neurons, and pelvic responses to mechanical stimulation. Results Knockout of TRPV1 gene did not eliminate the development of cross-sensitization between the colon and urinary bladder. However, TRPV1−/− mice had prolonged intermicturition interval and increased number of non-voiding contractions at baseline followed by reduced urodynamic responses during active colitis. Contractility of DSM was up-regulated in response to KCl in TRPV1−/− mice with inflamed colon. Application of Rho-kinase inhibitor caused relaxation of DSM in WT but not in TRPV1−/− mice during colonic inflammation. TRPV1−/− mice demonstrated blunted effects of TNBS-induced colitis on expression and function of voltage-gated sodium channels in bladder sensory neurons, and delayed development of abdominal hypersensitivity upon colon-bladder cross-talk in genetically modified animals. Conclusions The

  12. [Kv3.4 channel is involved in rat pulmonary vasoconstriction induced by 15-hydroxyeicosatetraenoic acid].

    Science.gov (United States)

    Li, Qian; Bi, Hai-Rong; Zhang, Rong; Zhu, Da-Ling

    2006-02-25

    We have reported that hypoxia increases the activation of 15-lipoxygenase (15-LO), which converts arachidonic acid (AA) into 15-hydroxyeicosatetraenoic acid (15-HETE) in small pulmonary arteries (PAs). Through inhibition of Kv channels, 15-HETE causes more robust concentration-dependent contraction of PA rings from the hypoxic compared to the normoxic controls. However, the subtypes of Kv channels inhibited by 15-HETE are incompletely understood. The aim of the present study was to identify the contribution of Kv3.4 channel in the process of pulmonary vasoconstriction induced by 15-HETE using the tension studies of PA rings from rat with Kv3.4 channel blocker in tissue bath; to explore the role of vascular endothelium in15-HETE-induced pulmonary vasoconstriction through denuded endothelia of PA rings; and to define the downregulation of 15-HETE on the expression of Kv3.4 channel in cultured pulmonary artery smooth muscle cells (PASMCs) with RT-PCR and Western blot. In the present study, healthy Wistar rats were divided randomly into two groups: Group A with normal oxygen supply and group B with hypoxia. Six days later, the rats were killed. Pulmonary artery rings were prepared for organ bath experiments. Firstly, different concentrations of 15-HETE (10~1 000 nmol/L) were added to the Krebs solution. The isometric tension was recorded using a four-channel force-displacement transducer. Then Kv3.4 channel blocker, 100 nmol/L BDS-I, was added, followed by adding 1 mumol/L 15-HETE, and the isometric tension was recorded. Furthermore, RT-PCR and Western blot were employed to identify the influence of 15-HETE on the expression of Kv3.4 channel in cultured rat PASMCs.The results showed the PA tension was significantly increased both in groups A and B by 15-HETE in a concentration-dependent manner (PKv3.4 channel blocker, BDS-I, significantly decreased the PA ring constriction induced by 15-HETE (PKv3.4 mRNA and protein in rat PASMCs were significantly downregulated by 15

  13. A Novel Statistical Channel Model for Turbulence-Induced Fading in Free-Space Optical Systems

    CERN Document Server

    Aminikashani, Mohammadreza; Kavehrad, Mohsen

    2015-01-01

    In this paper, we propose a new probability distribution function which accurately describes turbulence-induced fading under a wide range of turbulence conditions. The proposed model, termed Double Generalized Gamma (Double GG), is based on a doubly stochastic theory of scintillation and developed via the product of two Generalized Gamma (GG) distributions. The proposed Double GG distribution generalizes many existing turbulence channel models and provides an excellent fit to the published plane and spherical waves simulation data. Using this new statistical channel model, we derive closed form expressions for the outage probability and the average bit error as well as corresponding asymptotic expressions of free-space optical communication systems over turbulence channels. We demonstrate that our derived expressions cover many existing results in the literature earlier reported for Gamma-Gamma, Double-Weibull and K channels as special cases.

  14. Calcium channel antagonists increase morphine-induced analgesia and antagonize morphine tolerance.

    Science.gov (United States)

    Contreras, E; Tamayo, L; Amigo, M

    1988-04-13

    The influence of calcium channel blockers on morphine-induced analgesia and on tolerance to the chronic administration of the opiate was investigated in mice. The effects of a test dose of morphine were significantly increased by the administration of diltiazem, flunarizine, nicardipine and verapamil. In contrast, nifedipine induced an antagonistic effect. The calcium channel antagonists did not change the reaction time to thermal stimulation in mice (hot plate test). The administration of nifedipine, flunarizine and verapamil reduced the intensity of the tolerance induced by a single dose of morphine administered in a slow release preparation. Diltiazem induced a non-significant decrease of the process. The present results are in accordance with the known interaction of acute and chronic morphine administration with the intracellular calcium concentration in neurones of the central nervous system.

  15. Role of ATP-sensitive potassium channels in the piracetam induced blockade of opioid effects.

    Science.gov (United States)

    Rehni, Ashish K; Singh, Nirmal; Jindal, Seema

    2007-12-01

    The present study has been designed to investigate the effect of piracetam on morphine/ buprenorphine-induced antinociception in rats and effect of piracetam on morphine or minoxidil induced relaxation in KCl-precontracted isolated rat aortic ring preparation. Nociceptive threshold was measured by the tail flick test in rats. The cumulative dose responses of morphine or minoxidil were recorded in KCl-precontracted isolated rat aortic ring preparation. Piracetam attenuated buprenorphine-induced antinociception in rats. Piracetam significantly reduced the morphine and minoxidil induced relaxation in KCl precontracted isolated rat aortic ring preparation suggesting that piracetam interferes with opioid receptor and ATP-sensitive potassium channel (KATP) opener mediated responses in vitro. Thus, it may be suggested that piracetam attenuates opioid effects by an opioid receptor-KATP channel linked mechanism.

  16. Proces-based modeling of the overflow induced growth of erosional channels

    NARCIS (Netherlands)

    Tuan, T.Q.; Stive, M.J.F.; Verhagen, H.J.; Visser, P.J.

    2008-01-01

    A new process-based approach is introduced for a more efficient computation of the overflow-induced growth of an erosional channel in a noncohesive homogeneous narrow landmass such as the breach growth in a sand-dike. The approach is easy to incorporate in a 1D/2DV morphodynamic model to compute the

  17. Role of TRPV1 channels in ischemia/reperfusion-induced acute kidney injury.

    Directory of Open Access Journals (Sweden)

    Lan Chen

    Full Text Available OBJECTIVES: Transient receptor potential vanilloid 1 (TRPV1 -positive sensory nerves are widely distributed in the kidney, suggesting that TRPV1-mediated action may participate in the regulation of renal function under pathophysiological conditions. Stimulation of TRPV1 channels protects against ischemia/reperfusion (I/R-induced acute kidney injury (AKI. However, it is unknown whether inhibition of these channels is detrimental in AKI or not. We tested the role of TRPV1 channels in I/R-induced AKI by modulating these channels with capsaicin (TRPV1 agonist, capsazepine (TRPV1 antagonist and using Trpv1-/- mice. METHODS AND RESULTS: Anesthetized C57BL/6 mice were subjected to 25 min of renal ischemia and 24 hrs of reperfusion. Mice were pretreated with capsaicin (0.3 mg/kg body weight or capsazepine (50 mg/kg body weight. Capsaicin ameliorated the outcome of AKI, as measured by serum creatinine levels, tubular damage,neutrophil gelatinase-associated lipocalin (NGAL abundance and Ly-6B.2 positive polymorphonuclear inflammatory cells in injured kidneys. Neither capsazepine nor deficiency of TRPV1 did deteriorate renal function or histology after AKI. Measurements of endovanilloids in kidney tissue indicate that 20-hydroxyeicosatetraeonic acid (20-HETE or epoxyeicosatrienoic acids (EETs are unlikely involved in the beneficial effects of capsaicin on I/R-induced AKI. CONCLUSIONS: Activation of TRPV1 channels ameliorates I/R-induced AKI, but inhibition of these channels does not affect the outcome of AKI. Our results may have clinical implications for long-term safety of renal denervation to treat resistant hypertension in man, with respect to the function of primary sensory nerves in the response of the kidney to ischemic stimuli.

  18. Proline-induced hinges in transmembrane helices: possible roles in ion channel gating.

    Science.gov (United States)

    Tieleman, D P; Shrivastava, I H; Ulmschneider, M R; Sansom, M S

    2001-08-01

    A number of ion channels contain transmembrane (TM) alpha-helices that contain proline-induced molecular hinges. These TM helices include the channel-forming peptide alamethicin (Alm), the S6 helix from voltage-gated potassium (Kv) channels, and the D5 helix from voltage-gated chloride (CLC) channels. For both Alm and KvS6, experimental data implicate hinge-bending motions of the helix in an aspect of channel gating. We have compared the hinge-bending motions of these TM helices in bilayer-like environments by multi-nanosecond MD simulations in an attempt to describe motions of these helices that may underlie possible modes of channel gating. Alm is an alpha-helical channel-forming peptide, which contains a central kink associated with a Gly-x-x-Pro motif in its sequence. Simulations of Alm in a TM orientation for 10 ns in an octane slab indicate that the Gly-x-x-Pro motif acts as a molecular hinge. The S6 helix from Shaker Kv channels contains a Pro-Val-Pro motif. Modeling studies and recent experimental data suggest that the KvS6 helix may be kinked in the vicinity of this motif. Simulations (10 ns) of an isolated KvS6 helix in an octane slab and in a POPC bilayer reveal hinge-bending motions. A pattern-matching approach was used to search for possible hinge-bending motifs in the TM helices of other ion channel proteins. This uncovered a conserved Gly-x-Pro motif in TM helix D5 of CLC channels. MD simulations of a model of hCLC1-D5 spanning an octane slab suggest that this channel also contains a TM helix that undergoes hinge-bending motion. In conclusion, our simulations suggest a model in which hinge-bending motions of TM helices may play a functional role in the gating mechanisms of several different families of ion channels.

  19. Hyperglycemia Induced by Glucokinase Deficiency Accelerates Atherosclerosis Development and Impairs Lesion Regression in Combined Heterozygous Glucokinase and the Apolipoprotein E-Knockout Mice

    Science.gov (United States)

    Adingupu, Damilola D.; Andréasson, Anne-Christine; Ahnmark, Andrea

    2016-01-01

    Aim. Models combining diabetes and atherosclerosis are important in evaluating the cardiovascular (CV) effects and safety of antidiabetes drugs in the development of treatments targeting CV complications. Our aim was to evaluate if crossing the heterozygous glucokinase knockout mouse (GK+/−) and hyperlipidemic mouse deficient in apolipoprotein E (ApoE−/−) will generate a disease model exhibiting a diabetic and macrovascular phenotype. Methods. The effects of defective glucokinase on the glucose metabolism and on the progression and regression of atherosclerosis on high-fat diets were studied in both genders of GK+/−ApoE−/− and ApoE−/− mice. Coronary vascular function of the female GK+/−ApoE−/− and ApoE−/− mice was also investigated. Results. GK+/−ApoE−/− mice show a stable hyperglycemia which was increased on Western diet. In oral glucose tolerance test, GK+/−ApoE−/− mice showed significant glucose intolerance and impaired glucose-stimulated insulin secretion. Plasma lipids were comparable with ApoE−/− mice; nevertheless the GK+/−ApoE−/− mice showed slightly increased atherosclerosis development. Conclusions. The GK+/−ApoE−/− mice showed a stable and reproducible hyperglycemia, accelerated atherosclerotic lesion progression, and no lesion regression after lipid lowering. This novel model provides a promising tool for drug discovery, enabling the evaluation of compound effects against both diabetic and cardiovascular endpoints simultaneously in one animal model.

  20. Increased anion channel activity is an unavoidable event in ozone-induced programmed cell death.

    Directory of Open Access Journals (Sweden)

    Takashi Kadono

    Full Text Available BACKGROUND: Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. PRINCIPAL FINDINGS: By exposing cells to a strong pulse of ozonized air, an acute cell death was observed in suspension cells of Arabidopsis thaliana used as a model. We demonstrated that O(3 treatment induced the activation of a plasma membrane anion channel that is an early prerequisite of O(3-induced cell death in A. thaliana. Our data further suggest interplay of anion channel activation with well known plant responses to O(3, Ca(2+ influx and NADPH-oxidase generated reactive oxygen species (ROS in mediating the oxidative cell death. This interplay might be fuelled by several mechanisms in addition to the direct ROS generation by O(3; namely, H(2O(2 generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death. SIGNIFICANCE: Collectively, our data indicate that anion efflux is an early key component of morphological and biochemical events leading to O(3-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation.

  1. Microglial Hv1 proton channel promotes cuprizone-induced demyelination through oxidative damage.

    Science.gov (United States)

    Liu, Junli; Tian, Daishi; Murugan, Madhuvika; Eyo, Ukpong B; Dreyfus, Cheryl F; Wang, Wei; Wu, Long-Jun

    2015-10-01

    NADPH oxidase (NOX)-dependent reactive oxygen species (ROS) production in inflammatory cells including microglia plays an important role in demyelination and free radical-mediated tissue injury in multiple sclerosis (MS). However, the mechanism underlying microglial ROS production and demyelination remains largely unknown. The voltage-gated proton channel, Hv1, is selectively expressed in microglia and is required for NOX-dependent ROS generation in the brain. In the present study, we sought to determine the role of microglial Hv1 proton channels in a mouse model of cuprizone-induced demyelination, a model for MS. Following cuprizone exposure, wild-type mice presented obvious demyelination, decreased myelin basic protein expression, loss of mature oligodendrocytes, and impaired motor coordination in comparison to mice on a normal chow diet. However, mice lacking Hv1 (Hv1(-/-) ) are partially protected from demyelination and motor deficits compared with those in wild-type mice. These rescued phenotypes in Hv1(-/-) mice in cuprizone-induced demyelination is accompanied by reduced ROS production, ameliorated microglial activation, increased oligodendrocyte progenitor cell (NG2) proliferation, and increased number of mature oligodendrocytes. These results demonstrate that the Hv1 proton channel is required for cuprizone-induced microglial oxidative damage and subsequent demyelination. Our study suggests that the microglial Hv1 proton channel is a unique target for controlling NOX-dependent ROS production in the pathogenesis of MS.

  2. Dihydropyridine type calcium channel blocker-induced turbid dialysate in patients undergoing peritoneal dialysis.

    Science.gov (United States)

    Yoshimoto, K; Saima, S; Nakamura, Y; Nakayama, M; Kubo, H; Kawaguchi, Y; Nishitani, H; Nakamura, Y; Yasui, A; Yokoyama, K; Kuriyama, S; Shirai, D; Kugiyama, A; Hayano, K; Fukui, H; Horigome, I; Amagasaki, Y; Tsubakihara, Y; Kamekawa, T; Ando, R; Tomura, S; Okamoto, R; Miwa, S; Koyama, T; Echizen, H

    1998-08-01

    We previously reported that manidipine, a new dihydropyridine type calcium channel blocker, produced chylous peritoneal dialysate being visually indistinguishable from infective peritonitis in 5 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) [Yoshimoto et al. 1993]. To study whether such an adverse drug reaction would also be elicited by other commonly prescribed calcium channel blockers in CAPD patients, we have conducted postal inquiry to 15 collaborating hospitals and an institutional survey in International Medical Center of Japan as to the possible occurrence of calcium channel blocker-associated non-infective, turbid peritoneal dialysate in CAPD patients. Our diagnostic criteria for drug-induced turbidity of dialysate as a) it developed within 48 h after the administration of a newly introduced calcium channel blocker to the therapeutic regimen, b) absence of clinical symptoms of peritoneal inflammation (i.e., pyrexia, abdominal pain, nausea or vomiting), c) the fluid containing normal leukocyte counts and being negative for bacterial and fungal culture of the fluid, and d) it disappeared shortly after the withdrawal of the assumed causative agent. Results showed that 19 out of 251 CAPD patients given one of the calcium channel blockers developed non-infective turbid peritoneal dialysis that fulfilled all the above criteria. Four calcium channel blockers were suspected to be associated with the events: benidipine [2 out of 2 (100%) patients given the drug], manidipine [15 out of 36 (42%) patients], nisoldipine [1 out of 11 (9%) patients] and nifedipine [1 out of 159 (0.6%)] in descending order of frequency. None of the patients who received nicardipine, nilvadipine, nitrendipine, barnidipine and diltiazem (25, 7, 2, 1 and 8 patients, respectively) exhibited turbid dialysate. In conclusion, we consider that certain dihydropyridine type calcium channel blockers would cause turbid peritoneal dialysate being similar to that observed in

  3. Lack of GDAP1 induces neuronal calcium and mitochondrial defects in a knockout mouse model of charcot-marie-tooth neuropathy.

    Science.gov (United States)

    Barneo-Muñoz, Manuela; Juárez, Paula; Civera-Tregón, Azahara; Yndriago, Laura; Pla-Martin, David; Zenker, Jennifer; Cuevas-Martín, Carmen; Estela, Anna; Sánchez-Aragó, María; Forteza-Vila, Jerónimo; Cuezva, José M; Chrast, Roman; Palau, Francesc

    2015-04-01

    Mutations in GDAP1, which encodes protein located in the mitochondrial outer membrane, cause axonal recessive (AR-CMT2), axonal dominant (CMT2K) and demyelinating recessive (CMT4A) forms of Charcot-Marie-Tooth (CMT) neuropathy. Loss of function recessive mutations in GDAP1 are associated with decreased mitochondrial fission activity, while dominant mutations result in impairment of mitochondrial fusion with increased production of reactive oxygen species and susceptibility to apoptotic stimuli. GDAP1 silencing in vitro reduces Ca2+ inflow through store-operated Ca2+ entry (SOCE) upon mobilization of endoplasmic reticulum (ER) Ca2+, likely in association with an abnormal distribution of the mitochondrial network. To investigate the functional consequences of lack of GDAP1 in vivo, we generated a Gdap1 knockout mouse. The affected animals presented abnormal motor behavior starting at the age of 3 months. Electrophysiological and biochemical studies confirmed the axonal nature of the neuropathy whereas histopathological studies over time showed progressive loss of motor neurons (MNs) in the anterior horn of the spinal cord and defects in neuromuscular junctions. Analyses of cultured embryonic MNs and adult dorsal root ganglia neurons from affected animals demonstrated large and defective mitochondria, changes in the ER cisternae, reduced acetylation of cytoskeletal α-tubulin and increased autophagy vesicles. Importantly, MNs showed reduced cytosolic calcium and SOCE response. The development and characterization of the GDAP1 neuropathy mice model thus revealed that some of the pathophysiological changes present in axonal recessive form of the GDAP1-related CMT might be the consequence of changes in the mitochondrial network biology and mitochondria-endoplasmic reticulum interaction leading to abnormalities in calcium homeostasis.

  4. Lack of GDAP1 induces neuronal calcium and mitochondrial defects in a knockout mouse model of charcot-marie-tooth neuropathy.

    Directory of Open Access Journals (Sweden)

    Manuela Barneo-Muñoz

    2015-04-01

    Full Text Available Mutations in GDAP1, which encodes protein located in the mitochondrial outer membrane, cause axonal recessive (AR-CMT2, axonal dominant (CMT2K and demyelinating recessive (CMT4A forms of Charcot-Marie-Tooth (CMT neuropathy. Loss of function recessive mutations in GDAP1 are associated with decreased mitochondrial fission activity, while dominant mutations result in impairment of mitochondrial fusion with increased production of reactive oxygen species and susceptibility to apoptotic stimuli. GDAP1 silencing in vitro reduces Ca2+ inflow through store-operated Ca2+ entry (SOCE upon mobilization of endoplasmic reticulum (ER Ca2+, likely in association with an abnormal distribution of the mitochondrial network. To investigate the functional consequences of lack of GDAP1 in vivo, we generated a Gdap1 knockout mouse. The affected animals presented abnormal motor behavior starting at the age of 3 months. Electrophysiological and biochemical studies confirmed the axonal nature of the neuropathy whereas histopathological studies over time showed progressive loss of motor neurons (MNs in the anterior horn of the spinal cord and defects in neuromuscular junctions. Analyses of cultured embryonic MNs and adult dorsal root ganglia neurons from affected animals demonstrated large and defective mitochondria, changes in the ER cisternae, reduced acetylation of cytoskeletal α-tubulin and increased autophagy vesicles. Importantly, MNs showed reduced cytosolic calcium and SOCE response. The development and characterization of the GDAP1 neuropathy mice model thus revealed that some of the pathophysiological changes present in axonal recessive form of the GDAP1-related CMT might be the consequence of changes in the mitochondrial network biology and mitochondria-endoplasmic reticulum interaction leading to abnormalities in calcium homeostasis.

  5. Identical synchronization of chaotic secure communication systems with channel induced coherence resonance

    Science.gov (United States)

    Sepantaie, Marc M.; Namazi, Nader M.; Sepantaie, Amir M.

    2016-05-01

    This paper is devoted to addressing the synchronization, and detection of random binary data exposed to inherent channel variations existing in Free Space Optical (FSO) communication systems. This task is achieved by utilizing the identical synchronization methodology of Lorenz chaotic communication system, and its synergetic interaction in adversities imposed by the FSO channel. Moreover, the Lorenz system has been analyzed, and revealed to induce Stochastic Resonance (SR) once exposed to Additive White Gaussian Noise (AWGN). In particular, the resiliency of the Lorenz chaotic system, in light of channel adversities, has been attributed to the success of the proposed communication system. Furthermore, this paper advocates the use of Haar wavelet transform for enhanced detection capability of the proposed chaotic communication system, which utilizes Chaotic Parameter Modulation (CPM) technique for means of transmission.

  6. Activation of the KCa3.1 channel contributes to traumatic scratch injury-induced reactive astrogliosis through the JNK/c-Jun signaling pathway.

    Science.gov (United States)

    Yi, Mengni; Dou, Fangfang; Lu, Qin; Yu, Zhihua; Chen, Hongzhuan

    2016-06-15

    Reactive astrogliosis is widely considered to contribute to pathogenic responses to stress and brain injury and to diseases as diverse as ischemia and neurodegeneration. We previously found that expression of the intermediate-conductance calcium-activated potassium channel (KCa3.1) involved in TGF-β-activated astrogliosis. In the present study, we investigated whether migration of cortical astrocytes following mechanical scratch injury involves the KCa3.1 channel, which contributes to Ca(2+)-mediated migration in other cells. We found that scratch injury increased the expression of KCa3.1 protein in reactive astrocytes. Application of the KCa3.1 blocker TRAM-34 decreased glial fibrillary acidic protein (GFAP) expression and slowed migration in a concentration-dependent manner. Application of the Ca(2+) chelators, EGTA and BAPTA-AM, also slowed the migration of astrocytes. Blockade or genetic deletion of KCa3.1 both slowed and dramatically reduced the scratch injuries induced the sharp rise in astrocytes Ca(2+) concentrations. The scratch injury-induced phosphorylation of JNK and c-Jun proteins was also attenuated both by blockade of KCa3.1 with TRAM-34 and in KCa3.1(-/-) astrocytes. Using KCa3.1 knockout mice, we further confirmed that deletion of KCa3.1 reduced expression of GFAP in an in vivo stab wound model. Taken together, our findings highlight a novel role for KCa3.1 in phenotypic modulation of reactive astrocytes and in astrocyte mobilization in response to mechanical stress, providing a potential target for therapeutic intervention in brain injuries.

  7. Niflumic acid, a TRPV1 channel modulator, ameliorates stavudine-induced neuropathic pain.

    Science.gov (United States)

    Marwaha, Lovish; Bansal, Yashika; Singh, Raghunath; Saroj, Priyanka; Sodhi, Rupinder Kaur; Kuhad, Anurag

    2016-12-01

    TRP channels have been discovered as a specialized group of somatosensory neurons involved in the detection of noxious stimuli. Desensitization of TRPV1 located on dorsal root and trigeminal ganglia exhibits analgesic effect and makes it potential therapeutic target for treatment of neuropathic pain. With this background, the present study was aimed to investigate the protective effect of niflumic acid, a TRPV1 modulator, on stavudine (STV)-induced neuropathic pain in rats. Stavudine (50 mg/kg) was administered intravenously via tail vein in rats to induce neuropathic pain. Various behavioral tests were performed to access neuropathic pain (hyperalgesia and allodynia) on 7th, 14th, 21st, and 28th days. Electrophysiology (motor nerve conduction velocity; MNCV) and biochemical estimations were conducted after 28th day. Niflumic acid (10, 15, and 20 mg/kg) was administered intraperitoneally and evaluated against behavioral, electrophysiological (MNCV), and biochemical alterations in stavudine-treated rats. Pregabalin (30 mg/kg) was taken as reference standard and administered intraperitoneally. Four weeks after stavudine injection, rats developed behavioral, electrophysiological (MNCV), and biochemical (oxidative, nitrosative stress, and inflammatory cytokines, TRPV1) alterations. Niflumic acid restored core and associated symptoms of peripheral neuropathy by suppressing oxidative-nitrosative stress, inflammatory cytokines (TNF-α, IL-1β) and TRPV1 level in stavudine-induced neuropathic pain in rats. Pharmacological efficacy of niflumic acid (20 mg/kg) was equivalent to pregabalin (30 mg/kg). In conclusion, niflumic acid attenuates STV-induced behavioral, electrophysiological and biochemical alterations by manipulating TRP channel activity in two manners: (1) direct antagonistic action against TRPV1 channels and (2) indirect inhibition of TRP channels by blocking oxidative and inflammatory surge. Therefore, NA can be developed as a potential pharmacotherapeutic

  8. KCNN4 channels participate in the EMT induced by PRL-3 in colorectal cancer.

    Science.gov (United States)

    Lai, Wei; Liu, Lu; Zeng, Yujie; Wu, Heng; Xu, Heyang; Chen, Shuang; Chu, Zhonghua

    2013-01-01

    Studies have shown that phosphatase of regenerating liver-3 (PRL-3) promotes the invasion, migration, and metastasis of human tumor cells by facilitating an epithelial-mesenchymal transition (EMT). However, the mechanism by which PRL-3 induces tumor cell EMT is unknown. Our previous research revealed that PRL-3 promotes LoVo cell proliferation by up-regulating KCNN4 channels. In the current study, we explored the mechanism by which PRL-3 mediates EMT. We demonstrated that PRL-3 induced the expression of KCNN4 channels, leading to EMT and the down-regulation of E-cadherin. Further studies revealed that KCNN4 channels increased intracellular calcium levels and activated components of cell signaling downstream of calcium, including CaM-kinase II and glycogen synthase kinase-3 beta (GSK-3 beta), which increased Snail expression. Inhibiting KCNN4 with siRNA and TRAM-34, a specific inhibitor, restored E-cadherin expression and inhibited Snail expression. These results implicated the up-regulation of KCNN4 channels in the PRL-3-mediated induction of EMT and promotion of cancer metastasis.

  9. A DOUBLE KNOCKOUT; A NOVEL APPROACH TO UNDERSTANDING STRESS-INDUCIBLE 70 KDA HEAT SHOCK PROTEINS (HSP70S) ON DEVELOPMENT AND REPRODUCTION

    Science.gov (United States)

    Heat and chemical toxicants which disrupt spermatogenesis and cause male infertility are thought to induce the expression of Hsp70-1 and 70-3, the major inducible heat shock proteins of the 70kDa family. Previous studies from several laboratories including our own have characteri...

  10. Inhibition by acrolein of light-induced stomatal opening through inhibition of inward-rectifying potassium channels in Arabidopsis thaliana.

    Science.gov (United States)

    Islam, Md Moshiul; Ye, Wenxiu; Matsushima, Daiki; Khokon, Md Atiqur Rahman; Munemasa, Shintaro; Nakamura, Yoshimasa; Murata, Yoshiyuki

    2015-01-01

    Acrolein is a reactive α,β-unsaturated aldehyde derived from lipid peroxides, which are produced in plants under a variety of stress. We investigated effects of acrolein on light-induced stomatal opening using Arabidopsis thaliana. Acrolein inhibited light-induced stomatal opening in a dose-dependent manner. Acrolein at 100 μM inhibited plasma membrane inward-rectifying potassium (Kin) channels in guard cells. Acrolein at 100 μM inhibited Kin channel KAT1 expressed in a heterologous system using Xenopus leaves oocytes. These results suggest that acrolein inhibits light-induced stomatal opening through inhibition of Kin channels in guard cells.

  11. Sleep in Kcna2 knockout mice

    Directory of Open Access Journals (Sweden)

    Messing Albee

    2007-10-01

    Full Text Available Abstract Background Shaker codes for a Drosophila voltage-dependent potassium channel. Flies carrying Shaker null or hypomorphic mutations sleep 3–4 h/day instead of 8–14 h/day as their wild-type siblings do. Shaker-like channels are conserved across species but it is unknown whether they affect sleep in mammals. To address this issue, we studied sleep in Kcna2 knockout (KO mice. Kcna2 codes for Kv1.2, the alpha subunit of a Shaker-like voltage-dependent potassium channel with high expression in the mammalian thalamocortical system. Results Continuous (24 h electroencephalograph (EEG, electromyogram (EMG, and video recordings were used to measure sleep and waking in Kcna2 KO, heterozygous (HZ and wild-type (WT pups (P17 and HZ and WT adult mice (P67. Sleep stages were scored visually based on 4-s epochs. EEG power spectra (0–20 Hz were calculated on consecutive 4-s epochs. KO pups die by P28 due to generalized seizures. At P17 seizures are either absent or very rare in KO pups ( Conclusion Kv1.2, a mammalian homologue of Shaker, regulates neuronal excitability and affects NREM sleep.

  12. Diet-induced glucose intolerance in mice with decreased beta-cell ATP-sensitive K+ channels.

    Science.gov (United States)

    Remedi, Maria S; Koster, Joseph C; Markova, Kamelia; Seino, Susumu; Miki, Takashi; Patton, Brian L; McDaniel, Michael L; Nichols, Colin G

    2004-12-01

    ATP-sensitive K+ channels (K(ATP) channels) control electrical activity in beta-cells and therefore are key players in excitation-secretion coupling. Partial suppression of beta-cell K(ATP) channels in transgenic (AAA) mice causes hypersecretion of insulin and enhanced glucose tolerance, whereas complete suppression of these channels in Kir6.2 knockout (KO) mice leads to hyperexcitability, but mild glucose intolerance. To test the interplay of hyperexcitability and dietary stress, we subjected AAA and KO mice to a high-fat diet. After 3 months on the diet, both AAA and KO mice converted to an undersecreting and markedly glucose-intolerant phenotype. Although Kir6.2 is expressed in multiple tissues, its primary functional consequence in both AAA and KO mice is enhanced beta-cell electrical activity. The results of our study provide evidence that, when combined with dietary stress, this hyperexcitability is a causal diabetic factor. We propose an "inverse U" model for the response to enhanced beta-cell excitability: the expected initial hypersecretion can progress to undersecretion and glucose-intolerance, either spontaneously or in response to dietary stress.

  13. Amyloid-β-induced reactive oxygen species production and priming are differentially regulated by ion channels in microglia.

    Science.gov (United States)

    Schilling, Tom; Eder, Claudia

    2011-12-01

    Production of reactive oxygen species (ROS) by microglial cells and subsequent oxidative stress are strongly implicated in the pathogenesis of Alzheimer's disease. Although it is recognized that amyloid-β (Aβ) plays a major role in inducing and regulating microglial ROS production in Alzheimer's disease, to date little is known about cellular mechanisms underlying Aβ-stimulated ROS production. Here, we identified ion channels involved in Aβ-induced microglial ROS production and in Aβ-induced microglial priming. Acute stimulation of microglial cells with either fibrillar Aβ(1-42) (fAβ(1-42) ) or soluble Aβ(1-42) (sAβ(1-42) ) caused significant increases in microglial ROS production, which were abolished by inhibition of TRPV1 cation channels with 5-iodo-resiniferatoxin (I-RTX), but were unaffected by inhibition of K(+) channels with charybdotoxin (CTX). Furthermore, pretreatment with either fAβ(1-42) or sAβ(1-42) induced microglial priming, that is, increased ROS production upon secondary stimulation with the phorbol ester PMA. Microglial priming induced by fAβ(1-42) or sAβ(1-42) remained unaffected by TRPV1 channel inhibition with I-RTX. However, sAβ(1-42) -induced priming was inhibited by CTX and margatoxin, but not by TRAM-34 or paxilline, indicating a role of Kv1.3 voltage-gated K(+) channels, but not of Ca(2+) -activated K(+) channels, in the priming process. In summary, our data suggest that in microglia Aβ-induced ROS production and priming are differentially regulated by ion channels, and that TRPV1 cation channels and Kv1.3 K(+) channels may provide potential therapeutic targets to reduce microglia-induced oxidative stress in Alzheimer's disease.

  14. Statistical Hauser-Feshbach theory with width fluctuation correction including direct reaction channels for neutron induced reaction at low energies

    CERN Document Server

    Kawano, T; Hilaire, S

    2016-01-01

    A model to calculate particle-induced reaction cross sections with statistical Hauser-Feshbach theory including direct reactions is given. The energy average of scattering matrix from the coupled-channels optical model is diagonalized by the transformation proposed by Engelbrecht and Weidenm\\"{u}ller. The ensemble average of $S$-matrix elements in the diagonalized channel space is approximated by a model of Moldauer [Phys.Rev.C {\\bf 12}, 744 (1975)] using newly parametrized channel degree-of-freedom $\

  15. KnockoutJS web development

    CERN Document Server

    Farrar, John

    2015-01-01

    This book is for web developers and designers who work with HTML and JavaScript to help them manage data and interactivity with data using KnockoutJS. Knowledge about jQuery will be useful but is not necessary.

  16. PUFA-induced neuroprotection against cerebral or spinal cord ischemia via the TREK-1 channel

    Directory of Open Access Journals (Sweden)

    Heurteaux Catherine

    2007-05-01

    Full Text Available The nutritional interest of polyunsaturated fatty acids from omega-3, that are mainly present in vegetal and fish oils is now validated by the scientific community. Their beneficial effects have first been reported in coronary heart diseases. Many neurological and chronic diseases are often related to deficiencies in omega-3 and omega-6 and their derivatives. Polyunsaturated fatty acids from omega-3 family are essential to brain growth and cognitive functions. They are recently considered as factors of improvement in some mental diseases. Today, polyunsaturated fatty acids could play a key role in the prevention and/or or the treatment of cerebral diseases. With the development of in vitro and in vivo experimental models, it is now possible to demonstrate the PUFA-induced neuronal protection against major pathologies such as epileptic seizures, cerebral and spinal ischemia. The molecular mechanism of neuronal protection induced by polyunsaturated fatty acids and particularly alphalinolenic acid is now clarified. The alpha-linolenic target would be a potassium channel, TREK-1, which belongs to the new family of 2-P domain potassium channels (K-2P. The discovery of the physiopathological role of these K-2P channels can represent an important therapeutical challenge not only in cerebrovascular diseases and epilepsy, but also in psychiatry.

  17. An orally active TRPV4 channel blocker prevents and resolves pulmonary edema induced by heart failure.

    Science.gov (United States)

    Thorneloe, Kevin S; Cheung, Mui; Bao, Weike; Alsaid, Hasan; Lenhard, Stephen; Jian, Ming-Yuan; Costell, Melissa; Maniscalco-Hauk, Kristeen; Krawiec, John A; Olzinski, Alan; Gordon, Earl; Lozinskaya, Irina; Elefante, Lou; Qin, Pu; Matasic, Daniel S; James, Chris; Tunstead, James; Donovan, Brian; Kallal, Lorena; Waszkiewicz, Anna; Vaidya, Kalindi; Davenport, Elizabeth A; Larkin, Jonathan; Burgert, Mark; Casillas, Linda N; Marquis, Robert W; Ye, Guosen; Eidam, Hilary S; Goodman, Krista B; Toomey, John R; Roethke, Theresa J; Jucker, Beat M; Schnackenberg, Christine G; Townsley, Mary I; Lepore, John J; Willette, Robert N

    2012-11-01

    Pulmonary edema resulting from high pulmonary venous pressure (PVP) is a major cause of morbidity and mortality in heart failure (HF) patients, but current treatment options demonstrate substantial limitations. Recent evidence from rodent lungs suggests that PVP-induced edema is driven by activation of pulmonary capillary endothelial transient receptor potential vanilloid 4 (TRPV4) channels. To examine the therapeutic potential of this mechanism, we evaluated TRPV4 expression in human congestive HF lungs and developed small-molecule TRPV4 channel blockers for testing in animal models of HF. TRPV4 immunolabeling of human lung sections demonstrated expression of TRPV4 in the pulmonary vasculature that was enhanced in sections from HF patients compared to controls. GSK2193874 was identified as a selective, orally active TRPV4 blocker that inhibits Ca(2+) influx through recombinant TRPV4 channels and native endothelial TRPV4 currents. In isolated rodent and canine lungs, TRPV4 blockade prevented the increased vascular permeability and resultant pulmonary edema associated with elevated PVP. Furthermore, in both acute and chronic HF models, GSK2193874 pretreatment inhibited the formation of pulmonary edema and enhanced arterial oxygenation. Finally, GSK2193874 treatment resolved pulmonary edema already established by myocardial infarction in mice. These findings identify a crucial role for TRPV4 in the formation of HF-induced pulmonary edema and suggest that TRPV4 blockade is a potential therapeutic strategy for HF patients.

  18. Chronic ciguatoxin treatment induces synaptic scaling through voltage gated sodium channels in cortical neurons.

    Science.gov (United States)

    Martín, Víctor; Vale, Carmen; Rubiolo, Juan A; Roel, Maria; Hirama, Masahiro; Yamashita, Shuji; Vieytes, Mercedes R; Botana, Luís M

    2015-06-15

    Ciguatoxins are sodium channels activators that cause ciguatera, one of the most widespread nonbacterial forms of food poisoning, which presents with long-term neurological alterations. In central neurons, chronic perturbations in activity induce homeostatic synaptic mechanisms that adjust the strength of excitatory synapses and modulate glutamate receptor expression in order to stabilize the overall activity. Immediate early genes, such as Arc and Egr1, are induced in response to activity changes and underlie the trafficking of glutamate receptors during neuronal homeostasis. To better understand the long lasting neurological consequences of ciguatera, it is important to establish the role that chronic changes in activity produced by ciguatoxins represent to central neurons. Here, the effect of a 30 min exposure of 10-13 days in vitro (DIV) cortical neurons to the synthetic ciguatoxin CTX 3C on Arc and Egr1 expression was evaluated using real-time polymerase chain reaction approaches. Since the toxin increased the mRNA levels of both Arc and Egr1, the effect of CTX 3C in NaV channels, membrane potential, firing activity, miniature excitatory postsynaptic currents (mEPSCs), and glutamate receptors expression in cortical neurons after a 24 h exposure was evaluated using electrophysiological and western blot approaches. The data presented here show that CTX 3C induced an upregulation of Arc and Egr1 that was prevented by previous coincubation of the neurons with the NaV channel blocker tetrodotoxin. In addition, chronic CTX 3C caused a concentration-dependent shift in the activation voltage of NaV channels to more negative potentials and produced membrane potential depolarization. Moreover, 24 h treatment of cortical neurons with 5 nM CTX 3C decreased neuronal firing and induced synaptic scaling mechanisms, as evidenced by a decrease in the amplitude of mEPSCs and downregulation in the protein level of glutamate receptors that was also prevented by tetrodotoxin

  19. Functional remodeling of Ca2+-activated Cl- channel in pacing induced canine failing heart

    Institute of Scientific and Technical Information of China (English)

    Ning Li; Kejuan Ma; Siyong Teng; Jonathan C.Makielski; Jielin Pu

    2008-01-01

    Objective To determine whether Ca2+ activated Cl- current(Icl(Ca)) contributes to the functional remodeling of the failing heart.Methods Whole cell patch-clamp recording technique was employed to record the Icl(Ca) in cardiac myocytes enzymatically isolatedfrom rapidly pacing induced canine failing hearts at room temperature and compared that of the normal hearts (Nor).Results Thecurrent density of DIDS(200M)sensitive Icl(Ca) induced by intracellular Ca2+ release trigged by L-type Ca2+ current(Ica,L)wassignificantly decreased in heart failare(HE)cells compared to Nor cells.At membrane voltage of 20mV,the Icl(Ca) density was 3.02±0.54 pA/pF in Nor(n=6)vs.1.31±0.25 pA/pF in HF(n=8)cells,(P<0.01),while the averaged Ica,L density did not show differencebetween two groups.The time constant of current decay of Icl(Ca) was similar in both types of cells.On the other hand,in intra cellularCa2+ clamped mode,where the[Ca2+];was maintained at 100nmol/L,Icl(Ca) density be increased significantly in HF cells when themembrane voltage at+30mV or higher.Conclusions Our results suggest that Icl(Ca) density was decreased in pacing induced failingheart but the channel function be enhanced.Impaired Ca2+ handing in HF cells rather than reduced,Icl(Ca) channel function itself may havecaused this abnormality.The Icl(Ca) density reduction might contribute to the prolongation of action potential in failing heart.The Icl(Ca)channel function up-rugulation is likely to cause cardiac arrhythmia by inducing a delayed after depolarization,when Ca2+ overloadoccurred in diastolic failing heart cells.

  20. Inhibitory effects of oleoylethanolamide (OEA) on H₂O₂-induced human umbilical vein endothelial cell (HUVEC) injury and apolipoprotein E knockout (ApoE-/-) atherosclerotic mice.

    Science.gov (United States)

    Ma, Li; Guo, Xiaobing; Chen, Wei

    2015-01-01

    Atherosclerosis (AS) is initiated by vascular endothelial cell injury, which is induced by lipid and protein oxidation. Oleoylethanolamide (OEA), a dietary fat-derived lipid, has shown atheroprotective effect. In vitro studies demonstrated that OEA showed cytoprotective effects on H2O2-induced primary cultured human umbilical vein endothelial cell (HUVEC) injury model. Further investigation of the cytoprotective effects of OEA demonstrated that OEA exerted its function by scavenging for reactive oxygen species, as well as increasing anti-oxidative enzymes, reducing lipid peroxidation, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and apoptosis-related proteins expression. The in vivo study using an ApoE-/- mouse model fed with high-fat diet for 8 weeks showed that OEA (10 mg/kg/day, i.g.) administration reduced blood lipid levels, prevented endothelial cell damage and inhibited early AS plaque formation. In conclusion, our results suggested that OEA exerted a pharmacological effect on ameliorating atherosclerotic plaque formation through the inhibition of oxidative stress-induced endothelial cell injury and therefore OEA can be a potential candidate drug for anti-atherosclerosis.

  1. Effect of Laser-Induced Heating on Raman Measurement within a Silicon Microfluidic Channel

    Directory of Open Access Journals (Sweden)

    Ying Lin

    2015-06-01

    Full Text Available When Raman microscopy is adopted to detect the chemical and biological processes in the silicon microfluidic channel, the laser-induced heating effect will cause a temperature rise in the sample liquid. This undesired temperature rise will mislead the Raman measurement during the temperature-influencing processes. In this paper, computational fluid dynamics simulations were conducted to evaluate the maximum local temperature-rise (MLT. Through the orthogonal analysis, the sensitivity of potential influencing parameters to the MLT was determined. In addition, it was found from transient simulations that it is reasonable to assume the actual measurement to be steady-state. Simulation results were qualitatively validated by experimental data from the Raman measurement of diffusion, a temperature-dependent process. A correlation was proposed for the first time to estimate the MLT. Simple in form and convenient for calculation, this correlation can be efficiently applied to Raman measurement in a silicon microfluidic channel.

  2. The role of renal proximal tubule P450 enzymes in chloroform-induced nephrotoxicity: Utility of renal specific P450 reductase knockout mouse models

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Senyan [Kidney Institute and Division of Nephrology, Changzheng Hospital, Shanghai 200003 (China); Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York, Albany, NY 12201 (United States); Yao, Yunyi; Lu, Shijun; Aldous, Kenneth; Ding, Xinxin [Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York, Albany, NY 12201 (United States); Mei, Changlin, E-mail: chlmei1954@126.com [Kidney Institute and Division of Nephrology, Changzheng Hospital, Shanghai 200003 (China); Gu, Jun, E-mail: jungu@wadsworth.org [Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York, Albany, NY 12201 (United States)

    2013-10-01

    The kidney is a primary target for numerous toxic compounds. Cytochrome P450 enzymes (P450) are responsible for the metabolic activation of various chemical compounds, and in the kidney are predominantly expressed in proximal tubules. The aim of this study was to test the hypothesis that renal proximal tubular P450s are critical for nephrotoxicity caused by chemicals such as chloroform. We developed two new mouse models, one having proximal tubule-specific deletion of the cytochrome P450 reductase (Cpr) gene (the enzyme required for all microsomal P450 activities), designated proximal tubule-Cpr-null (PTCN), and the other having proximal tubule-specific rescue of CPR activity with the global suppression of CPR activity in all extra-proximal tubular tissues, designated extra-proximal tubule-Cpr-low (XPT-CL). The PTCN, XPT-CL, Cpr-low (CL), and wild-type (WT) mice were treated with a single oral dose of chloroform at 200 mg/kg. Blood, liver and kidney samples were obtained at 24 h after the treatment. Renal toxicity was assessed by measuring BUN and creatinine levels, and by pathological examination. The blood and tissue levels of chloroform were determined. The severity of toxicity was less in PTCN and CL mice, compared with that of WT and XPT-CL mice. There were no significant differences in chloroform levels in the blood, liver, or kidney, between PTCN and WT mice, or between XPT-CL and CL mice. These findings indicate that local P450-dependent activities play an important role in the nephrotoxicity induced by chloroform. Our results also demonstrate the usefulness of these novel mouse models for studies of chemical-induced kidney toxicity. - Highlights: • New mouse models were developed with varying P450 activities in the proximal tubule. • These mouse models were treated with chloroform, a nephrotoxicant. • Studies showed the importance of local P450s in chloroform-induced nephrotoxicity.

  3. DNA Damage-Inducible Transcript 4 Is an Innate Surveillant of Hair Follicular Stress in Vitamin D Receptor Knockout Mice and a Regulator of Wound Re-Epithelialization

    Directory of Open Access Journals (Sweden)

    Hengguang Zhao

    2016-11-01

    Full Text Available Mice and human patients with impaired vitamin D receptor (VDR signaling have normal developmental hair growth but display aberrant post-morphogenic hair cycle progression associated with alopecia. In addition, VDR–/– mice exhibit impaired cutaneous wound healing. We undertook experiments to determine whether the stress-inducible regulator of energy homeostasis, DNA damage-inducible transcript 4 (Ddit4, is involved in these processes. By analyzing hair cycle activation in vivo, we show that VDR−/− mice at day 14 exhibit increased Ddit4 expression within follicular stress compartments. At day 29, degenerating VDR−/− follicular keratinocytes, but not bulge stem cells, continue to exhibit an increase in Ddit4 expression. At day 47, when normal follicles and epidermis are quiescent and enriched for Ddit4, VDR−/− skin lacks Ddit4 expression. In a skin wound healing assay, the re-epithelialized epidermis in wildtype (WT but not VDR−/− animals harbor a population of Ddit4- and Krt10-positive cells. Our study suggests that VDR regulates Ddit4 expression during epidermal homeostasis and the wound healing process, while elevated Ddit4 represents an early growth-arresting stress response within VDR−/− follicles.

  4. Clopidogrel attenuates lithium-induced alterations in renal water and sodium channels/transporters in mice.

    Science.gov (United States)

    Zhang, Yue; Peti-Peterdi, János; Heiney, Kristina M; Riquier-Brison, Anne; Carlson, Noel G; Müller, Christa E; Ecelbarger, Carolyn M; Kishore, Bellamkonda K

    2015-12-01

    Lithium (Li) administration causes deranged expression and function of renal aquaporins and sodium channels/transporters resulting in nephrogenic diabetes insipidus (NDI). Extracellular nucleotides (ATP/ADP/UTP), via P2 receptors, regulate these transport functions. We tested whether clopidogrel bisulfate (CLPD), an antagonist of ADP-activated P2Y(12) receptor, would affect Li-induced alterations in renal aquaporins and sodium channels/transporters. Adult mice were treated for 14 days with CLPD and/or Li and euthanized. Urine and kidneys were collected for analysis. When administered with Li, CLPD ameliorated polyuria, attenuated the rise in urine prostaglandin E2 (PGE2), and resulted in significantly higher urinary arginine vasopressin (AVP) and aldosterone levels as compared to Li treatment alone. However, urine sodium excretion remained elevated. Semi-quantitative immunoblotting revealed that CLPD alone increased renal aquaporin 2 (AQP2), Na-K-2Cl cotransporter (NKCC2), Na-Cl cotransporter (NCC), and the subunits of the epithelial Na channel (ENaC) in medulla by 25-130 %. When combined with Li, CLPD prevented downregulation of AQP2, Na-K-ATPase, and NKCC2 but was less effective against downregulation of cortical α- or γ-ENaC (70 kDa band). Thus, CLPD primarily attenuated Li-induced downregulation of proteins involved in water conservation (AVP-sensitive), with modest effects on aldosterone-sensitive proteins potentially explaining sustained natriuresis. Confocal immunofluorescence microscopy revealed strong labeling for P2Y(12)-R in proximal tubule brush border and blood vessels in the cortex and less intense labeling in medullary thick ascending limb and the collecting ducts. Therefore, there is the potential for CLPD to be directly acting at the tubule sites to mediate these effects. In conclusion, P2Y(12)-R may represent a novel therapeutic target for Li-induced NDI.

  5. Optical characterization of femtosecond laser induced active channel waveguides in lithium fluoride crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chiamenti, I.; Kalinowski, H. J., E-mail: hjkalin@utfpr.edu.br [Federal University of Technology–Paraná, Photonics Laboratory, 80230-901 Curitiba (Brazil); Bonfigli, F.; Montereali, R. M. [ENEA C.R. Frascati, Photonics Micro and Nanostructures Laboratory, V. E. Fermi, 45, 00044 Frascati (RM) (Italy); Gomes, A. S. L. [Universidade Federal de Pernambuco, Department of Physics, 50740-560 Recife (Brazil); Michelotti, F. [Universitá degli Studi di Roma “La Sapienza,” Dipartimento di Scienze di Base e Applicate per l' Ingegneria, Via A. Scarpa, 16, 00161, Rome (Italy)

    2014-01-14

    We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10{sup −3} to 10{sup −4} depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths.

  6. Optical characterization of femtosecond laser induced active channel waveguides in lithium fluoride crystals

    Science.gov (United States)

    Chiamenti, I.; Bonfigli, F.; Gomes, A. S. L.; Michelotti, F.; Montereali, R. M.; Kalinowski, H. J.

    2014-01-01

    We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10-3 to 10-4 depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths.

  7. Inspiration of induced magnetic field on nano hyperbolic tangent fluid in a curved channel

    Science.gov (United States)

    Nadeem, S.; Shahzadi, Iqra

    2016-01-01

    In this research, peristaltic flow of nano hyperbolic tangent fluid is investigated in a curved channel. The model used for the nanofluid includes the effects of thermophoresis and Brownian motion. The resulting equations are assembled in wave frame of reference under the effects of curvature. Influence of induced magnetic field is studied. Long wavelength and low Reynolds number supposition are treated. The travelling wave front of peristaltic flow is chosen sinusoidal (extension /reduction). Analytical solutions are computed by homotopy perturbation method. Results of substantial quantities are explained with particular attention to rheological aspects.

  8. Inspiration of induced magnetic field on nano hyperbolic tangent fluid in a curved channel

    Directory of Open Access Journals (Sweden)

    S. Nadeem

    2016-01-01

    Full Text Available In this research, peristaltic flow of nano hyperbolic tangent fluid is investigated in a curved channel. The model used for the nanofluid includes the effects of thermophoresis and Brownian motion. The resulting equations are assembled in wave frame of reference under the effects of curvature. Influence of induced magnetic field is studied. Long wavelength and low Reynolds number supposition are treated. The travelling wave front of peristaltic flow is chosen sinusoidal (extension /reduction. Analytical solutions are computed by homotopy perturbation method. Results of substantial quantities are explained with particular attention to rheological aspects.

  9. Aggravation of north channels' shrinkage and south channels' development in the Yangtze Estuary under dam-induced runoff discharge flattening

    Science.gov (United States)

    Zhu, Bo-yuan; Li, Yi-tian; Yue, Yao; Yang, Yun-ping

    2017-03-01

    Construction of dams on rivers has progressively affected the seasonal variability of runoff discharge, which has consequently produced remarkable impacts on the morphology of estuarine channels. This paper considers four-typical-order bifurcations of the Yangtze Estuary and adopts an ebb partition ratio (defined as the diversion ratio of ebb flow in a given branch divided by the total ebb tidal discharge immediately upstream of the river node where the bifurcation occurs) as a measure of water excavating force in the bifurcation channels. Results show that the seasonal variability of runoff discharge at Datong Hydrological Station (Datong) is flattened, being mainly driven by upstream runoff flattening observed at Yichang Hydrological Station (Yichang) and the tributary rivers. Yearly ebb partition ratios of the channels located to the north and south of the islands present decreasing and increasing trends respectively, and as also do the yearly north and south channel volume of the bifurcations. Yearly ebb partition ratio is proved to be an effective index to represent the water excavating force considering the stability of yearly ebb tidal discharge and its relationship with the channel erosion-deposition. River dams are the driving factors behind the runoff flattening at Datong because of their flattening effects on its main contributors (Yichang and tributary rivers). This flattening significantly helps reduce and enlarge the yearly ebb partition ratios of the north and south channels respectively, and then aggravates the shrinkage and development of the north and south channels separately. Yearly ebb partition ratio of the North Passage (NP) must be enlarged in order for the NP to maintain its function as a shipping channel.

  10. Homojunction solution-processed metal oxide thin-film transistors using passivation-induced channel definition.

    Science.gov (United States)

    Kim, Jung Hyun; Rim, You Seung; Kim, Hyun Jae

    2014-04-09

    A simple method of channel passivation and physical definition of solution-processed metal oxide thin-film transistors (TFTs) has been developed for aluminum oxide (AlOx) and indium oxide (InOx) thin films. A photoresist-free-based ultraviolet (UV) patterning process was used to define an InOx layer as the source/drain region and an AlOx layer as a passivation layer on the InOx layer. The Al diffused into the patterned InOx thin film during a thermal annealing step. As an electrode, the patterned InOx thin film had low resistivity, and as a channel, the Al-diffused InOx thin film had a low carrier concentration. Furthermore, the diffused Al behaved as a carrier suppressor by reducing oxygen vacancies within the InOx thin film. We succeeded in forming a coplanar homojunction-structured metal oxide TFT that used the passivation-induced channel-defining (PCD) method with an AlOx/InOx bilayer. The PCD TFT had a field-effect mobility of 0.02 cm(2)/V·s, a threshold voltage of -1.88 V, a subthreshold swing of 0.73 V/decade, and an on/off current ratio of 2.75 × 10(6) with a width/length (W/L) of 2000 μm/400 μm.

  11. TRPV3 Channels Mediate Strontium-Induced Mouse-Egg Activation

    Directory of Open Access Journals (Sweden)

    Ingrid Carvacho

    2013-12-01

    Full Text Available In mammals, calcium influx is required for oocyte maturation and egg activation. The molecular identities of the calcium-permeant channels that underlie the initiation of embryonic development are not established. Here, we describe a transient receptor potential (TRP ion channel current activated by TRP agonists that is absent in TrpV3−/− eggs. TRPV3 current is differentially expressed during oocyte maturation, reaching a peak of maximum density and activity at metaphase of meiosis II (MII, the stage of fertilization. Selective activation of TRPV3 channels provokes egg activation by mediating massive calcium entry. Widely used to activate eggs, strontium application is known to yield normal offspring in combination with somatic cell nuclear transfer. We show that TRPV3 is required for strontium influx, because TrpV3−/− eggs failed to conduct Sr2+ or undergo strontium-induced activation. We propose that TRPV3 is a major mediator of calcium influx in mouse eggs and is a putative target for artificial egg activation.

  12. NR4A1 (Nur77 mediates thyrotropin-releasing hormone-induced stimulation of transcription of the thyrotropin β gene: analysis of TRH knockout mice.

    Directory of Open Access Journals (Sweden)

    Yasuyo Nakajima

    Full Text Available Thyrotropin-releasing hormone (TRH is a major stimulator of thyrotropin-stimulating hormone (TSH synthesis in the anterior pituitary, though precisely how TRH stimulates the TSHβ gene remains unclear. Analysis of TRH-deficient mice differing in thyroid hormone status demonstrated that TRH was critical for the basal activity and responsiveness to thyroid hormone of the TSHβ gene. cDNA microarray and K-means cluster analyses with pituitaries from wild-type mice, TRH-deficient mice and TRH-deficient mice with thyroid hormone replacement revealed that the largest and most consistent decrease in expression in the absence of TRH and on supplementation with thyroid hormone was shown by the TSHβ gene, and the NR4A1 gene belonged to the same cluster as and showed a similar expression profile to the TSHβ gene. Immunohistochemical analysis demonstrated that NR4A1 was expressed not only in ACTH- and FSH- producing cells but also in thyrotrophs and the expression was remarkably reduced in TRH-deficient pituitary. Furthermore, experiments in vitro demonstrated that incubation with TRH in GH4C1 cells increased the endogenous NR4A1 mRNA level by approximately 50-fold within one hour, and this stimulation was inhibited by inhibitors for PKC and ERK1/2. Western blot analysis confirmed that TRH increased NR4A1 expression within 2 h. A series of deletions of the promoter demonstrated that the region between bp -138 and +37 of the TSHβ gene was responsible for the TRH-induced stimulation, and Chip analysis revealed that NR4A1 was recruited to this region. Conversely, knockdown of NR4A1 by siRNA led to a significant reduction in TRH-induced TSHβ promoter activity. Furthermore, TRH stimulated NR4A1 promoter activity through the TRH receptor. These findings demonstrated that 1 TRH is a highly specific regulator of the TSHβ gene, and 2 TRH mediated induction of the TSHβ gene, at least in part by sequential stimulation of the NR4A1-TSHβ genes through a PKC and

  13. Pathophysiological significance of the two-pore domain K+ channel K2P5.1 in splenic CD4+CD25− T cell subset from a chemically-induced murine inflammatory bowel disease model

    Science.gov (United States)

    Nakakura, Sawa; Matsui, Miki; Sato, Aya; Ishii, Mizuki; Endo, Kyoko; Muragishi, Sayaka; Murase, Miki; Kito, Hiroaki; Niguma, Hiroki; Kurokawa, Natsumi; Fujii, Masanori; Araki, Masatake; Araki, Kimi; Ohya, Susumu

    2015-01-01

    The alkaline pH-activated, two-pore domain K+ channel K2P5.1 (also known as TASK2/KCNK5) plays an important role in maintaining the resting membrane potential, and contributes to the control of Ca2+ signaling in several types of cells. Recent studies highlighted the potential role of the K2P5.1 K+ channel in the pathogenesis of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. The aim of the present study was to elucidate the pathological significance of the K2P5.1 K+ channel in inflammatory bowel disease (IBD). The degrees of colitis, colonic epithelial damage, and colonic inflammation were quantified in the dextran sulfate sodium-induced mouse IBD model by macroscopic and histological scoring systems. The expression and functional activity of K2P5.1 in splenic CD4+ T cells were measured using real-time PCR, Western blot, and fluorescence imaging assays. A significant increase was observed in the expression of K2P5.1 in the splenic CD4+ T cells of the IBD model. Concomitant with this increase, the hyperpolarization response induced by extracellular alkaline pH was significantly larger in the IBD model with the corresponding intracellular Ca2+ rises. The expression of K2P5.1 was higher in CD4+CD25− T cells than in CD4+CD25+ regulatory T cells. The knockout of K2P5.1 in mice significantly suppressed the disease responses implicated in the IBD model. Alternations in intracellular Ca2+ signaling following the dysregulated expression of K2P5.1 were associated with the disease pathogenesis of IBD. The results of the present study suggest that the K2P5.1 K+ channel in CD4+CD25− T cell subset is a potential therapeutic target and biomarker for IBD. PMID:26578971

  14. Calcium channel blocker prevents stress-induced activation of renin and aldosterone in conscious pig

    Energy Technology Data Exchange (ETDEWEB)

    Ceremuzynski, L.K.; Klos, J.; Barcikowski, B.; Herbaczynska-Cedro, K. (Department of Cardiology, Postgraduate Medical School, Warsaw (Poland))

    1991-06-01

    A considerable amount of data suggest the involvement of calcium-mediated processes in the activation of the renin-angiotensin-aldosterone (RAA) cascade. To investigate the effect of calcium-channel inhibition on the RAA system, the authors studied 21 conscious pigs. Blood renin and aldosterone levels increased by subjecting animals to 24 hours of immobilization stress. Renin and aldosterone levels were repeatedly measured by radioimmunoassay in blood samples taken periodically over 24 hours from a chronically implanted arterial cannula. Pretreatment of the animals (N = 11) with nisoldipine, 2 {times} 20 mg p.o. daily for 2 days before and on the day of immobilization, transiently attenuated the stress-induced increase of plasma renin activity and completely prevented the rise of aldosterone, as compared to nontreated controls (N = 10). The finding that nisoldipine suppresses RAA activation induced by a nonpharmacologic stimulus in the conscious intact animal may have clinical implications.

  15. Effects of chloride channel blockers on hypotonicity-induced contractions of the rat trachea

    Science.gov (United States)

    Coelho, Roberta R; Souza, Emmanuel P; Soares, Pedro M G; Meireles, Ana Vaneska P; Santos, Geam C M; Scarparo, Henrique C; Assreuy, Ana Maria S; Criddle, David N

    2003-01-01

    We have investigated the inhibitory effects of blockers of volume-activated (Clvol) and calcium-activated (ClCa) chloride channels on hypotonic solution (HS)-induced contractions of rat trachea, comparing their effects with those of the voltage-dependent calcium channel (VDCC) blocker nifedpine. HS elicited large, stable contractions that were partially dependent on the cellular chloride gradient; a reduction to 41.45±7.71% of the control response was obtained when extracellular chloride was removed. In addition, HS-induced responses were reduced to 26.8±5.6% of the control by 1 μM nifedipine, and abolished under calcium-free conditions, indicating a substantial requirement for extracellular calcium entry, principally via VDCCs. The established Clvol blockers tamoxifen (⩽10 μM) and 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (1–100 μM), at concentrations previously reported to inhibit Clvol in smooth muscle, did not significantly inhibit HS-induced contractions. In contrast, the recognized ClCa blocker niflumic acid (NFA; 1–100 μM) produced a reversible, concentration-dependent inhibition of HS responses, with a reduction to 36.6±6.4% of control contractions at the highest concentration. The mixed Clvol and ClCa blocker, 5-nitro 2-(3-phenylpropylamine) benzoic acid (NPPB; 10–100 μM) also elicited concentration-related inhibition of HS-induced contractions, producing a decrease to 35.9±11.3% of the control at 100 μM. Our results show that HS induces reversible, chloride-dependent contractions of rat isolated trachea that were inhibited by NFA and NPPB, while exhibiting little sensitivity to recognized blockers of Clvol. The data support the possibility that opening of calcium-activated chloride channels under hypotonic conditions in respiratory smooth muscle may ultimately lead to VDCC-mediated calcium entry and contraction. PMID:14691057

  16. Voltage dependent potassium channel remodeling in murine intestinal smooth muscle hypertrophy induced by partial obstruction.

    Science.gov (United States)

    Liu, Dong-Hai; Huang, Xu; Guo, Xin; Meng, Xiang-Min; Wu, Yi-Song; Lu, Hong-Li; Zhang, Chun-Mei; Kim, Young-chul; Xu, Wen-Xie

    2014-01-01

    Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV) was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV) to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process.

  17. Voltage dependent potassium channel remodeling in murine intestinal smooth muscle hypertrophy induced by partial obstruction.

    Directory of Open Access Journals (Sweden)

    Dong-Hai Liu

    Full Text Available Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process.

  18. Mechanism and pharmacological rescue of berberine-induced hERG channel deficiency

    Directory of Open Access Journals (Sweden)

    Yan M

    2015-10-01

    Full Text Available Meng Yan,1 Kaiping Zhang,1 Yanhui Shi,1 Lifang Feng,1 Lin Lv,1 Baoxin Li1,2 1Department of Pharmacology, Harbin Medical University, 2State-Province Key Laboratory of Biopharmaceutical Engineering, Harbin, Heilongjiang, People’s Republic of China Abstract: Berberine (BBR, an isoquinoline alkaloid mainly isolated from plants of Berberidaceae family, is extensively used to treat gastrointestinal infections in clinics. It has been reported that BBR can block human ether-a-go-go-related gene (hERG potassium channel and inhibit its membrane expression. The hERG channel plays crucial role in cardiac repolarization and is the target of diverse proarrhythmic drugs. Dysfunction of hERG channel can cause long QT syndrome. However, the regulatory mechanisms of BBR effects on hERG at cell membrane level remain unknown. This study was designed to investigate in detail how BBR decreased hERG expression on cell surface and further explore its pharmacological rescue strategies. In this study, BBR decreases caveolin-1 expression in a concentration-dependent manner in human embryonic kidney 293 (HEK293 cells stably expressing hERG channel. Knocking down the basal expression of caveolin-1 alleviates BBR-induced hERG reduction. In addition, we found that aromatic tyrosine (Tyr652 and phenylalanine (Phe656 in S6 domain mediate the long-term effect of BBR on hERG by using mutation techniques. Considering both our previous and present work, we propose that BBR reduces hERG membrane stability with multiple mechanisms. Furthermore, we found that fexofenadine and resveratrol shorten action potential duration prolongated by BBR, thus having the potential effects of alleviating the cardiotoxicity of BBR. Keywords: berberine, hERG, cavoline-1, cardiotoxicity, LQTS, pharmacological rescue

  19. Laser-Induced Motion of a Nanofluid in a Micro-Channel

    Directory of Open Access Journals (Sweden)

    Tran X. Phuoc

    2016-10-01

    Full Text Available Since a photon carries both energy and momentum, when it interacts with a particle, photon-particle energy and momentum transfer occur, resulting in mechanical forces acting on the particle. In this paper we report our theoretical study on the use of a laser beam to manipulate and control the flow of nanofluids in a micro-channel. We calculate the velocity induced by a laser beam for TiO2, Fe2O3, Al2O3 MgO, and SiO2 nanoparticles with water as the base fluid. The particle diameter is 50 nm and the laser beam is a 4 W continuous beam of 6 mm diameter and 532 nm wavelength. The results indicate that, as the particle moves, a significant volume of the surrounding water (up to about 8 particle diameters away from the particle surface is disturbed and dragged along with the moving particle. The results also show the effect of the particle refractive index on the particle velocity and the induced volume flow rate. The velocity and the volume flowrate induced by the TiO2 nanoparticle (refractive index n = 2.82 are about 0.552 mm/s and 9.86 fL, respectively, while those induced by SiO2 (n = 1.46 are only about 7.569 μm/s and 0.135, respectively.

  20. Activation of TRPC6 channels is essential for lung ischaemia–reperfusion induced oedema in mice

    Science.gov (United States)

    Weissmann, Norbert; Sydykov, Akylbek; Kalwa, Hermann; Storch, Ursula; Fuchs, Beate; Schnitzler, Michael Mederos y; Brandes, Ralf P.; Grimminger, Friedrich; Meissner, Marcel; Freichel, Marc; Offermanns, Stefan; Veit, Florian; Pak, Oleg; Krause, Karl-Heinz; Schermuly, Ralph T.; Brewer, Alison C; Schmidt, Harald H.H.W.; Seeger, Werner; Shah, Ajay M.; Gudermann, Thomas; Ghofrani, Hossein A.; Dietrich, Alexander

    2012-01-01

    Lung ischaemia–reperfusion-induced oedema (LIRE) is a life-threatening condition that causes pulmonary oedema induced by endothelial dysfunction. Here we show that lungs from mice lacking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2y/−) or the classical transient receptor potential channel 6 (TRPC6−/−) are protected from LIR-induced oedema (LIRE). Generation of chimeric mice by bone marrow cell transplantation and endothelial-specific Nox2 deletion showed that endothelial Nox2, but not leukocytic Nox2 or TRPC6, are responsible for LIRE. Lung endothelial cells from Nox2- or TRPC6-deficient mice showed attenuated ischaemia-induced Ca2+ influx, cellular shape changes and impaired barrier function. Production of reactive oxygen species was completely abolished in Nox2y/− cells. A novel mechanistic model comprising endothelial Nox2-derived production of superoxide, activation of phospholipase C-γ, inhibition of diacylglycerol (DAG) kinase, DAG-mediated activation of TRPC6 and ensuing LIRE is supported by pharmacological and molecular evidence. This mechanism highlights novel pharmacological targets for the treatment of LIRE. PMID:22337127

  1. Intradermal Immunization of Leishmania donovani Centrin Knock-Out Parasites in Combination with Salivary Protein LJM19 from Sand Fly Vector Induces a Durable Protective Immune Response in Hamsters.

    Directory of Open Access Journals (Sweden)

    Jacqueline Araújo Fiuza

    2016-01-01

    Full Text Available Visceral leishmaniasis (VL is a neglected tropical disease and is fatal if untreated. There is no vaccine available against leishmaniasis. The majority of patients with cutaneous leishmaniasis (CL or VL develop a long-term protective immunity after cure from infection, which indicates that development of an effective vaccine against leishmaniasis is possible. Such protection may also be achieved by immunization with live attenuated parasites that do not cause disease. We have previously reported a protective response in mice, hamsters and dogs with Leishmania donovani centrin gene knock-out parasites (LdCen-/-, a live attenuated parasite with a cell division specific centrin1 gene deletion. In this study we have explored the effects of salivary protein LJM19 as an adjuvant and intradermal (ID route of immunization on the efficacy of LdCen-/- parasites as a vaccine against virulent L. donovani.To explore the potential of a combination of LdCen-/- parasites and salivary protein LJM19 as vaccine antigens, LdCen-/- ID immunization followed by ID challenge with virulent L. donovani were performed in hamsters in a 9-month follow up study. We determined parasite burden (serial dilution, antibody production (ELISA and cytokine expression (qPCR in these animals. Compared to controls, animals immunized with LdCen-/- + LJM19 induced a strong antibody response, a reduction in spleen and liver parasite burden and a higher expression of pro-inflammatory cytokines after immunization and one month post-challenge. Additionally, a low parasite load in lymph nodes, spleen and liver, and a non-inflamed spleen was observed in immunized animals 9 months after the challenge infection.Our results demonstrate that an ID vaccination using LdCen-/-parasites in combination with sand fly salivary protein LJM19 has the capability to confer long lasting protection against visceral leishmaniasis that is comparable to intravenous or intracardial immunization.

  2. Intradermal Immunization of Leishmania donovani Centrin Knock-Out Parasites in Combination with Salivary Protein LJM19 from Sand Fly Vector Induces a Durable Protective Immune Response in Hamsters

    Science.gov (United States)

    Fiuza, Jacqueline Araújo; Dey, Ranadhir; Davenport, Dwann; Abdeladhim, Maha; Meneses, Claudio; Oliveira, Fabiano; Kamhawi, Shaden; Valenzuela, Jesus G.; Gannavaram, Sreenivas; Nakhasi, Hira L.

    2016-01-01

    Background Visceral leishmaniasis (VL) is a neglected tropical disease and is fatal if untreated. There is no vaccine available against leishmaniasis. The majority of patients with cutaneous leishmaniasis (CL) or VL develop a long-term protective immunity after cure from infection, which indicates that development of an effective vaccine against leishmaniasis is possible. Such protection may also be achieved by immunization with live attenuated parasites that do not cause disease. We have previously reported a protective response in mice, hamsters and dogs with Leishmania donovani centrin gene knock-out parasites (LdCen-/-), a live attenuated parasite with a cell division specific centrin1 gene deletion. In this study we have explored the effects of salivary protein LJM19 as an adjuvant and intradermal (ID) route of immunization on the efficacy of LdCen-/- parasites as a vaccine against virulent L. donovani. Methodology/Principal Findings To explore the potential of a combination of LdCen-/- parasites and salivary protein LJM19 as vaccine antigens, LdCen-/- ID immunization followed by ID challenge with virulent L. donovani were performed in hamsters in a 9-month follow up study. We determined parasite burden (serial dilution), antibody production (ELISA) and cytokine expression (qPCR) in these animals. Compared to controls, animals immunized with LdCen-/- + LJM19 induced a strong antibody response, a reduction in spleen and liver parasite burden and a higher expression of pro-inflammatory cytokines after immunization and one month post-challenge. Additionally, a low parasite load in lymph nodes, spleen and liver, and a non-inflamed spleen was observed in immunized animals 9 months after the challenge infection. Conclusions Our results demonstrate that an ID vaccination using LdCen-/-parasites in combination with sand fly salivary protein LJM19 has the capability to confer long lasting protection against visceral leishmaniasis that is comparable to intravenous or

  3. Changes of neuronal calcium channel following brain damage induced by injection of pertussis bacilli in rats

    Institute of Scientific and Technical Information of China (English)

    陈立华; 于嘉; 刘丽旭; 曹美鸿

    2002-01-01

    To explore changes of neuronal calcium channel following brain damage induced by injection of pertussis bacilli in rats, and to investigate the relationship between cytosolic free calcium concentration ( [ Ca2 + ] i ) in the synaptosome and Ca2 + -ATPase activities of mitochondria. Methods: The level of [ Ca2+ ]i in the synaptosome and Ca2+ -ATPase activities of mitochondria in the acute brain damage induced by injection of pertussis bacilli (PB)in rat was determined and nimodipine was administrated to show its effects on [ Ca2+ ]i in the synaptosome and on alteration of Ca2+ -ATPase activity in the mitochondria.Seventy-three rats were randomly divided into four groups,ie, normal control group (Group A ), sham-operation control group (Group B), PB group (Group C) and nimodipine treatment group (Group D). Results: The level of [ Ca2+ ]i was significantly increased in the PB-injected cerebral hemisphere in the Group C as compared with that in the Group A and the Group B at 30 minutes after injection of PB. The level of [ Ca2+ ]i was kept higher in the 4 hours and 24 hours subgroups after the injection in the Group C ( P < 0.05).In contrast, the Ca2+ -ATPase activities were decreased remarkably among all of the subgroups in the Group C.Nimodipine, which was administered after injection of PB,could significantly decrease the [ Ca2+ ]i and increase the activity of Ca2 + -ATPase ( P < 0.05 ). Conclusions: The neuronal calcium channel is opened after injection of PB. There is a negative correlation between activities of Ca2 +-ATPase and [ Ca2 + ]i.Nimodipine can reduce brain damage through stimulating the activities of Ca2+ -ATPase in the mitochondria, and decrease the level of [ Ca2+ ]i in the synaptosome.Treatment with nimodipine dramatically reduces the effects of brain damage induced by injection of PB.

  4. L-type calcium channel blockers enhance 5-HTP-induced antinociception in mice

    Institute of Scientific and Technical Information of China (English)

    Jian-hui LIANG; Jun-xu LI; Xu-hua WANG; Bi CHEN; Ying LU; Pan ZHANG; Rong HAN; Xiang-feng YE

    2004-01-01

    AIM: To investigate the involvement of L-type Ca2+ channels in antinociceptive action induced by the 5-HT precursor,5-hydroxytryptophan (5-HTP). METHODS: Female Kunming mice were treated with either 5-HTP (20-80 mg/kg,ip) alone, or the combination of 5-HTP and fluoxetine (2-8 mg/kg, ip), pargyline (15-60 mg/kg, ip), nimodipine (2.5-10 mg/kg, ip), nifedipine (2.5-10 mg/kg, ip), verapamil (2.5-10 mg/kg, ip), CaC12 (5-20 mmol/L, icv), or EGTA (0.5-3 mmol/L, icv) prior to the hot-plate test (55 ℃, hind-paw licking latency). In addition, locomotor activity in mice treated with 5-HTP alone was measured using an ambulometer with five activity boxes. RESULTS: Ip injection of 5-HTP alone had no influence on the spontaneous locomotor activity, whereas dose-dependently increased the latency to licking hind-paw in the hot-plate test in mice. The inhibitory effects of 5-HTP on nociceptive response were significantly enhanced by fluoxetine in the mouse hot-plate test. At a sub-effective dose, pargyline could cause a leftward shift in the dose-response curve of 5-HTP-induced antinociception. Co-administration with 5-HTP and nimodipine, nifedipine, or verapamil obviously potentiated the antinociceptive effects elicited by 5-HTP.Interestingly, 5-HTP-induced antinociception was antagonized by CaC12 and enhanced by EGTA injected icv in the mouse hot-plate test. CONCLUSION: These findings suggest that systemic administration of 5-HTP may yield the antinociceptive effects, which are related to Ca2+ influx from extracellular fluid through L-type Ca2+ channels.

  5. Antibodies against potassium channel interacting protein 2 induce necrosis in isolated rat cardiomyocytes.

    Science.gov (United States)

    Choudhury, Sangita; Schnell, Michael; Bühler, Thomas; Reinke, Yvonne; Lüdemann, Jan; Nießner, Felix; Brinkmeier, Heinrich; Herda, Lars R; Staudt, Alexander; Kroemer, Heyo K; Völker, Uwe; Felix, Stephan B; Landsberger, Martin

    2014-04-01

    Auto-antibodies against cardiac proteins have been described in patients with dilated cardiomyopathy. Antibodies against the C-terminal part of KChIP2 (anti-KChIP2 [C-12]) enhance cell death of rat cardiomyocytes. The underlying mechanisms are not fully understood. Therefore, we wanted to explore the mechanisms responsible for anti-KChIP2-mediated cell death. Rat cardiomyocytes were treated with anti-KChIP2 (C-12). KChIP2 RNA and protein expressions, nuclear NF-κB, mitochondrial membrane potential Δψm, caspase-3 and -9 activities, necrotic and apoptotic cells, total Ca(2+) and K(+) concentrations, and the effects on L-type Ca(2+) channels were quantified. Anti-KChIP2 (C-12) induced nuclear translocation of NF-κB. Anti-KChIP2 (C-12)-treatment for 2 h significantly reduced KChIP2 mRNA and protein expression. Anti-KChIP2 (C-12) induced nuclear translocation of NF-κB after 1 h. After 6 h, Δψm and caspase-3 and -9 activities were not significantly changed. After 24 h, anti-KChIP2 (C-12)-treated cells were 75 ± 3% necrotic, 2 ± 1% apoptotic, and 13 ± 2% viable. Eighty-six ± 1% of experimental buffer-treated cells were viable. Anti-KChIP2 (C-12) induced significant increases in total Ca(2+) (plus 11 ± 2%) and K(+) (plus 18 ± 2%) concentrations after 5 min. Anti-KChIP2 (C-12) resulted in an increased Ca(2+) influx through L-type Ca(2+) channels. In conclusion, our results suggest that anti-KChIP2 (C-12) enhances cell death of rat cardiomyocytes probably due to necrosis.

  6. Systemic Administration of Substance P Recovers Beta Amyloid-Induced Cognitive Deficits in Rat: Involvement of Kv Potassium Channels

    OpenAIRE

    Patrizia Campolongo; Patrizia Ratano; Maria Teresa Ciotti; Fulvio Florenzano; Stefania Lucia Nori; Roberta Marolda; Maura Palmery; Anna Maria Rinaldi; Cristina Zona; Roberta Possenti; Pietro Calissano; Cinzia Severini

    2013-01-01

    Reduced levels of Substance P (SP), an endogenous neuropeptide endowed with neuroprotective and anti-apoptotic properties, have been found in brain and spinal fluid of Alzheimer's disease (AD) patients. Potassium (K(+)) channel dysfunction is implicated in AD development and the amyloid-β (Aβ)-induced up-regulation of voltage-gated potassium channel subunits could be considered a significant step in Aβ brain toxicity. The aim of this study was to evaluate whether SP could reduce, in vivo, Aβ-...

  7. Energetics of discrete selectivity bands and mutation-induced transitions in the calcium-sodium ion channels family

    CERN Document Server

    Kaufman, I; Tindjong, R; McClintock, P V E; Eisenberg, R S

    2013-01-01

    We use Brownian dynamics simulations to study the permeation properties of a generic electrostatic model of a biological ion channel as a function of the fixed charge Q_f at its selectivity filter. We reconcile the recently-discovered discrete calcium conduction bands M0 (Q_f=1e), M1 (3e), M2 (5e) with the set of sodium conduction bands L0 (0.5-0.7e), L1 (1.5-2e) thereby obtaining a completed pattern of conduction and selectivity bands v Q_f for the sodium-calcium channels family. An increase of Q_f leads to an increase of calcium selectivity: L0 (sodium selective, non-blocking channel) -> M0 (non-selective channel) -> L1 (sodium selective channel with divalent block) -> M1 (calcium selective channel exhibiting the anomalous mole fraction effect). We create a consistent identification scheme where the L1 band is identified with the eukaryotic (DEKA) sodium channel, and L0 (speculatively) with the bacterial NaChBac channel. The scheme created is able to account for the experimentally observed mutation-induced ...

  8. Radiation characteristics of femtosecond laser-induced plasma channel Vee antenna

    Science.gov (United States)

    Choe, Yun-Sik; Hao, Zuoqiang; Lin, Jingquan

    2015-06-01

    A virtual reconfigurable plasma Vee antenna consisting of a set of laser plasma filaments produced by femtosecond laser pulses in air is investigated in this paper. The calculation results show that radiation pattern becomes more complex and gain shows initially rapid rise but gradually saturate as the leg length increases, but the pattern and gain are not seriously affected by the plasma conductivity; particularly, the gain of the Vee antenna with plasma conductivity σ = 100S/m can reach about 80% of that of a copper antenna. Radiation efficiency of the antenna has shown a strong dependence on radius of the antenna leg, and an efficiency of 65%, considered to have a proper performance, can be obtained with the channel radius of about 10 mm. Apex angle variation can lead to significant change of the radiation pattern and influence the gain; the best apex angle corresponding to maximal gain and good directivity for the third resonance antenna leg length is found to be at 74° at 600 MHz and σ = 100 S/m. The calculation has shown that at terawatt laser power level, the plasma channel conductivity is close to that of conventional plasma antenna, and peak gain of the Vee antenna is more than 8 dB with a good directivity. In addition, the radiation pattern of special Vee antennas with apex angle 180°-dipole antennas, for first and third resonance leg lengths, is compared and underneath physics of the difference is given. The laser-induced plasma channel antenna is especially suitable for achieving good directivity and gain, which has advantage over conventional plasma antenna with gas discharge tube or metal antenna.

  9. The effects of calcium channel blockade on agouti-induced obesity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Han; Moustaid, N.; Zemel, M.B. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1996-12-01

    We have previously observed that obese viable yellow (A{sup vy}/a) mice exhibit increased intracellular Ca{sup 2+} ([Ca{sup 2+}]i) and fatty acid synthase (FAS) gene expression; further, recombinant agouti protein increases in cultured adipocytes and these effects are inhibited by Ca{sup 2+} channel blockade. Accordingly, we determined the effect of Ca{sup 2+} channel blockade (nifedipine for 4 wk) on FAS and obesity in transgenic mice expressing the agouti gene in a ubiquitous manner. The transgenic mice initially were significantly heavier (30.5 {+-} 0.6 vs. 27.3 {+-} 0.3 g; P<0.001) and exhibited a 0.81{degrees}C lower initial core temperature (P<0.0005), an approximately twofold increase in fat pad weights (P=0.002), a sevenfold increase in adipose FAS activity (P=0.009), and a twofold increase in plasma insulin level (P<0.05) compared to control mice. Nifedipine treatment resulted in an 18% decrease in fat pad weights (P<0.007) and a 74% decrease in adipose FAS activity (P=0.03), normalized circulating insulin levels and insulin sensitivity (P,0.05), and transiently elevated core temperature in the transgenic mice, but was without effect in the control mice. These data suggest that agouti regulates FAS, fat storage, and possibly thermogenesis, at least partially, via a [Ca{sup 2+}]{sub i}-dependent mechanism, and that Ca{sup 2+} channel blockade may partially attenuate agouti-induced obesity. 42 refs., 4 figs., 1 tab.

  10. Radiation characteristics of femtosecond laser-induced plasma channel Vee antenna

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yun-Sik [School of Science, Changchun University of Science and Technology, 130022 Changchun (China); Department of Physics, University of Science, Pyongyang, North Korea (Korea, Republic of); Hao, Zuoqiang; Lin, Jingquan, E-mail: linjingquan@cust.edu.cn [School of Science, Changchun University of Science and Technology, 130022 Changchun (China)

    2015-06-15

    A virtual reconfigurable plasma Vee antenna consisting of a set of laser plasma filaments produced by femtosecond laser pulses in air is investigated in this paper. The calculation results show that radiation pattern becomes more complex and gain shows initially rapid rise but gradually saturate as the leg length increases, but the pattern and gain are not seriously affected by the plasma conductivity; particularly, the gain of the Vee antenna with plasma conductivity σ = 100S/m can reach about 80% of that of a copper antenna. Radiation efficiency of the antenna has shown a strong dependence on radius of the antenna leg, and an efficiency of 65%, considered to have a proper performance, can be obtained with the channel radius of about 10 mm. Apex angle variation can lead to significant change of the radiation pattern and influence the gain; the best apex angle corresponding to maximal gain and good directivity for the third resonance antenna leg length is found to be at 74° at 600 MHz and σ = 100 S/m. The calculation has shown that at terawatt laser power level, the plasma channel conductivity is close to that of conventional plasma antenna, and peak gain of the Vee antenna is more than 8 dB with a good directivity. In addition, the radiation pattern of special Vee antennas with apex angle 180°-dipole antennas, for first and third resonance leg lengths, is compared and underneath physics of the difference is given. The laser-induced plasma channel antenna is especially suitable for achieving good directivity and gain, which has advantage over conventional plasma antenna with gas discharge tube or metal antenna.

  11. Epithelial sodium channel is involved in H2S-induced acute pulmonary edema.

    Science.gov (United States)

    Jiang, Lei; Wang, Yixin; Su, Chenglei; Sun, Hao; Zhang, Huazhong; Zhu, Baoli; Zhang, Hengdong; Xiao, Hang; Wang, Jun; Zhang, Jinsong

    2015-01-01

    Acute pulmonary edema is one of the major outcomes of exposure to high levels of hydrogen sulfide (H2S). However, the mechanisms involved in H2S-induced acute pulmonary edema are still poorly understood. Therefore, the present study is designed to evaluate the role of epithelial sodium channel (ENaC) in H2S-induced acute pulmonary edema. The Sprague-Dawley rats were exposed to sublethal concentrations of inhaled H2S, then the pulmonary histological and lung epithelial cell injury were evaluated by hematoxylin-eosin staining and electron microscopy, respectively. In addition to morphological investigation, our results also revealed that H2S exposure significantly decreased the alveolar fluid clearance and increased the lung tissue wet-dry ratio. These changes were demonstrated to be associated with decreased ENaC expression. Furthermore, the extracellular-regulated protein kinases 1/2 pathway was demonstrated to be implicated in H2S-mediated ENaC expression, because PD98059, an ERK1/2 antagonist, significantly mitigated H2S-mediated ENaC down-regulation. Therefore, our results show that ENaC might represent a novel pharmacological target for the treatment of acute pulmonary edema induced by H2S and other hazardous gases.

  12. Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-out

    CERN Document Server

    Aoki, Mayumi

    2016-01-01

    We consider a model of two-component dark matter based on a hidden $U(1)_D$ symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden $U(1)_D$ symmetry is spontaneously broken to a residual $\\mathbb{Z}_4$ symmetry, and the lightest $\\mathbb{Z}_4$ charged particle can be a dark matter candidate. Moreover, depending on the mass hierarchy in the dark sector, we have two-component dark matter. We show that the relic density of the lighter dark matter component can be determined by forbidden annihilation channels which require larger couplings compared to the normal freeze-out mechanism. As a result, a large self-interaction of the lighter dark matter component can be induced, which may solve small scale problems of $\\Lambda$CDM model. On the other hand, the heavier dark matter component is produced by normal freeze-out mechanism. We find that interesting implications emerge between the two dark matter components in this framework. We explore dete...

  13. Thermodynamically Consistent Fluid Mixing in Porous Media Induced by Viscous Fingering and Channeling of Multiphase Flow

    Science.gov (United States)

    Amooie, Mohammad Amin; Soltanian, Mohammad Reza; Moortgat, Joachim

    2016-11-01

    Fluid mixing and its interplay with viscous fingering as well as flow channeling through heterogeneous media have been traditionally studied for fully (im)miscible conditions in which a (two-) single-phase system is represented by two components, e.g. a solvent and a solute, with (zero) infinite mutual solubility. However, many subsurface problems, e.g. gas injection/migration in hydrocarbon reservoirs, involve multiple species transfer. Multicomponent fluid properties behave non-linearly, through an equation of state, as a function of temperature, pressure, and compositions. Depending on the minimum miscibility pressure, a two-phase region with finite, non-zero mutual solubility may develop, e.g. in a partially-miscible system. Here we study mixing of fluids with partial mutual solubility, induced by viscous flow fingering, channeling, and species transport within and between phases. We uncover non-linear mixing dynamics of a finite-size slug of a less viscous fluid attenuated by a carrier fluid during rectilinear displacement. We perform accurate numerical simulations that are thermodynamically-consistent to capture fingering patterns and complex phase behavior of mixtures. The results provide a broad perspective into how multiphase flow can alter fluid mixing in porous media.

  14. Mutant connexin 50 (S276F) inhibits channel and hemichannel functions inducing cataract

    Indian Academy of Sciences (India)

    Yuanyuan Liu; Chen Qiao; Tanwei Wei; Fang Zheng; Shuren Guo; Qiang Chen; Ming Yan; Xin Zhou

    2015-06-01

    This study was designed to detect the expression, detergent resistance, subcellular localization, and channel and hemichannel functions of mutant Cx50 to understand the forming mechanism for inducing congenital cataract by a novel mutation p.S276F in connexin 50 (Cx50) reported previously by us. HeLa and human lens epithelial (HLE) cells were transfected with wild-type Cx50 and mutant Cx50 (S276F). We examined the functional characteristics of mutant Cx50 (S276F) in comparison with those of wild-type Cx50 using immunoblot, confocal fluorescence microscopy, dye transfer analysis and dye uptake assay. The mutant and wild-type Cx50 were expressed in equal levels and could efficiently localize to the plasma membrane without transportation and assembly problems. Scrape loading dye transfer was significantly evident in cells transfected with wild-type Cx50 compared to those in cells transfected with mutant Cx50 and cotransfected with wild-type and mutant Cx50. The dye uptake was found to be significantly lower in cells transfected with mutant Cx50 than in cells transfected with wild-type Cx50 and cells cotransfected with wild-type and mutant Cx50. The transfected HeLa and HLE cell lines showed similar performance in all the experiments. These results indicated that the mutant Cx50 (S276F) might inhibit the function of gap junction channel in a dominant negative manner, but inhibit the hemichannel function in a recessive negative manner.

  15. CB1 Knockout Mice Unveil Sustained CB2-Mediated Antiallodynic Effects of the Mixed CB1/CB2 Agonist CP55,940 in a Mouse Model of Paclitaxel-Induced Neuropathic Pain.

    Science.gov (United States)

    Deng, Liting; Cornett, Benjamin L; Mackie, Ken; Hohmann, Andrea G

    2015-07-01

    Cannabinoids suppress neuropathic pain through activation of cannabinoid CB1 and/or CB2 receptors; however, unwanted CB1-mediated cannabimimetic effects limit clinical use. We asked whether CP55,940 [(-)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl)cyclohexanol], a potent cannabinoid that binds with similar affinity to CB1 and CB2 in vitro, produces functionally separable CB1- and CB2-mediated pharmacological effects in vivo. We evaluated antiallodynic effects, possible tolerance, and cannabimimetic effects (e.g., hypothermia, catalepsy, CB1-dependent withdrawal signs) after systemic CP55,940 treatment in a mouse model of toxic neuropathy produced by a chemotherapeutic agent, paclitaxel. The contribution of CB1 and CB2 receptors to in vivo actions of CP55,940 was evaluated using CB1 knockout (KO), CB2KO, and wild-type (WT) mice. Low-dose CP55,940 (0.3 mg/kg daily, i.p. ) suppressed paclitaxel-induced allodynia in WT and CB2KO mice, but not CB1KO mice. Low-dose CP55,940 also produced hypothermia and rimonabant-precipitated withdrawal in WT, but not CB1KO, mice. In WT mice, tolerance developed to CB1-mediated hypothermic effects of CP55,940 earlier than to antiallodynic effects. High-dose CP55,940 (10 mg/kg daily, i.p.) produced catalepsy in WT mice, which precluded determination of antiallodynic efficacy but produced sustained CB2-mediated suppression of paclitaxel-induced allodynia in CB1KO mice; these antiallodynic effects were blocked by the CB2 antagonist 6-iodopravadoline (AM630). High-dose CP55,940 did not produce hypothermia or rimonabant-precipitated withdrawal in CB1KO mice. Our results using the mixed CB1/CB2 agonist CP55,940 document that CB1 and CB2 receptor activations produce mechanistically distinct suppression of neuropathic pain. Our study highlights the therapeutic potential of targeting cannabinoid CB2 receptors to bypass unwanted central effects associated with CB1 receptor activation.

  16. Effect of knockout of α2δ-1 on action potentials in mouse sensory neurons

    Science.gov (United States)

    Margas, Wojciech; Ferron, Laurent; Nieto-Rostro, Manuela; Schwartz, Arnold; Dolphin, Annette C.

    2016-01-01

    Gene deletion of the voltage-gated calcium channel auxiliary subunit α2δ-1 has been shown previously to have a cardiovascular phenotype, and a reduction in mechano- and cold sensitivity, coupled with delayed development of neuropathic allodynia. We have also previously shown that dorsal root ganglion (DRG) neuron calcium channel currents were significantly reduced in α2δ-1 knockout mice. To extend our findings in these sensory neurons, we have examined here the properties of action potentials (APs) in DRG neurons from α2δ-1 knockout mice in comparison to their wild-type (WT) littermates, in order to dissect how the calcium channels that are affected by α2δ-1 knockout are involved in setting the duration of individual APs and their firing frequency. Our main findings are that there is reduced Ca2+ entry on single AP stimulation, particularly in the axon proximal segment, reduced AP duration and reduced firing frequency to a 400 ms stimulation in α2δ-1 knockout neurons, consistent with the expected role of voltage-gated calcium channels in these events. Furthermore, lower intracellular Ca2+ buffering also resulted in reduced AP duration, and a lower frequency of AP firing in WT neurons, mimicking the effect of α2δ-1 knockout. By contrast, we did not obtain any consistent evidence for the involvement of Ca2+-activation of large conductance calcium-activated potassium (BK) and small conductance calcium-activated potassium (SK) channels in these events. In conclusion, the reduced Ca2+ elevation as a result of single AP stimulation is likely to result from the reduced duration of the AP in α2δ-1 knockout sensory neurons. This article is part of the themed issue ‘Evolution brings Ca2+ and ATP together to control life and death’. PMID:27377724

  17. Seasonal and pollution-induced variations in biomarkers of transplanted mussels within the Beagle Channel.

    Science.gov (United States)

    Giarratano, Erica; Gil, Mónica N; Malanga, Gabriela

    2011-06-01

    The occurrence of biomarker variations linked to environmental factors makes it difficult to distinguish the effect of pollution. In an attempt to evaluate spatial and seasonal effects of environmental parameters on biomarker responses, mussels Mytilus edulis chilensis coming from an aquaculture farm were transplanted to several points within Ushuaia Bay (Beagle Channel) for 6 weeks in summer and winter. Activities of superoxide dismutase, catalase, glutathione-S-transferase and levels of lipid peroxidation were measured in gills and digestive gland. Cu, Zn, Fe, Cd and Pb concentrations were also assessed. Results indicated a significant effect of seasons on biological responses as well as in metal bioaccumulation showing the influence of natural factors such as dissolved oxygen, temperature and food availability. The interdependence of those environmental factors is important for the homeostasis of thermoconformers, especially regarding their oxidative metabolism and should also be taken into consideration to distinguish natural from pollution-induced variations.

  18. The impact of plasma induced flow on the boundary layer in a narrow channel

    Directory of Open Access Journals (Sweden)

    Procházka P.

    2015-01-01

    Full Text Available The induced flow generated by dielectric barrier discharge (DBD actuator working in steady and unsteady regime will be used to modify properties of naturally developed boundary layer (BL in short and long rectangular perspex channel which is connected to the blow-down wind tunnel. The actuator is placed in spanwise configuration and the inlet velocities will range between 5 and 20 m•s-1. Previously, mean flow field and statistical quantities were subjugated to investigation. In this paper, there will be presented dynamical features of the BL. Oscillation pattern decomposition (OPD of influenced flow field and frequency analysis will be presented. These results should be taken into account regarding to use in the flow around a bluff body.

  19. Pentachlorophenol-Induced Cytotoxic, Mitogenic, and Endocrine-Disrupting Activities in Channel Catfish, Ictalurus punctatus

    Directory of Open Access Journals (Sweden)

    Paul B. Tchounwou

    2004-09-01

    Full Text Available Pentachlorophenol (PCP is an organochlorine compound that has been widely used as a biocide in several industrial, agricultural, and domestic applications. Although it has been shown to induce systemic toxicity and carcinogenesis in several experimental studies, the literature is scarce regarding its toxic mechanisms of action at the cellular and molecular levels. Recent investigations in our laboratory have shown that PCP induces cytotoxicity and transcriptionally activates stress genes in human liver carcinoma (HepG2 cells [1]. In this research, we hypothesize that environmental exposure to PCP may trigger cytotoxic, mitogenic, and endocrine-disrupting activities in aquatic organisms including fish. To test this hypothesis, we carried out in vitro cultures of male channel catfish hepatocytes, and performed the fluorescein diacetate assay (FDA to assess for cell viability, and the Western Blot analysis to assess for vitellogenin expression following exposure to PCP. Data obtained from FDA experiments indicated a strong dose-response relationship with respect to PCP cytotoxicity. Upon 48 hrs of exposure, the chemical dose required to cause 50% reduction in cell viability (LD50 was computed to be 1,987.0 + 9.6 μg PCP/mL. The NOAEL and LOAEL were 62.5 + 10.3 μg PCP/mL and 125.0+15.2 μg PCP/mL, respectively. At lower levels of exposure, PCP was found to be mitogenic, showing a strong dose- and time-dependent response with regard to cell proliferation. Western Blot analysis demonstrated the potential of PCP to cause endocrine-disrupting activity, as evidenced by the up regulation of the 125-kDa vitellogenin protein the hepatocytes of male channel catfish.

  20. Contribution of K(+) channels to endothelium-derived hypolarization-induced renal vasodilation in rats in vivo and in vitro.

    Science.gov (United States)

    Rasmussen, Kasper Moller Boje; Braunstein, Thomas Hartig; Salomonsson, Max; Brasen, Jens Christian; Sorensen, Charlotte Mehlin

    2016-07-01

    We investigated the mechanisms behind the endothelial-derived hyperpolarization (EDH)-induced renal vasodilation in vivo and in vitro in rats. We assessed the role of Ca(2+)-activated K(+) channels and whether K(+) released from the endothelial cells activates inward rectifier K(+) (Kir) channels and/or the Na(+)/K(+)-ATPase. Also, involvement of renal myoendothelial gap junctions was evaluated in vitro. Isometric tension in rat renal interlobar arteries was measured using a wire myograph. Renal blood flow was measured in isoflurane anesthetized rats. The EDH response was defined as the ACh-induced vasodilation assessed after inhibition of nitric oxide synthase and cyclooxygenase using L-NAME and indomethacin, respectively. After inhibition of small conductance Ca(2+)-activated K(+) channels (SKCa) and intermediate conductance Ca(2+)-activated K(+) channels (IKCa) (by apamin and TRAM-34, respectively), the EDH response in vitro was strongly attenuated whereas the EDH response in vivo was not significantly reduced. Inhibition of Kir channels and Na(+)/K(+)-ATPases (by ouabain and Ba(2+), respectively) significantly attenuated renal vasorelaxation in vitro but did not affect the response in vivo. Inhibition of gap junctions in vitro using carbenoxolone or 18α-glycyrrhetinic acid significantly reduced the endothelial-derived hyperpolarization-induced vasorelaxation. We conclude that SKCa and IKCa channels are important for EDH-induced renal vasorelaxation in vitro. Activation of Kir channels and Na(+)/K(+)-ATPases plays a significant role in the renal vascular EDH response in vitro but not in vivo. The renal EDH response in vivo is complex and may consist of several overlapping mechanisms some of which remain obscure.

  1. Heteromultimeric TRPML channel assemblies play a crucial role in the regulation of cell viability models and starvation-induced autophagy.

    Science.gov (United States)

    Zeevi, David A; Lev, Shaya; Frumkin, Ayala; Minke, Baruch; Bach, Gideon

    2010-09-15

    The mucolipin (TRPML) subfamily of transient receptor potential (TRP) cation channels consists of three members that play various roles in the regulation of membrane and protein sorting along endo-lysosomal pathways. Loss-of-function mutations in TRPML1 cause the neurodegenerative lysosomal storage disorder, mucolipidosis type IV (MLIV), whereas a gain-of-function mutation in TRPML3 is principally implicated in the hearing-impaired and abnormally pigmented varitint-waddler mouse. Currently, TRPML2 is not implicated in any pathological disorder, but we have recently shown that it is a functional cation channel that physically interacts with TRPML1 and TRPML3 to potentially regulate lysosomal integrity. Here, we show that mutant TRPMLs heteromultimerize with other mutant and wild-type TRPMLs to regulate cell viability and starvation-induced autophagy, a process that mediates macromolecular and organellar turnover under cell starvation conditions. Heteromultimerization of dominant-negative TRPMLs with constitutively active TRPMLs rescues cells from the cytotoxic effects of TRPML constitutive activity. Moreover, dominant-negative TRPML1 channels, including a mutant channel directly implicated in MLIV pathology, also inhibit starvation-induced autophagy by interacting with and affecting native TRPML channel function. Collectively, our results indicate that heteromultimerization of TRPML channels plays a role in various TRPML-regulated mechanisms.

  2. A STAT-1 Knockout Mouse Model for Machupo Virus Pathogenesis

    Science.gov (United States)

    2011-06-14

    antiviral therapeutics discovery. Because arenaviruses can block host IFN responses to establish infection, mice lacking elements of the interferon... arenaviruses (including MACV) binds to the retinoic acid-inducible gene I (RIG-I) protein and subsequently inhibits IFN-beta responses [19...although this mechanism has yet to be precisely described for arenaviruses [26]. Although it is probable that cytokine levels in STAT-1 knockout mice will

  3. R-type calcium channels are crucial for semaphorin 3A-induced DRG axon growth cone collapse.

    Directory of Open Access Journals (Sweden)

    Rimantas Treinys

    Full Text Available Semaphorin 3A (Sema3A is a secreted protein involved in axon path-finding during nervous system development. Calcium signaling plays an important role during axonal growth in response to different guidance cues; however it remains unclear whether this is also the case for Sema3A. In this study we used intracellular calcium imaging to figure out whether Sema3A-induced growth cone collapse is a Ca2+ dependent process. Intracellular Ca2+ imaging results using Fura-2 AM showed Ca2+ increase in E15 mice dorsal root ganglia neurons upon Sema3A treatment. Consequently we analyzed Sema3A effect on growth cones after blocking or modifying intracellular and extracellular Ca2+ channels that are expressed in E15 mouse embryos. Our results demonstrate that Sema3A increased growth cone collapse rate is blocked by the non-selective R- and T- type Ca2+ channel blocker NiCl2 and by the selective R-type Ca2+ channel blocker SNX482. These Ca2+ channel blockers consistently decreased the Sema3A-induced intracellular Ca2+ concentration elevation. Overall, our results demonstrate that Sema3A-induced growth cone collapses are intimately related with increase in intracellular calcium concentration mediated by R-type calcium channels.

  4. The serotonin transporter knockout rat : A review

    NARCIS (Netherlands)

    Olivier, Jocelien; Cools, Alexander; Ellenbroek, Bart A.; Cuppen, E.; Homberg, Judith; Kalueff, Allan V.; LaPorte, Justin L.

    2010-01-01

    This chapter dicusses the most recent data on the serotonin transporter knock-out rat, a unique rat model that has been generated by target-selected N-ethyl-N-nitrosourea (ENU) driven mutagenesis. The knock-out rat is the result of a premature stopcodon in the serotonin transporter gene, and the abs

  5. Involvement of water channel Aquaporin 5 in H2S-induced pulmonary edema.

    Science.gov (United States)

    Xu, Chunyang; Jiang, Lei; Zou, Yuxia; Xing, Jingjing; Sun, Hao; Zhu, Baoli; Zhang, Hengdong; Wang, Jun; Zhang, Jinsong

    2017-01-01

    Acute exposure to hydrogen sulfide (H2S) poses a significant threat to life, and the lung is one of the primary target organs of H2S. However, the mechanisms involved in H2S-induced acute pulmonary edema are poorly understood. This study aims to investigate the effects of H2S on the expression of water channel aquaporin 5 (AQP5) and to elucidate the signaling pathways involved in AQP5 regulation. In an in vivo study, C57BL6 mice were exposed to sub-lethal concentrations of inhaled H2S, and histological injury of the lungs and ultrastructure injury of the epithelial cells were evaluated. With real-time PCR and western blot assays, we found that H2S exposure contributed to a significant decrease in AQP5 expression both in murine lung tissue and the A549 cell line, and the ERK1/2 and p38 MAPK signaling pathways were demonstrated to be implicated in AQP5 regulation. Therefore, adjusting AQP5 protein levels could be considered a therapeutic strategy for the treatment of APE induced by H2S and other hazardous gases.

  6. Role of Induced Magnetic Field on Transient Natural Convection Flow in a Vertical Channel: The Riemann Sum Approximation Approach

    Directory of Open Access Journals (Sweden)

    Jha B.K.

    2015-02-01

    Full Text Available This paper investigates the role of induced magnetic field on a transient natural convection flow of an electrically conducting, incompressible and viscous fluid in a vertical channel formed by two infinite vertical parallel plates. The transient flow formation inside the channel is due to sudden asymmetric heating of channel walls. The time dependent momentum, energy and magnetic induction equations are solved semi-analytically using the Laplace transform technique along with the Riemann-sum approximation method. The solutions obtained are validated by comparisons with the closed form solutions obtained for the steady states which have been derived separately and also by the implicit finite difference method. Graphical results for the temperature, velocity, induced magnetic field, current density, and skin-friction based on the semi-analytical solutions are presented and discussed.

  7. Curcumin-induced heme oxygenase-1 expression prevents H2O2-induced cell death in wild type and heme oxygenase-2 knockout adipose-derived mesenchymal stem cells.

    Science.gov (United States)

    Cremers, Niels A J; Lundvig, Ditte M S; van Dalen, Stephanie C M; Schelbergen, Rik F; van Lent, Peter L E M; Szarek, Walter A; Regan, Raymond F; Carels, Carine E; Wagener, Frank A D T G

    2014-10-08

    Mesenchymal stem cell (MSC) administration is a promising adjuvant therapy to treat tissue injury. However, MSC survival after administration is often hampered by oxidative stress at the site of injury. Heme oxygenase (HO) generates the cytoprotective effector molecules biliverdin/bilirubin, carbon monoxide (CO) and iron/ferritin by breaking down heme. Since HO-activity mediates anti-apoptotic, anti-inflammatory, and anti-oxidative effects, we hypothesized that modulation of the HO-system affects MSC survival. Adipose-derived MSCs (ASCs) from wild type (WT) and HO-2 knockout (KO) mice were isolated and characterized with respect to ASC marker expression. In order to analyze potential modulatory effects of the HO-system on ASC survival, WT and HO-2 KO ASCs were pre-treated with HO-activity modulators, or downstream effector molecules biliverdin, bilirubin, and CO before co-exposure of ASCs to a toxic dose of H2O2. Surprisingly, sensitivity to H2O2-mediated cell death was similar in WT and HO-2 KO ASCs. However, pre-induction of HO-1 expression using curcumin increased ASC survival after H2O2 exposure in both WT and HO-2 KO ASCs. Simultaneous inhibition of HO-activity resulted in loss of curcumin-mediated protection. Co-treatment with glutathione precursor N-Acetylcysteine promoted ASC survival. However, co-incubation with HO-effector molecules bilirubin and biliverdin did not rescue from H2O2-mediated cell death, whereas co-exposure to CO-releasing molecules-2 (CORM-2) significantly increased cell survival, independently from HO-2 expression. Summarizing, our results show that curcumin protects via an HO-1 dependent mechanism against H2O2-mediated apoptosis, and likely through the generation of CO. HO-1 pre-induction or administration of CORMs may thus form an attractive strategy to improve MSC therapy.

  8. Curcumin-Induced Heme Oxygenase-1 Expression Prevents H2O2-Induced Cell Death in Wild Type and Heme Oxygenase-2 Knockout Adipose-Derived Mesenchymal Stem Cells

    Directory of Open Access Journals (Sweden)

    Niels A. J. Cremers

    2014-10-01

    Full Text Available Mesenchymal stem cell (MSC administration is a promising adjuvant therapy to treat tissue injury. However, MSC survival after administration is often hampered by oxidative stress at the site of injury. Heme oxygenase (HO generates the cytoprotective effector molecules biliverdin/bilirubin, carbon monoxide (CO and iron/ferritin by breaking down heme. Since HO-activity mediates anti-apoptotic, anti-inflammatory, and anti-oxidative effects, we hypothesized that modulation of the HO-system affects MSC survival. Adipose-derived MSCs (ASCs from wild type (WT and HO-2 knockout (KO mice were isolated and characterized with respect to ASC marker expression. In order to analyze potential modulatory effects of the HO-system on ASC survival, WT and HO-2 KO ASCs were pre-treated with HO-activity modulators, or downstream effector molecules biliverdin, bilirubin, and CO before co-exposure of ASCs to a toxic dose of H2O2. Surprisingly, sensitivity to H2O2-mediated cell death was similar in WT and HO-2 KO ASCs. However, pre-induction of HO-1 expression using curcumin increased ASC survival after H2O2 exposure in both WT and HO-2 KO ASCs. Simultaneous inhibition of HO-activity resulted in loss of curcumin-mediated protection. Co-treatment with glutathione precursor N-Acetylcysteine promoted ASC survival. However, co-incubation with HO-effector molecules bilirubin and biliverdin did not rescue from H2O2-mediated cell death, whereas co-exposure to CO-releasing molecules-2 (CORM-2 significantly increased cell survival, independently from HO-2 expression. Summarizing, our results show that curcumin protects via an HO-1 dependent mechanism against H2O2-mediated apoptosis, and likely through the generation of CO. HO-1 pre-induction or administration of CORMs may thus form an attractive strategy to improve MSC therapy.

  9. Dopamine Induces LTP Differentially in Apical and Basal Dendrites through BDNF and Voltage-Dependent Calcium Channels

    Science.gov (United States)

    Navakkode, Sheeja; Sajikumar, Sreedharan; Korte, Martin; Soong, Tuck Wah

    2012-01-01

    The dopaminergic modulation of long-term potentiation (LTP) has been studied well, but the mechanism by which dopamine induces LTP (DA-LTP) in CA1 pyramidal neurons is unknown. Here, we report that DA-LTP in basal dendrites is dependent while in apical dendrites it is independent of activation of L-type voltage-gated calcium channels (VDCC).…

  10. Cell volume control in phospholemman (PLM) knockout mice: do cardiac myocytes demonstrate a regulatory volume decrease and is this influenced by deletion of PLM?

    Science.gov (United States)

    Bell, James R; Lloyd, David; Curl, Claire L; Delbridge, Lea M D; Shattock, Michael J

    2009-03-01

    In addition to modulatory actions on Na+-K+-ATPase, phospholemman (PLM) has been proposed to play a role in cell volume regulation. Overexpression of PLM induces ionic conductances, with 'PLM channels' exhibiting selectivity for taurine. Osmotic challenge of host cells overexpressing PLM increases taurine efflux and augments the cellular regulatory volume decrease (RVD) response, though a link between PLM and cell volume regulation has not been studied in the heart. We recently reported a depressed cardiac contractile function in PLM knockout mice in vivo, which was exacerbated in crystalloid-perfused isolated hearts, indicating that these hearts were osmotically challenged. To address this, the present study investigated the role of PLM in osmoregulation in the heart. Isolated PLM wild-type and knockout hearts were perfused with a crystalloid buffer supplemented with mannitol in a bid to prevent perfusate-induced cell swelling and maintain function. Accordingly, and in contrast to wild-type control hearts, contractile function was improved in PLM knockout hearts with 30 mM mannitol. To investigate further, isolated PLM wild-type and knockout cardiomyocytes were subjected to increasing hyposmotic challenges. Initial validation studies showed the IonOptix video edge-detection system to be a simple and accurate 'real-time' method for tracking cell width as a marker of cell size. Myocytes swelled equally in both genotypes, indicating that PLM, when expressed at physiological levels in cardiomyocytes, is not essential to limit water accumulation in response to a hyposmotic challenge. Interestingly, freshly isolated adult cardiomyocytes consistently failed to mount RVDs in response to cell swelling, adding to conflicting reports in the literature. A proposed perturbation of the RVD response as a result of the cell isolation process was not restored, however, with short-term culture in either adult or neonatal cardiomyocytes.

  11. Impaired social behavior in 5-HT(3A) receptor knockout mice

    NARCIS (Netherlands)

    L.A. Smit-Rigter; W.J. Wadman; J.A. van Hooft

    2010-01-01

    The 5-HT(3) receptor is a ligand-gated ion channel expressed on interneurons throughout the brain. So far, analysis of the 5-HT(3A) knockout mouse revealed changes in nociceptive processing and a reduction in anxiety related behavior. Recently, it was shown that the 5-HT(3) receptor is also expresse

  12. Hypervitaminosis D mediates compensatory Ca2+ hyperabsorption in TRPV5 knockout mice.

    NARCIS (Netherlands)

    Renkema, K.Y.R.; Nijenhuis, T.; Eerden, B.C. van der; Kemp, J.W.C.M. van der; Weinans, H.; Leeuwen, J.P.P.M. van; Bindels, R.J.M.; Hoenderop, J.G.J.

    2005-01-01

    Vitamin D plays an important role in Ca(2+) homeostasis by controlling Ca(2+) (re)absorption in intestine, kidney, and bone. The epithelial Ca(2+) channel TRPV5 mediates the Ca(2+) entry step in active Ca(2+) reabsorption. TRPV5 knockout (TRPV5(-/-)) mice show impaired Ca(2+) reabsorption, hypercalc

  13. Evidence for altered Ca2+ handling in Growth Associated Protein 43-knockout skeletal muscle

    Directory of Open Access Journals (Sweden)

    Giusy A. Caprara

    2016-10-01

    Full Text Available Neuronal growth-associated protein 43 (GAP43 has crucial roles in the nervous system, and during development, regeneration after injury, and learning and memory. GAP43 is expressed in mouse skeletal muscle fibers and satellite cells, with suggested its involvement in intracellular Ca2+ handling. However, the physiological role of GAP43 in muscle remains unknown. Using a GAP43-knockout (GAP43-/- mouse, we have defined the role of GAP43 in skeletal muscle. GAP43-/- mice showed low survival beyond weaning, reduced adult body weight, decreased muscle strength, and changed myofiber ultrastructure, with no significant differences in the expression of markers of satellite cell and myotube progression through the myogenic program. Thus GAP43 expression is involved in timing of muscle maturation in-vivo. Intracellular Ca2+ measurements in-vitro in myotubes revealed GAP43 involvement in Ca2+ handling. In the absence of GAP43 expression, the spontaneous Ca2+ variations had greater amplitudes and higher frequency. In GAP43-/- myotubes, also the intracellular Ca2+ variations induced by the activation of dihydropyridine and ryanodine Ca2+ channels, resulted modified. These evidences suggested dysregulation of Ca2+ homeostasis. The emerging hypothesis indicates that GAP43 interacts with calmodulin to indirectly modulate the activities of dihydropyridine and ryanodine Ca2+ channels. This thus influences intracellular Ca2+ dynamics and its related intracellular patterns, from functional excitation-contraction coupling, to cell metabolism, and gene expression.

  14. Constitutive activity of the human TRPML2 channel induces cell degeneration.

    Science.gov (United States)

    Lev, Shaya; Zeevi, David A; Frumkin, Ayala; Offen-Glasner, Vered; Bach, Gideon; Minke, Baruch

    2010-01-22

    The mucolipin (TRPML) ion channel proteins represent a distinct subfamily of channel proteins within the transient receptor potential (TRP) superfamily of cation channels. Mucolipin 1, 2, and 3 (TRPML1, -2, and -3, respectively) are channel proteins that share high sequence homology with each other and homology in the transmembrane domain with other TRPs. Mutations in the TRPML1 protein are implicated in mucolipidosis type IV, whereas mutations in TRPML3 are found in the varitint-waddler mouse. The properties of the wild type TRPML2 channel are not well known. Here we show functional expression of the wild type human TRPML2 channel (h-TRPML2). The channel is functional at the plasma membrane and characterized by a significant inward rectification similar to other constitutively active TRPML mutant isoforms. The h-TRPML2 channel displays nonselective cation permeability, which is Ca(2+)-permeable and inhibited by low extracytosolic pH but not Ca(2+) regulated. In addition, constitutively active h-TRPML2 leads to cell death by causing Ca(2+) overload. Furthermore, we demonstrate by functional mutation analysis that h-TRPML2 shares similar characteristics and structural similarities with other TRPML channels that regulate the channel in a similar manner. Hence, in addition to overall structure, all three TRPML channels also share common modes of regulation.

  15. Dam-induced and natural channel changes in the Saskatchewan River below the E.B. Campbell Dam, Canada

    Science.gov (United States)

    Smith, Norman D.; Morozova, Galina S.; Pérez-Arlucea, Marta; Gibling, Martin R.

    2016-09-01

    portions of the avulsion belt, including the Mossy delta, but little bedload is returned to the parent channel. Dam-induced sediment starvation is speeding the rate at which a single dominant channel is evolving between the avulsion site and rejoined parent, a process that will likely shift the patterns of flood inundation in the future.

  16. Mitochondrial small conductance SK2 channels prevent glutamate-induced oxytosis and mitochondrial dysfunction.

    Science.gov (United States)

    Dolga, Amalia M; Netter, Michael F; Perocchi, Fabiana; Doti, Nunzianna; Meissner, Lilja; Tobaben, Svenja; Grohm, Julia; Zischka, Hans; Plesnila, Nikolaus; Decher, Niels; Culmsee, Carsten

    2013-04-12

    Small conductance calcium-activated potassium (SK2/K(Ca)2.2) channels are known to be located in the neuronal plasma membrane where they provide feedback control of NMDA receptor activity. Here, we provide evidence that SK2 channels are also located in the inner mitochondrial membrane of neuronal mitochondria. Patch clamp recordings in isolated mitoplasts suggest insertion into the inner mitochondrial membrane with the C and N termini facing the intermembrane space. Activation of SK channels increased mitochondrial K(+) currents, whereas channel inhibition attenuated these currents. In a model of glutamate toxicity, activation of SK2 channels attenuated the loss of the mitochondrial transmembrane potential, blocked mitochondrial fission, prevented the release of proapoptotic mitochondrial proteins, and reduced cell death. Neuroprotection was blocked by specific SK2 inhibitory peptides and siRNA targeting SK2 channels. Activation of mitochondrial SK2 channels may therefore represent promising targets for neuroprotective strategies in conditions of mitochondrial dysfunction.

  17. The opening of maitotoxin-sensitive calcium channels induces the acrosome reaction in human spermatozoa: differences from the zona pellucida

    Institute of Scientific and Technical Information of China (English)

    Julio C Chávez; Claudia L Trevi(n)o; Gerardo A de Blas; José L de la Vega-Beltrán; Takuya Nishigaki; Mayel Chirinos; María Elena González-González; Fernando Larrea; Alejandra Solís; Alberto Darszon

    2011-01-01

    The acrosome reaction(AR),an absolute requirement for spermatozoa and egg fusion,requires the influx of Ca2+into the spermatozoa through voltage-dependent Ca2+channels and store-operated channels.Maitotoxin(MTx),a Ca2+-mobilizing agent,has been shown to be a potent inducer of the mouse sperm AR,with a pharmacology similar to that of the zona pellucida(ZP),possibly suggesting a common pathway for both inducers.Using recombinant human ZP3(rhZP3),mouse ZP and two MTx channel blockers(U73122 and U73343),we investigated and compared the MTx-and ZP-induced ARs in human and mouse spermatozoa.Herein,we report that MTx induced AR and elevated intracellular Ca2+([Ca2+]1)in human spermatozoa,both of which were blocked by U73122 and U73343.These two compounds also inhibited the MTx-induced AR in mouse spermatozoa.In disagreement with our previous proposal,the AR triggered by rhZP3 or mouse ZP was not blocked by U73343,indicating that in human and mouse spermatozoa,the AR induction by the physiologicalligands or by MTx occurred through distinct pathways.U73122,but not U73343(inactive analogue),can block phospholipase C(PLC).Another PLC inhibitor,edelfosine,also blocked the rhZP3-and ZP-induced ARs.These findings confirmed the participation of a PLC-dependent signalling pathway in human and mouse zona protein-induced AR.Notably,edelfosine also inhibited the MTx-induced mouse sperm AR but not that of the human,suggesting that toxin-induced AR is PLC-dependent in mice and PLC-independent in humans.

  18. Activation of mitochondrial ATP-sensitive potassium channels delays ischemia-induced cellular uncoupling in rat heart

    Institute of Scientific and Technical Information of China (English)

    Yue-liangSHEN; Ying-yingCHEN; Xun-dongWU; IainCBRUCE; QiangXIA

    2004-01-01

    AIM: To test the hypothesis that cellular uncoupling induced by myocardial ischemia is mediated by activation of mitochondrial ATP-sensitive potassium channels (mitoKATP). METHODS: Rat hearts were perfused on a Langendorff apparatus and subjected to 40-min ischemia followed by 30-min reperfusion (I/R). Changes in cellular coupling were monitored by measuring whole-tissue resistance. RESULTS: (1) In hearts subjected to I/R, the onset of uncoupling started at (13.3± 1.0) min of ischemia; (2) Ischemic preconditioning (IPC) delayed the onset of uncoupling until (22.7±1.3) min. Blocking mitoKATP channels with 5-hydroxydecanoate (5-HD) before the IPC abolishedthe uncoupling delay [(12.6±1.6)min]; (3) Calcium preconditioning (CPC) had the same effect as IPC. And this effect was reversed by blocking the mitoKATP channel again. In the CPC group the onset of uncoupling occurred after (20.6±1.3) min, and this was canceled by 5-HD [(13.6±0.8) min]; (4) In hearts pretreated with the specific mitoKATP channel opener diazoxide before sustained ischemia, the onset was delayed to (18.4±1.4) min; (5) 5-HD canceled the protective effects of diazoxide (12.6±1.0) min; and both the L-type Ca2+ channel inhibitor verapamiland the free radical scavenger N-(2-mercaptopropionyl)glycine, reduced the extended onset time induced by diazoxide[to (13.3±1.8) min and (13.4±2.1) min, respectively]. CONCLUSION: IPC and CPC delay the onset of cellular uncoupling induced by acute ischemia in rat heart, and the underlying mechanism involves activation of the mitoKATP channels.

  19. Endostatin is protective against monocrotaline-induced right heart disease through the inhibition of T-type Ca(2+) channel.

    Science.gov (United States)

    Imoto, Keisuke; Kumatani, Sayaka; Okada, Muneyoshi; Yamawaki, Hideyuki

    2016-07-01

    Endostatin (ES), a C-terminal fragment of collagen XVIIIα1, has a potent anti-angiogenic effect. ES prevents tumor proliferation through inhibiting T-type Ca(2+) channel. T-type Ca(2+) channel is re-expressed during heart diseases including monocrotaline (MCT)-induced right heart failure. The present study aimed to clarify the effects of ES on T-type Ca(2+) channel and pathogenesis of MCT-induced right ventricular disease. MCT or saline was injected intraperitoneally to rats. After cardiomyocytes were isolated from right ventricles (RVs), T-type Ca(2+) channel current (I CaT) was measured by a patch-clamp method. After ES small interfering RNA (siRNA) or control siRNA (20 μg) was administrated for 1 week via the right jugular vein 1 week after MCT injection, echocardiography and histological analysis were done. I CaT was significantly increased in RV from MCT-injected rats, and ES significantly inhibited it. The survival rate of ES siRNA-administrated MCT rats (MCT ES si group) was decreased. In echocardiography, although ES siRNA did not affect pulmonary arterial pressure, RV systolic function was impaired in MCT ES si group compared with control siRNA-administrated MCT rats (MCT cont si group). In the histological analysis of RV, ES expression was increased in MCT cont si group, and ES siRNA inhibited it. Furthermore, although MCT cont si group showed only cardiomyocyte hypertrophy, MCT ES si group showed notable enlargement of intercellular spaces. The present study for the first time revealed that ES inhibits T-type Ca(2+) channel activity in RV from MCT-injected rats. ES gene knockdown deteriorates MCT-induced right heart disease. ES is thus cardioprotective possibly through inhibiting T-type Ca(2+) channel activity.

  20. Expressional analysis of the astrocytic Kir4.1 channel in a pilocarpine–induced temporal lobe epilepsy model

    Science.gov (United States)

    Nagao, Yuki; Harada, Yuya; Mukai, Takahiro; Shimizu, Saki; Okuda, Aoi; Fujimoto, Megumi; Ono, Asuka; Sakagami, Yoshihisa; Ohno, Yukihiro

    2013-01-01

    The inwardly rectifying potassium (Kir) channel Kir4.1 in brain astrocytes mediates spatial K+ buffering and regulates neural activities. Recent studies have shown that loss-of-function mutations in the human gene KCNJ10 encoding Kir4.1 cause epileptic seizures, suggesting a close relationship between the Kir4.1 channel function and epileptogenesis. Here, we performed expressional analysis of Kir4.1 in a pilocarpine-induced rat model of temporal lobe epilepsy (TLE) to explore the role of Kir4.1 channels in modifying TLE epileptogenesis. Treatment of rats with pilocarpine (350 mg/kg, i.p.) induced acute status epilepticus, which subsequently caused spontaneous seizures 7–8 weeks after the pilocarpine treatment. Western blot analysis revealed that TLE rats (interictal condition) showed significantly higher levels of Kir4.1 than the control animals in the cerebral cortex, striatum, and hypothalamus. However, the expression of other Kir subunits, Kir5.1 and Kir2.1, remained unaltered. Immunohistochemical analysis illustrated that Kir4.1-immunoreactivity-positive astrocytes in the pilocarpine-induced TLE model were markedly increased in most of the brain regions examined, concomitant with an increase in the number of glial fibrillary acidic protein (GFAP)-positive astrocytes. In addition, Kir4.1 expression ratios relative to the number of astrocytes (Kir4.1-positive cells/GFAP-positive cells) were region-specifically elevated in the amygdala (i.e., medial and cortical amygdaloid nuclei) and sensory cortex. The present study demonstrated for the first time that the expression of astrocytic Kir4.1 channels was elevated in a pilocarpine-induced TLE model, especially in the amygdala, suggesting that astrocytic Kir4.1 channels play a role in modifying TLE epileptogenesis, possibly by acting as an inhibitory compensatory mechanism. PMID:23922547

  1. Expressional analysis of the astrocytic Kir4.1 channel in a pilocarpine-induced temporal lobe epilepsy model.

    Science.gov (United States)

    Nagao, Yuki; Harada, Yuya; Mukai, Takahiro; Shimizu, Saki; Okuda, Aoi; Fujimoto, Megumi; Ono, Asuka; Sakagami, Yoshihisa; Ohno, Yukihiro

    2013-01-01

    The inwardly rectifying potassium (Kir) channel Kir4.1 in brain astrocytes mediates spatial K(+) buffering and regulates neural activities. Recent studies have shown that loss-of-function mutations in the human gene KCNJ10 encoding Kir4.1 cause epileptic seizures, suggesting a close relationship between the Kir4.1 channel function and epileptogenesis. Here, we performed expressional analysis of Kir4.1 in a pilocarpine-induced rat model of temporal lobe epilepsy (TLE) to explore the role of Kir4.1 channels in modifying TLE epileptogenesis. Treatment of rats with pilocarpine (350 mg/kg, i.p.) induced acute status epilepticus, which subsequently caused spontaneous seizures 7-8 weeks after the pilocarpine treatment. Western blot analysis revealed that TLE rats (interictal condition) showed significantly higher levels of Kir4.1 than the control animals in the cerebral cortex, striatum, and hypothalamus. However, the expression of other Kir subunits, Kir5.1 and Kir2.1, remained unaltered. Immunohistochemical analysis illustrated that Kir4.1-immunoreactivity-positive astrocytes in the pilocarpine-induced TLE model were markedly increased in most of the brain regions examined, concomitant with an increase in the number of glial fibrillary acidic protein (GFAP)-positive astrocytes. In addition, Kir4.1 expression ratios relative to the number of astrocytes (Kir4.1-positive cells/GFAP-positive cells) were region-specifically elevated in the amygdala (i.e., medial and cortical amygdaloid nuclei) and sensory cortex. The present study demonstrated for the first time that the expression of astrocytic Kir4.1 channels was elevated in a pilocarpine-induced TLE model, especially in the amygdala, suggesting that astrocytic Kir4.1 channels play a role in modifying TLE epileptogenesis, possibly by acting as an inhibitory compensatory mechanism.

  2. Expressional analysis of the astrocytic Kir4.1 channel in a pilocarpine-induced temporal lobe epilepsy model

    Directory of Open Access Journals (Sweden)

    Yuki eNagao

    2013-07-01

    Full Text Available The inwardly-rectifying potassium (Kir channel Kir4.1 in brain astrocytes mediates spatial K+ buffering and regulates neural activities. Recent studies have shown that loss-of-function mutations in the human gene KCNJ10 encoding Kir4.1 cause epileptic seizures, suggesting a close relationship between the Kir4.1 channel function and epileptogenesis. Here, we performed expressional analysis of Kir4.1 in a pilocarpine-induced rat model of temporal lobe epilepsy (TLE to explore the role of Kir4.1 channels in modifying TLE epileptogenesis. Treatment of rats with pilocarpine (350 mg/kg, i.p. induced acute status epilepticus, which subsequently caused spontaneous seizures 7–8 weeks after the pilocarpine treatment. Western blot analysis revealed that TLE rats (interictal condition showed significantly higher levels of Kir4.1 than the control animals in the cerebral cortex, striatum and hypothalamus. However, the expression of other Kir subunits, Kir5.1 and Kir2.1, remained unaltered. Immunohistochemical analysis illustrated that Kir4.1-immunoreactivity-positive astrocytes in the pilocarpine-induced TLE model were markedly increased in most of the brain regions examined, concomitant with an increase in the number of glial fibrillary acidic protein (GFAP-positive astrocytes. In addition, Kir4.1 expression ratios relative to the number of astrocytes (Kir4.1-positive cells/GFAP-positive cells were region-specifically elevated in the amygdala (i.e., medial and cortical amygdaloid nuclei and sensory cortex. The present study demonstrated for the first time that the expression of astrocytic Kir4.1 channels was elevated in a pilocarpine-induced TLE model, especially in the amygdala, suggesting that astrocytic Kir4.1 channels play a role in modifying TLE epileptogenesis, possibly by acting as an inhibitory compensatory mechanism.

  3. Transient Receptor Potential Vanilloid 4-Induced Modulation of Voltage-Gated Sodium Channels in Hippocampal Neurons.

    Science.gov (United States)

    Hong, Zhiwen; Jie, Pinghui; Tian, Yujing; Chen, Tingting; Chen, Lei; Chen, Ling

    2016-01-01

    Transient receptor potential vanilloid 4 (TRPV4) is reported to control the resting membrane potential and increase excitability in many types of cells. Voltage-gated sodium channels (VGSCs) play an important role in initiating action potentials in neurons. However, whether VGSCs can be modulated by the activation of TRPV4 in hippocampal pyramidal neurons remains unknown. In this study, we tested the effect of TRPV4 agonists (GSK1016790A and 4α-PDD) on voltage-gated sodium current (I Na) in hippocampal CA1 pyramidal neurons and the protein levels of α/β-subunit of VGSCs in the hippocampus of mice subjected to intracerebroventricular (icv.) injection of GSK1016790A (GSK-injected mice). Herein, we report that I Na was inhibited by acute application of GSK1016790A or 4α-PDD. In the presence of TRPV4 agonists, the voltage-dependent inactivation curve shifted to the hyperpolarization, whereas the voltage-dependent activation curve remained unchanged. The TRPV4 agonist-induced inhibition of I Na was blocked by the TRPV4 antagonist or tetrodotoxin. Moreover, blocking protein kinase A (PKA) markedly attenuated the GSK1016790A-induced inhibition of I Na, whereas antagonism of protein kinase C or p38 mitogen-activated protein kinase did not change GSK1016790A action. Finally, the protein levels of Nav1.1, Nav1.2, and Nav1.6 in the hippocampus increased in GSK-injected mice, whereas those of Nav1.3 and Navβ1 remained nearly unchanged. We conclude that I Na is inhibited by the acute activation of TRPV4 through PKA signaling pathway in hippocampal pyramidal neurons, but protein expression of α-subunit of VGSCs is increased by sustained TRPV4 activation, which may compensate for the acute inhibition of I Na and provide a possibility for hyper-excitability upon sustained TRPV4 activation.

  4. SNC-80-induced preconditioning: selective activation of the mitochondrial adenosine triphosphate-gated potassium channel.

    Science.gov (United States)

    Fischbach, Peter S; Barrett, Terrance D; Reed, Nathan J; Lucchesi, Benedict R

    2003-05-01

    Pharmacologic preconditioning by delta-opioid agonists occurs via activation of an adenosine triphosphate (ATP)-gated potassium channel (I(KATP)). Opening of mitochondrial I(KATP) confers pharmacologic preconditioning whereas opening the sarcolemmal I(KATP) shortens action potential duration and is proarrhythmic. This study investigated whether SNC-80, a selective delta-opioid agonist, is associated with development of ventricular arrhythmia due to activation of I(KATP). Rabbit isolated hearts were subjected to 12 min of hypoxia and 40 min of reoxygenation after pretreatment with SNC-80 (1 microM, n = 6), pinacidil (1.25 microM, n = 12), or BMS-191095 (6.0 microM, n = 4). Nine additional hearts served as controls. The cytoprotective effects of SNC-80 at a concentration of 1 microM were confirmed using 30 min of regional ischemia followed by 120 min of reperfusion. Ventricular fibrillation (VF) developed in 11 of 12 pinacidil-treated hearts whereas none of the SNC-80-treated (zero of six) hearts developed VF (P SNC-80 reduced infarct size expressed as a percentage of the area at risk from 33 +/- 4% to 14 +/- 3% (P = 0.004) compared with control. SNC-80, which selectively activates the delta-opioid receptor, provided cytoprotection but did not induce VF after hypoxia reoxygenation. The results indicate that pinacidil-induced nonselective activation of I(KATP) results in proarrhythmia that is dependent on activation of the sarcolemmal I(KATP). Selectivity for the mitochondrial I(KATP) is necessary to prevent induction of a proarrhythmic state.

  5. Transient Receptor Potential Melastatin 7 Cation Channel Kinase: New Player in Angiotensin II-Induced Hypertension.

    Science.gov (United States)

    Antunes, Tayze T; Callera, Glaucia E; He, Ying; Yogi, Alvaro; Ryazanov, Alexey G; Ryazanova, Lillia V; Zhai, Alexander; Stewart, Duncan J; Shrier, Alvin; Touyz, Rhian M

    2016-04-01

    Transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein comprising a magnesium (Mg(2+))/cation channel and a kinase domain. We previously demonstrated that vasoactive agents regulate vascular TRPM7. Whether TRPM7 plays a role in the pathophysiology of hypertension and associated cardiovascular dysfunction is unknown. We studied TRPM7 kinase-deficient mice (TRPM7Δkinase; heterozygous for TRPM7 kinase) and wild-type (WT) mice infused with angiotensin II (Ang II; 400 ng/kg per minute, 4 weeks). TRPM7 kinase expression was lower in heart and aorta from TRPM7Δkinase versus WT mice, effects that were further reduced by Ang II infusion. Plasma Mg(2+) was lower in TRPM7Δkinase versus WT mice in basal and stimulated conditions. Ang II increased blood pressure in both strains with exaggerated responses in TRPM7Δkinase versus WT groups (Phypertension is exaggerated, cardiac remodeling and left ventricular dysfunction are amplified, and endothelial function is impaired. These processes are associated with hypomagnesemia, blunted TRPM7 kinase expression/signaling, endothelial nitric oxide synthase downregulation, and proinflammatory vascular responses. Our findings identify TRPM7 kinase as a novel player in Ang II-induced hypertension and associated vascular and target organ damage.

  6. Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

    Science.gov (United States)

    Leksin, P. V.; Garif'yanov, N. N.; Kamashev, A. A.; Validov, A. A.; Fominov, Ya. V.; Schumann, J.; Kataev, V.; Thomas, J.; Büchner, B.; Garifullin, I. A.

    2016-03-01

    We have studied the proximity-induced superconducting triplet pairing in CoOx/Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni0.81Fe0.19 ). By optimizing the parameters of this structure we found a triplet channel assisted full switching between the normal and superconducting states. To observe an "isolated" triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect Δ Tc in the dependence of the Py2-layer thickness dP y 2. We determined the value of dP y 2 at which Δ Tc caused by the ordinary spin-valve effect (the difference in the superconducting transition temperature Tc between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers) is suppressed. For such a sample a "pure" triplet spin-valve effect which causes the minimum in Tc at the orthogonal configuration of magnetizations has been observed.

  7. Lipid transport in cholecystokinin knockout mice.

    Science.gov (United States)

    King, Alexandra; Yang, Qing; Huesman, Sarah; Rider, Therese; Lo, Chunmin C

    2015-11-01

    Cholecystokinin (CCK) is released in response to lipid feeding and regulates pancreatic digestive enzymes vital to the absorption of nutrients. Our previous reports demonstrated that cholecystokinin knockout (CCK-KO) mice fed for 10 weeks of HFD had reduced body fat mass, but comparable glucose uptake by white adipose tissues and skeletal muscles. We hypothesized that CCK is involved in energy homeostasis and lipid transport from the small intestine to tissues in response to acute treatment with dietary lipids. CCK-KO mice with comparable fat absorption had increased energy expenditure and were resistant to HFD-induced obesity. Using intraduodenal infusion of butter fat and intravenous infusion using Liposyn III, we determined the mechanism of lipid transport from the small intestine to deposition in lymph and adipocytes in CCK-KO mice. CCK-KO mice had delayed secretion of Apo B48-chylomicrons, lipid transport to the lymphatic system, and triglyceride (TG)-derived fatty acid uptake by epididymal fat in response to acute treatment of intraduodenal lipids. In contrast, CCK-KO mice had comparable TG clearance and lipid uptake by white adipocytes in response to TGs in chylomicron-like emulsion. Thus, we concluded that CCK is important for lipid transport and energy expenditure to control body weight in response to dietary lipid feeding.

  8. Plasmodium induces swelling-activated ClC-2 anion channels in the host erythrocyte

    OpenAIRE

    Huber, Stephan M.; Duranton, Christophe; Henke, Guido; Van De Sand, Claudia; Heussler, Volker; Shumilina, Ekaterina; Sandu, Ciprian D.; Tanneur, Valerie; Brand, Verena; Kasinathan, Ravi S.; Lang, Karl S; Peter G Kremsner; Christian A. Hübner; Rust, Marco B.; Dedek, Karin

    2004-01-01

    Intraerythrocytic growth of the human malaria parasite Plasmodium falciparum depends on delivery of nutrients. Moreover, infection challenges cell volume constancy of the host erythrocyte requiring enhanced activity of cell volume regulatory mechanisms. Patch clamp recording demonstrated inwardly and outwardly rectifying anion channels in infected but not in control erythrocytes. The molecular identity of those channels remained elusive. We show here for one channel type that voltage dependen...

  9. Distribution of induced electromagnetic fields in the MHD-channel with electrodes and its integral characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Lavrent' yev, I.V.

    1982-01-01

    A solution is provided to the task of distributing electromagnetic fields in the MHD channel with nonconducting partitions of finite length with random magnetic Reynolds numbers. Local and integral characteristics of these channels are obtained. It is indicated that their high effectiveness can be guaranteed only by arranging partitions at the inlet to the channel at a certain distance from the electronic zone which must be greater the greater the magnetic Reynolds number.

  10. NUMERICAL SIMULATION OF BED TOPOGRAPHY CHANGES INDUCED BY DEEP WATER NAVIGATION CHANNEL PROJECT IN THE YANGTZE ESTUARY

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing-xin; Liu Hua; He You-sheng; Zhang Fu-ran; Qi Ding-man

    2003-01-01

    A study on the mathematical modeling of the two dimensional,time-dependent variation of bottom topography caused by the spur dikes of the deep water navigation channel project in the Yangtze estuary is reported. The hydrodynamic flows are computed using the DELFT3D which serves as the base of computation of sediment transport and bottom deformation. A model of fine sediment transport is developed and implemented in an orthogonal curvilinear coordinate system by the finite difference method. Using the observed water depth of the North Channel of Yangtze estuary from 2001 to 2002, the model is calibrated and validated to determine the parameters in the sediment model. The computational results of the changes of the bed in the North Channel induced by the spur dikes coincide with the measured data except the area near the structures.

  11. Calcium influx through TRP channels induced by short-lived reactive species in plasma-irradiated solution.

    Science.gov (United States)

    Sasaki, Shota; Kanzaki, Makoto; Kaneko, Toshiro

    2016-05-12

    Non-equilibrium helium atmospheric-pressure plasma (He-APP), which allows for a strong non-equilibrium chemical reaction of O2 and N2 in ambient air, uniquely produces multiple extremely reactive products, such as reactive oxygen species (ROS), in plasma-irradiated solution. We herein show that relatively short-lived unclassified reactive species (i.e., deactivated within approximately 10 min) generated by the He-APP irradiation can trigger physiologically relevant Ca(2+) influx through ruthenium red- and SKF 96365-sensitive Ca(2+)-permeable channel(s), possibly transient receptor potential channel family member(s). Our results provide novel insight into understanding of the interactions between cells and plasmas and the mechanism by which cells detect plasma-induced chemically reactive species, in addition to facilitating development of plasma applications in medicine.

  12. Effects of Eaf2 gene knockout on cataract induced by ultraviolet irradiation in mice%Eaf2基因敲除对紫外线诱导的鼠白内障形成的影响

    Institute of Scientific and Technical Information of China (English)

    姜艳华; 张劲松

    2016-01-01

    目的:分析Eaf2基因敲除对紫外线诱导的小鼠白内障形成的影响。方法:将15只野生型( WT)小鼠作为对照组,10只Eaf2基因敲除( Eaf2 KO)小鼠作为实验组。两组均取14周龄左右的小鼠作为研究对象。进一步分组为:WT-nonUV、WT-UV、Eaf2 KO-nonUV、Eaf2 KO-UV,共4组。使用裂隙灯显微镜观察小鼠白内障程度,利用晶状体混浊分类系统Ⅱ( LOCSⅡ)对小鼠白内障进行分级。然后断颈处死小鼠,摘取晶状体进行暗视野显微镜照相,利用Image J软件对晶状体混浊程度进行分析,并将各测量结果进行统计学处理。结果:裂隙灯显微镜和暗视野显微镜的结果一致:WT-UV组及 Eaf2 KO-UV 组晶状体混浊程度明显高于 WT-nonUV组及Eaf2 KO-nonUV组,其中WT-UV组明显高于Eaf2 KO-UV组,均具有统计学差异(P<0.05)。结论:紫外线辐射能够导致小鼠白内障的形成,Eaf2蛋白质具有促进紫外线所致的小鼠白内障形成的作用。%Abstract•AIM:To evaluate the effects of Eaf2 gene knockout on cataract in mice induced by ultraviolet irradiation.•METHODS:Fifteen wild type mice were used as the control group, and 10 Eaf2 KO mice were used as the experimental group.The 14-week mice were taken as the research objects in the two groups. So the subgroups were:WT -nonUV, WT -UV, Eaf2 KO-nonUV and Eaf2 KO-UV, a total of 4 groups.Observe the lens of mice in vivo with slit lamp microscope, grade the lens opacity with Lens Opacities Classification System II ( LOCSII ) . Then the mice were sacrificed by breaking the neck, the lens were removed and were observed by dark field microscopy. According to the captured images, the proportion of cataract region was analyzed using Image J software.The data of the two groups were statistically analyzed.•RESULTS: The results detected by the two methods were similar.In WT-UV group and Eaf2 KO-UV group, the degree of lens

  13. Amino acid substitutions in the FXYD motif enhance phospholemman-induced modulation of cardiac L-type calcium channels.

    Science.gov (United States)

    Guo, Kai; Wang, Xianming; Gao, Guofeng; Huang, Congxin; Elmslie, Keith S; Peterson, Blaise Z

    2010-11-01

    We have found that phospholemman (PLM) associates with and modulates the gating of cardiac L-type calcium channels (Wang et al., Biophys J 98: 1149-1159, 2010). The short 17 amino acid extracellular NH(2)-terminal domain of PLM contains a highly conserved PFTYD sequence that defines it as a member of the FXYD family of ion transport regulators. Although we have learned a great deal about PLM-dependent changes in calcium channel gating, little is known regarding the molecular mechanisms underlying the observed changes. Therefore, we investigated the role of the PFTYD segment in the modulation of cardiac calcium channels by individually replacing Pro-8, Phe-9, Thr-10, Tyr-11, and Asp-12 with alanine (P8A, F9A, T10A, Y11A, D12A). In addition, Asp-12 was changed to lysine (D12K) and cysteine (D12C). As expected, wild-type PLM significantly slows channel activation and deactivation and enhances voltage-dependent inactivation (VDI). We were surprised to find that amino acid substitutions at Thr-10 and Asp-12 significantly enhanced the ability of PLM to modulate Ca(V)1.2 gating. T10A exhibited a twofold enhancement of PLM-induced slowing of activation, whereas D12K and D12C dramatically enhanced PLM-induced increase of VDI. The PLM-induced slowing of channel closing was abrogated by D12A and D12C, whereas D12K and T10A failed to impact this effect. These studies demonstrate that the PFXYD motif is not necessary for the association of PLM with Ca(V)1.2. Instead, since altering the chemical and/or physical properties of the PFXYD segment alters the relative magnitudes of opposing PLM-induced effects on Ca(V)1.2 channel gating, PLM appears to play an important role in fine tuning the gating kinetics of cardiac calcium channels and likely plays an important role in shaping the cardiac action potential and regulating Ca(2+) dynamics in the heart.

  14. Knockout Reaction Mechanism for 6He+%Knockout Reaction Mechanism for 6He+

    Institute of Scientific and Technical Information of China (English)

    吕林辉; 叶沿林; 曹中鑫; 肖军; 江栋兴; 郑涛; 华辉; 李智焕; 葛俞成; 李湘庆; 楼建玲; 李阔昂; 李奇特; 乔锐; 游海波; 陈瑞九

    2012-01-01

    A knockout reaction experiment was carried out by using the 6He beam at 82.5 MeV/nucleon impinging on CH2 and C targets. The a core fragments at forward angles were detected in coincidence with the recoiled protons at larger angles. From this exclusive measure- ment the valence nucleon knockout mechanism and the core knockout mechanism are separated. This study provides a basis for the exclusive spectroscopic investigation of the exotic nuclei.

  15. Mouth breathing increases the pentylenetetrazole-induced seizure threshold in mice: a role for ATP-sensitive potassium channels.

    Science.gov (United States)

    Niaki, Seyed Esfandiar Akhavan; Shafaroodi, Hamed; Ghasemi, Mehdi; Shakiba, Bijan; Fakhimi, Ali; Dehpour, Ahamd Reza

    2008-08-01

    Nasal obstruction and consequent mouth breathing have been shown to change the acid-base balance, producing respiratory acidosis. Additionally, there exists a large body of evidence maintaining that acidosis affects the activity of ATP-sensitive potassium (K(ATP)) channels, which play a crucial role in the function of the central nervous system (CNS), for example, in modulating seizure threshold. Thus, in the study described here, we examined whether mouth breathing, induced by surgical ligation of nostrils, could affect the seizure threshold induced by pentylenetetrazole in male NMRI mice. Using the selective K(ATP) channel opener (diazoxide) and blocker (glibenclamide), we also evaluated the possible role of K(ATP) channels in this process. Our data revealed that seizure threshold was increased 6 to 72 hours after nasal obstruction, reaching a peak 48 hours afterward, compared with either control or sham-operated mice (Pmouth breathing, which could result in respiratory acidosis, increases seizure threshold in mice and K(ATP) channels may play a role in this effect.

  16. Noise-induced plasticity of KCNQ2/3 and HCN channels underlies vulnerability and resilience to tinnitus.

    Science.gov (United States)

    Li, Shuang; Kalappa, Bopanna I; Tzounopoulos, Thanos

    2015-08-27

    Vulnerability to noise-induced tinnitus is associated with increased spontaneous firing rate in dorsal cochlear nucleus principal neurons, fusiform cells. This hyperactivity is caused, at least in part, by decreased Kv7.2/3 (KCNQ2/3) potassium currents. However, the biophysical mechanisms underlying resilience to tinnitus, which is observed in noise-exposed mice that do not develop tinnitus (non-tinnitus mice), remain unknown. Our results show that noise exposure induces, on average, a reduction in KCNQ2/3 channel activity in fusiform cells in noise-exposed mice by 4 days after exposure. Tinnitus is developed in mice that do not compensate for this reduction within the next 3 days. Resilience to tinnitus is developed in mice that show a re-emergence of KCNQ2/3 channel activity and a reduction in HCN channel activity. Our results highlight KCNQ2/3 and HCN channels as potential targets for designing novel therapeutics that may promote resilience to tinnitus.

  17. Exercise-induced expression of cardiac ATP-sensitive potassium channels promotes action potential shortening and energy conservation

    Science.gov (United States)

    Zingman, Leonid V.; Zhu, Zhiyong; Sierra, Ana; Stepniak, Elizabeth; Burnett, Colin M-L.; Maksymov, Gennadiy; Anderson, Mark E.; Coetzee, William A.; Hodgson-Zingman, Denice M.

    2011-01-01

    Physical activity is one of the most important determinants of cardiac function. The ability of the heart to increase delivery of oxygen and metabolic fuels relies on an array of adaptive responses necessary to match bodily demand while avoiding exhaustion of cardiac resources. The ATP-sensitive potassium (KATP) channel has the unique ability to adjust cardiac membrane excitability in accordance with ATP and ADP levels, and up-regulation of its expression that occurs in response to exercise could represent a critical element of this adaption. However, the mechanism by which KATP channel expression changes result in a beneficial effect on cardiac excitability and function remains to be established. Here, we demonstrate that an exercise-induced rise in KATP channel expression enhanced the rate and magnitude of action potential shortening in response to heart rate acceleration. This adaptation in membrane excitability promoted significant reduction in cardiac energy consumption under escalating workloads. Genetic disruption of normal KATP channel pore function abolished the exercise-related changes in action potential duration adjustment and caused increased cardiac energy consumption. Thus, an expression-driven enhancement in the KATP channel-dependent membrane response to alterations in cardiac workload represents a previously unrecognized mechanism for adaptation to physical activity and a potential target for cardioprotection. PMID:21439969

  18. Hydralazine-induced vasodilation involves opening of high conductance Ca2+-activated K+ channels

    DEFF Research Database (Denmark)

    Bang, Lone; Nielsen-Kudsk, J E; Gruhn, N;

    1998-01-01

    The purpose of this study was to investigate whether high conductance Ca2+-activated K+ channels (BK(Ca)) are mediating the vasodilator action of hydralazine. In isolated porcine coronary arteries, hydralazine (1-300 microM), like the K+ channel opener levcromakalim, preferentially relaxed...

  19. Kinetics properties of voltage induced colicin Ia channels into a lipid bilayer

    CERN Document Server

    Cassia-Moura, R

    1998-01-01

    The activation kinetics of the ion channels formed by colicin Ia incorporated into a planar bilayer lipid membrane (BLM) was investigated by the voltage clamp technique using different step voltage stimuli. The temporal behaviour of ion channels put in evidence a gain or a loss of memory, revealed by a specific sequence of electrical pulses used for stimulation.

  20. Global ischemia-induced increases in the gap junctional proteins connexin 32 (Cx32) and Cx36 in hippocampus and enhanced vulnerability of Cx32 knock-out mice.

    Science.gov (United States)

    Oguro, K; Jover, T; Tanaka, H; Lin, Y; Kojima, T; Oguro, N; Grooms, S Y; Bennett, M V; Zukin, R S

    2001-10-01

    Gap junctions are conductive channels that connect the interiors of coupled cells. In the hippocampus, GABA-containing hippocampal interneurons are interconnected by gap junctions, which mediate electrical coupling and synchronous firing and thereby promote inhibitory transmission. The present study was undertaken to examine the hypothesis that the gap junctional proteins connexin 32 (Cx32; expressed by oligodendrocytes, interneurons, or both), Cx36 (expressed by interneurons), and Cx43 (expressed by astrocytes) play a role in defining cell-specific patterns of neuronal death in hippocampus after global ischemia in mice. Global ischemia did not significantly alter Cx32 and Cx36 mRNA expression and slightly increased Cx43 mRNA expression in the vulnerable CA1, as assessed by Northern blot analysis and in situ hybridization. Global ischemia induced a selective increase in Cx32 and Cx36 but not Cx43 protein abundance in CA1 before onset of neuronal death, as assessed by Western blot analysis. The increase in Cx32 and Cx36 expression was intense and specific to parvalbumin-positive inhibitory interneurons of CA1, as assessed by double immunofluorescence. Protein abundance was unchanged in CA3 and dentate gyrus. The finding of increase in connexin protein without increase in mRNA suggests regulation of Cx32 and Cx36 expression at the translational or post-translational level. Cx32(Y/-) null mice exhibited enhanced vulnerability to brief ischemic insults, consistent with a role for Cx32 gap junctions in neuronal survival. These findings suggest that Cx32 and Cx36 gap junctions may contribute to the survival and resistance of GABAergic interneurons, thereby defining cell-specific patterns of global ischemia-induced neuronal death.

  1. Closure of multiple types of K+ channels is necessar to induce changes in renal vascular resistance in vivo in rats

    DEFF Research Database (Denmark)

    Sørensen, Charlotte Mehlin; Giese, Isaiah; Braunstein, Thomas Hartig

    2011-01-01

    flow (RBF) in vivo in anesthetized Sprague-Dawley rats. Test agents were infused directly into the renal artery to avoid systemic effects. Inhibition of BK(Ca) and K(ir) channels (with TEA and Ba(2+), respectively) caused small and transient reductions in RBF (to 93¿±¿2% and 95¿±¿1% of baseline...... the vasoconstriction induced by bolus injections of norepinephrine or angiotensin II (by 33¿±¿5% and 60¿±¿5%, respectively). Our results indicate that closure of numerous types of K(+) channels could participate in the mediation of agonist-induced renal vasoconstriction. Our results also suggest that renal...

  2. Niflumic acid affects store-operated Ca(2+)-permeable (SOC) and Ca (2+)-dependent K (+) and Cl (-) ion channels and induces apoptosis in K562 cells.

    Science.gov (United States)

    Kucherenko, Yuliya V; Lang, Florian

    2014-07-01

    Non-steroidal anti-inflammatory drugs (NSAIDs) are known to induce apoptosis in a variety of cancer cells. However, the precise mechanisms by which NSAIDs facilitate apoptosis in tumor cells are not clear. In the present study, we show that niflumic acid (NA), a member of the fenamates group of NSAIDs and Cl(-) and Ca(2+)-activated Cl(-) (CAC) channels blocker, induced apoptosis (by ~8 %, 24 h treatment) and potentiated (by 8-10 %) apoptotic effect of endoplasmic reticulum Ca(2+) mobilizer thapsigargin (Tg) in human erythroleukemic K562 cell line. The whole-cell patch clamp and Fluo-3 flow cytometric experiments confirmed an inhibitory effect of NA (100 and 300 µM) on store-operated (SOC) channels. We also found that NA-blocked CAC channels were activated by acute application of Tg (2 µM) in K562 cells. NA blockage of CAC channels was accompanied by activation of Ca(2+)-activated K(+) (SK4) channels. The observed effects of NA were not connected with COX-2 inhibition since 100-nM NA (IC50 for COX-2 inhibition) did not induce either apoptosis or affect the channels activity. We conclude that inhibition of SOC channels plays a major role in NA-induced apoptosis. Increased apoptotic levels in Tg-treated K562 cells in the presence of NA may be due to the blockage of CAC and stimulation of SK4 channels in addition to SOC channels inhibition.

  3. Using a terrestrial laser scanner to characterize vegetation-induced flow resistance in a controlled channel

    CERN Document Server

    Vinatier, Fabrice; Belaud, Gilles; Combemale, David

    2016-01-01

    Vegetation characteristics providing spatial heterogeneity at the channel reach scale can produce complex flow patterns and the relationship between plant patterns morphology and flow resistance is still an open question (Nepf 2012). Unlike experiments in laboratory, measuring the vegetation characteristics related to flow resistance on open channel in situ is difficult. Thanks to its high resolution and light weight, scanner lasers allow now to collect in situ 3D vegetation characteristics. In this study we used a 1064 nm usual Terrestrial Laser Scanner (TLS) located 5 meters at nadir above a 8 meters long equipped channel in order to both i) characterize the vegetation structure heterogeneity within the channel form a single scan (blockage factor, canopy height) and ii) to measure the 2D water level all over the channel during steady flow within a few seconds scan. This latter measuring system was possible thanks to an additive dispersive product sprinkled at the water surface. Vegetation characteristics an...

  4. Role of calcium-activated potassium channels with small conductance in bradykinin-induced vasodilation of porcine retinal arterioles

    DEFF Research Database (Denmark)

    Dalsgaard, Thomas; Kroigaard, Christel; Bek, Toke

    2009-01-01

    (Ca)) conductance are involved in regulation of endothelium-dependent vasodilation in retinal arterioles was investigated. METHODS: Porcine retinal arterioles (diameter approximately 112 microm, N = 119) were mounted in microvascular myographs for isometric tension recordings. The arterioles were contracted......(Ca) channels contribute to NO-mediated relaxation induced by bradykinin and NS309 and, hence, may play an important role in retinal arterial endothelial function....

  5. Effects of vitamin D on kidney histology and trpv1 channels in doxorubicin-induced nephropathy.

    Science.gov (United States)

    Gurel, Ali; Atli, Hasan; Kaya, Nalan; Onalan, Ebru; Kuloglu, Tuncay; Aygen, Bilge

    2015-01-01

    Doxorubicin (DXR) is an antineoplastic agent of the anthracycline group, and may show nephrotoxic effects in animal models and humans. We investigated changes in kidney tissue following doxorubicin treatment and the effects of vitamin D on kidney tissue and TRPV1 channels. In this study, 24 adult male Wistar Albino rats were used. The animals were divided into four groups of six animals. During the 14-day experiment period, Group I did not have any application. 200 IU/day cholecalciferol was administered orally to Group II. Group III received 10 mg/kg single dose of DXR intraperitoneally (IP); and Group IV had a single 10 mg/kg dose of IP DXR and 200 IU/day of oral cholecalciferol. At the end of the experiment, the rats were decapitated, and their kidney tissues were removed. TRPV1 expression and apoptosis were detected in the tissue section by using immunohistochemical, TUNEL and real time-PCR (RT-PCR) techniques. The findings were examined and photographed with BH2 Olympus photomicroscope. As result of immunohistochemical staining, RT-PCR and examination with light microscope, it was found that the TRPV 1 immunoreactivity of the DXR group decreased in comparison with the control group, and the vitamin D application did not reverse this effect. Apoptosis detected by the TUNEL method tended to increase in the doxorubicin group and was relatively reversed with the administration of vitamin D. Tissue malondialdehyde (MDA) levels were observed to correlate with the findings of apoptosis. This study showed that vitamin D has anti- apoptotic and antioxidant effects on kidney tissue after DXR-induced injury.

  6. Role of KATP channels in cephalic vasodilatation induced by calcitonin gene-related peptide, nitric oxide, and transcranial electrical stimulation in the rat

    DEFF Research Database (Denmark)

    Gozalov, Aydin; Jansen-Olesen, Inger; Klærke, Dan Arne;

    2008-01-01

    in migraine pathogenesis. We hypothesized that vasodilatation induced by CGRP and the NO donor glyceryltrinitrate (GTN) is mediated via K(ATP) channels. METHODS: We examined the effects of the K(ATP) channel inhibitor glibenclamide on dural and pial vasodilatation induced by CGRP, NO, and endogenously....... In anesthetized rats glibenclamide significantly attenuated CGRP induced dural and TES induced dural/pial artery dilatation (P = .001; P = .001; P = .005), but had no effect on dural/pial vasodilatation induced by GTN. In vitro glibenclamide failed to significantly inhibit CGRP- and GTN-induced vasodilatation....... CONCLUSIONS: These results show that a K(ATP) channel blocker in vivo but not in vitro inhibits CGRP, but not GTN-induced dilatation of dural and pial arteries, a mechanism thought to be important in migraine....

  7. Effect of Decoherence Induced by a Spin Environment on Quantum Channel Capacity

    Institute of Scientific and Technical Information of China (English)

    MA Xiao-San; CHENG Mu-Tian; ZHAO Guang-Xing; WANG An-Min

    2012-01-01

    We investigate the effect of decoherence from a spin environment on the quantum channel capacity. Our results imply that the time evolution of the quantum channel capacity depends on the number of freedom degrees of the environment, the tunneling element, the initial state of the environment, and the system-environment coupling strength. From the analysis, we find that the strong tunneling elements and the weak coupling strength can enhance the quantum channel capacity while the environment with a large number of freedom degrees and the strong coupling strength will shrink it.

  8. Investigation of Heat Transfer in Mini Channels using Planar Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Bøgild, Morten Ryge; Poulsen, Jonas Lundsted; Rath, Emil Zacho

    2012-01-01

    In this paper an experimental investigation of the heat transfer in mini channels with a hydraulic diameter of 889 m is conducted. The method used is planar laser induceduorescence (PLIF), which uses the principle of laser excitation of rhodamine B in water. The goal of this study is to validate...... the applicability of PLIF to determine the convective heat transfer coecient in mini channels against conventional correlations of the convective heat transfer coecient. The applicability of the conventional theory in micro and mini channels has been discussed by several researchers, but to the authors knowledge...

  9. Hydrogen sulfide-induced itch requires activation of Cav3.2 T-type calcium channel in mice

    Science.gov (United States)

    Wang, Xue-Long; Tian, Bin; Huang, Ya; Peng, Xiao-Yan; Chen, Li-Hua; Li, Jun-Cheng; Liu, Tong

    2015-01-01

    The contributions of gasotransmitters to itch sensation are largely unknown. In this study, we aimed to investigate the roles of hydrogen sulfide (H2S), a ubiquitous gasotransmitter, in itch signaling. We found that intradermal injection of H2S donors NaHS or Na2S, but not GYY4137 (a slow-releasing H2S donor), dose-dependently induced scratching behavior in a μ-opioid receptor-dependent and histamine-independent manner in mice. Interestingly, NaHS induced itch via unique mechanisms that involved capsaicin-insensitive A-fibers, but not TRPV1-expressing C-fibers that are traditionally considered for mediating itch, revealed by depletion of TRPV1-expressing C-fibers by systemic resiniferatoxin treatment. Moreover, local application of capsaizapine (TRPV1 blocker) or HC-030031 (TRPA1 blocker) had no effects on NaHS-evoked scratching. Strikingly, pharmacological blockade and silencing of Cav3.2 T-type calcium channel by mibefradil, ascorbic acid, zinc chloride or Cav3.2 siRNA dramatically decreased NaHS-evoked scratching. NaHS induced robust alloknesis (touch-evoked itch), which was inhibited by T-type calcium channels blocker mibefradil. Compound 48/80-induced itch was enhanced by an endogenous precursor of H2S (L-cysteine) but attenuated by inhibitors of H2S-producing enzymes cystathionine γ-lyase and cystathionine β-synthase. These results indicated that H2S, as a novel nonhistaminergic itch mediator, may activates Cav3.2 T-type calcium channel, probably located at A-fibers, to induce scratching and alloknesis in mice. PMID:26602811

  10. Impaired social behavior in 5-HT3A receptor knockout mice

    Directory of Open Access Journals (Sweden)

    Laura A Smit-Rigter

    2010-11-01

    Full Text Available The 5-HT3 receptor is a ligand-gated ion channel expressed on interneurons throughout the brain. So far, analysis of the 5-HT3A knockout mouse revealed changes in nociceptive processing and a reduction in anxiety related behavior. Recently, it was shown that the 5-HT3 receptor is also expressed on Cajal-Retzius cells which play a key role in cortical development and that knockout mice lacking this receptor showed aberrant growth of the dendritic tree of cortical layer II/III pyramidal neurons. Other mouse models in which serotonergic signaling was disrupted during development showed similar morphological changes in the cortex, and in addition, also deficits in social behavior. Here, we subjected male and female 5-HT3A knockout mice and their non-transgenic littermates to several tests of social behavior. We found that 5-HT3A knockout mice display impaired social communication in the social transmission of food preference task. Interestingly, we showed that in the social interaction test only female 5-HT3A knockout mice spent less time in reciprocal social interaction starting after 5 minutes of testing. Moreover, we observed differences in preference for social novelty for male and female 5-HT3A knockout mice during the social approach test. However, no changes in olfaction, exploratory activity and anxiety were detected. These results indicate that the 5-HT3A knockout mouse displays impaired social behavior with specific changes in males and females, reminiscent to other mouse models in which serotonergic signaling is disturbed in the developing brain.

  11. Entropically induced asymmetric passage times of charged tracers across corrugated channels.

    Science.gov (United States)

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J Miguel

    2016-01-21

    We analyze the diffusion of charged and neutral tracers suspended in an electrolyte embedded in a channel of varying cross section. Making use of systematic approximations, the diffusion equation governing the motion of tracers is mapped into an effective 1D equation describing the dynamics along the longitudinal axis of the channel where its varying-section is encoded as an effective entropic potential. This simplified approach allows us to characterize tracer diffusion under generic confinement by measuring their mean first passage time (MFPT). In particular, we show that the interplay between geometrical confinement and electrostatic interactions strongly affect the MFTP of tracers across corrugated channels hence leading to alternative means to control tracers translocation across charged pores. Finally, our results show that the MFPTs of a charged tracer in opposite directions along an asymmetric channel may differ We expect our results to be relevant for biological as well synthetic devices whose dynamics is controlled by the detection of diluted tracers.

  12. Entropically induced asymmetric passage times of charged tracers across corrugated channels

    Energy Technology Data Exchange (ETDEWEB)

    Malgaretti, Paolo, E-mail: malgaretti@is.mpg.de [Max-Planck-Institut für Intelligente Systeme, Heisenbergstr. 3, D-70569 Stuttgart (Germany); IV Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart (Germany); Department de Fisica Fonamental, Universitat de Barcelona, Barcelona (Spain); Pagonabarraga, Ignacio; Miguel Rubi, J. [Department de Fisica Fonamental, Universitat de Barcelona, Barcelona (Spain)

    2016-01-21

    We analyze the diffusion of charged and neutral tracers suspended in an electrolyte embedded in a channel of varying cross section. Making use of systematic approximations, the diffusion equation governing the motion of tracers is mapped into an effective 1D equation describing the dynamics along the longitudinal axis of the channel where its varying-section is encoded as an effective entropic potential. This simplified approach allows us to characterize tracer diffusion under generic confinement by measuring their mean first passage time (MFPT). In particular, we show that the interplay between geometrical confinement and electrostatic interactions strongly affect the MFTP of tracers across corrugated channels hence leading to alternative means to control tracers translocation across charged pores. Finally, our results show that the MFPTs of a charged tracer in opposite directions along an asymmetric channel may differ We expect our results to be relevant for biological as well synthetic devices whose dynamics is controlled by the detection of diluted tracers.

  13. Neuron-specific (pro)renin receptor knockout prevents the development of salt-sensitive hypertension.

    Science.gov (United States)

    Li, Wencheng; Peng, Hua; Mehaffey, Eamonn P; Kimball, Christie D; Grobe, Justin L; van Gool, Jeanette M G; Sullivan, Michelle N; Earley, Scott; Danser, A H Jan; Ichihara, Atsuhiro; Feng, Yumei

    2014-02-01

    The (pro)renin receptor (PRR), which binds both renin and prorenin, is a newly discovered component of the renin-angiotensin system that is highly expressed in the central nervous system. The significance of brain PRRs in mediating local angiotensin II formation and regulating blood pressure remains unclear. The current study was performed to test the hypothesis that PRR-mediated, nonproteolytic activation of prorenin is the main source of angiotensin II in the brain. Thus, PRR knockout in the brain is expected to prevent angiotensin II formation and development of deoxycorticosterone acetate-salt-induced hypertension. A neuron-specific PRR (ATP6AP2) knockout mouse model was generated using the Cre-LoxP system. Physiological parameters were recorded by telemetry. PRR expression, detected by immunostaining and reverse transcription-polymerase chain reaction, was significantly decreased in the brains of knockout mice compared with wild-type mice. Intracerebroventricular infusion of mouse prorenin increased blood pressure and angiotensin II formation in wild-type mice. This hypertensive response was abolished in PRR-knockout mice in association with a reduction in angiotensin II levels. Deoxycorticosterone acetate-salt increased PRR expression and angiotensin II formation in the brains of wild-type mice, an effect that was attenuated in PRR-knockout mice. PRR knockout in neurons prevented the development of deoxycorticosterone acetate-salt-induced hypertension as well as activation of cardiac and vasomotor sympathetic tone. In conclusion, nonproteolytic activation of prorenin through binding to the PRR mediates angiotensin II formation in the brain. Neuron-specific PRR knockout prevents the development of deoxycorticosterone acetate-salt-induced hypertension, possibly through diminished angiotensin II formation.

  14. Maltodextrin and fat preference deficits in "taste-blind" P2X2/P2X3 knockout mice.

    Science.gov (United States)

    Sclafani, Anthony; Ackroff, Karen

    2014-07-01

    Adenosine triphosphate is a critical neurotransmitter in the gustatory response to the 5 primary tastes in mice. Genetic deletion of the purinergic P2X2/P2X3 receptor greatly reduces the neural and behavioral response to prototypical primary taste stimuli. In this study, we examined the behavioral response of P2X double knockout mice to maltodextrin and fat stimuli, which appear to activate additional taste channels. P2X double knockout and wild-type mice were given 24-h choice tests (vs. water) with ascending concentrations of Polycose and Intralipid. In Experiment 1, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.5-4%) Polycose solutions but preferred concentrated (8-32%) Polycose to water. In a retest, the Polycose-experienced double knockout mice, like wild-type mice, preferred all Polycose concentrations. In Experiment 2, naive double knockout mice, unlike wild-type mice, were indifferent to dilute (0.313-2.5%) Intralipid emulsions but preferred concentrated (5-20%) Intralipid to water. In a retest, the fat-experienced double knockout mice, like wild-type mice, strongly preferred 0.313-5% Intralipid to water. These results indicate that the inherent preferences of mice for maltodextrin and fat are dependent upon adenosine triphosphate taste cell signaling. With experience, however, P2X double knockout mice develop strong preferences for the nontaste flavor qualities of maltodextrin and fat conditioned by the postoral actions of these nutrients.

  15. Heart failure drug digitoxin induces calcium uptake into cells by forming transmembrane calcium channels.

    Science.gov (United States)

    Arispe, Nelson; Diaz, Juan Carlos; Simakova, Olga; Pollard, Harvey B

    2008-02-19

    Digitoxin and other cardiac glycosides are important, centuries-old drugs for treating congestive heart failure. However, the mechanism of action of these compounds is still being elucidated. Calcium is known to potentiate the toxicity of these drugs, and we have hypothesized that digitoxin might mediate calcium entry into cells. We report here that digitoxin molecules mediate calcium entry into intact cells. Multimers of digitoxin molecules also are able to form calcium channels in pure planar phospholipid bilayers. These digitoxin channels are blocked by Al(3+) and La(3+) but not by Mg(2+) or the classical l-type calcium channel blocker, nitrendipine. In bilayers, we find that the chemistry of the lipid affects the kinetics of the digitoxin channel activity, but not the cation selectivity. Antibodies against digitoxin promptly neutralize digitoxin channels in both cells and bilayers. We propose that these digitoxin calcium channels may be part of the mechanism by which digitoxin and other active cardiac glycosides, such as digoxin, exert system-wide actions at and above the therapeutic concentration range.

  16. Piroxicam treatment augments bone abnormalities in interleukin-10 knockout mice

    DEFF Research Database (Denmark)

    Holgersen, Kristine; Dobie, Ross; Farquharson, Colin;

    2015-01-01

    inflammation in an experimental colitis model. METHODS: Colitis was induced in interleukin-10 knockout mice (PAC IL-10 k.o.) by peroral administration of piroxicam for 12 days. The degree of colitis was assessed by clinical, macroscopic, and microscopic evaluation. Trabecular and cortical bone...... and focal transmural inflammation, which was consistent with Crohn's disease-like pathology. The gut inflammation was accompanied by a 14% and 12% reduction in trabecular thickness relative to piroxicam-treated wild type and untreated wild type mice, respectively (P

  17. Rectified motion in an asymmetrically structured channel due to induced-charge electrokinetic and thermo-kinetic phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Sugioka, Hideyuki, E-mail: hsugioka@shinshu-u.ac.jp [Frontier Research Center, Canon Inc. 30-2, Shimomaruko 3-chome, Ohta-ku, Tokyo 146-8501, Japan and Department of Mechanical Systems Engineering, Shinshu University 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2016-02-15

    It would be advantageous to move fluid by the gradient of random thermal noises that are omnipresent in the natural world. To achieve this motion, we propose a rectifier that uses a thermal noise along with induced-charge electroosmosis and electrophoresis (ICEO and ICEP) around a metal post cylinder in an asymmetrically structured channel and numerically examine its rectification performance. By the boundary element method combined with the thin double layer approximation, we find that rectified motion occurs in the asymmetrically structured channel due to ICEO and ICEP. Further, by thermodynamical and equivalent circuit methods, we discuss a thermal voltage that drives a rectifier consisting of a fluidic channel of an electrolyte and an impedance as a noise source. Our calculations show that fluid can be moved in the asymmetrically structured channel by the fluctuation of electric fields due to a thermal noise only when there is a temperature difference. In addition, our simple noise argument provides a different perspective for the thermo-kinetic phenomena (around a metal post) which was predicted based on the electrolyte Seebeck effect in our previous paper [H. Sugioka, “Nonlinear thermokinetic phenomena due to the Seebeck effect,” Langmuir 30, 8621 (2014)].

  18. Increased pressure-induced tone in rat parenchymal arterioles vs. middle cerebral arteries: role of ion channels and calcium sensitivity.

    Science.gov (United States)

    Cipolla, Marilyn J; Sweet, Julie; Chan, Siu-Lung; Tavares, Matthew J; Gokina, Natalia; Brayden, Joseph E

    2014-07-01

    Brain parenchymal arterioles (PAs) are high-resistance vessels that branch off pial arteries and perfuse the brain parenchyma. PAs are the target of cerebral small vessel disease and have been shown to have greater pressure-induced tone at lower pressures than pial arteries. We investigated mechanisms by which brain PAs have increased myogenic tone compared with middle cerebral arteries (MCAs), focusing on differences in vascular smooth muscle (VSM) calcium and ion channel function. The amount of myogenic tone and VSM calcium was measured using Fura 2 in isolated and pressurized PAs and MCAs. Increases in intraluminal pressure caused larger increases in tone and cytosolic calcium in PAs compared with MCAs. At 50 mmHg, myogenic tone was 37 ± 5% for PAs vs. 6.5 ± 4% for MCAs (P channel (VDCC) inhibitor nifedipine than MCAs (EC50 for PAs was 3.5 ± 0.4 vs. 82.1 ± 2.1 nmol/l for MCAs;P channel inhibitor iberiotoxin, whereas MCAs constricted ∼15%. Thus increased myogenic tone in PAs appears related to differences in ion channel activity that promotes VSM membrane depolarization but not to a direct sensitization of the contractile apparatus to calcium.

  19. Voltage-Gated K+ Channel, Kv3.3 Is Involved in Hemin-Induced K562 Differentiation.

    Science.gov (United States)

    Song, Min Seok; Choi, Seon Young; Ryu, Pan Dong; Lee, So Yeong

    2016-01-01

    Voltage-gated K+ (Kv) channels are well known to be involved in cell proliferation. However, even though cell proliferation is closely related to cell differentiation, the relationship between Kv channels and cell differentiation remains poorly investigated. This study demonstrates that Kv3.3 is involved in K562 cell erythroid differentiation. Down-regulation of Kv3.3 using siRNA-Kv3.3 increased hemin-induced K562 erythroid differentiation through decreased activation of signal molecules such as p38, cAMP response element-binding protein, and c-fos. Down-regulation of Kv3.3 also enhanced cell adhesion by increasing integrin β3 and this effect was amplified when the cells were cultured with fibronectin. The Kv channels, or at least Kv3.3, appear to be associated with cell differentiation; therefore, understanding the mechanisms of Kv channel regulation of cell differentiation would provide important information regarding vital cellular processes.

  20. Definitive Endoderm Formation from Plucked Human Hair-Derived Induced Pluripotent Stem Cells and SK Channel Regulation

    Directory of Open Access Journals (Sweden)

    Anett Illing

    2013-01-01

    Full Text Available Pluripotent stem cells present an extraordinary powerful tool to investigate embryonic development in humans. Essentially, they provide a unique platform for dissecting the distinct mechanisms underlying pluripotency and subsequent lineage commitment. Modest information currently exists about the expression and the role of ion channels during human embryogenesis, organ development, and cell fate determination. Of note, small and intermediate conductance, calcium-activated potassium channels have been reported to modify stem cell behaviour and differentiation. These channels are broadly expressed throughout human tissues and are involved in various cellular processes, such as the after-hyperpolarization in excitable cells, and also in differentiation processes. To this end, human induced pluripotent stem cells (hiPSCs generated from plucked human hair keratinocytes have been exploited in vitro to recapitulate endoderm formation and, concomitantly, used to map the expression of the SK channel (SKCa subtypes over time. Thus, we report the successful generation of definitive endoderm from hiPSCs of ectodermal origin using a highly reproducible and robust differentiation system. Furthermore, we provide the first evidence that SKCas subtypes are dynamically regulated in the transition from a pluripotent stem cell to a more lineage restricted, endodermal progeny.

  1. Neuroplastic alteration of TTX-resistant sodium channel with visceral pain and morphine-induced hyperalgesia

    Directory of Open Access Journals (Sweden)

    Chen J

    2012-11-01

    Full Text Available Jinghong Chen,1,2,4 Ze-hui Gong,4 Hao Yan,2 Zhijun Qiao,3 Bo-yi Qin41Department of Internal Medicine, Neuroscience Program, The University of Texas Medical Branch, Galveston, TX, USA; 2The Divisions of Pharmacy, Pharmacology core lab, MD Anderson Cancer Center, Houston, TX, USA; 3University of Texas-Pan American, Edinburg, TX, USA; 4Beijing Institute of Pharmacology and Toxicology, Beijing, China Abstract: The discovery of the tetrodotoxin-resistant (TTX-R Na+ channel in nociceptive neurons has provided a special target for analgesic intervention. In a previous study we found that both morphine tolerance and persistent visceral inflammation resulted in visceral hyperalgesia. It has also been suggested that hyperexcitability of sensory neurons due to altered TTX-R Na+ channel properties and expression contributes to hyperalgesia; however, we do not know if some TTX-R Na+ channel property changes can be triggered by visceral hyperalgesia and morphine tolerance, or whether there are similar molecular or channel mechanisms in both situations. To evaluate the effects of morphine tolerance and visceral inflammation on the channel, we investigated the dorsal root ganglia (DRG neuronal change following these chronic treatments. Using whole-cell patch clamp recording, we recorded TTX-R Na+ currents in isolated adult rat lumbar and sacral (L6-S2 DRG neurons from normal and pathologic rats with colon inflammatory pain or chronic morphine treatment. We found that the amplitudes of TTX-R Na+ currents were signiflcantly increased in small-diameter DRG neurons with either morphine tolerance or visceral inflammatory pain. Meanwhile, the result also showed that those treatments altered the kinetics properties of the electrical current (ie, the activating and inactivating speed of the channel was accelerated. Our current results suggested that in both models, visceral chronic inflammatory pain and morphine tolerance causes electrophysiological changes in voltage

  2. L-Type Calcium Channels Do Not Play a Critical Role in Chest Blow Induced Ventricular Fibrillation: Commotio Cordis

    Directory of Open Access Journals (Sweden)

    Christopher Madias

    2016-01-01

    Full Text Available Background. In a commotio cordis swine model, ventricular fibrillation (VF can be induced by a ball blow to the chest believed secondary to activation of mechanosensitive ion channels. The purpose of the current study is to evaluate whether stretch induced activation of the L-type calcium channel may cause intracellular calcium overload and underlie the VF in commotio cordis. Method and Results. Anesthetized juvenile swine received 6 chest wall strikes with a 17.9 m/s lacrosse ball timed to the vulnerable period for VF induction. Animals were randomized to IV verapamil (n=6 or placebo (n=6. There was no difference in the observed frequency of VF between verapamil (19/26: 73% and placebo (20/36: 56% treated animals (p=0.16. There was also no significant difference in the combined endpoint of VF or nonsustained VF (21/26: 81% in verapamil versus 24/36: 67% in controls, p=0.22. Conclusions. In this experimental model of commotio cordis, verapamil did not prevent VF induction. Thus, in commotio cordis it is unlikely that stretch activation of the L-type calcium channel with resultant intracellular calcium overload plays a prominent role.

  3. Involvement of presynaptic voltage-dependent Kv3 channel in endothelin-1-induced inhibition of noradrenaline release from rat gastric sympathetic nerves.

    Science.gov (United States)

    Nakamura, Kumiko; Shimizu, Takahiro; Tanaka, Kenjiro; Taniuchi, Keisuke; Yokotani, Kunihiko

    2012-11-05

    We previously reported that two types of K(+) channels, the BK type Ca(2+)-activated K(+) channel coupled with phospholipase C (PLC) and the voltage-dependent K(+) channel (Kv channel), are, respectively, involved in the prostanoid TP receptor- and muscarinic M(2) receptor-mediated inhibition of noradrenaline (NA) release from rat gastric sympathetic nerves. In the present study, therefore, we examined whether these K(+) channels are involved in endothelin-1-induced inhibition of NA release, using an isolated, vascularly perfused rat stomach. The gastric sympathetic postganglionic nerves around the left gastric artery were electrically stimulated twice at 2.5 Hz for 1 min, and endothelin-1 was added during the second stimulation. Endothelin-1 (1, 2 and 10 nM) dose-dependently inhibited gastric NA release. Endothelin-1 (2 nM)-induced inhibition of NA release was neither attenuated by PLC inhibitors [U-73122 (3 μM) and ET-18-OCH(3) (3 μM)] nor by Ca(2+)-activated K(+) channel blockers [charybdotoxin (0.1 μM) (a blocker of BK type K(+) channel) and apamin (0.3 μM) (a blocker of SK type K(+) channel)]. The endothelin-1-induced inhibitory response was also not attenuated by α-dendrotoxin (0.1 μM) (a selective inhibitor of Kv1 channel), but abolished by 4-aminopyridine (20 μM) (a selectively inhibitory dose for Kv3 channel). These results suggest the involvement of a voltage-dependent Kv3 channel in the endothelin-1-induced inhibition of NA release from the gastric sympathetic nerves in rats.

  4. Effect of Channel Sidewalls on Joule Heating Induced Sample Dispersion in Rectangular Ducts.

    Science.gov (United States)

    Dutta, Debashis

    2016-02-01

    In this article, we analyze the effect of channel sidewalls on the broadening of analyte bands resulting from Joule heating during their electrokinetic migration through a rectangular conduit. A method-of-moments formulation has been used to numerically evaluate the Taylor-Aris dispersivity of sample zones under these conditions for thin electrical double layers applicable to a majority of microfluidic assays. Our analysis shows that the larger surface area to volume ratio around the side regions of a rectangular channel causes these corners to stay cooler than the rest of the conduit. While such a thermal profile does not modify the electroosmotic flow in the system for a fixed temperature at the channel walls, it reduces the electrophoretic transport rate by about 10% for small temperature differentials across the channel cross-section (effect of these thermal gradients on the hydrodynamic dispersion of analyte bands is more significant however, increasing such band broadening by nearly an order of magnitude in large aspect ratio designs. Our analyses further show that the trends noted above are magnified when a fixed heat transfer coefficient is assumed at the channel walls, in which case, the temperature along this boundary is no longer constant. The non-isothermal channel walls combined with the temperature dependence of zeta potential and other material properties in this situation leads to a non-uniform electroosmotic slip velocity in the system modifying both fluid and analyte transport rates. Again, while the resulting solute flow profile reduces the migration velocity of sample zones only to a moderate extent, it is found to increase the hydrodynamic dispersion of analyte bands by several orders of magnitude in large aspect ratio rectangular channels.

  5. Hypoxia-induced 15-HETE enhances the constriction of internal carotid arteries by down-regulating potassium channels.

    Science.gov (United States)

    Zhu, Yanmei; Chen, Li; Liu, Wenjuan; Wang, Weizhi; Zhu, Daling; Zhu, Yulan

    2010-08-15

    Severe hypoxia induces the constriction of internal carotid arteries (ICA), which worsens ischemic stroke in the brain. A few metabolites are presumably involved in hypoxic vasoconstriction, however, less is known about how such molecules provoke this vasoconstriction. We have investigated the influence of 15-hydroxyeicosatetrienoic acid (15-HETE) produced by 15-lipoxygenase (15-LOX) on vasoconstriction during hypoxia. As showed in our results, 15-LOX level increases in ICA endothelia and smooth muscles. 15-HETE enhances the tension of ICA ring in a dose-dependent manner, as well as attenuates the activities and expression of voltage-gated potassium channels (Kv 1.5 and Kv 2.1). Therefore, the down-regulation of Kv channels by 15-HETE during hypoxia may weaken the repolarization of action potentials and causes a dominant influx of calcium ions to enhance smooth muscle tension and ICA constriction.

  6. Role of BKCa channels in cephalic vasodilation induced by CGRP, NO and transcranial electrical stimulation in the rat

    DEFF Research Database (Denmark)

    Gozalov, A.; Jansen-Olesen, I.; Klærke, Dan Arne;

    2007-01-01

    by the NO donor glyceryltrinitrate (GTN) or by CGRP is partially mediated via large conductance calcium-activated potassium (BK(Ca)) channels. The effects of the BK(Ca) channel selective inhibitor iberiotoxin on dural and pial vasodilation induced by CGRP, GTN and endogenously released CGRP by transcranial...... electrical stimulation (TES) were examined. Iberiotoxin significantly attenuated GTN-induced dural and pial artery dilation in vivo and in vitro, but had no effect on vasodilation induced by CGRP and TES. Our results show that GTN- but not CGRP-induced dural and pial vasodilation involves opening of BK...

  7. Funny current and cardiac rhythm: insights from HCN knockout mouse models

    Directory of Open Access Journals (Sweden)

    Mirko eBaruscotti

    2012-07-01

    Full Text Available In the adult animal the sinoatrial node (SAN rhythmically generates a depolarizing wave that propagates to the rest of the heart. However, the SAN is more than a simple clock; it is a clock that adjusts its pace according to the metabolic requirements of the organism. The Hyperpolarization-activated Cyclic Nucleotide-gated channels (HCN1-4 are the structural component of the funny (If channels; in the SAN the If current is the main driving electrical force of the diastolic depolarization and the HCN4 is the most abundant isoform. The generation of HCN KO mouse models has advanced the understanding of the role of these channels in cardiac excitability. The HCN4 KO models that were first developed allowed either global or cardiac-specific constitutive ablation of HCN4 channels, and resulted in embryonic lethality. A further progress was made with the development of three separate inducible HCN4 KO models; in one model KO was induced globally in the entire organism, in a second, ablation occurred only in HCN4-expressing cells, and finally in a third model KO was confined to cardiac cells. Unexpectedly, the three models yielded different results; similarities and differences among these models will be presented and discussed. The functional effects of HCN2 and HCN3 knockout models and transgenic HCN4 mouse models will also be discussed.In conclusion, HCN KO/transgenic models have allowed to evaluate the functional role of the If currents in intact animals as well as in single SAN cells isolated from the same animals. This opportunity is therefore unique since it allows to 1 verify the contribution of specific HCN isoforms to cardiac activity in intact animals, and 2 to compare these results to those obtained in single cell experiments. These combined studies were not possible prior to the development of KO models. Finally, these models represent critical tools to improve our understanding of the molecular basis of some inheritable arrhythmic human

  8. Phenotype of the taurine transporter knockout mouse.

    Science.gov (United States)

    Warskulat, Ulrich; Heller-Stilb, Birgit; Oermann, Evelyn; Zilles, Karl; Haas, Helmut; Lang, Florian; Häussinger, Dieter

    2007-01-01

    This chapter reports present knowledge on the properties of mice with disrupted gene coding for the taurine transporter (taut-/- mice). Study of those mice unraveled some of the roles of taurine and its membrane transport for the development and maintenance of normal organ functions and morphology. When compared with wild-type controls, taut-/- mice have decreased taurine levels in skeletal and heart muscle by about 98%, in brain, kidney, plasma, and retina by 80 to 90%, and in liver by about 70%. taut-/- mice exhibit a lower body mass as well as a strongly reduced exercise capacity compared with taut+/- and wild-type mice. Furthermore, taut-/- mice show a variety of pathological features, for example, subtle derangement of renal osmoregulation, changes in neuroreceptor expression, and loss of long-term potentiation in the striatum, and they develop clinically relevant age-dependent disorders, for example, visual, auditory, and olfactory dysfunctions, unspecific hepatitis, and liver fibrosis. Taurine-deficient animal models such as acutely dietary-manipulated foxes and cats, pharmacologically induced taurine-deficient rats, and taurine transporter knockout mouse are powerful tools allowing identification of the mechanisms and complexities of diseases mediated by impaired taurine transport and taurine depletion (Chapman et al., 1993; Heller-Stilb et al., 2002; Huxtable, 1992; Lake, 1993; Moise et al., 1991; Novotny et al., 1991; Pion et al., 1987; Timbrell et al., 1995; Warskulat et al., 2004, 2006b). Taurine, which is the most abundant amino acid in many tissues, is normally found in intracellular concentrations of 10 to 70 mmol/kg in mammalian heart, brain, skeletal muscle, liver, and retina (Chapman et al., 1993; Green et al., 1991; Huxable, 1992; Timbrell et al., 1995). These high taurine levels are maintained by an ubiquitous expression of Na(+)-dependent taurine transporter (TAUT) in the plasma membrane (Burg, 1995; Kwon and Handler, 1995; Lang et al., 1998

  9. Inhibitors of arachidonate-regulated calcium channel signaling suppress triggered activity induced by the late sodium current.

    Science.gov (United States)

    Wolkowicz, Paul; Umeda, Patrick K; Sharifov, Oleg F; White, C Roger; Huang, Jian; Mahtani, Harry; Urthaler, Ferdinand

    2014-02-05

    Disturbances in myocyte calcium homeostasis are hypothesized to be one cause for cardiac arrhythmia. The full development of this hypothesis requires (i) the identification of all sources of arrhythmogenic calcium and (ii) an understanding of the mechanism(s) through which calcium initiates arrhythmia. To these ends we superfused rat left atria with the late sodium current activator type II Anemonia sulcata toxin (ATXII). This toxin prolonged atrial action potentials, induced early afterdepolarization, and provoked triggered activity. The calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93 (N-[2-[[[3-(4-chlorophenyl)-2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulphon-amide) suppressed ATXII triggered activity but its inactive congener KN-92 (2-[N-(4-methoxy benzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine) did not. Neither drug affected normal atrial contractility. Calcium entry via L-type channels or calcium leakage from sarcoplasmic reticulum stores are not critical for this type of ectopy as neither verapamil ((RS)-2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl]-(methyl)amino}-2-prop-2-ylpentanenitrile) nor ryanodine affected ATXII triggered activity. By contrast, inhibitors of the voltage independent arachidonate-regulated calcium (ARC) channel and the store-operated calcium channel specifically suppressed ATXII triggered activity without normalizing action potentials or affecting atrial contractility. Inhibitors of cytosolic calcium-dependent phospholipase A2 also suppressed triggered activity suggesting that this lipase, which generates free arachidonate, plays a key role in ATXII ectopy. Thus, increased left atrial late sodium current appears to activate atrial Orai-linked ARC and store operated calcium channels, and these voltage-independent channels may be unexpected sources for the arrhythmogenic calcium that underlies triggered activity.

  10. Negative-shift activation, current reduction and resurgent currents induced by β-toxins from Centruroides scorpions in sodium channels.

    Science.gov (United States)

    Schiavon, Emanuele; Pedraza-Escalona, Martha; Gurrola, Georgina B; Olamendi-Portugal, Timoteo; Corzo, Gerardo; Wanke, Enzo; Possani, Lourival D

    2012-02-01

    The β-toxins purified from the New World scorpion venoms of the Centruroides species affect several voltage-gated sodium channels (VGSCs) and thus are essential tools not only for the discrimination of different channel sub-types but also for studying the structure-function relationship between channels and toxins. This communication reports the results obtained with four different peptides purified from three species of Centruroides scorpions and assayed on seven distinct isoforms of VGSC (Na(v)1.1-Na(v)1.7) by specific functional analysis conducted through single cell electrophysiology. The toxins studied were CssII from Centruroides suffusus suffusus, Cll1 and Cll2 from Centruroides limpidus limpidus and a novel toxin from Centruroides noxius, which was characterized for the first time here. It has 67 amino acid residues and four disulfide bridges with a molecular mass of 7626 Da. Three different functional features were identified: current reduction of macroscopic conductance, left shift of the voltage-dependent activation and induction of resurgent currents at negative voltages following brief, strong depolarizations. The isoforms which revealed to be more affected resulted to be Na(v)1.6 > 1.1 > 1.2 and, for the first time, a β-toxin is here shown to induce resurgent current also in isoforms different from Na(v)1.6. Additionally, these results were analyzed with molecular modelling. In conclusion, although the four toxins have a high degree of identity, they display tri-modal function, each of which shows selectivity among the different sub-types of Na+ -channels. Thus, they are invaluable as tools for structure-function studies of β-toxins and offer a basis for the design of novel ion channel-specific drugs.

  11. Spontaneous and CRH-Induced Excitability and Calcium Signaling in Mice Corticotrophs Involves Sodium, Calcium, and Cation-Conducting Channels.

    Science.gov (United States)

    Zemkova, Hana; Tomić, Melanija; Kucka, Marek; Aguilera, Greti; Stojilkovic, Stanko S

    2016-04-01

    Transgenic mice expressing the tdimer2(12) form of Discosoma red fluorescent protein under control of the proopiomelanocortin gene's regulatory elements are a useful model for studying corticotrophs. Using these mice, we studied the ion channels and mechanisms controlling corticotroph excitability. Corticotrophs were either quiescent or electrically active, with a 22-mV difference in the resting membrane potential (RMP) between the 2 groups. In quiescent cells, CRH depolarized the membrane, leading to initial single spiking and sustained bursting; in active cells, CRH further facilitated or inhibited electrical activity and calcium spiking, depending on the initial activity pattern and CRH concentration. The stimulatory but not inhibitory action of CRH on electrical activity was mimicked by cAMP independently of the presence or absence of arachidonic acid. Removal of bath sodium silenced spiking and hyperpolarized the majority of cells; in contrast, the removal of bath calcium did not affect RMP but reduced CRH-induced depolarization, which abolished bursting electrical activity and decreased the spiking frequency but not the amplitude of single spikes. Corticotrophs with inhibited voltage-gated sodium channels fired calcium-dependent action potentials, whereas cells with inhibited L-type calcium channels fired sodium-dependent spikes; blockade of both channels abolished spiking without affecting the RMP. These results indicate that the background voltage-insensitive sodium conductance influences RMP, the CRH-depolarization current is driven by a cationic conductance, and the interplay between voltage-gated sodium and calcium channels plays a critical role in determining the status and pattern of electrical activity and calcium signaling.

  12. Lattice location of impurities in semiconductors: a RBS/channeling and proton-induced x-ray emission study

    Energy Technology Data Exchange (ETDEWEB)

    Kringhoj, P. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

    1993-12-31

    Rutherford backscattering spectrometry (RBS)/channeling and proton-induced x-ray emission (PIXE) are two well established and characterised techniques. Over the last three decades RBS/channeling measurements has been performed to extract the substitutional fraction of impurities in both elemental and compound semiconductors. However, due to the limitation of RBS, only elements heavier than the host crystal can be examined (except for a few elements, where a nuclear reaction or a resonance can be used). In silicon this limitation is acceptable, due to the low mass of Si, but in the III-V compounds (e.g. InP), the technique is limited to a few elements of hardly no technological or fundamental interest. One can overcome this by combining RBS/channeling with PIXE, where PIXE is applied to detect elements with a mass lower than the host crystal. In the present work, the lattice location of Ge in InP has been studied and compared to the group-III impurity Ga, and the group-VI impurity Se which is known to be a donor. The (RBS)/channeling technique has been used to detect not only the substitutional fraction, but also the relative population of the two sublattices. The half-width is approximately equal to the characteristic angle, {psi}{sub 1}. The channeling data obtained indicate that all three dopants are located exclusively on substitutional sites and that Ga is occuping the In position, Se theP position and that Ge is distributed equally between both sublattices. 6 refs., 1 tab., 3 figs.

  13. Nanostructured Mesoporous Silica Wires with Intrawire Lamellae via Evaporation-Induced Self-Assembly in Space-Confined Channels

    Directory of Open Access Journals (Sweden)

    Michael Z. Hu

    2014-01-01

    Full Text Available Evaporation-induced self-assembly (EISA of silica sol-gel ethanol-water solution mixtures with block-copolymer were studied inside uniform micro/nano-channels. Nanostructured mesoporous silica wires, with various intrawire self-assembly structures including lamellae, were prepared via EISA process but in space-confined channels with the diameter ranging from 50 nm to 200 nm. Membranes made of anodized aluminum oxide (AAO and track-etched polycarbonate (EPC were utilized as the arrays of space-confined channels (i.e., 50, 100, and 200 nm EPC and 200 nm AAO for infiltration and drying of mixture solutions; these substrate membranes were submerged in mixture solutions consisting of a silica precursor, a structure-directing agent, ethanol, and water. After the substrate channels were filled with the solution under vacuum impregnation, the membrane was removed from the solution and dried in air. The silica precursor used was tetraethyl othosilicate (TEOS, and the structure-directing agent employed was triblock copolymer Pluronic-123 (P123. It was found that the formation of the mesoporous nanostructures in silica wires within uniform channels were significantly affected by the synthesis conditions including (1 preassemble TEOS aging time, (2 the evaporation rate during the vacuum impregnation, and (3 the air-dry temperature. The obtained intrawire structures, including 2D hexagonal rods and lamellae, were studied by scanning transmission electron microscopy (STEM. A steric hindrance effect seems to explain well the observed polymer-silica mesophase formation tailored by TEOS aging time. The evaporation effect, air-drying effect, and AAO versus EPC substrate effect on the mesoporous structure of the formed silica wires were also presented and discussed.

  14. Neuroprotective effects of ClC-3 chloride channel in glutamate-induced retinal ganglion cell RGC-5 apoptosis

    Institute of Scientific and Technical Information of China (English)

    Li Yu; Ning Han; Ligang Jiang; Yajuan Zheng; Lifeng Liu

    2011-01-01

    Transforming growth factor β plays a role in regulation of apoptosis in ClC-3 and the Smads signaling pathway, although the underlying mechanisms remain unclear. The present study determined possible signal transduction mechanisms based on CIC-3 expression, which accordingly affected apoptosis of retinal ganglion cells in a glutamate-induced retinal ganglion cell RGC-5 apoptosis model. Results revealed significantly increased cell survival rate and significantly decreased apoptosis rate following apoptosis of ClC-3 cDNA-transfected glutamate-induced retinal ganglion cells. Following inhibition of the ClC-3 chloride channel using RNAi technology, cell survival and apoptosis rates were reversed. In addition, expression of transforming growth factor β2, Smads2, Smads3, Smads4, and Smads7 increased to varying degrees. These results suggest that ClC-3 chloride channel plays a protective role in glutamate-induced apoptosis of retinal ganglion cells, and transforming growth factor β/Smads signal transduction pathways are involved in this process.

  15. Observation and modeling of the storm-induced fluid mud dynamics in a muddy-estuarine navigational channel

    Science.gov (United States)

    Wan, Yuanyang; Roelvink, Dano; Li, Weihua; Qi, Dingman; Gu, Fengfeng

    2014-07-01

    Observations of storm-induced fluid mud dynamics have been conducted at the North Passage deepwater navigational channel (DNC) of the Yangtze Estuary in October to December 2010, during the occurrence of a cold-air front. The measurement data reveal that just after the critical wind wave event, a large amount of fine sediment was trapped in a state of fluid mud along the channel. The observed thickness of the fluid mud was up to about 1-5 m, which caused some significant economic and safety problems for shipping traffic in the Yangtze Delta area. The mechanisms and transport processes of the storm-induced fluid mud are analyzed and presented from the angles of both process-oriented and engineering-oriented methods. With the help of hydrodynamics and wave modeling, it could be inferred that the behavior of the storm-induced fluid mud event mainly depends on the overall hydrodynamic regimes and the exchanges of sediment, which is released by storm-wave agitation from adjacent tidal flats. These sediments are accumulated as fluid mud, and subsequently oscillate and persist at those locations with weaker longitudinal residuals in the river- and tide-dominated estuary. In addition, the downslope transport of fluid mud is also thought to have stimulated and worsened the fluid mud event observed in this study. Our modeling results and observations demonstrate that: (1) the transport of fluid mud is an advective phenomenon determining the central position of fluid mud layer along the channel, and it's also a tidal energy influenced phenomenon controlling the erosion and accumulation of fluid mud; and (2) both suspended particulate matter availability and local residual flow regime are of critical importance in determining the trapping probability of sediment and the occurrence of fluid mud.

  16. [6]-Shogaol Induces Ca2+ Signals by Activating the TRPV1 Channels in the Rat Insulinoma INS-1E Cells

    Directory of Open Access Journals (Sweden)

    Paola Rebellato

    2014-01-01

    Full Text Available Context [6]-shogaol is a vanilloid compound present in steamed ginger (Zingiber officinale, a commonly used spice. Pancreatic beta-cells respond to nutrients like glucose, amino acids and fatty acids, by an increase in the cytoplasmic free Ca2+ concentration ([Ca2+]i, which mediates diverse cellular processes in these cells. Some vanilloid compounds activate the transient receptor potential vanilloid receptor type 1 (TRPV1 channel. Objective We investigated whether [6]-shogaol could trigger Ca2+ signals in the beta-cell. Methods [Ca2+]i was measured from single INS-1E cells by microscope-based fluorometry using fura-2 as the Ca2+ indicator. Results In fura-2 loaded single rat insulinoma INS-1E cells, a widely used model of beta-cell, [6]-shogaol increased [Ca2+]i in a concentration-dependent manner. [Ca2+]i increase by [6]-shogaol was completely blocked when Ca2+ was omitted from the extracellular medium. Capsazepine, an inhibitor of the TRPV1 ion channel completely inhibited the [6]-shogaol-induced [Ca2+]i increase. [Ca2+]i increase obtained by 1 μM [6]-shogaol was greater than that obtained by 10 mM glucose. Moreover, a sub-stimulatory concentration of [6]-shogaol (300 nM, significantly enhanced the glucose-induced [Ca2+]i increase in these cells. Conclusion We conclude that [6]-shogaol induces Ca2+ signals in the beta-cell by activating the TRPV1 channels, and it sensitizes the beta-cells to stimulation by glucose.

  17. Cl- channel blockers NPPB and niflumic acid blunt Ca(2+)-induced erythrocyte 'apoptosis'.

    Science.gov (United States)

    Myssina, Svetlana; Lang, Philipp A; Kempe, Daniela S; Kaiser, Stefanie; Huber, Stephan M; Wieder, Thomas; Lang, Florian

    2004-01-01

    Exposure to Ca2+ ionophore ionomycin, osmotic shock, oxidative stress and glucose depletion trigger cell shrinkage and scramblase-mediated phosphatidylserine exposure at the outer leaflet of the erythrocyte cell membrane. The effects are partially due to activation of GARDOS channels and subsequent cellular K+ loss leading not only to cell shrinkage but also participating in the triggering of erythrocyte scramblase. As conductive loss of K+ would depend on the parallel loss of anions we hypothesised that activation of scramblase is similarly dependent on the activity of Cl- channels. To test this hypothesis, we used Cl- channel blockers NPPB and niflumic acid. It is shown here that treatment of erythrocytes with 1 microM ionomycin leads to cellular K+ loss, decrease of hematocrit and decrease of forward scatter in FACS analysis reflecting cell shrinkage as well as increase of annexin positive cells reflecting phosphatidylserine exposure. Those events were significantly blunted in the presence of 100 microM NPPB by 34% (K+ loss), 45% (hematocrit), 32% (forward scatter) and 69% (annexin binding), or in the presence of 100 microM niflumic acid by 15% (forward scatter) and 45% (annexin binding), respectively. Moreover, oxidative stress triggered annexin binding which was again significantly inhibited (by 51%) in the presence of 100 microM NPPB. In conclusion, Cl- channels presumably participate in the regulation of erythrocyte 'apoptosis'.

  18. A two-channel R-matrix analysis of magnetic field induced Feshbach resonances

    DEFF Research Database (Denmark)

    Nygaard, Nicolai; Schneider, B. I.; Julienne, P. S.

    2006-01-01

    such an effective Feshbach model can be constructed from knowledge of a few key parameters, characterizing the atomic Born-Oppenheimer potentials and the low energy scattering near the resonance. These parameters may be obtained either from experiment or full coupled channels calculations. Using R-matrix theory we...

  19. Peristaltic flow of a couple stress fluid under the effect of induced magnetic field in an asymmetric channel

    Energy Technology Data Exchange (ETDEWEB)

    Nadeem, Sohail; Akram, Safia [Quaid-i-Azam University, Department of Mathematics, Islamabad (Pakistan)

    2011-01-15

    The present paper investigates the peristaltic transport of a couple stress fluid in an asymmetric channel with the effect of the induced magnetic field. The exact solutions of momentum and the magnetic field equations have been calculated under the assumptions of long wave length and low but finite Reynolds number. The expression for pressure rise has been computed numerically using mathematics software Mathematica. The graphical results have been presented to discuss the physical behavior of various physical parameters of interest. Finally, the trapping phenomena have been discussed for various physical parameters. (orig.)

  20. TRPM7 channel regulates PDGF-BB-induced proliferation of hepatic stellate cells via PI3K and ERK pathways

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Ling, E-mail: fangling_1984@126.com; Zhan, Shuxiang; Huang, Cheng; Cheng, Xi; Lv, Xiongwen; Si, Hongfang; Li, Jun, E-mail: lj@ahmu.edu.cn

    2013-11-01

    TRPM7, a non-selective cation channel of the TRP channel superfamily, is implicated in diverse physiological and pathological processes including cell proliferation. Recently, TRPM7 has been reported in hepatic stellate cells (HSCs). Here, we investigated the contribution role of TRPM7 in activated HSC-T6 cell (a rat hepatic stellate cell line) proliferation. TRPM7 mRNA and protein were measured by RT-PCR and Western blot in rat model of liver fibrosis in vivo and PDGF-BB-activated HSC-T6 cells in vitro. Both mRNA and protein of TRPM7 were dramatically increased in CCl{sub 4}-treated rat livers. Stimulation of HSC-T6 cells with PDGF-BB resulted in a time-dependent increase of TRPM7 mRNA and protein. However, PDGF-BB-induced HSC-T6 cell proliferation was inhibited by non-specific TRPM7 blocker 2-aminoethoxydiphenyl borate (2-APB) or synthetic siRNA targeting TRPM7, and this was accompanied by downregulation of cell cycle proteins, cyclin D1, PCNA and CDK4. Blockade of TRPM7 channels also attenuated PDGF-BB induced expression of myofibroblast markers as measured by the induction of α-SMA and Col1α1. Furthermore, the phosphorylation of ERK and AKT, associated with cell proliferation, decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TRPM7 channels contribute to perpetuated fibroblast activation and proliferation of PDGF-BB induced HSC-T6 cells via the activation of ERK and PI3K pathways. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis. - Highlights: • Upregulation of TRPM7 mRNA and protein in the fibrotic livers from CCl{sub 4}-treated rats. • Increasing expression of TRPM7 mRNA and protein during HSC activation. • Blockade of TRPM7 inhibited the PDGF-BB induced proliferation of HSC-T6 cells. • Blockade of TRPM7 decreased α-SMA and Col1α1 expressions in activated HSC-T6 cells. • TRPM7 up-regulation contributes to the activation of ERK and AKT pathways.

  1. Potassium and calcium channel gene expression in small arteries in porcine and rat models of diet-induced obesity (Poster)

    DEFF Research Database (Denmark)

    Jensen, Lars Jørn; Salomonsson, Max; Sørensen, Charlotte Mehlin

    2014-01-01

    Obesity is an increasing problem worldwide leading to cardiovascular morbidity. Only limited information exists on the transcriptional regulation of arterial K+ and Ca2+ channels in obesity. We quantified, by real-time PCR, mRNA expression of K+ channels and L-type Ca2+ channels (LTCC) in small...... mesenteric (MA), middle cerebral (MCA), and left coronary arteries (LCA) of lean vs. obese rats and minipigs. Male Sprague Dawley rats were fed a high-fat (FAT; N=5), high-fructose (FRUC; N=7), high-fat/high-fructose (FAT/FRUC; N=7) or standard diet (STD; N=7-11) for 28 Weeks. FAT and FAT/FRUC became obese...... increased in OB and OB+DIAB. BKca, IKca, SKca and/or LTCC mRNA was up-regulated in LCA from OB and OB+DIAB (n.s.). Expression of BKca mRNA was increased, whereas IKca mRNA decreased in MCA from OB (n.s.). SKca mRNA was decreased in MA from OB (n.s.). Diet-induced obesity in rats and minipigs lead to complex...

  2. Stress-induced glucocorticoid signaling remodels neurovascular coupling through impairment of cerebrovascular inwardly rectifying K+ channel function.

    Science.gov (United States)

    Longden, Thomas A; Dabertrand, Fabrice; Hill-Eubanks, David C; Hammack, Sayamwong E; Nelson, Mark T

    2014-05-20

    Studies of stress effects on the brain have traditionally focused on neurons, without considering the cerebral microcirculation. Here we report that stress impairs neurovascular coupling (NVC), the process that matches neuronal activity with increased local blood flow. A stressed phenotype was induced in male rats by administering a 7-d heterotypical stress paradigm. NVC was modeled by measuring parenchymal arteriole (PA) vasodilation in response to neuronal stimulation in amygdala brain slices. After stress, vasodilation of PAs to neuronal stimulation was greatly reduced, and dilation of isolated PAs to external K(+) was diminished, suggesting a defect in smooth muscle inwardly rectifying K(+) (KIR) channel function. Consistent with these observations, stress caused a reduction in PA KIR2.1 mRNA and smooth muscle KIR current density, and blocking KIR channels significantly inhibited NVC in control, but not in stressed, slices. Delivery of corticosterone for 7 d (without stressors) or RU486 (before stressors) mimicked and abrogated NVC impairment by stress, respectively. We conclude that stress causes a glucocorticoid-mediated decrease in functional KIR channels in amygdala PA myocytes. This renders arterioles less responsive to K(+) released from astrocytic endfeet during NVC, leading to impairment of this process. Because the fidelity of NVC is essential for neuronal health, the impairment characterized here may contribute to the pathophysiology of brain disorders with a stress component.

  3. The mechanism of KV4.3 voltage-gated potassium channel in arrhythmia induced by sleep deprivation in rat

    Directory of Open Access Journals (Sweden)

    Ya-jing ZHANG

    2011-03-01

    Full Text Available Objective To investigate the effect of sleep deprivation(SD on the changes in electrocardiogram and mRNA and protein expression of KV4.3 voltage-gated potassium channel in rats,and explore the related mechanisms of arrhythmia induced by SD.Methods A total of 48 adult male SD rats were randomly divided into 6 groups(8 each: normal control(CC group,tank control(TC group,1-,3-,5-and 7-day SD group.Animal model of SD was established by modified multiple platform method,and electrocardiogram was recorded on 1st,3rd,5th,and 7th of experiment.Protein and mRNA expressions of KV4.3 voltage-gated potassium channel were measured by real-time PCR and Western blotting analysis.Results The main changes on electrocardiogram following SD were arrhythmia.Compared with the CC group,rats in TC group showed sinus tachycardia in electrocardiogram: frequent atrial premature beats were observed one day after SD;ventricular arrhythmias,such as frequent polymorphic ventricular premature beats and paroxysmal ventricular tachycardia were observed three days after SD;incomplete right bundle branch block wave occurred five days after SD;the electrocardiogram showed third-degree atrioventricular(AV block wave seven days after SD,which indicated atrial arrhythmia and ventricular arrhythmia respectively.Ventricular escape beat,sinus arrest as well as the fusion of obviously elevated ST segment and T-wave were also observed.The expression levels of KV4.3 voltage-gated potassium channel decreased with prolongation of SD time.The expression of mRNA and protein of KV4.3 potassium channel in 7-day SD rats were only the one ninth and one fourth of levels in CC group.Conclusion Sleep deprivation can cause arrhythmia,and decreased expression of KV4.3 voltage-gated potassium channel may possibly be one of the reasons of arrhythmia induced by SD.

  4. Natural and human-induced driving factors in the evolution of tidal channels: case studies in the Venice Lagoon (Italy).

    Science.gov (United States)

    Rizzetto, Federica

    2013-04-01

    Coastal wetlands are largely affected by a complex variety of both natural and anthropogenic factors, which induce evident, often irreversible, geomorphological transformations. In particular, this research focuses on the main processes that influence the evolution of tidal channels in salt marshes and shows the results derived from the analysis of some case studies in the Venice Lagoon (northwestern Adriatic Sea, Italy). Here tidal network has been recognized as significantly sensitive to sea-level rise and tide oscillations (Rizzetto and Tosi, 2011; Rizzetto and Tosi, 2012), but it is also vulnerable to human impact. The sites were selected in areas characterized by low anthropogenic pressure to prevent strong human interferences from completely masking the effects of natural forces. The interpretation of a large number of high-resolution aerial photographs, taken since the mid 1930s, allowed identifying in detail tidal channel evolution, both in the long- and in the short-term. The observation of historical and recent topographic maps completed the study and provided other important data to define the modifications occurred in the past two centuries. The channel planform changes were determined through the morphometric analysis of the tidal network, carried out using a Geographic Information System software. These modifications were interpreted in the light of sea-level oscillations (i.e. relative sea-level rise and strength/frequency of high tides, which are increasing owing to climate changes), variations of sediment supply, and human activities occurred in the past century. The joint analysis of all the data allowed distinguishing the changes induced by both relative sea-level rise and high tides on planform pattern and evolution of tidal channels, and identifying the effects of human interferences, which magnified the impact of natural factors (e.g. groundwater exploitation responsible for high subsidence rates between 1950 and 1970 and, consequently, for an

  5. Evodiamine suppresses capsaicin-induced thermal hyperalgesia through activation and subsequent desensitization of the transient receptor potential V1 channels.

    Science.gov (United States)

    Iwaoka, Emiko; Wang, Shenglan; Matsuyoshi, Nobuyuki; Kogure, Yoko; Aoki, Shunji; Yamamoto, Satoshi; Noguchi, Koichi; Dai, Yi

    2016-01-01

    Evodiae fructus (EF), a fruit of Evodia rutaecarpa Bentham, has long been used as an analgesic drug in traditional Chinese and Japanese medicine. However, the underlying molecular mechanism of its pharmacological action is unclear. Here, using calcium imaging, whole-cell patch-clamp recording, and behavioral analysis, we investigated the pharmacological action of EF and its principal compound, evodiamine, on the transient receptor potential (TRP) V1 channels. Dorsal root ganglion (DRG) neurons and TRPV1- or TRPA1-transfected human embryonic kidney-derived (HEK) 293 cells were used for calcium imaging or whole-cell patch-clamp recording. Twenty male adult Sprague-Dawley rats were used for the capsaicin-induced thermal hyperalgesia behavioral analyses. We found that evodiamine induced significant increases in intracellular calcium and robust inward currents in a subpopulation of isolated rat DRG neurons, most of which were also sensitive to capsaicin. The effect of evodiamine was completely blocked by capsazepine, a competitive antagonist of TRPV1. Evodiamine induced significant inward currents in TRPV1-, but not TRPA1-transfected HEK293 cells. Pretreatment with evodiamine reduced capsaicin-induced currents significantly. Furthermore, the in vivo pre-treatment of evodiamine suppressed thermal hyperalgesia induced by intraplantar injection of capsaicin in rats. These results identify that the analgesic effect of EF and evodiamine may be due to the activation and subsequent desensitization of TRPV1 in sensory neurons.

  6. Activation of PPARβ/δ prevents hyperglycaemia-induced impairment of Kv7 channels and cAMP-mediated relaxation in rat coronary arteries.

    Science.gov (United States)

    Morales-Cano, Daniel; Moreno, Laura; Barreira, Bianca; Briones, Ana M; Pandolfi, Rachele; Moral-Sanz, Javier; Callejo, Maria; Mondejar-Parreño, Gema; Cortijo, Julio; Salaices, Mercedes; Duarte, Juan; Perez-Vizcaino, Francisco; Cogolludo, Angel

    2016-10-01

    PPARβ/δ activation protects against endothelial dysfunction in diabetic models. Elevated glucose is known to impair cAMP-induced relaxation and Kv channel function in coronary arteries (CA). Herein, we aimed to analyse the possible protective effects of the PPARβ/δ agonist GW0742 on the hyperglycaemic-induced impairment of cAMP-induced relaxation and Kv channel function in rat CA. As compared with low glucose (LG), incubation under high glucose (HG) conditions attenuated the relaxation induced by the adenylate cyclase activator forskolin in CA and this was prevented by GW0742. The protective effect of GW0742 was supressed by a PPARβ/δ antagonist. In myocytes isolated from CA under LG, forskolin enhanced Kv currents and induced hyperpolarization. In contrast, when CA were incubated with HG, Kv currents were diminished and the electrophysiological effects of forskolin were abolished. These deleterious effects were prevented by GW0742. The protective effects of GW0742 on forskolin-induced relaxation and Kv channel function were confirmed in CA from type-1 diabetic rats. In addition, the differences in the relaxation induced by forskolin in CA incubated under LG, HG or HG + GW0742 were abolished by the Kv7 channel inhibitor XE991. Accordingly, GW0742 prevented the down-regulation of Kv7 channels induced by HG. Finally, the preventive effect of GW0742 on oxidative stress and cAMP-induced relaxation were overcome by the pyruvate dehydrogenase kinase 4 (PDK4) inhibitor dichloroacetate (DCA). Our results reveal that the PPARβ/δ agonist GW0742 prevents the impairment of the cAMP-mediated relaxation in CA under HG. This protective effect was associated with induction of PDK4, attenuation of oxidative stress and preservation of Kv7 channel function.

  7. Kv3 channels modulate calcium signals induced by fast firing patterns in the rat retinal ganglion cells.

    Science.gov (United States)

    Kuznetsov, Kirill I; Grygorov, Oleksii O; Maslov, Vitaly Yu; Veselovsky, Nikolay S; Fedulova, Svetlana A

    2012-11-01

    Expression of non-inactivating Kv3.1/Kv3.2 potassium channels determines fast-spiking phenotype of many types of neurones including retinal ganglion cells (RGCs); furthermore Kv3 channels regulate neurotransmitter release from presynaptic terminals. In the present study we investigated how inhibition of Kv3 channel by low TEA concentrations modifies firing properties and Ca2+ influx in the rat RGCs. Experiments were performed on the whole-mount retinal preparations from 4 to 6 weeks old Wistar rats using simultaneous whole cell patch clamp and intracellular Ca2+ measurements in combination with single-cell RT-PCR. In response to 500-ms depolarization step the RGCs demonstrated fast firing tonic behaviour with a mean frequency of spiking 61±5 Hz (n=28). All of the tonic cells tested (n=9) expressed specific mRNA for either Kv3.1 or Kv3.2 or for both channels. Bath applications of TEA (250 μM, 500 μM and 1 mM) modified firing patterns dose-dependently as follows: firing frequency was decreased, mean action potential (AP) half-width increased and mean amplitude of after hyperpolarization was reduced. The amplitude of the Ca2+ signals induced by the cells firing was linearly dependent on number of APs with a mean slope of 7.3±0.9 nM per one AP (n=8). APs widening by TEA increased the slope of the amplitude vs. AP number plots in a dose-dependent manner: 250 μM of TEA increased the mean slope value to 9.5±1.2 nM/AP, 500 μM to 12.4±2.4 nM/AP and 1 mM to 13.2±2.9 nM/AP (n=6). All these parameters, as well as the cells firing properties, were significantly different from controls and from each other except between 500 μM and 1 mM. This is consistent with the pharmacological properties of Kv3.1/Kv3.2 channels: the TEA IC50 is in the range 150-300 μM with almost complete block at 1 mM. This suggests that Kv3.1/Kv3.2 channels underlie the fast firing of the rat RGCs and provide at a given firing frequency 1.8-fold restriction Ca2+ influx, thus protecting the cells

  8. Electron gas polarization effect induced by heavy H-like ions of moderate velocities channeled in a silicon crystal

    CERN Document Server

    Dauvergne, D; Bosch, F; Bräuning, H; Chevallier, M; Cohen, C; Gumberidze, A; Hagmann, S; L'Hoir, A; Kirsch, R; Kozhuharov, C; Liesen, D; Mokler, P H; Poizat, J C; Ray, C; Rozet, J P; Stöhlker, T; Toleikis, S; Toulemonde, M; Verma, P; St\\"{o}hlker, Th.

    2006-01-01

    We report on the observation of a strong perturbation of the electron gas induced by 20 MeV/u U$^{91+}$ ions and 13 MeV/u Pb$^{81+}$ ions channeled in silicon crystals. This collective response (wake effect) in-duces a shift of the continuum energy level by more than 100 eV, which is observed by means of Radiative Electron Capture into the K and L-shells of the projectiles. We also observe an increase of the REC probability by 20-50% relative to the probability in a non-perturbed electron gas. The energy shift is in agreement with calculations using the linear response theory, whereas the local electron density enhancement is much smaller than predicted by the same model. This shows that, for the small values of the adiabaticity parameter achieved in our experiments, the density fluctuations are not strongly localized at the vicinity of the heavy ions.

  9. Electron gas polarization effect induced by heavy H-like ions of moderate velocities channeled in a silicon crystal

    Energy Technology Data Exchange (ETDEWEB)

    Testa, E. [Institut de Physique Nucleaire de Lyon, CNRS-IN2P3, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne (France); Dauvergne, D. [Institut de Physique Nucleaire de Lyon, CNRS-IN2P3, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne (France)]. E-mail: d.dauvergne@ipnl.in2p3.fr; Braeuning-Demian, A. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); Bosch, F. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); Braeuning, H. [Institut fuer Kernphysik, Justus Liebig Universitaet, D-35392 Giessen (Germany); Chevallier, M. [Institut de Physique Nucleaire de Lyon, CNRS-IN2P3, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne (France); Cohen, C. [Institut des Nano-Sciences de Paris, CNRS-UMR75-88, Universites Paris VI et Paris VII, 75251 Paris cedex 05 (France); Gumberidze, A. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); Hagmann, S. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); L' Hoir, A. [Institut des Nano-Sciences de Paris, CNRS-UMR75-88, Universites Paris VI et Paris VII, 75251 Paris cedex 05 (France); Kirsch, R. [Institut de Physique Nucleaire de Lyon, CNRS-IN2P3, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne (France); Kozhuharov, C.; Liesen, D.; Mokler, P.H. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); Poizat, J.-C.; Ray, C. [Institut de Physique Nucleaire de Lyon, CNRS-IN2P3, Universite Claude Bernard Lyon 1, F-69622 Villeurbanne (France); Rozet, J.-P. [Institut des Nano-Sciences de Paris, CNRS-UMR75-88, Universites Paris VI et Paris VII, 75251 Paris cedex 05 (France); Stoehlker, Th.; Toleikis, S. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany); Toulemonde, M. [Centre Interdisciplinaire de Recherche Ions-Lasers, UMR 11, CEA-CNRS, 14040 Caen cedex (France); Verma, P. [Gesellschaft fuer Schwerionen Forschung (GSI), D-64291 Darmstadt (Germany)

    2006-04-15

    We report on the observation of a strong perturbation of the electron gas induced by 20 MeV/u U{sup 91+} ions and 13 MeV/u Pb{sup 81+} ions channeled in silicon crystals. This collective response (wake effect) induces a shift of the continuum energy level by more than 100 eV, which is observed by means of radiative electron capture into the K- and L-shells of the projectiles. We also observe an increase of the REC probability by 20-50% relative to the probability in a non-perturbed electron gas. The energy shift is in agreement with calculations using the linear response theory, whereas the local electron density enhancement is much smaller than predicted by the same model. This shows that, for the small values of the adiabaticity parameter achieved in our experiments, the density fluctuations are not strongly localized in the vicinity of the heavy ions.

  10. Helicobacter pylori arginase mutant colonizes arginase Ⅱ knockout mice

    Institute of Scientific and Technical Information of China (English)

    Songhee H Kim; Melanie L Langford; Jean-Luc Boucher; Traci L Testerman; David J McGee

    2011-01-01

    AIM: To investigate the role of host and bacterial argi-nases in the colonization of mice by Helicobacter pylori (H. Pylori).METHODS: H. Pylori produces a very powerful urease that hydrolyzes urea to carbon dioxide and ammonium, which neutralizes acid. Urease is absolutely essential to H. Pylori pathogenesis; therefore, the urea substrate must be in ample supply for urease to work efficiently. The urea substrate is most likely provided by arginase activity, which hydrolyzes L-arginine to L-ornithine and urea. Previous work has demonstrated that H. Pylori arginase is surprisingly not required for colonization of wild-type mice. Hence, another in vivo source of the critical urea substrate must exist. We hypothesized that the urea source was provided by host arginase Ⅱ, since this enzyme is expressed in the stomach, and H. Pylori has previously been shown to induce the expres-sion of murine gastric arginase Ⅱ. To test this hypoth-esis, wild-type and arginase (rocF) mutant H. Pylori strain SS1 were inoculated into arginase Ⅱ knockout mice. RESULTS: Surprisingly, both the wild-type and rocF mutant bacteria still colonized arginase Ⅱ knock-out mice. Moreover, feeding arginase Ⅱ knockout mice the host arginase inhibitor S-(2-boronoethyl)-L-cysteine (BEC), while inhibiting > 50% of the host arginase Ⅰactivity in several tissues, did not block the ability of the rocF mutant H. Pylori to colonize. In con-trast, BEC poorly inhibited H. Pylori arginase activity. CONCLUSION: The in vivo source for the essential urea utilized by H. Pylori urease is neither bacterial arginase nor host arginase Ⅱ; instead, either residual host arginase Ⅰor agmatinase is probably responsible.

  11. Knockout of endothelial cell-derived endothelin-1 attenuates skin fibrosis but accelerates cutaneous wound healing.

    Directory of Open Access Journals (Sweden)

    Katsunari Makino

    Full Text Available Endothelin (ET-1 is known for the most potent vasoconstrictive peptide that is released mainly from endothelial cells. Several studies have reported ET-1 signaling is involved in the process of wound healing or fibrosis as well as vasodilation. However, little is known about the role of ET-1 in these processes. To clarify its mechanism, we compared skin fibrogenesis and wound repair between vascular endothelial cell-specific ET-1 knockout mice and their wild-type littermates. Bleomycin-injected fibrotic skin of the knockout mice showed significantly decreased skin thickness and collagen content compared to that of wild-type mice, indicating that bleomycin-induced skin fibrosis is attenuated in the knockout mice. The mRNA levels of transforming growth factor (TGF-β were decreased in the bleomycin-treated skin of ET-1 knockout mice. On the other hand, skin wound healing was accelerated in ET-1 knockout mice, which was indicated by earlier granulation tissue reduction and re-epithelialization in these mice. The mRNA levels of TGF-β, tumor necrosis factor (TNF-α and connective tissue growth factor (CTGF were reduced in the wound of ET-1 knockout mice. In endothelial ET-1 knockout mouse, the expression of TNF-α, CTGF and TGF-β was down-regulated. Bosentan, an antagonist of dual ET receptors, is known to attenuate skin fibrosis and accelerate wound healing in systemic sclerosis, and such contradictory effect may be mediated by above molecules. The endothelial cell-derived ET-1 is the potent therapeutic target in fibrosis or wound healing, and investigations of the overall regulatory mechanisms of these pathological conditions by ET-1 may lead to a new therapeutic approach.

  12. Mu-opioid receptor knockout mice show diminished food-anticipatory activity

    NARCIS (Netherlands)

    Kas, Martien J H; van den Bos, Ruud; Baars, Annemarie M; Lubbers, Marianne; Lesscher, Heidi M B; Hillebrand, Jacquelien J G; Schuller, Alwin G; Pintar, John E; Spruijt, Berry M

    2004-01-01

    We have previously suggested that during or prior to activation of anticipatory behaviour to a coming reward, mu-opioid receptors are activated. To test this hypothesis schedule induced food-anticipatory activity in mu-opioid receptor knockout mice was measured using running wheels. We hypothesized

  13. Heart failure drug digitoxin induces calcium uptake into cells by forming transmembrane calcium channels

    OpenAIRE

    2008-01-01

    Digitoxin and other cardiac glycosides are important, centuries-old drugs for treating congestive heart failure. However, the mechanism of action of these compounds is still being elucidated. Calcium is known to potentiate the toxicity of these drugs, and we have hypothesized that digitoxin might mediate calcium entry into cells. We report here that digitoxin molecules mediate calcium entry into intact cells. Multimers of digitoxin molecules also are able to form calcium channels in pure plan...

  14. P-gp substrate-induced neurotoxicity in an Abcb1a knock-in/Abcb1b knock-out mouse model with a mutated canine ABCB1 targeted insertion.

    Science.gov (United States)

    Swain, M D; Orzechowski, K L; Swaim, H L; Jones, Y L; Robl, M G; Tinaza, C A; Myers, M J; Jhingory, M V; Buckely, L E; Lancaster, V A; Yancy, H F

    2013-06-01

    Certain dog breeds, especially Collies, are observed to exhibit neurotoxicity to avermectin drugs, which are P-glycoprotein (P-gp) substrates. This neurotoxicity is due to an ABCB1 gene mutation (ABCB1-1Δ) that results in non-functional P-gp expression. A developed Abcb1a knock-in/Abcb1b knock-out mouse model expressing the ABCB1-1Δ canine gene was previously reported and mice exhibited sensitivity upon ivermectin administration. Here, model and wild-type mice were administered P-gp substrates doramectin, moxidectin, and digoxin. While knock-in/knock-out mice exhibited ataxia, lethargy and tremor, wild-type mice remained unaffected. In addition, no neurotoxic clinical signs were observed in either mouse type administered domperidone, a P-gp substrate with no reported neurotoxicity in ABCB1-1Δ Collies. Overall, neurotoxic signs displayed by model mice closely paralleled those observed in ivermectin-sensitive Collies. This model can be used to identify toxic P-gp substrates with altered safety in dog populations and may reduce dog use in safety studies that are part of the drug approval process.

  15. Endothelin induces two types of contractions of rat uterus: phasic contractions by way of voltage-dependent calcium channels and developing contractions through a second type of calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Kozuka, M.; Ito, T.; Hirose, S.; Takahashi, K.; Hagiwara, H.

    1989-02-28

    Effects of endothelin on nonvascular smooth muscle have been examined using rat uterine horns and two modes of endothelin action have been revealed. Endothelin (0.3 nM) caused rhythmic contractions of isolated uterus in the presence of extracellular calcium. The rhythmic contractions were completely inhibited by calcium channel antagonists. These characteristics of endothelin-induced contractions were very similar to those induced by oxytocin. Binding assays using /sup 125/I-endothelin showed that endothelin and the calcium channel blockers did not compete for the binding sites. However, endothelin was unique in that it caused, in addition to rhythmic contractions, a slowly developing monophasic contraction that was insensitive to calcium channel blockers. This developing contraction became dominant at higher concentrations of endothelin and was also calcium dependent.

  16. The corticosteroid hormone induced factor: a new modulator of KCNQ1 channels?

    DEFF Research Database (Denmark)

    Jespersen, Thomas; Grunnet, Morten; Rasmussen, Hanne B;

    2006-01-01

    The corticosteroid hormone induced factor (CHIF) is a member of the one-transmembrane segment protein family named FXYD, which also counts phospholemman and the Na,K-pump gamma-subunit. Originally it was suggested that CHIF could induce the expression of the I(Ks) current when expressed in Xenopus...

  17. Fluoxetine-induced inhibition of synaptosomal ( sup 3 H)5-HT release: Possible Ca sup 2+ -channel inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Stauderman, K.A. (Marion Merrell Dow Research Inst., Cincinnati, OH (United States)); Gandhi, V.C.; Jones, D.J. (Univ. of Texas Health Science Center, San Antonio, TX (United States))

    1992-01-01

    Fluoxetine, a selective 5-Ht uptake inhibitor, inhibited 15 mM K{sup +}-induced ({sup 3}H)5-HT release from rat spinal cord and cortical synaptosomes at concentrations > 0.5 uM. This effect reflected a property shared by another selective 5-HT uptake inhibitor paroxetine but not by less selective uptake inhibitors such as amitriptyline, desipramine, imipramine or nortriptyline. Inhibition of release by fluoxetine was inversely related to both the concentration of K{sup +} used to depolarize the synaptosomes and the concentration of external Ca{sup 2+}. Experiments aimed at determining a mechanism of action revealed that fluoxetine did not inhibit voltage-independent release of ({sup 3}H)5-HT release induced by the Ca{sup 2+}-ionophore A 23187 or Ca{sup 2+}-independent release induced by fenfluramine. Moreover the 5-HT autoreceptor antagonist methiothepin did not reverse the inhibitory actions of fluoxetine on K{sup +}-induced release. Further studies examined the effects of fluoxetine on voltage-dependent Ca{sup 2+} channels and Ca{sup 2+} entry.

  18. Low intensity ultrasound induces apoptosis via MPT channel on mitochondrial membrane: Target for regulating cancer therapy or not?

    Science.gov (United States)

    Feng, Yi; Wan, Mingxi

    2017-03-01

    To discuss how the mitochondrion is involved in low intensity ultrasound induced apoptosis, HepG2 cells were irradiated by low intensity focused ultrasound (ISPTA = 3W/cm2, 1 min) and then cultured from 3-12 h post irradiation in the study. The morphological alteration was examined by light and fluorescent microscopy respectively. Cell viability and apoptosis were examined by trypan blue staining and flow cytometry with double staining of FITC-labelled Annexin-V/PI. Key proteins responded to irradiation were screened out by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and shotgun proteomic methods with Agilent 1100 HPLC-Chip-MS technology. Representative apoptotic morphological characteristics and increased percentage of apoptotic cells were achieved. Six important proteins (4 up-regulated and 2 down-regulated) were selected and analyzed. It revealed low intensity focused ultrasound could induce apoptosis in HepG2 cells and the US-induced apoptosis was mitochondria-dependent and caspases-dependent. Moreover, mitochondrial membrane permeability transition (MPT) is related to ultrasound induced apoptosis, but VDAC may be not the main MPT channel. Understanding it could help to assist the cancer therapy by regulating the MPT as the target.

  19. Types of voltage—dependent calcium channels involved in high potassium depolarization—induced amylase secretion in the exocrine pancreatic tumour cell line AR4—2J

    Institute of Scientific and Technical Information of China (English)

    CUIZONGJIE

    1998-01-01

    In the perifused fura-2 loaded exocrine pancreatic acinar cell line AR4-2J pulses of high potassium induced repetitive increases in intracellular calcium,Attached cells when stimulated with high potassium secreted large amount of amylase.High potassium-induced secretion was dependent both on the concentration of potassium and duration of stimulation.High potassium induced increases in intracellular calcium were inhibited by voltage-dependent calcium channel anatagonists with an order of potency as follows:nifedipine>ω-agatoxin IVA>ω-conotoxin GVIA.In contrast,the L-type calcium channel anatagonist nifedipine almost completely inhibited potassium-induced amylase secretion,whereas the N-type channel antagonist ω-conotoxin GVIA was without effect.The P-type channel antagonist ω-agatoxin IVA had a small inhibitory effect,but this inhibition was not significant at the level of amylase secretion.In conclusion,the AR4-2J cell line posesses different voltage-dependent calcium channels(L,P,N)with the L-type predominantly involved in depolarization induced amylase secretion.

  20. An S-type anion channel SLAC1 is involved in cryptogein-induced ion fluxes and modulates hypersensitive responses in tobacco BY-2 cells.

    Directory of Open Access Journals (Sweden)

    Takamitsu Kurusu

    Full Text Available Pharmacological evidence suggests that anion channel-mediated plasma membrane anion effluxes are crucial in early defense signaling to induce immune responses and hypersensitive cell death in plants. However, their molecular bases and regulation remain largely unknown. We overexpressed Arabidopsis SLAC1, an S-type anion channel involved in stomatal closure, in cultured tobacco BY-2 cells and analyzed the effect on cryptogein-induced defense responses including fluxes of Cl(- and other ions, production of reactive oxygen species (ROS, gene expression and hypersensitive responses. The SLAC1-GFP fusion protein was localized at the plasma membrane in BY-2 cells. Overexpression of SLAC1 enhanced cryptogein-induced Cl(- efflux and extracellular alkalinization as well as rapid/transient and slow/prolonged phases of NADPH oxidase-mediated ROS production, which was suppressed by an anion channel inhibitor, DIDS. The overexpressor also showed enhanced sensitivity to cryptogein to induce downstream immune responses, including the induction of defense marker genes and the hypersensitive cell death. These results suggest that SLAC1 expressed in BY-2 cells mediates cryptogein-induced plasma membrane Cl(- efflux to positively modulate the elicitor-triggered activation of other ion fluxes, ROS as well as a wide range of defense signaling pathways. These findings shed light on the possible involvement of the SLAC/SLAH family anion channels in cryptogein signaling to trigger the plasma membrane ion channel cascade in the plant defense signal transduction network.

  1. Differential Effects of TRPA and TRPV Channels on Behaviors of Caenorhabditis elegans

    Science.gov (United States)

    Thies, Jennifer; Neutzler, Vanessa; O’Leary, Fidelma; Liu, He

    2016-01-01

    TRPA and TRPV ion channels are members of the transient receptor potential (TRP) cation channel superfamily, which mediates various sensory transductions. In Caenorhabditis elegans, the TRPV channels are known to affect chemosensation, while the TRPA-1 channel is associated with thermosensation and mechanosensation. We examined thermosensation, chemosensation, and osmosensation in strains lacking TRPA-1 or TRPV channels. We found that TRPV channel knockout worms exhibited similar behavioral deficits associated with thermotaxis as the TRPA-1 channel knockout, suggesting a dual role for TRPV channels. In contrast, chemosensation responses, assessed by both avoidance reversal behavior and NaCl osmosensation, were dependent on TRPV channels but seemed independent of TRPA-1 channel. Our findings suggest that, in addition to TRPA-1 channel, TRPV channels are necessary for thermotaxis and may activate, or modulate, the function of TRPA-1 channels. In contrast, TRPA-1 channels do not have a dual responsibility, as they have no functional role in odorant avoidance or osmosensation. PMID:27168724

  2. Romk1 Knockout Mice Do Not Produce Bartter Phenotype but Exhibit Impaired K Excretion.

    Science.gov (United States)

    Dong, Ke; Yan, Qingshang; Lu, Ming; Wan, Laxiang; Hu, Haiyan; Guo, Junhua; Boulpaep, Emile; Wang, WenHui; Giebisch, Gerhard; Hebert, Steven C; Wang, Tong

    2016-03-04

    Romk knock-out mice show a similar phenotype to Bartter syndrome of salt wasting and dehydration due to reduced Na-K-2Cl-cotransporter activity. At least three ROMK isoforms have been identified in the kidney; however, unique functions of any of the isoforms in nephron segments are still poorly understood. We have generated a mouse deficient only in Romk1 by selective deletion of the Romk1-specific first exon using an ES cell Cre-LoxP strategy and examined the renal phenotypes, ion transporter expression, ROMK channel activity, and localization under normal and high K intake. Unlike Romk(-/-) mice, there was no Bartter phenotype with reduced NKCC2 activity and increased NCC expression in Romk1(-/-) mice. The small conductance K channel (SK) activity showed no difference of channel properties or gating in the collecting tubule between Romk1(+/+) and Romk1(-/-) mice. High K intake increased SK channel number per patch and increased the ROMK channel intensity in the apical membrane of the collecting tubule in Romk1(+/+), but such regulation by high K intake was diminished with significant hyperkalemia in Romk1(-/-) mice. We conclude that 1) animal knockouts of ROMK1 do not produce Bartter phenotype. 2) There is no functional linking of ROMK1 and NKCC2 in the TAL. 3) ROMK1 is critical in response to high K intake-stimulated K(+) secretion in the collecting tubule.

  3. Hydraulic and Vegetative Models of Historic Environmental Conditions Isolate the Role of Riparian Vegetation in Inducing Channel Change

    Science.gov (United States)

    Manners, R.; Schmidt, J. C.; Wheaton, J. M.

    2011-12-01

    An enduring question in geomorphology is the role of riparian vegetation in inducing or exacerbating channel narrowing. It is typically difficult to isolate the role of vegetation in causing channel narrowing, because narrowing typically occurs where there are changes in stream flow, sediment supply, the invasion of non-native vegetation, and sometimes climate change. Therefore, linkages between changes in vegetation communities and changes in channel form are often difficult to identify. We took a mechanistic approach to isolate the role of the invasive riparian shrub tamarisk (Tamarix spp) in influencing channel narrowing in the Colorado River basin. Detailed geomorphic reconstructions of two sites on the Yampa and Green Rivers, respectively, in Dinosaur National Monument show that channel narrowing has been progressive and that tamarisk encroachment has also occurred; at the same time, dams have been constructed, diversions increased, and spring snowmelt runoff has been occurring earlier in spring. We simulated hydraulic and sediment transport conditions during the two largest floods of record -- 1984 and 2011. Two-dimensional hydraulic models were built to reflect these conditions and allowed us to perform sensitivity tests to determine the dominant determinants of the observed patterns of erosion and deposition. Channel and floodplain topography were constrained through detailed stratigraphic analysis, including precise dating of deposits based on dating of buried tamarisk plants in a series of floodplain trenches and pits. We also used historical air photos to establish past channel topography. To parameterize the influence of riparian vegetation, we developed a model that links detailed terrestrial laser scan (TLS) measurements of stand structure and its corresponding hydraulic roughness at the patch scale to reach-scale riparian vegetation patterns determined from airborne LiDaR (ALS). This model, in conjunction with maps of the ages and establishment

  4. Screening methods to identify TALEN-mediated knockout mice.

    Science.gov (United States)

    Nakagawa, Yoshiko; Yamamoto, Takashi; Suzuki, Ken-Ichi; Araki, Kimi; Takeda, Naoki; Ohmuraya, Masaki; Sakuma, Tetsushi

    2014-01-01

    Genome editing with site-specific nucleases, such as zinc-finger nucleases or transcription activator-like effector nucleases (TALENs), and RNA-guided nucleases, such as the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated) system, is becoming the new standard for targeted genome modification in various organisms. Application of these techniques to the manufacture of knockout mice would be greatly aided by simple and easy methods for genotyping of mutant and wild-type pups among litters. However, there are no detailed or comparative reports concerning the identification of mutant mice generated using genome editing technologies. Here, we genotyped TALEN-derived enhanced green fluorescent protein (eGFP) knockout mice using a combination of approaches, including fluorescence observation, heteroduplex mobility assay, restriction fragment length polymorphism analysis and DNA sequencing. The detection sensitivities for TALEN-induced mutations differed among these methods, and we therefore concluded that combinatorial testing is necessary for the screening and determination of mutant genotypes. Since the analytical methods tested can be carried out without specialized equipment, costly reagents and/or sophisticated protocols, our report should be of interest to a broad range of researchers who are considering the application of genome editing technologies in various organisms.

  5. N-methyl-D-aspartate receptor channel blockers prevent pentylenetetrazole-induced convulsions and morphological changes in rat brain neurons.

    Science.gov (United States)

    Zaitsev, Aleksey V; Kim, Kira Kh; Vasilev, Dmitry S; Lukomskaya, Nera Ya; Lavrentyeva, Valeria V; Tumanova, Natalia L; Zhuravin, Igor A; Magazanik, Lev G

    2015-03-01

    Alterations in inhibitory and excitatory neurotransmission play a central role in the etiology of epilepsy, with overstimulation of glutamate receptors influencing epileptic activity and corresponding neuronal damage. N-methyl-D-aspartate (NMDA) receptors, which belong to a class of ionotropic glutamate receptors, play a primary role in this process. This study compared the anticonvulsant properties of two NMDA receptor channel blockers, memantine and 1-phenylcyclohexylamine (IEM-1921), in a pentylenetetrazole (PTZ) model of seizures in rats and investigated their potencies in preventing PTZ-induced morphological changes in the brain. The anticonvulsant properties of IEM-1921 (5 mg/kg) were more pronounced than those of memantine at the same dose. IEM-1921 and memantine decreased the duration of convulsions by 82% and 37%, respectively. Both compounds were relatively effective at preventing the tonic component of seizures but not myoclonic seizures. Memantine significantly reduced the lethality caused by PTZ-induced seizures from 42% to 11%, and all animals pretreated with IEM-1921 survived. Morphological examination of the rat brain 24 hr after administration of PTZ revealed alterations in the morphology of 20-25% of neurons in the neocortex and the hippocampus, potentially induced by excessive glutamate. The expression of the excitatory amino acid transporter 1 protein was increased in the hippocampus of the PTZ-treated rats. However, dark neurons did not express caspase-3 and were immunopositive for the neuronal nuclear antigen protein, indicating that these neurons were alive. Both NMDA antagonists prevented neuronal abnormalities in the brain. These results suggest that NMDA receptor channel blockers might be considered possible neuroprotective agents for prolonged seizures or status epilepticus leading to neuronal damage.

  6. Methylene blue counteracts H2S toxicity-induced cardiac depression by restoring L-type Ca channel activity.

    Science.gov (United States)

    Judenherc-Haouzi, Annick; Zhang, Xue-Qian; Sonobe, Takashi; Song, Jianliang; Rannals, Matthew D; Wang, JuFang; Tubbs, Nicole; Cheung, Joseph Y; Haouzi, Philippe

    2016-06-01

    We have previously reported that methylene blue (MB) can counteract hydrogen sulfide (H2S) intoxication-induced circulatory failure. Because of the multifarious effects of high concentrations of H2S on cardiac function, as well as the numerous properties of MB, the nature of this interaction, if any, remains uncertain. The aim of this study was to clarify 1) the effects of MB on H2S-induced cardiac toxicity and 2) whether L-type Ca(2+) channels, one of the targets of H2S, could transduce some of the counteracting effects of MB. In sedated rats, H2S infused at a rate that would be lethal within 5 min (24 μM·kg(-1)·min(-1)), produced a rapid fall in left ventricle ejection fraction, determined by echocardiography, leading to a pulseless electrical activity. Blood concentrations of gaseous H2S reached 7.09 ± 3.53 μM when cardiac contractility started to decrease. Two to three injections of MB (4 mg/kg) transiently restored cardiac contractility, blood pressure, and V̇o2, allowing the animals to stay alive until the end of H2S infusion. MB also delayed PEA by several minutes following H2S-induced coma and shock in unsedated rats. Applying a solution containing lethal levels of H2S (100 μM) on isolated mouse cardiomyocytes significantly reduced cell contractility, intracellular calcium concentration ([Ca(2+)]i) transient amplitudes, and L-type Ca(2+) currents (ICa) within 3 min of exposure. MB (20 mg/l) restored the cardiomyocyte function, ([Ca(2+)]i) transient, and ICa The present results offer a new approach for counteracting H2S toxicity and potentially other conditions associated with acute inhibition of L-type Ca(2+) channels.

  7. Ropivacaine-Induced Contraction Is Attenuated by Both Endothelial Nitric Oxide and Voltage-Dependent Potassium Channels in Isolated Rat Aortae

    Directory of Open Access Journals (Sweden)

    Seong-Ho Ok

    2013-01-01

    Full Text Available This study investigated endothelium-derived vasodilators and potassium channels involved in the modulation of ropivacaine-induced contraction. In endothelium-intact rat aortae, ropivacaine concentration-response curves were generated in the presence or absence of the following inhibitors: the nonspecific nitric oxide synthase (NOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, the neuronal NOS inhibitor Nω-propyl-L-arginine hydrochloride, the inducible NOS inhibitor 1400W dihydrochloride, the nitric oxide-sensitive guanylyl cyclase (GC inhibitor ODQ, the NOS and GC inhibitor methylene blue, the phosphoinositide-3 kinase inhibitor wortmannin, the cytochrome p450 epoxygenase inhibitor fluconazole, the voltage-dependent potassium channel inhibitor 4-aminopyridine (4-AP, the calcium-activated potassium channel inhibitor tetraethylammonium (TEA, the inward-rectifying potassium channel inhibitor barium chloride, and the ATP-sensitive potassium channel inhibitor glibenclamide. The effect of ropivacaine on endothelial nitric oxide synthase (eNOS phosphorylation in human umbilical vein endothelial cells was examined by western blotting. Ropivacaine-induced contraction was weaker in endothelium-intact aortae than in endothelium-denuded aortae. L-NAME, ODQ, and methylene blue enhanced ropivacaine-induced contraction, whereas wortmannin, Nω-propyl-L-arginine hydrochloride, 1400W dihydrochloride, and fluconazole had no effect. 4-AP and TEA enhanced ropivacaine-induced contraction; however, barium chloride and glibenclamide had no effect. eNOS phosphorylation was induced by ropivacaine. These results suggest that ropivacaine-induced contraction is attenuated primarily by both endothelial nitric oxide and voltage-dependent potassium channels.

  8. Universal statistics of the knockout tournament

    OpenAIRE

    Baek, Seung Ki; Yi, Il Gu; Park, Hye Jin; Kim, Beom Jun

    2013-01-01

    We study statistics of the knockout tournament, where only the winner of a fixture progresses to the next. We assign a real number called competitiveness to each contestant and find that the resulting distribution of prize money follows a power law with an exponent close to unity if the competitiveness is a stable quantity and a decisive factor to win a match. Otherwise, the distribution is found narrow. The existing observation of power law distributions in various kinds of real sports tourn...

  9. Taurine-induced modulation of voltage-sensitive Na+ channels in rat dorsal root ganglion neurons.

    Science.gov (United States)

    Yu, Shan-Shan; Yu, Kuai; Gu, Yan; Ruan, Di-Yun

    2005-08-15

    The physiological role of taurine, an abundant free amino acid in the neural system, is still poorly understood. The aim of this study was to investigate its effect on TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Na+ currents in enzymatically dissociated neurons from rat dorsal root ganglion (DRG) with conventional whole-cell recording manner under voltage-clamp conditions. A TTX-S Na+ current was recorded preferentially from large DRG neurons and a TTX-R Na+ current preferentially from small ones. For TTX-S Na+ channel, taurine of the concentration > or = 10 mM shifted the activation curve in the depolarizing direction and the inactivation curve in the hyperpolarizing direction. There was no change in the activation curve for TTX-R Na+ channel and the inactivation curve was shifted in the hyperpolarizing direction slightly in the presence of taurine > or = 20 mM. When the recovery kinetics was examined, the presence of taurine resulted in a slower recovery from inactivation of TTX-S currents and no change of TTX-R ones. All the effects of taurine were weakly concentration-dependent and partly recovered quite slowly after washout. Our data indicate that taurine alters the properties of Na+ currents in intact DRG neurons. These may contribute to the understanding of taurine as a natural neuroprotectant and the potential of taurine as a useful medicine for the treatment of sensory neuropathies.

  10. A novel anticonvulsant modulates voltage-gated sodium channel inactivation and prevents kindling-induced seizures.

    Science.gov (United States)

    Ashraf, Muhammad N; Gavrilovici, Cezar; Shah, Syed U Ali; Shaheen, Farzana; Choudhary, Muhammad I; Rahman, Atta-ur; Fahnestock, Margaret; Simjee, Shabana U; Poulter, Michael O

    2013-09-01

    Here, we explore the mechanism of action of isoxylitone (ISOX), a molecule discovered in the plant Delphinium denudatum, which has been shown to have anticonvulsant properties. Patch-clamp electrophysiology assayed the activity of ISOX on voltage-gated sodium channels (VGSCs) in both cultured neurons and brain slices isolated from controls and rats with experimental epilepsy(kindling model). Quantitative transcription polymerase chain reaction (qRT-PCR) (QPCR) assessed brain-derived neurotrophic factor (BDNF) mRNA expression in kindled rats, and kindled rats treated with ISOX. ISOX suppressed sodium current (I(Na)) showing an IC50 value of 185 nM in cultured neurons. ISOX significantly slowed the recovery from inactivation (ISOX τ = 18.7 ms; Control τ = 9.4 ms; p kindled cortical neurons, the IC50 for sodium current block was identical to that found in cultured neurons. ISOX prevented kindled stage 5 seizures and decreased the enhanced BDNF mRNA expression that is normally associated with kindling (p kindling is likely a secondary outcome that nevertheless would suppress epileptogenesis. These data show a new class of anti-seizure compound that inhibits sodium channel function and prevents the development of epileptic seizures.

  11. Inhibition of nitrite-induced toxicity in channel catfish by calcium chloride and sodium chloride

    Science.gov (United States)

    Tommasso J.R., Wright; Simco, B.A.; Davis, K.B.

    1980-01-01

    Environmental chloride has been shown to inhibit methemoglobin formation in fish, thereby offering a protective effect against nitrite toxicity. Channel catfish (Ictalurus punctatus) were simultaneously exposed to various environmental nitrite and chloride levels (as either CaCl2 or NaCl) in dechlorinated tap water (40 mg/L total hardness, 47 mg/L alkalinity, 4 mg/L chloride, pH = 6.9-7.1, and temperature 21-24°C). Methemoglobin levels in fish simultaneously exposed to 2.5 mg/L nitrite and up to 30 mg/L chloride as either CaCl2 or NaCl were similar but significantly lower than in unprotected fish. Exposure to 10 mg/L nitrite and 60 mg/L chloride resulted in methemoglobin levels similar to those of the controls; most unprotected fish died. Fish exposed to 10 mg/L nitrite had significantly lower methemoglobin levels when protected with 15.0 mg/L chloride as CaCl2 than with NaCl. Fish exposed to nitrite in the presence of 60 mg/L chloride (as either CaCl2 or NaCl) had similar 24-h LC50 values that were significantly elevated above those obtained in the absence of chloride. Calcium had little effect on tolerance to nitrite toxicity in channel catfish in contrast to its large effect reported in steelhead trout (Salmo gairdneri).

  12. TRP channels and traffic-related environmental pollution-induced pulmonary disease.

    Science.gov (United States)

    Akopian, Armen N; Fanick, E Robert; Brooks, Edward G

    2016-05-01

    Environmental pollutant exposures are major risk factors for adverse health outcomes, with increased morbidity and mortality in humans. Diesel exhaust (DE) is one of the major harmful components of traffic-related air pollution. Exposure to DE affects several physiological systems, including the airways, and pulmonary diseases are increased in highly populated urban areas. Hence, there are urgent needs to (1) create newer and lesser polluting fuels, (2) improve exhaust aftertreatments and reduce emissions, and (3) understand mechanisms of actions for toxic effects of both conventional and cleaner diesel fuels on the lungs. These steps could aid the development of diagnostics and interventions to prevent the negative impact of traffic-related air pollution on the pulmonary system. Exhaust from conventional, and to a lesser extent, clean fuels, contains particulate matter (PM) and more than 400 additional chemical constituents. The major toxic constituents are nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons (PAHs). PM and PAHs could potentially act via transient receptor potential (TRP) channels. In this review, we will first discuss the associations between DE from conventional as well as clean fuel technologies and acute and chronic airway inflammation. We will then review possible activation and/or potentiation of TRP vanilloid type 1 (TRPV1) and ankyrin 1 (TRPA1) channels by PM and PAHs. Finally, we will discuss and summarize recent findings on the mechanisms whereby TRPs could control the link between DE and airway inflammation, which is a primary determinant leading to pulmonary disease.

  13. Functional upregulation of nav1.8 sodium channels on the membrane of dorsal root Ganglia neurons contributes to the development of cancer-induced bone pain.

    Directory of Open Access Journals (Sweden)

    Xiao-Dan Liu

    Full Text Available We have previously reported that enhanced excitability of dorsal root ganglia (DRG neurons contributes to the development of bone cancer pain, which severely decreases the quality of life of cancer patients. Nav1.8, a tetrodotoxin-resistant (TTX-R sodium channel, contributes most of the sodium current underlying the action potential upstroke and accounts for most of the current in later spikes in a train. We speculate that the Nav1.8 sodium channel is a potential candidate responsible for the enhanced excitability of DRG neurons in rats with bone cancer pain. Here, using electrophysiology, Western blot and behavior assays, we documented that the current density of TTX-R sodium channels, especially the Nav1.8 channel, increased significantly in DRG neurons of rats with cancer-induced bone pain. This increase may be due to an increased expression of Nav1.8 on the membrane of DRG neurons. Accordantly, blockade of Nav1.8 sodium channels by its selective blocker A-803467 significantly alleviated the cancer-induced mechanical allodynia and thermal hyperalgesia in rats. Taken together, these results suggest that functional upregulation of Nav1.8 channels on the membrane of DRG neurons contributes to the development of cancer-induced bone pain.

  14. A1-adenosine acute withdrawal response and cholecystokinin-8 induced contractures are regulated by Ca(2+)- and ATP-activated K(+) channels.

    Science.gov (United States)

    Cascio, Maria Grazia; Valeri, Daniela; Tucker, Steven J; Marini, Pietro

    2015-01-01

    In isolated guinea-pig ileum (GPI), the A1-adenosine acute withdrawal response is under the control of several neuronal signalling systems, including the μ/κ-opioid and the cannabinoid CB1 systems. It is now well established that after the stimulation of the A1-adenosine system, the indirect activation of both μ/κ-opioid and CB1 systems is prevented by the peptide cholecystokinin-8 (CCk-8). In the present study, we have investigated the involvement of the Ca(2+)/ATP-activated K(+) channels in the regulation of both acute A1-withdrawal and CCk-8-induced contractures in the GPI preparation. Interestingly, we found that: (a) the A1-withdrawal contracture is inhibited by voltage dependent Ca(2+)-activated K(+) channels, Kv, while it is enhanced by the voltage independent Ca(2+)-activated K(+) channels, SKCa; (b) in the presence of CCk-8, the inhibitory effect of the A1 agonist, CPA, on the peptide induced contracture is significantly enhanced by the voltage independent Ca(2+)-activated K(+) channel, SKCa; and (c) the A1-withdrawal contracture precipitated in the presence of CCk-8 is controlled by the ATP-sensitive potassium channels, KATP. Our data suggest, for the first time, that both Ca(2+)- and ATP-activated K(+) channels are involved in the regulation of both A1-withdrawal precipitated and CCk-8 induced contractures.

  15. Suppression of Space Charge Induced Beam Halo in Nonlinear Focusing Channel

    CERN Document Server

    Batygin, Yuri K; Kurennoy, Sergey; Li, Chao

    2016-01-01

    An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.

  16. Flow of a Burger’s Fluid in a Channel Induced by Peristaltic Compliant Walls

    Directory of Open Access Journals (Sweden)

    I. Ahmad

    2014-01-01

    Full Text Available A theoretical analysis is presented for the peristaltic motion of a magneto-hydrodynamic (MHD non-Newtonian fluid in channel with complaint walls. The fluid obeys viscoelastic non-Newtonian model with Burger’s constitutive equation. The relevant equations are first developed and then solved using perturbation technique. Expressions of stream function and velocity components are constructed under the assumption that δ (characteristic ratio of transversal and axial scales of peristaltic motion is small. The results indicate the strong effects of Burger’s fluid parameter, Hartman number, Reynolds number, and complaint wall parameters on the velocity field and stream function. The obtained solutions are shown graphically for the different values of involved parameters.

  17. Suppression of space charge induced beam halo in nonlinear focusing channel

    Science.gov (United States)

    Batygin, Yuri K.; Scheinker, Alexander; Kurennoy, Sergey; Li, Chao

    2016-04-01

    An intense non-uniform particle beam exhibits strong emittance growth and halo formation in focusing channels due to nonlinear space charge forces of the beam. This phenomenon limits beam brightness and results in particle losses. The problem is connected with irreversible distortion of phase space volume of the beam in conventional focusing structures due to filamentation in phase space. Emittance growth is accompanied by halo formation in real space, which results in inevitable particle losses. A new approach for solving a self-consistent problem for a matched non-uniform beam in two-dimensional geometry is discussed. The resulting solution is applied to the problem of beam transport, while avoiding emittance growth and halo formation by the use of nonlinear focusing field. Conservation of a beam distribution function is demonstrated analytically and by particle-in-cell simulation for a beam with a realistic beam distribution.

  18. Effect of subclinical, clinical and supraclinical doses of calcium channel blockers on models of drug-induced hepatotoxicity in rats.

    Science.gov (United States)

    Okwa, Iniviefien B; Akindele, Abidemi J; Agbaje, Esther O; Oshinuga, Oladoyin T; Anunobi, Chidozie C; Adeyemi, Olufunmilayo O

    2013-01-01

    Drug-related hepatotoxicity is the leading cause of acute liver failure, and hepatic problems are responsible for a significant number of liver transplantations and deaths worldwide. Calcium has been associated with various metabolic processes that lead to cell death and apoptosis, and increased cytosolic Ca(2+) has been implicated in hepatotoxicity. This study was designed to investigate the effects of calcium channel blockers (CCBs) on isoniazid-rifampicin, zidovudine and erythromycin-induced hepatotoxicity in rats. Treatment groups comprised control, hepatotoxicant, hepatotoxicant along with each of silymarin, nifedipine, verapamil and diltiazem at subclinical, clinical and supraclinical doses. A day to the end of treatment for each model, rats were subjected to the hexobarbitone-induced hypnosis test. On the last days of treatment, blood samples were collected and serum was analyzed for relevant biochemical parameters. Animals were sacrificed after blood collection and livers were harvested, and samples obtained for in vivo antioxidant indices assay and histopathology. The hepatotoxicants significantly increased serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP), as well as duration of sleep in the hypnosis test. These drugs significantly reduced the hepatic levels of reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and increased the level of malondialdehyde (MDA). The CCBs at the various doses significantly reversed the effects of isoniazid-rifampicin, zidovudine and erythromycin. The results obtained in this study suggest that the CCBs possess hepatoprotective activity in drug-induced hepatotoxicity and may be beneficial at the subclinical and clinical doses.

  19. L-Carnitine Reduces in Human Conjunctival Epithelial Cells Hypertonic-Induced Shrinkage through Interacting with TRPV1 Channels

    Directory of Open Access Journals (Sweden)

    Noushafarin Khajavi

    2014-08-01

    Full Text Available Background/Aims: Ocular surface health depends on conjunctival epithelial (HCjE layer integrity since it protects against pathogenic infiltration and contributes to tissue hydration maintenance. As the same increases in tear film hyperosmolarity described in dry eye disease can increase corneal epithelial transient receptor potential vanilloid type-1 (TRPV1 channel activity, we evaluated its involvement in mediating an osmoprotective effect by L-carnitine against such stress. Methods: Using siRNA gene silencing, Ca2+ imaging, planar patch-clamping and relative cell volume measurements, we determined if the protective effects of this osmolyte stem from its interaction with TRPV1. Results: TRPV1 activation by capsaicin (CAP and an increase in osmolarity to ≈ 450 mOsM both induced increases in Ca2+ levels. In contrast, blocking TRPV1 activation with capsazepine (CPZ fully reversed this response. Similarly, L-carnitine (1 mM also reduced underlying whole-cell currents. In calcein-AM loaded cells, hypertonic-induced relative cell volume shrinkage was fully blocked during exposure to L-carnitine. On the other hand, in TRPV1 gene-silenced cells, this protective effect by L-carnitine was obviated. Conclusion: The described L-carnitine osmoprotective effect is elicited through suppression of hypertonic-induced TRPV1 activation leading to increases in L-carnitine uptake through a described Na+-dependent L-carnitine transporter.

  20. Transcranial Random Noise Stimulation-induced plasticity is NMDA-receptor independent but sodium-channel blocker and benzodiazepines sensitive

    Directory of Open Access Journals (Sweden)

    Leila eChaieb

    2015-04-01

    Full Text Available Background: Application of transcranial random noise stimulation (tRNS between 0.1 and 640 Hz of the primary motor cortex (M1 for 10 minutes induces a persistent excitability increase lasting for at least 60 minutes. However, the mechanism of tRNS-induced cortical excitability alterations is not yet fully understood. Objective: The main aim of this study was to get first efficacy data with regard to the possible neuronal effect of tRNS. Methods: Single-pulse transcranial magnetic stimulation (TMS was used to measure levels of cortical excitability before and after combined application of tRNS at an intensity of 1mA for 10mins stimulation duration and a pharmacological agent (or sham on 8 healthy male participants. Results: The sodium channel blocker carbamazepine showed a tendency towards inhibiting MEPs 5-60 mins poststimulation. The GABAA agonist lorazepam suppressed tRNS-induced cortical excitability increases at 0-20 and 60 min time points. The partial NMDA receptor agonist D-cycloserine, the NMDA receptor antagonist dextromethorphan and the D2/D3 receptor agonist ropinirole had no significant effects on the excitability increases seen with tRNS.Conclusions: In contrast to transcranial direct current stimulation (tDCS, aftereffects of tRNS are seem to be not NMDA receptor dependent and can be suppressed by benzodiazepines suggesting that tDCS and tRNS depend upon different mechanisms.

  1. Arctigenin, a Potential Anti-Arrhythmic Agent, Inhibits Aconitine-Induced Arrhythmia by Regulating Multi-Ion Channels

    Directory of Open Access Journals (Sweden)

    Zhenying Zhao

    2013-11-01

    Full Text Available Background/Aims: Arctigenin possesses biological activities, but its underlying mechanisms at the cellular and ion channel levels are not completely understood. Therefore, the present study was designed to identify the anti-arrhythmia effect of arctigenin in vivo, as well as its cellular targets and mechanisms. Methods: A rat arrhythmia model was established via continuous aconitine infusion, and the onset times of ventricular premature contraction, ventricular tachycardia and death were recorded. The Action Potential Duration (APD, sodium current (INa, L-type calcium current (ICa, L and transient outward potassium current (Ito were measured and analysed using a patch-clamp recording technique in normal rat cardiomyocytes and myocytes of arrhythmia aconitine-induced by. Results: Arctigenin significantly delayed the arrhythmia onset in the aconitine-induced rat model. The 50% and 90% repolarisations (APD50 and APD90 were shortened by 100 µM arctigenin; the arctigenin dose also inhibited the prolongation of APD50 and APD90 caused by 1 µM aconitine. Arctigenin inhibited INa and ICa,L and attenuated the aconitine-increased INa and ICa,L by accelerating the activation process and delaying the inactivation process. Arctigenin enhanced Ito by facilitating the activation process and delaying the inactivation process, and recoverd the decreased Ito induced by aconitine. Conclusions: Arctigenin has displayed anti-arrhythmia effects, both in vivo and in vitro. In the context of electrophysiology, INa, ICa, L, and Ito may be multiple targets of arctigenin, leading to its antiarrhythmic effect.

  2. Age- and location-dependent differences in store depletion-induced h-channel plasticity in hippocampal pyramidal neurons.

    Science.gov (United States)

    Clemens, Ann M; Johnston, Daniel

    2014-03-01

    Disruptions of endoplasmic reticulum (ER) Ca(2+) homeostasis are heavily linked to neuronal pathology. Depletion of ER Ca(2+) stores can result in cellular dysfunction and potentially cell death, although adaptive processes exist to aid in survival. We examined the age and region dependence of one postulated, adaptive response to ER store-depletion (SD), hyperpolarization-activated cation-nonspecific (h)-channel plasticity in neurons of the dorsal and ventral hippocampus (DHC and VHC, respectively) from adolescent and adult rats. With the use of whole-cell patch-clamp recordings from the soma and dendrites of CA1 pyramidal neurons, we observed a change in h-sensitive measurements in response to SD, induced by treatment with cyclopiazonic acid, a sarcoplasmic reticulum/ER Ca(2+)-ATPase blocker. We found that whereas DHC and VHC neurons in adolescent animals respond to SD with a perisomatic expression of SD h plasticity, adult animals express SD h plasticity with a dendritic and somatodendritic locus of plasticity in DHC and VHC neurons, respectively. Furthermore, SD h plasticity in adults was dependent on membrane potential and on the activation of L-type voltage-gated Ca(2+) channels. These results suggest that cellular responses to the impairment of ER function, or ER stress, are dependent on brain region and age and that the differential expression of SD h plasticity could provide a neural basis for region- and age-dependent disease vulnerabilities.

  3. Dark-matter production through loop-induced processes at the LHC: the s-channel mediator case.

    Science.gov (United States)

    Mattelaer, Olivier; Vryonidou, Eleni

    We show how studies relevant for mono-X searches at the LHC in simplified models featuring a dark-matter candidate and an s-channel mediator can be performed within the MadGraph5_aMC@NLO framework. We focus on gluon-initiated loop-induced processes, mostly relevant to the case where the mediator couples preferentially to third generation quarks and in particular to the top quark. Our implementation allows us to study signatures at hadron colliders involving missing transverse energy plus jets or plus neutral bosons ([Formula: see text]), possibly including the effects of extra radiation by multi-parton merging and matching to the parton shower.

  4. Dark-matter production through loop-induced processes at the LHC: the s-channel mediator case

    Energy Technology Data Exchange (ETDEWEB)

    Mattelaer, Olivier [Durham University, Institute for Particle Physics Phenomenology (IPPP), Durham (United Kingdom); Vryonidou, Eleni [Universite catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium)

    2015-09-15

    We show how studies relevant for mono-X searches at the LHC in simplified models featuring a dark-matter candidate and an s-channel mediator can be performed within the MadGraph5{sub a}MC rate at NLO framework. We focus on gluon-initiated loop-induced processes, mostly relevant to the case where the mediator couples preferentially to third generation quarks and in particular to the top quark. Our implementation allows us to study signatures at hadron colliders involving missing transverse energy plus jets or plus neutral bosons (γ,Z,H), possibly including the effects of extra radiation by multi-parton merging and matching to the parton shower. (orig.)

  5. SNARE function analyzed in synaptobrevin/VAMP knockout mice.

    Science.gov (United States)

    Schoch, S; Deák, F; Königstorfer, A; Mozhayeva, M; Sara, Y; Südhof, T C; Kavalali, E T

    2001-11-01

    SNAREs (soluble NSF-attachment protein receptors) are generally acknowledged as central components of membrane fusion reactions, but their precise function has remained enigmatic. Competing hypotheses suggest roles for SNAREs in mediating the specificity of fusion, catalyzing fusion, or actually executing fusion. We generated knockout mice lacking synaptobrevin/VAMP 2, the vesicular SNARE protein responsible for synaptic vesicle fusion in forebrain synapses, to make use of the exquisite temporal resolution of electrophysiology in measuring fusion. In the absence of synaptobrevin 2, spontaneous synaptic vesicle fusion and fusion induced by hypertonic sucrose were decreased approximately 10-fold, but fast Ca2+-triggered fusion was decreased more than 100-fold. Thus, synaptobrevin 2 may function in catalyzing fusion reactions and stabilizing fusion intermediates but is not absolutely required for synaptic fusion.

  6. Nitric oxide and Kir6.1 potassium channel mediate isoquercitrin-induced endothelium-dependent and independent vasodilation in the mesenteric arterial bed of rats.

    Science.gov (United States)

    Gasparotto Junior, Arquimedes; Dos Reis Piornedo, Renê; Assreuy, Jamil; Da Silva-Santos, José Eduardo

    2016-10-05

    The vascular effect of flavonoid isoquercitrin was investigated in the perfused mesenteric vascular bed of rats. In preparations with functional endothelium isoquercitrin (100, 300 and 1000nmol) dose-dependently reduced the perfusion pressure by 13±2.2, 33±3.9, and 58±3.7mm Hg, respectively. Endothelium removal or inhibition of the nitric oxide synthase enzymes by l-NAME did not change the effects of 100 and 300 nmol isoquercitrin, but reduced by 30-40% the vasodilation induced by 1000 nmol isoquercitrin. Perfusion with nutritive solution containing 40mM KCl abolished the vasodilatory effect of all isoquercitrin doses. Treatment with glibenclamide, a Kir6.1 (ATP-sensitive) potassium channel blocker, inhibited vasodilation induced by 100 and 300 nmol isoquercitrin, but only partially reduced the effect of 1000 nmol isoquercitrin. The non-selective KCa (calcium-activated) potassium channel blocker tetraethylammonium, but not the selective KCa1.1 channel blocker iberiotoxin, reduced by around 60% vasodilation induced by all isoquercitrin doses. In addition, association of tetraethylammonium and glibenclamide, or l-NAME and glibenclamide, fully inhibited isoquercitrin-induced vasodilation. Our study shows that isoquercitrin induces vasodilation in resistance arteries, an effect mediated by K(+) channel opening and endothelial nitric oxide production.

  7. 1,25 (OH)2D3 enhances PTH-induced Ca2+ transients in preosteoblasts by activating L-type Ca2+ channels

    Science.gov (United States)

    Li, W.; Duncan, R. L.; Karin, N. J.; Farach-Carson, M. C.

    1997-01-01

    We previously demonstrated electrophysiologically that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] shifts the activation threshold of L-type Ca2+ channels in osteoblasts toward the resting potential and prolongs mean open time. Presently, we used single-cell Ca2+ imaging to study the combined effects of 1,25(OH)2D3 and parathyroid hormone (PTH) during generation of Ca2+ transients in fura 2-loaded MC3T3-E1 cells. Pretreatment with 1,25(OH)2D3 concentrations, which alone did not produce Ca2+ transients, consistently enhanced Ca2+ responses to PTH. Enhancement was dose dependent over the range of 1 to 10 nM and was blocked by pretreatment with 5 microM nitrendipine during pretreatment. A 1,25(OH)2D3 analog that activates L-type channels and shifts their activation threshold also enhanced PTH responses. In contrast, an analog devoid of membrane Ca2+ effects did not enhance PTH-induced Ca2+ transients. The PTH-induced Ca2+ transient involved activation of a dihydropyridine-insensitive cation channel that was inhibited by Gd3+. Together, these data suggest that 1,25(OH)2D3 increases osteoblast responsiveness to PTH through rapid modification of L-type Ca2+ channel gating properties, whose activation enhances Ca2+ entry through other channels such as the PTH-responsive, Gd(3+)-sensitive cation channel.

  8. Effects of HAb18G/CD147 knockout on hepatocellular carcinoma cells in vitro using a novel zinc-finger nuclease-targeted gene knockout approach.

    Science.gov (United States)

    Li, Hong-Wei; Yang, Xiang-Min; Tang, Juan; Wang, Shi-Jie; Chen, Zhi-Nan; Jiang, Jian-Li

    2015-03-01

    HAb18G/CD147 belongs to the immunoglobulin superfamily and predominantly functions as an inducer of matrix metalloproteinase secretion for tumor invasion and metastasis. This study was designed to investigate the effects of HAb18G/CD147 knockout on hepatocellular carcinoma cells using zinc-finger nuclease (ZFNs)-targeted gene knockout approach. The HCC cell line SMMC-7721 was used for ZFNs-targeted cleavage of the HAb18G/CD147 gene. RT-PCR and Western blot assays were used to detect HAb18G/CD147 expression. HAb18G phenotypic changes following HAb18G/CD147 knockout in SMMC-K7721 cells were assessed using tumor cell adhesion, invasion, migration and colony formation and flow cytometric assays. These data demonstrated that tumor cell adhesion, invasion, migration, and colony formation capabilities of SMMC-K7721 were significantly reduced compared to parental cells or SMMC-7721 with re-expression of HAb18G/CD147 protein transfected with HAb18G/CD147 cDNA. Moreover, knockout of HAb18G/CD147 expression also induced SMMC-K7721 cells to undergo apoptosis compared to SMMC-7721 and SMMC-R7721 (P CD147 reduced p53 levels in SMMC-R7721 cells, possibly through inhibition of the PI3K-Akt-MDM2 signaling pathway. The findings provide a novel insight into the mechanisms underlying HAb18G/CD147-induced progression of HCC cells.

  9. Endothelin-1 induces intracellular [Ca2+] increase via Ca2+ influx through the L-type Ca2+ channel, Ca2+-induced Ca2+ release and a pathway involving ETA receptors, PKC, PKA and AT1 receptors in cardiomyocytes

    Institute of Scientific and Technical Information of China (English)

    ZENG QingHua; LI XingTing; ZHONG GuoGan; ZHANG WenJie; SUN ChengWen

    2009-01-01

    Using fura-2-acetoxymethyl eater (AM) fluorescence imaging and patch clamp techniques, we found that endothelin-1 (ET-1) significantly elevated the intracellular calcium level ([Ca2+]1) in a dose-dependent manner and activated the L-type Ca2+ channel in cardiomyocytes isolated from rats.The effect of ET-1 on [Ca2+]1 elevation was abolished in the presence of the ETA receptor blocker BQ123,but was not affected by the ETa receptor blocker BQ788. ET-1-induced an increase in [Ca2+]1, which was inhibited 46.7% by pretreatment with a high concentration of ryanodine (10 μmol/L), a blocker of the ryanodine receptor. The ET-1-induced [Ca2+]i increase was also inhibited by the inhibltors of protein kinase A (PKA), protein kinase C (PKC) and angiotensin type 1 receptor (AT1 receptor). We found that ET-1 induced an enhancement of the amplitude of the whole cell L-type Ca2+ channel current and an Increase of open-state probability (NPo) of an L-type single Ca2+ channel. BQ123 completely blocked the ET-1-induced increase in calcium channel open-state probability. In this study we demonstrated that ET-1 regulates calcium overload through a series of mechanisms that include L-type Ca2+ channel activation and Ca2+-induced Ca2+ release (CICR). ETa receptors, PKC, PKA and AT1 receptors may also contribute to this pathway.

  10. Endothelin-1 induces intracellular [Ca2+] increase via Ca2+ influx through the L-type Ca2+ channel, Ca2+-induced Ca2+ release and a pathway involving ETA receptors, PKC, PKA and AT1 receptors in cardiomyocytes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Using fura-2-acetoxymethyl ester (AM) fluorescence imaging and patch clamp techniques, we found that endothelin-1 (ET-1) significantly elevated the intracellular calcium level ([Ca2+]i) in a dose-dependent manner and activated the L-type Ca2+ channel in cardiomyocytes isolated from rats. The effect of ET-1 on [Ca2+]i elevation was abolished in the presence of the ETA receptor blocker BQ123, but was not affected by the ETB receptor blocker BQ788. ET-1-induced an increase in [Ca2+]i, which was inhibited 46.7% by pretreatment with a high concentration of ryanodine (10 μmol/L), a blocker of the ryanodine receptor. The ET-1-induced [Ca2+]i increase was also inhibited by the inhibitors of protein kinase A (PKA), protein kinase C (PKC) and angiotensin type 1 receptor (AT1 receptor). We found that ET-1 induced an enhancement of the amplitude of the whole cell L-type Ca2+ channel current and an increase of open-state probability (NPo) of an L-type single Ca2+ channel. BQ123 completely blocked the ET-1-induced increase in calcium channel open-state probability. In this study we demonstrated that ET-1 regulates calcium overload through a series of mechanisms that include L-type Ca2+ channel activation and Ca2+-induced Ca2+ release (CICR). ETA receptors, PKC, PKA and AT1 receptors may also contribute to this pathway.

  11. Universal statistics of the knockout tournament

    CERN Document Server

    Baek, Seung Ki; Park, Hye Jin; Kim, Beom Jun

    2014-01-01

    We study statistics of the knockout tournament, where only the winner of a fixture progresses to the next. We assign a real number called competitiveness to each contestant and find that the resulting distribution of prize money follows a power law with an exponent close to unity if the competitiveness is a stable quantity and a decisive factor to win a match. Otherwise, the distribution is found narrow. The existing observation of power law distributions in various kinds of real sports tournaments therefore suggests that the rules of those games are constructed in such a way that it is possible to understand the games in terms of the contestants' inherent characteristics of competitiveness.

  12. Universal statistics of the knockout tournament

    Science.gov (United States)

    Baek, Seung Ki; Yi, Il Gu; Park, Hye Jin; Kim, Beom Jun

    2013-11-01

    We study statistics of the knockout tournament, where only the winner of a fixture progresses to the next. We assign a real number called competitiveness to each contestant and find that the resulting distribution of prize money follows a power law with an exponent close to unity if the competitiveness is a stable quantity and a decisive factor to win a match. Otherwise, the distribution is found narrow. The existing observation of power law distributions in various kinds of real sports tournaments therefore suggests that the rules of those games are constructed in such a way that it is possible to understand the games in terms of the contestants' inherent characteristics of competitiveness.

  13. Relaxation of endothelin-1-induced pulmonary arterial constriction by niflumic acid and NPPB: mechanism(s) independent of chloride channel block.

    Science.gov (United States)

    Kato, K; Evans, A M; Kozlowski, R Z

    1999-03-01

    We investigated the effects of the Cl- channel blockers niflumic acid, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and 4, 4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) on endothelin-1 (ET-1)-induced constriction of rat small pulmonary arteries (diameter 100-400 microm) in vitro, following endothelium removal. ET-1 (30 nM) induced a sustained constriction of rat pulmonary arteries in physiological salt solution. Arteries preconstricted with ET-1 were relaxed by niflumic acid (IC50: 35.8 microM) and NPPB (IC50: 21.1 microM) in a reversible and concentration-dependent manner. However, at concentrations known to block Ca++-activated Cl- channels, DIDS (induced constriction. Similar results were obtained when pulmonary arteries were preincubated with these Cl- channel blockers. When L-type Ca++ channels were blocked by nifedipine (10 microM), the ET-1-induced (30 nM) constriction was inhibited by only 5.8%. However, niflumic acid (30 microM) and NPPB (30 microM) inhibited the ET-1-induced constriction by approximately 53% and approximately 60%, respectively, both in the continued presence of nifedipine and in Ca++-free physiological salt solution. The Ca++ ionophore A23187 (10 microM) also evoked a sustained constriction of pulmonary arteries. Surprisingly, the A23187-induced constriction was also inhibited in a reversible and concentration-dependent manner by niflumic acid (IC50: 18.0 microM) and NPPB (IC50: 8.8 microM), but not by DIDS (channel blockade. One possibility is that these compounds may block the Ca++-dependent contractile processes.

  14. Effect of potassium channel blocker Tetraethylammonium pretreatment on prevention of the 6-OHDA-induced chronic Parkinson's disease in rats

    Directory of Open Access Journals (Sweden)

    H. Haghdoost-Yazdi

    2016-06-01

    Full Text Available Background: Nuclease and caspase activities that promote death signals and cause apoptosis are dependent to potassium ion. Objective: The aim of this study was to investigate the effect of potassium channel blocker tetraethylammonium (TEA on prevention of Parkinson's disease in rats. Methods: This experimental study was conducted on 33 male rats in Qazvin University of Medical Sciences, 2014. 6-hydroxydopamine (6-OHDA was injected into the striatum of the brain. The rats received different doses of TEA twice daily the day before the 6-OHDA injection till 15 days after the injection. The severity of Parkinsonism was assessed by the apomorphine-induced rotational behavior, the elevated body swing test (EBST, and the rotarod test. Data were analyzed using Kruskal Wallis and Mann Whitney U tests. Findings: Pretreatment with 5 mg/kg TEA significantly reduced the severity of rotations compared to the saline group. TEA did not reduce the swings in the EBST. In the rotarod test, TEA caused significant improvement in the motor performance of the rats. Conclusion: With regards to the results, it seems that pretreatment with TEA can partly reduce the severity of behavioral symptoms in the 6-OHDA-induced chronic Parkinson's disease. The higher the TEA dose, the more significant the reduction in the severity of symptoms.

  15. KR-31378, a potassium-channel opener, induces the protection of retinal ganglion cells in rat retinal ischemic models.

    Science.gov (United States)

    Choi, Anho; Choi, Jun-Sub; Yoon, Yone-Jung; Kim, Kyung-A; Joo, Choun-Ki

    2009-04-01

    KR-31378 is a newly developed K(ATP)-channel opener. To investigate the ability of KR-31378 to protect retinal ganglion cells (RGC), experiments were conducted using two retinal ischemia models. Retinal ischemia was induced by transient high intraocular pressure (IOP) for acute ischemia and by three episcleral vein occlusion for chronic retinal ischemia. KR-31378 was injected intraperitoneally and administered orally in the acute and chronic ischemia models, respectively. Under the condition of chronic ischemia, RGC density in the KR-31378-treated group was statistically higher than that in the non-treated group, and IOP was reduced. In the acute retinal ischemia model, 90% of RGC were degenerated after one week in non-treated retina, but, RGC in KR-31378-treated retina were protected from ischemic damage in a dose-dependent manner and showed inhibited glial fibrillary acidic protein (GFAP) expression. Furthermore, the KR-31378 protective effect was inhibited by glibenclamide treatment in acute ischemia. These findings indicate that systemic KR-31378 treatment may protect against ischemic injury-induced ganglion cell loss in glaucoma.

  16. The chloride intracellular channel 5A stimulates podocyte Rac1, protecting against hypertension-induced glomerular injury.

    Science.gov (United States)

    Tavasoli, Mahtab; Li, Laiji; Al-Momany, Abass; Zhu, Lin-Fu; Adam, Benjamin A; Wang, Zhixiang; Ballermann, Barbara J

    2016-04-01

    Glomerular capillary hypertension elicits podocyte remodeling and is a risk factor for the progression of glomerular disease. Ezrin, which links podocalyxin to actin in podocytes, is activated through the chloride intracellular channel 5A (CLIC5A)-dependent phosphatidylinositol 4,5 bisphosphate (PI[4,5]P2) accumulation. Because Rac1 is involved in podocyte actin remodeling and can promote PI[4,5]P2 production we determined whether CLIC5A-dependent PI[4,5]P2 generation and ezrin activation are mediated by Rac1. In COS7 cells, CLIC5A expression stimulated Rac1 but not Cdc42 or Rho activity. CLIC5A also stimulated phosphorylation of the Rac1 effector Pak1 in COS7 cells and in cultured mouse podocytes. CLIC5A-induced PI[4,5]P2 accumulation and Pak1 and ezrin phosphorylation were all Rac1 dependent. In DOCA/Salt hypertension, phosphorylated Pak increased in podocytes of wild-type, but not CLIC5-deficient mice. In DOCA/salt hypertensive mice lacking CLIC5, glomerular capillary microaneurysms were more frequent and albuminuria was greater than in wild-type mice. Thus, augmented hypertension-induced glomerular capillary injury in mice lacking CLIC5 results from abrogation of Rac1-dependent Pak and ezrin activation, perhaps reducing the tensile strength of the podocyte actin cytoskeleton.

  17. Alterations of N-3 polyunsaturated fatty acid-activated K2P channels in hypoxia-induced pulmonary hypertension

    DEFF Research Database (Denmark)

    Nielsen, Gorm; Wandall-Frostholm, Christine; Sadda, Veeranjaneyulu

    2013-01-01

    in pulmonary vasorelaxation and that alterations of channel expression are pathophysiologically linked to pulmonary hypertension. Expression of PUFA-activated K2P in the murine lung was investigated by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), by patch...... clamp (PC) and myography. K2P -gene expression was examined in chronic hypoxic mice. qRT-PCR showed that the K2P 2.1 and K2P 6.1 were the predominantly expressed K2P in the murine lung. IHC revealed protein expression of K2P 2.1 and K2P 6.1 in the endothelium of pulmonary arteries and of K2P 6.......1 in bronchial epithelium. PC showed pimozide-sensitive K2P -like K(+) -current activated by docosahexaenoic acid (DHA) in freshly isolated endothelial cells as well as DHA-induced membrane hyperpolarization. Myography on pulmonary arteries showed that DHA induced concentration-dependent instantaneous...

  18. Modulation of MAA-induced apoptosis in male germ cells: role of Sertoli cell P/Q-type calcium channels

    Directory of Open Access Journals (Sweden)

    Aguanno Salvatore

    2005-04-01

    Full Text Available Abstract Spontaneous germ cell death by apoptosis occurs during normal spermatogenesis in mammals and is thought to play a role in the physiological mechanism limiting the clonal expansion of such cell population in the male gonad. In the prepubertal rat testis, the most conspicuous dying cells are pachytene spermatocytes, which are also the primary target of the apoptosis experimentally induced by the methoxyacetic acid (MAA. Since we have recently reported that Sertoli cells, the somatic component of the seminiferous epithelium, regulate not only germ cell viability and differentiation but also their death, we have further investigated the mechanism involved in such a control. In this paper we have used the protein clusterin, produced by Sertoli cells and associated with tissue damage or injury, as indicator of germ cell apoptosis in rat seminiferous tubules treated with MAA in the presence or in the absence of omega-agatoxin, a specific inhibitor of P/Q type voltage-operated calcium channels (VOCC's. We performed both a qualitative analysis of clusterin content and germ cell apoptosis by immunofluorescence experiments and a quantitative analysis by in situ end labelling of apoptotic germ cells followed by flow cytometry. The results obtained demonstrate that Sertoli cells modulate germ cell apoptosis induced by methoxyacetic acid also throughout the P/Q-type VOCC's.

  19. Flow-induced vibrations of two tandem cylinders in a channel

    Directory of Open Access Journals (Sweden)

    Jiang Ren-Jie

    2012-01-01

    Full Text Available We numerically studied flow-induced vibrations of two tandem cylinders in transverse direction between two parallel walls. The effect of the horizontal separation between two cylinders, ranging from 1.1 to 10, on the motions of the cylinders and the flow structures were investigated and a variety of periodic and non-periodic vibration regimes were observed. The results show that when two cylinders are placed in close proximity to each other, compared with the case of an isolated cylinder, the gap flow plays an important role. As the separation ratio is increased, the fluid-structure interaction decouples and the cylinders behave as two isolated cylinders.

  20. Cytoprotective role of autophagy against BH3 mimetic gossypol in ATG5 knockout cells generated by CRISPR-Cas9 endonuclease.

    Science.gov (United States)

    Kim, Na-Yeon; Han, Byeal-I; Lee, Michael

    2016-01-01

    Previously, we demonstrated the association between autophagy and gossypol-induced growth inhibition of mutant BRAF melanoma cells. Here, we investigate the role of autophagy in ATG5 knockout cell lines generated by the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas-mediated genome editing. The MTT assay revealed that the inhibitory effect of gossypol was weaker on ATG5 knockout cells than that on the wild type (WT) cells. The conversion of non-autophagic LC3-I to autophagic LC3-II and RT-PCR confirmed the functional gene knockout. However, Cyto-ID autophagy assay revealed that gossypol induced ATG5- and LC3-independent autophagy in ATG5 knockout cells. Moreover, gossypol acts as an autophagy inducer in ATG5 knockout cells while blocking the later stages of the autophagy process in WT cells, which was determined by measuring autophagic flux after co-treatment of gossypol with chloroquine (late-stage autophagy inhibitor). On the other hand, inhibition of autophagy with 3-MA or Beclin-1 siRNA caused a partial increase in the sensitivity to gossypol in ATG5 knockout cells, but not in the WT cells. Together, our findings suggest that the resistance to gossypol in ATG5 knockout cells is associated with increased cytoprotective autophagy, independent of ATG5.

  1. Involvement of transient receptor potential melastatin type 7 channels on Poncirus fructus-induced depolarizations of pacemaking activity in interstitial cells of Cajal from murine small intestine

    Directory of Open Access Journals (Sweden)

    Byung Joo Kim

    2013-06-01

    Conclusion: These results suggest that the PTE-induced depolarization of pacemaking activity occurs in a G-protein-, phospholipase C-, and 1,4,5-inositol triphosphate-dependent manner via TRPM7 channels in cultured ICCs from murine small intestine, which indicates that ICCs are PTE targets and that their interactions affect intestinal motility.

  2. Altered reward circuitry in the norepinephrine transporter knockout mouse.

    Directory of Open Access Journals (Sweden)

    Joseph J Gallagher

    Full Text Available Synaptic levels of the monoamine neurotransmitters dopamine, serotonin, and norepinephrine are modulated by their respective plasma membrane transporters, albeit with a few exceptions. Monoamine transporters remove monoamines from the synaptic cleft and thus influence the degree and duration of signaling. Abnormal concentrations of these neuronal transmitters are implicated in a number of neurological and psychiatric disorders, including addiction, depression, and attention deficit/hyperactivity disorder. This work concentrates on the norepinephrine transporter (NET, using a battery of in vivo magnetic resonance imaging techniques and histological correlates to probe the effects of genetic deletion of the norepinephrine transporter on brain metabolism, anatomy and functional connectivity. MRS recorded in the striatum of NET knockout mice indicated a lower concentration of NAA that correlates with histological observations of subtle dysmorphisms in the striatum and internal capsule. As with DAT and SERT knockout mice, we detected minimal structural alterations in NET knockout mice by tensor-based morphometric analysis. In contrast, longitudinal imaging after stereotaxic prefrontal cortical injection of manganese, an established neuronal circuitry tracer, revealed that the reward circuit in the NET knockout mouse is biased toward anterior portions of the brain. This is similar to previous results observed for the dopamine transporter (DAT knockout mouse, but dissimilar from work with serotonin transporter (SERT knockout mice where Mn(2+ tracings extended to more posterior structures than in wildtype animals. These observations correlate with behavioral studies indicating that SERT knockout mice display anxiety-like phenotypes, while NET knockouts and to a lesser extent DAT knockout mice display antidepressant-like phenotypic features. Thus, the mainly anterior activity detected with manganese-enhanced MRI in the DAT and NET knockout mice is likely

  3. Two Proton Knockout from ^32Mg

    Science.gov (United States)

    Fallon, P.; Rodriguez-Vieitez, E.; Macchiavelli, A. O.; Clark, R. M.; Lee, I.-Y.; Wiedeking, M.; Gade, A.; Adrich, P.; Bazin, D.; Bowen, M.; Campbell, C. M.; Cook, J. M.; Dinca, D. C.; Glasmacher, T.; McDaniel, S.; Mueller, W. F.; Ratiewicz, A. F.; Siwek, K.; Terry, J. R.; Wiesshaar, D.; Yoneda, K.; Brown, B. A.; Otsuka, T.; Tostevin, J. A.; Utsuno, Y.

    2009-05-01

    We present data and calculations on the near-dripline nucleus ^30Ne. Gamma-ray decays from excited states as well as inclusive and exclusive cross-sections were measured in the ^9Be(^32Mg,^30Ne γ)X two-proton knockout reaction at incident beam energies of 99.7 and 86.7 MeV/A. The measured inclusive cross section sigma = 0.22(4)mb is suppressed compared to calculation and is indicative of a reduced overlap of initial and final state wavefunctions. We interpret this reduction as a result of large 4p4h intruder components present in ^30Ne, but not ^32Mg. Large 4p4h amplitudes are predicted to generate increased T=1 paring strengths and to help stabilize the heavier fluorine isotopes against neutron decay. A new gamma-ray transition at 1443 keV is assigned to the decay of the 4^+ state based on the spin dependent sigma for 2 proton knockout from the (d5/2)^4 configuration.

  4. The roles of thermal transient receptor potential channels in thermotactic behavior and in thermal acclimation in the red flour beetle, Tribolium castaneum.

    Science.gov (United States)

    Kim, Hong Geun; Margolies, David; Park, Yoonseong

    2015-05-01

    To survive in variable or fluctuating temperature, organisms should show appropriate behavioral and physiological responses which must be mediated through properly attuned thermal sensory mechanisms. Transient receptor potential channels (TRPs) are a family of cation channels a number of which, called thermo-TRPs, are known to function as thermosensors. We investigated the potential role of thermo-TPRs that have been previously identified in the fruit fly, Drosophila melanogaster, in thermotaxis and thermal acclimation in the red flour beetle, Tribolium castaneum. Phylogenetic analysis of the trp genes showed generally one-to-one orthology between those in D. melanogaster and in T. castaneum, although there are putative gene-losses in two TRP subfamilies of D. melanogaster. With RNA interference (RNAi) of T. castaneum thermo-TRP candidates painless, pyrexia and trpA1, we measured thermal avoidance behavior. RNAi of trpA1 resulted in reduced avoidance of high temperatures, 39 and 42 °C. We also measured the effects of RNAi on heat-induced knockout and death under a short exposure to high temperature (1min at 52 °C) either with or without a 10-min acclimation period at 42 °C. Relatively short exposure to high temperature was enough to induce high temperature thermal acclimation. RNAi of trpA1 led to faster knockout at 52 °C. RNAi of painless showed lower recovery rates from heat-induced knockout after thermal acclimation, and RNAi of pyrexia showed lower long-term survivorship without thermal acclimation. Therefore, we concluded that trpA1 is important in high temperature sensing and also in enhanced tolerance to high-temperature induced knockout; painless plays a role in rapid acclimation to high temperature; and pyrexia functions in protecting beetles from acute heat stress without acclimation.

  5. Low glucose-induced ghrelin secretion is mediated by an ATP-sensitive potassium channel.

    Science.gov (United States)

    Oya, Manami; Kitaguchi, Tetsuya; Harada, Kazuki; Numano, Rika; Sato, Takahiro; Kojima, Masayasu; Tsuboi, Takashi

    2015-07-01

    Ghrelin is synthesized in X/A-like cells of the gastric mucosa, which plays an important role in the regulation of energy homeostasis. Although ghrelin secretion is known to be induced by neurotransmitters or hormones or by nutrient sensing in the ghrelin-secreting cells themselves, the mechanism of ghrelin secretion is not clearly understood. In the present study, we found that changing the extracellular glucose concentration from elevated (25  mM) to optimal (10 mM) caused an increase in the intracellular Ca2+ concentration ([Ca2+]i) in ghrelin-secreting mouse ghrelinoma 3-1 (MGN3-1) cells (n=32, Pghrelin secretion (n≥3, Pghrelin secretion (n≥3, Pghrelin secretion (n≥5, Pghrelin secretion in MGN3-1 cells.

  6. Locomotor activity induced by MK-801 is enhanced in dopamine D3 receptor knockout mice but suppression by dopamine D3/D2 antagonists does not occur through the dopamine D3 receptor.

    Science.gov (United States)

    Yarkov, Alex V; Der, Terry C; Joyce, Jeffrey N

    2010-02-10

    There are contradictory data regarding the role of the dopamine D(3) receptor in regulating N-methyl-d-aspartate (NMDA) receptor antagonist (e.g., dizocilpine) induced hyperactivity. The purpose of the present study was to examine the interaction of dopamine D(3) receptor preferring antagonists U99194A (5,6-dimethoxy-2(dipropylamino)indan) and S33804 ((3aR,9bS)-N[4-(8-cyano-1,3a,4,9b-tetrahydro-3H-benzopyrano[3,4-c]pyrrole-2-yl)-butyl] (4-phenyl)benzamide)) with dizocilpine (MK-801)-induced hyperactivity in wild type (WT) and dopamine D(3) receptor mutant (D(3)R KO) mice. D(3)R KO and WT mice were administered vehicle (saline, 1 ml/100g body weight, i.p.), or S33084 (1.0mg/kg.) and U99194A (0.1mg/kg or 0.01 mg/kg), and horizontal and vertical activity counts were recorded for 30 min. Mice were then treated with vehicle or MK-801 (0.12 mg/kg i.p.) and returned to the open field for an additional 55 min. D(3)R KO mice showed a significantly higher level of locomotor and rearing activity during the 1st 30 min after vehicle treatment compared to WT mice. MK-801-hyperactivity was significantly higher in D(3)R KO mice than WT mice. Dopamine D(3) receptor preferring antagonists suppressed the locomotor activity response to MK-801 to an equal extent in D(3)R KO and WT mice. The results confirm that MK-801-induced hyperactivity and novelty-induced behavioral activity and rearing are enhanced in D(3)R KO mice, but suppression by dopamine D(3) receptor preferring antagonists is not through dopamine D(3) receptor antagonism.

  7. ATP-sensitive K/sup +/ channels that are blocked by hypoglycemia-inducing sulfonylureas in insulin-secreting cells are activated by galanin, a hyperglycemia-inducing hormone

    Energy Technology Data Exchange (ETDEWEB)

    de Weille, J.; Schmid-Antomarchi, H.; Fosset, M.; Lazdunski, M.

    1988-02-01

    The action of the hyperglycemia-inducing hormone galanin, a 29-amino acid peptide names from its N-terminal glycine and C-terminal amidated alanine, was studied in rat insulinoma (RINm5F) cells using electrophysiological and /sup 86/Rb/sup +/ flux techniques. Galanin hyperpolarizes and reduces spontaneous electrical activity by activating a population of APT-sensitive K/sup +/ channels with a single-channel conductance of 30 pS (at -60 mV). Galanin-induced hyperpolarization and reduction of spike activity are reversed by the hypoglycemia-inducing sulfonylurea glibenclamine. Glibenclamide blocks the galanin-activated ATP-sensitive K/sup +/ channel. /sup 86/Rb/sup +/ efflux from insulinoma cells is stimulated by galanin in a dose-dependent manner. The half-maximum value of activation is found at 1.6 nM. Galanin-induced /sup 86/Rb/sup +/ efflux is abolished by glibenclamide. The half-maximum value of inhibition is found at 0.3 nM, which is close to the half-maximum value of inhibition of the ATP-dependent K/sup +/ channel reported earlier. /sup 86/Rb/sup +/ efflux studies confirm the electrophysiological demonstration that galanin activates and ATP-dependent K/sup +/ channel.

  8. Results of gal-knockout porcine thymokidney xenografts.

    Science.gov (United States)

    Griesemer, A D; Hirakata, A; Shimizu, A; Moran, S; Tena, A; Iwaki, H; Ishikawa, Y; Schule, P; Arn, J S; Robson, S C; Fishman, J A; Sykes, M; Sachs, D H; Yamada, K

    2009-12-01

    Clinical transplantation for the treatment of end-stage organ disease is limited by a shortage of donor organs. Successful xenotransplantation could immediately overcome this limitation. The development of homozygous alpha1,3-galactosyltransferase knockout (GalT-KO) pigs removed hyperacute rejection as the major immunologic hurdle to xenotransplantation. Nevertheless, GalT-KO organs stimulate robust immunologic responses that are not prevented by immunosuppressive drugs. Murine studies show that recipient thymopoiesis in thymic xenografts induces xenotolerance. We transplanted life-supporting composite thymokidneys (composite thymus and kidneys) prepared in GalT-KO miniature swine to baboons in an attempt to induce tolerance in a preclinical xenotransplant model. Here, we report the results of seven xenogenic thymokidney transplants using a steroid-free immunosuppressive regimen that eliminated whole-body irradiation in all but one recipient. The regimen resulted in average recipient survival of over 50 days. This was associated with donor-specific unresponsiveness in vitro and early baboon thymopoiesis in the porcine thymus tissue of these grafts, suggesting the development of T-cell tolerance. The kidney grafts had no signs of cellular infiltration or deposition of IgG, and no grafts were lost due to rejection. These results show that xenogeneic thymus transplantation can support early primate thymopoiesis, which in turn may induce T-cell tolerance to solid organ xenografts.

  9. Hypericum perforatum Attenuates Spinal Cord Injury-Induced Oxidative Stress and Apoptosis in the Dorsal Root Ganglion of Rats: Involvement of TRPM2 and TRPV1 Channels.

    Science.gov (United States)

    Özdemir, Ümit Sinan; Nazıroğlu, Mustafa; Şenol, Nilgün; Ghazizadeh, Vahid

    2016-08-01

    Oxidative stress and cytosolic Ca(2+) overload have important roles on apoptosis in dorsal root ganglion (DRG) neurons after spinal cord injury (SCI). Hypericum perforatum (HP) has an antioxidant property in the DRGs due to its ability to modulate NADPH oxidase and protein kinase C pathways. We aimed to investigate the protective property of HP on oxidative stress, apoptosis, and Ca(2+) entry through transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) channels in SCI-induced DRG neurons of rats. Rats were divided into four groups as control, HP, SCI, and SCI + HP. The HP groups received 30 mg/kg HP for three concessive days after SCI induction. The SCI-induced TRPM2 and TRPV1 currents and cytosolic free Ca(2+) concentration were reduced by HP. The SCI-induced decrease in glutathione peroxidase and cell viability values were ameliorated by HP treatment, and the SCI-induced increase in apoptosis, caspase 3, caspase 9, cytosolic reactive oxygen species (ROS) production, and mitochondrial membrane depolarization values in DRG of SCI group were overcome by HP treatment. In conclusion, we observed a protective role of HP on SCI-induced oxidative stress, apoptosis, and Ca(2+) entry through TRPM2 and TRPV1 in the DRG neurons. Our findings may be relevant to the etiology and treatment of SCI by HP. Graphical Abstract Possible molecular pathways of involvement of Hypericum perforatum (HP) on apoptosis, oxidative stress, and calcium accumulation through TRPM2 and TRPV1 channels in DRG neurons of SCI-induced rats. The TRPM2 channel is activated by ADP-ribose and oxidative stress through activation of ADP-ribose pyrophosphate although it was inhibited by N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethyl diphenylborinate (2APB). The TRPV1 channel is activated by oxidative stress and capsaicin and it is blocked by capsazepine. Injury in the DRG can result in augmented ROS release, leading to Ca(2+) uptake through

  10. ROLE OF SERUM AND ION CHANNEL BLOCK ON GROWTH AND HORMONALLY-INDUCED DIFFERENTIATION OF Spodoptera frugiperda (Sf21) INSECT CELLS.

    Science.gov (United States)

    Jenson, Lacey J; Bloomquist, Jeffrey R

    2015-11-01

    A neuronal morphological phenotype can be induced in cultured Spodoptera frugiperda insect cells (Sf21) by supplementing serum-containing media with 20-hydroxyecdysone (20-HE) and/or insulin. In this study, the primary objectives were to determine any role of ion channels in mediating the morphological change in cells treated with 20-HE and insulin, and whether serum was required to observe this effect. Results showed serum-free media also induced growth of processes in Sf21 cells, but at a lower percentage than that found previously in cells bathed in serum-containing media. Veratridine, a sodium channel activator, increased cell survival when applied in combination with 20-HE to Sf21 cells, and the effect was blocked by tetrodotoxin (1 μM) a known sodium channel blocker. Cobalt, a calcium channel blocker, showed significant inhibition of cell process growth when applied in combination with both 20-HE and 20-HE plus veratridine. Cobalt also showed significant inhibition of cell process growth when applied in combination with insulin. Thus, some type of sodium channel, as well as a mechanism for transmembrane calcium ion movement, are apparently expressed in Sf21 cells and are involved in the differentiation process. These cell lines may be used in a wide variety of endeavors, including the screening of insecticides, as well as foster basic studies of neurodevelopment and ecdysone action.

  11. Maximal Oxygen Consumption is Reduced in Aquaporin-1 Knockout Mice

    Directory of Open Access Journals (Sweden)

    Samer Al-Samir

    2016-08-01

    Full Text Available We have measured maximal oxygen consumption (V’O2,max of mice lacking one or two of the established mouse red-cell CO2 channels AQP1, AQP9 and Rhag. We intended to study whether these proteins, by acting as channels for O2, determine O2 exchange in the lung and in the periphery. We found that V’O2,max as determined by the Helox technique is reduced by ~ 16%, when AQP1 is knocked out, but not when AQP9 or Rhag are lacking. This figure holds for animals respiring normoxic as well as hypoxic gas mixtures. To see whether the reduction of V’O2,max is due to impaired O2 uptake in the lung, we measured carotid arterial O2 saturation (SO2 by pulse oximetry. Neither under normoxic (inspiratory O2 21% nor under hypoxic conditions (11% O2 is there a difference in SO2 between AQP1null and WT mice, suggesting that AQP1 is not critical for O2 uptake in the lung. The fact that the % reduction of V’O2,max is identical in normoxia and hypoxia indicates moreover that the limitation of V’O2,max is not due to an O2 diffusion problem, neither in the lung nor in the periphery. Instead, it appears likely that AQP1null animals exhibit a reduced V’O2,max due to the reduced wall thickness and muscle mass of the left ventricles of their hearts, as reported previously. We conclude that very likely the properties of the hearts of AQP1 knockout mice cause a reduced maximal cardiac output and thus cause a reduced V’O2,max, which constitutes a new phenotype of these mice.

  12. Electromagnetic radiation (Wi-Fi) and epilepsy induce calcium entry and apoptosis through activation of TRPV1 channel in hippocampus and dorsal root ganglion of rats.

    Science.gov (United States)

    Ghazizadeh, Vahid; Nazıroğlu, Mustafa

    2014-09-01

    Incidence rates of epilepsy and use of Wi-Fi worldwide have been increasing. TRPV1 is a Ca(2+) permeable and non-selective channel, gated by noxious heat, oxidative stress and capsaicin (CAP). The hyperthermia and oxidant effects of Wi-Fi may induce apoptosis and Ca(2+) entry through activation of TRPV1 channel in epilepsy. Therefore, we tested the effects of Wi-Fi (2.45 GHz) exposure on Ca(2+) influx, oxidative stress and apoptosis through TRPV1 channel in the murine dorsal root ganglion (DRG) and hippocampus of pentylentetrazol (PTZ)-induced epileptic rats. Rats in the present study were divided into two groups as controls and PTZ. The PTZ groups were divided into two subgroups namely PTZ + Wi-Fi and PTZ + Wi-Fi + capsazepine (CPZ). The hippocampal and DRG neurons were freshly isolated from the rats. The DRG and hippocampus in PTZ + Wi-Fi and PTZ + Wi-Fi + CPZ groups were exposed to Wi-Fi for 1 hour before CAP stimulation. The cytosolic free Ca(2+), reactive oxygen species production, apoptosis, mitochondrial membrane depolarization, caspase-3 and -9 values in hippocampus were higher in the PTZ group than in the control although cell viability values decreased. The Wi-Fi exposure induced additional effects on the cytosolic Ca(2+) increase. However, pretreatment of the neurons with CPZ, results in a protection against epilepsy-induced Ca(2+) influx, apoptosis and oxidative damages. In results of whole cell patch-clamp experiments, treatment of DRG with Ca(2+) channel antagonists [thapsigargin, verapamil + diltiazem, 2-APB, MK-801] indicated that Wi-Fi exposure induced Ca(2+) influx via the TRPV1 channels. In conclusion, epilepsy and Wi-Fi in our experimental model is involved in Ca(2+) influx and oxidative stress-induced hippocampal and DRG death through activation of TRPV1 channels, and negative modulation of this channel activity by CPZ pretreatment may account for the neuroprotective activity against oxidative stress.

  13. Sites and mechanisms of antibiotic-induced neuromuscular block: a pharmacological analysis using quantal content, voltage clamped end-plate currents and single channel analysis.

    Science.gov (United States)

    Fiekers, J F

    1999-01-01

    Since the original observation of Vital Brazil and Corrado (1957) concerning the antibiotic induced neuromuscular block produced by streptomycin, there has been considerable interest in the mechanisms responsible for not only neuromuscular block but also the effects of antibiotics on different systems. We used the voltage clamped end-plate of transacted skeletal muscle to examine the concentration-dependent actions of several groups of antibiotics. The aminoglycoside antibiotics, neomycin and streptomycin, were both more effective at reducing quantal release of acetylcholine (ACh) than interacting with the postjunctional ACh receptor-channel complex. Neomycin was approximately 10 X more potent prejunctionally than streptomycin and the prejunctional effects of each antibiotic were reversed competitively by raising extracellular calcium. Both neomycin and streptomycin also had postjunctional actions at higher concentrations. Neomycin interacted with the open state of the ACh receptor ion channel complex while streptomycin blocks the ACh receptor. The lincosamide antibiotics, lincomycin and clindamycin produced their neuromuscular block postjunctionally by interacting with the open state of the ACh-receptor channel complex. Clindamycin is approximately 20 X more effective at blocking the open channel than was lincomycin. Using cell attached patch clamp recordings in cultured rat myotubes, we demonstrated a lincosamide-induced block of open ion channels with clindamycin having a much slower unblocking rate than lincomycin. Using epimers of the lincosamides, we demonstrated that lipophilicity of the molecule, rather than stereochemical considerations, is important for open channel blockade affecting primarily the "off" rate of channel blocking. This mechanism appears important for not only the lincosamide antibiotics but also for the postjunctional actions of the aminoglycoside antibiotics, particularly neomycin.

  14. 2-(1-Hexyn-1-yl)adenosine-induced intraocular hypertension is mediated via K+ channel opening through adenosine A2A receptor in rabbits.

    Science.gov (United States)

    Konno, Takashi; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2005-08-22

    The present study was performed to clarify the mechanism of change in intraocular pressure by 2-(1-hexyn-1-yl)adenosine (2-H-Ado), a selective adenosine A2 receptor agonist, in rabbits. 2-H-Ado (0.1%, 50 microl)-induced ocular hypertension (E(max): 7.7 mm Hg) was inhibited by an adenosine A2A receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, ATP-sensitive K+ channel blocker glibenclamide or 5-hydroxydecanoic acid, but not by an adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A2B receptor antagonist alloxazine or a cyclooxygenase inhibitor indomethacin. The outflow facility induced by 2-H-Ado seems to be independent of increase in intraocular pressure or ATP-sensitive K+ channel. In contrast, the recovery rate in intraocular pressure decreased by hypertonic saline was accelerated by 2-H-Ado, and this response was dependent on ATP-sensitive K+ channel. These results suggest that 2-H-Ado-induced ocular hypertension is mediated via K+ channel opening through adenosine A2A receptor, and this is probably due to aqueous formation, but independent of change in outflow facility or prostaglandin production.

  15. Reduced emotional and corticosterone responses to stress in μ-opioid receptor knockout mice

    OpenAIRE

    Ide, Soichiro; Sora,Ichiro; Ikeda, Kazutaka; Minami, Masabumi; Uhl, George R.; Ishihara, Kumatoshi

    2009-01-01

    The detailed mechanisms of emotional modulation in the nervous system by opioids remain to be elucidated, although the opioid system is well known to play important roles in the mechanisms of analgesia and drug dependence. In the present study, we conducted behavioral tests of anxiety and depression and measured corticosterone concentrations in both male and female μ-opioid receptor knockout (MOP-KO) mice to reveal the involvement of μ-opioid receptors in stress-induced emotional responses. M...

  16. Effect of potassium channel blocker 4-aminopyridine pretreatment on the 6-OHDA-induced Parkinson's disease in rats

    Directory of Open Access Journals (Sweden)

    M. Sofiabadi

    2015-06-01

    Full Text Available Background: Nuclease and caspase enzymes activities which promote death signals and lead to apoptosis are dependent to potassium ions. Objective: The aim of this study was to determine the effect of 4-aminopyridine (4-AP potassium channel blocker on the animal model of Parkinson's disease. Methods: This experimental study was performed in Qazvin University of Medical Sciences, 2013. Male Rats were received different doses of 4-AP twice daily from half an hour before injection of 6-hydroxydopamine (6-OHDA to 7 or 15 days after that. 6-OHDA was injected into medial forebrain bundle (MFB in acute model groups and into striatum in chronic model groups. The severity of Parkinsonism was assessed by standard behavioral methods. Data were analyzed using Kruskal-Wallis and Mann Whitney U tests. Findings: In acute model groups, administration of 0.5 mg/kg 4-AP (n=9 had no remarkable effect on behavioral symptoms, but 1 mg/kg 4-AP (n=8 significantly reduced the severity of apomorphine-induced rotations and improved motor learning in rotarod test. In chronic model groups, although 1 mg/kg 4-AP (n=7 significantly reduced the severity of rotations and improved motor learning, but 0.5 mg/kg 4-AP (n=8 was more effective. Conclusion: Pretreatment with 4-AP can reduce 6-OHDA-induced dopaminergic neuron death. Since the chronic model of 6-OHDA is more similar to Parkinson's disease in human, the low dose of 4-AP is recommended for treatment of this disease.

  17. Inhibition of the cation channel TRPV4 improves bladder function in mice and rats with cyclophosphamide-induced cystitis.

    Science.gov (United States)

    Everaerts, Wouter; Zhen, Xiaoguang; Ghosh, Debapriya; Vriens, Joris; Gevaert, Thomas; Gilbert, James P; Hayward, Neil J; McNamara, Colleen R; Xue, Fenqin; Moran, Magdalene M; Strassmaier, Timothy; Uykal, Eda; Owsianik, Grzegorz; Vennekens, Rudi; De Ridder, Dirk; Nilius, Bernd; Fanger, Christopher M; Voets, Thomas

    2010-11-02

    Reduced functional bladder capacity and concomitant increased micturition frequency (pollakisuria) are common lower urinary tract symptoms associated with conditions such as cystitis, prostatic hyperplasia, neurological disease, and overactive bladder syndrome. These symptoms can profoundly affect the quality of life of afflicted individuals, but available pharmacological treatments are often unsatisfactory. Recent work has demonstrated that the cation channel TRPV4 is highly expressed in urothelial cells and plays a role in sensing the normal filling state of the bladder. In this article, we show that the development of cystitis-induced bladder dysfunction is strongly impaired in Trpv4(-/-) mice. Moreover, we describe HC-067047, a previously uncharacterized, potent, and selective TRPV4 antagonist that increases functional bladder capacity and reduces micturition frequency in WT mice and rats with cystitis. HC-067047 did not affect bladder function in Trpv4(-/-) mice, demonstrating that its in vivo effects are on target. These results indicate that TRPV4 antagonists may provide a promising means of treating bladder dysfunction.

  18. KR-31762, a novel KATP channel opener, exerts cardioprotective effects by opening SarcKATP channels in rat models of ischemia/reperfusion-induced heart injury.

    Science.gov (United States)

    Lee, Sung-Hun; Yang, Min-Kyu; Lim, Jong-Hyun; Seo, Ho-Won; Yi, Kyu-Yang; Yoo, Sung-Eun; Lee, Byung-Ho; Won, Hyung-Sik; Lee, Chang-Soo; Choi, Wahn-Soo; Shin, Hwa-Sup

    2008-04-01

    The cardioprotective effects of KR-31762, a newly synthesized K+(ATP) opener, were evaluated in rat models of ischemia/reperfusion (I/R) heart injury. In isolated rat hearts subjected to 30-min global ischemia followed by 30-min reperfusion, KR-31762 (3 and 10 microM) significantly increased the left ventricular developed pressure (LVDP) and double product (heart rate x LVDP) after 30-min reperfusion in a concentration-dependent manner, while decreasing the left ventricular end-diastolic pressure (LVEDP). KR-31762 also significantly increased the time to contracture (TTC) during ischemic period (20.0, 22.4 and 26.4 min for control, 3 and 10 microM, respectively), while decreasing the release of lactate dehydrogenase (LDH) from the heart during 30 min reperfusion (30.4, 14.3 and 19.7 U/g heart weight, respectively). All these parameters except LDH release were reversed by glyburide (1 microM), a nonselective blocker of K+(ATP) channel, but not by 5-hydroxydecanoate, a selective blocker of mitoK+(ATP) channel. In anesthetized rats subjected to 45-min occlusion of left anterior descending coronary artery followed by 90-min reperfusion, KR-31762 significantly decreased the infarct size (60.8, 40.5 and 37.8% for control, 0.3 and 1.0 mg/kg, iv, respectively). KR-31762 slightly relaxed the isolated rat aorta precontracted with methoxamine (IC(50): 23.5 microM). These results suggest that KR-31762 exerts potent cardioprotective effects through the opening of sarcolemmal K(ATP) channel in rat hearts with the minimal vasorelaxant effects.

  19. The Methanolic Extract from Murraya koenigii L. Inhibits Glutamate-Induced Pain and Involves ATP-Sensitive K+ Channel as Antinociceptive Mechanism

    Science.gov (United States)

    Sharmin Ani, Nushrat; Chakraborty, Sudip

    2016-01-01

    Murraya koenigii L. is a perennial shrub, belonging to the family Rutaceae. Traditionally, the leaves of this plant are extensively used in treatment of a wide range of diseases and disorders including pain and inflammation. Although researchers have revealed the antinociceptive effects of this plant's leaves during past few years, the mechanisms underlying these effects are still unknown. Therefore, the present study evaluated some antinociceptive mechanisms of the methanolic extract of M. koenigii (MEMK) leaves along with its antinociceptive potential using several animal models. The antinociceptive effects of MEMK were evaluated using formalin-induced licking and acetic acid-induced writhing tests at the doses of 50, 100, and 200 mg/kg. In addition, we also justified the possible participations of glutamatergic system and ATP-sensitive potassium channels in the observed activities. Our results demonstrated that MEMK significantly (p < 0.01) inhibited the pain thresholds induced by formalin and acetic acid in a dose-dependent manner. MEMK also significantly (p < 0.01) suppressed glutamate-induced pain. Moreover, pretreatment with glibenclamide (an ATP-sensitive potassium channel blocker) at 10 mg/kg significantly (p < 0.05) reversed the MEMK-mediated antinociception. These revealed that MEMK might have the potential to interact with glutamatergic system and the ATP-sensitive potassium channels to exhibit its antinociceptive activities. Therefore, our results strongly support the antinociceptive effects of M. koenigii leaves and provide scientific basis of their analgesic uses in the traditional medicine. PMID:27812367

  20. Reversal of novelty-induced hyperlocomotion and hippocampal c-Fos expression in GluA1 knockout male mice by the mGluR2/3 agonist LY354740.

    Science.gov (United States)

    Procaccini, C; Maksimovic, M; Aitta-Aho, T; Korpi, E R; Linden, A-M

    2013-10-10

    Dysfunctional glutamatergic neurotransmission has been implicated in schizophrenia and mood disorders. As a putative model for these disorders, a mouse line lacking the GluA1 subunit (GluA1-KO) of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor displays a robust novelty-induced hyperlocomotion associated with excessive neuronal activation in the hippocampus. Agonists of metabotropic glutamate 2/3 receptors (mGluR2/3) inhibit glutamate release in various brain regions and they have been shown to inhibit neuronal activation in the hippocampus. Here, we tested a hypothesis that novelty-induced hyperlocomotion in the GluA1-KO mice is mediated via excessive hippocampal neuronal activation by analyzing whether an mGluR2/3 agonist inhibits this phenotypic feature. GluA1-KO mice and littermate wildtype (WT) controls were administered with (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY354740) (15 mg/kg, i.p.) 30 min before a 2-h exposure to novel arenas after which c-Fos immunopositive cells were analyzed in the hippocampus. LY354740 (15 mg/kg) decreased hyperactivity in male GluA1-KO mice, with only a minimal effect in WT controls. This was observed in two cohorts of animals, one naïve to handling and injections, another pre-handled and accustomed to injections. LY354740 (15 mg/kg) also reduced the excessive c-Fos expression in the dorsal hippocampal CA1 pyramidal cell layer in maleGluA1-KO mice, while not affecting c-Fos levels in WT mice. In female mice, no significant effect for LY354740 (15 mg/kg) on hyperactive behavior or hippocampal c-Fos was observed in either genotype or treatment cohort. A higher dose of LY354740 (30 mg/kg) alleviated hyperlocomotion of GluA1-KO males, but not that of GluA1-KO females. In conclusion, the excessive behavioral hyperactivity of GluA1-KO mice can be partly prevented by reducing neuronal excitability in the hippocampus with the mGluR2/3 agonist suggesting that the hippocampal

  1. Novel mechanism of hydrogen sulfide-induced guinea pig urinary bladder smooth muscle contraction: role of BK channels and cholinergic neurotransmission.

    Science.gov (United States)

    Fernandes, Vítor S; Xin, Wenkuan; Petkov, Georgi V

    2015-07-15

    Hydrogen sulfide (H2S) is a key signaling molecule regulating important physiological processes, including smooth muscle function. However, the mechanisms underlying H2S-induced detrusor smooth muscle (DSM) contractions are not well understood. This study investigates the cellular and tissue mechanisms by which H2S regulates DSM contractility, excitatory neurotransmission, and large-conductance voltage- and Ca(2+)-activated K(+) (BK) channels in freshly isolated guinea pig DSM. We used a multidisciplinary experimental approach including isometric DSM tension recordings, colorimetric ACh measurement, Ca(2+) imaging, and patch-clamp electrophysiology. In isolated DSM strips, the novel slow release H2S donor, P-(4-methoxyphenyl)-p-4-morpholinylphosphinodithioic acid morpholine salt (GYY4137), significantly increased the spontaneous phasic and nerve-evoked DSM contractions. The blockade of neuronal voltage-gated Na(+) channels or muscarinic ACh receptors with tetrodotoxin or atropine, respectively, reduced the stimulatory effect of GYY4137 on DSM contractility. GYY4137 increased ACh release from bladder nerves, which was inhibited upon blockade of L-type voltage-gated Ca(2+) channels with nifedipine. Furthermore, GYY4137 increased the amplitude of the Ca(2+) transients and basal Ca(2+) levels in isolated DSM strips. GYY4137 reduced the DSM relaxation induced by the BK channel opener, NS11021. In freshly isolated DSM cells, GYY4137 decreased the amplitude and frequency of transient BK currents recorded in a perforated whole cell configuration and reduced the single BK channel open probability measured in excised inside-out patches. GYY4137 inhibited spontaneous transient hyperpolarizations and depolarized the DSM cell membrane potential. Our results reveal the novel findings that H2S increases spontaneous phasic and nerve-evoked DSM contractions by activating ACh release from bladder nerves in combination with a direct inhibition of DSM BK channels.

  2. [6]-gingerol and [6]-shogaol, active ingredients of the traditional Japanese medicine hangeshashinto, relief oral ulcerative mucositis-induced pain via action on Na(+) channels.

    Science.gov (United States)

    Hitomi, Suzuro; Ono, Kentaro; Terawaki, Kiyoshi; Matsumoto, Chinami; Mizuno, Keita; Yamaguchi, Kiichiro; Imai, Ryota; Omiya, Yuji; Hattori, Tomohisa; Kase, Yoshio; Inenaga, Kiyotoshi

    2017-03-01

    The traditional Japanese herbal medicine hangeshashinto (HST) has beneficial effects for the treatment of oral ulcerative mucositis (OUM) in cancer patients. However, the ingredient-based mechanism that underlies its pain-relieving activity remains unknown. In the present study, to clarify the analgesic mechanism of HST on OUM-induced pain, we investigated putative HST ingredients showing antagonistic effects on Na(+) channels in vitro and in vivo. A screen of 21 major ingredients using automated patch-clamp recordings in channel-expressing cells showed that [6]-gingerol and [6]-shogaol, two components of a Processed Ginger extract, considerably inhibited voltage-activated Na(+) currents. These two ingredients inhibited the stimulant-induced release of substance P and action potential generation in cultured rat sensory neurons. A submucosal injection of a mixture of [6]-gingerol and [6]-shogaol increased the mechanical withdrawal threshold in healthy rats. In a rat OUM model, OUM-induced mechanical pain was alleviated 30min after the swab application of HST despite the absence of anti-bacterial and anti-inflammatory actions in the OUM area. A swab application of a mixture of [6]-gingerol and [6]-shogaol induced sufficient analgesia of OUM-induced mechanical or spontaneous pain when co-applied with a Ginseng extract containing abundant saponin. The Ginseng extract demonstrated an acceleration of substance permeability into the oral ulcer tissue without an analgesic effect. These findings suggest that Na(+) channel blockage by gingerol/shogaol plays an essential role in HST-associated analgesia of OUM-induced pain. This pharmacological mechanism provides scientific evidence supporting the use of this herbal medicine in patients suffering from OUM-induced pain.

  3. Reduction in traumatic brain injury-induced oxidative stress, apoptosis, and calcium entry in rat hippocampus by melatonin: Possible involvement of TRPM2 channels.

    Science.gov (United States)

    Yürüker, Vehbi; Nazıroğlu, Mustafa; Şenol, Nilgün

    2015-02-01

    Melatonin, which is a very effective reactive oxygen species (ROS) scavenger, acts through a direct reaction with free radicals. Ca(2+) entry induced by traumatic brain injury (TBI) has deleterious effects on human hippocampal function. TRPM2 is a Ca(2+) permeable non-selective channel in hippocampal neurons, and its activation of during oxidative stress has been linked to cell death. Despite the importance of oxidative stress in TBI, its role in apoptosis and Ca(2+) entry in TBI is poorly understood. Therefore, we tested the effects of melatonin on apoptosis, oxidative stress, and Ca(2+) entry through the TRPM2 channel in the hippocampal neurons of TBI-induced rats. Thirty-two rats were divided into the following four groups: control, melatonin, TBI, and TBI + melatonin groups. Melatonin (5 mg/kg body weight) was intraperitoneally given to animals in the melatonin group and the TBI + melatonin group after 1 h of brain trauma. Hippocampal neurons were freshly isolated from the four groups, incubated with a nonspecific TRPM2 blocker (2-aminoethyl diphenylborinate, 2-APB), and then stimulated with cumene hydroperoxide. Apoptosis, caspase-3, caspase-9, intracellular ROS production, mitochondrial membrane depolarization and intracellular free Ca(2+) ([Ca(2+)]i) values were high in the TBI group, and low in the TBI + melatonin group. The [Ca(2+)]i concentration was decreased in the four groups by 2-APB. In our TBI experimental model, TRPM2 channels were involved in Ca(2+) entry-induced neuronal death, and the negative modulation of the activity of this channel by melatonin pretreatment may account for the neuroprotective activity of TRPM2 channels against oxidative stress, apoptosis, and Ca(2+) entry.

  4. Novel Flow Field with Superhydrophobic Gas Channels Prepared by One-step Solvent-induced Crystallization for Micro Direct Methanol Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    Junsheng Liang; Kuanyao Liu; Shouzuo Li; Dazhi Wang; Tongqun Ren; Xiaoying Xu; Ying Luo

    2015-01-01

    The CO2-induced capillary blocking in anode flow field is one of the key adverse factors to reduce the performance of a micro-direct methanol fuel cell (lDMFC). In order to solve this problem, new polycarbonate (PC) flow field plates with nested arrangement of hydrophilic fuel channels and superhydrophobic gas channels were designed, fabricated, and tested in this work. The gas channels were treated with solvent-induced crystallization using acetone solution. The superhydrophobicity with 160? water contact angle and 2? tilting angle was obtained on the PC substrates. A dummy cell using hydrogen peroxide decomposition reaction and a test loop were separately set up to evaluate the flow fields’ performance. It was found that a 37% pressure drop decrease can be obtained in the new serpentine flow field compared with that of the conventional one. The benefit of the new flow field to remove gas bubbles was also confirmed by an in situ visualization study on the dummy cell. Results show that the auxiliary superhydrophobic gas channels can speed up the discharge of the gas bubbles from the flow field, which will in turn improve the lDMFC performance.

  5. Nitric oxide and L-type calcium channel influences the changes in arterial blood pressure and heart rate induced by central angiotesin II

    Directory of Open Access Journals (Sweden)

    Guarda Ismael FMS

    2008-05-01

    Full Text Available Abstract We study the voltage dependent calcium channels and nitric oxide involvement in angiotensin II-induced pressor effect. The antipressor action of L-Type calcium channel antagonist, nifedipine, has been studied when it was injected into the third ventricle prior to angiotensin II. The influence of nitric oxide on nifedipine antipressor action has also been studied by utilizing NW-nitro-L-arginine methyl ester (LNAME (40 μg/0.2 μl a nitric oxide synthase inhibitor and L-arginine (20 μg/0.2 μl, a nitric oxide donor agent. Adult male Holtzman rats weighting 200–250 g, with cannulae implanted into the third ventricle were injected with angiotensin II. Angiotensin II produced an elevation in mean arterial pressure and a decreased in heart rate. Such effects were potentiated by the prior injection of LNAME. L-arginine and nifedipine blocked the effects of angiotensin II. These data showed the involvement of L-Type calcium channel and a free radical gas nitric oxide in the central control of angiotensin II-induced pressor effect. This suggested that L-Type calcium channel of the circunventricular structures of central nervous system participated in both short and long term neuronal actions of ANG II with the influence of nitrergic system.

  6. Pancreatic β-cell Na+ channels control global Ca2+ signaling and oxidative metabolism by inducing Na+ and Ca2+ responses that are propagated into mitochondria.

    Science.gov (United States)

    Nita, Iulia I; Hershfinkel, Michal; Kantor, Chase; Rutter, Guy A; Lewis, Eli C; Sekler, Israel

    2014-08-01

    Communication between the plasma membrane and mitochondria is essential for initiating the Ca(2+) and metabolic signals required for secretion in β cells. Although voltage-dependent Na(+) channels are abundantly expressed in β cells and activated by glucose, their role in communicating with mitochondria is unresolved. Here, we combined fluorescent Na(+), Ca(2+), and ATP imaging, electrophysiological analysis with tetrodotoxin (TTX)-dependent block of the Na(+) channel, and molecular manipulation of mitochondrial Ca(2+) transporters to study the communication between Na(+) channels and mitochondria. We show that TTX inhibits glucose-dependent depolarization and blocks cytosolic Na(+) and Ca(2+) responses and their propagation into mitochondria. TTX-sensitive mitochondrial Ca(2+) influx was largely blocked by knockdown of the mitochondrial Ca(2+) uniporter (MCU) expression. Knockdown of the mitochondrial Na(+)/Ca(2+) exchanger (NCLX) and Na(+) dose response analysis demonstrated that NCLX mediates the mitochondrial Na(+) influx and is tuned to sense the TTX-sensitive cytosolic Na(+) responses. Finally, TTX blocked glucose-dependent mitochondrial Ca(2+) rise, mitochondrial metabolic activity, and ATP production. Our results show that communication of the Na(+) channels with mitochondria shape both global Ca(2+) and metabolism signals linked to insulin secretion in β cells.- Nita, I. I., Hershfinkel, M., Kantor, C., Rutter, G. A., Lewis, E. C., Sekler, I. Pancreatic β-cell Na(+) channels control global Ca(2+) signaling and oxidative metabolism by inducing Na(+) and Ca(2+) responses that are propagated into mitochondria.

  7. Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model

    Directory of Open Access Journals (Sweden)

    N. Baldev

    2015-12-01

    Full Text Available Purpose: Sodium thiosulfate (STS is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. Materials and Methods: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. Results: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. Conclusion: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

  8. Activation of transient receptor potential vanilloid type-1 channel prevents adipogenesis and obesity

    DEFF Research Database (Denmark)

    Zhang, Li Li; Yan Liu, Dao; Ma, Li Qun

    2007-01-01

    in visceral adipose tissue from obese humans was accompanied by reduced capsaicin-induced calcium influx. The oral administration of capsaicin for 120 days prevented obesity in male wild type mice but not in TRPV1 knockout mice assigned to high fat diet. We conclude that the activation of TRPV1 channels......We tested the hypothesis that activation of transient receptor potential vanilloid type-1 (TRPV1) by capsaicin prevents adipogenesis. TRPV1 channels in 3T3-L1-preadipocytes and visceral adipose tissue from mice and humans were detected by immunoblotting and quantitative real-time RT-PCR. The effect...... of TRPV1 on cytosolic calcium was determined fluorometrically in 3T3-L1-preadipocytes and in human visceral fat tissue. Adipogenesis in stimulated 3T3-L1-preadipocytes was determined by oil red O-staining of intracellular lipid droplets, triglyceride levels, expression of peroxisome proliferator...

  9. From channel-forming ionic liquid crystals exhibiting humidity-induced phase transitions to nanostructured ion-conducting polymer membranes (adv. Mater. 26/2013).

    Science.gov (United States)

    Zhang, Heng; Li, Lei; Möller, Martin; Zhu, Xiaomin; Rueda, Jaime J Hernandez; Rosenthal, Martin; Ivanov, Dimitri A

    2013-07-12

    A novel wedge-shaped amphiphilic molecule bearing a sulfonate group at the tip displays humidity-induced phase transitions from a hexagonal columnar structure to a bicontinuous cubic phase. The mesophases can be frozen by photopolymerization of acrylic end-groups resulting in free-standing membranes with different topology of ionic nanochannels. The obtained membranes with a well-ordered ionic channel structure hold promise for applications in separation and catalysis.

  10. Novel Roles for Kv7 Channels in Shaping Histamine-Induced Contractions and Bradykinin-Dependent Relaxations in Pig Coronary Arteries.

    Science.gov (United States)

    Chen, Xingjuan; Li, Wennan; Hiett, S Christopher; Obukhov, Alexander G

    2016-01-01

    Voltage-gated Kv7 channels are inhibited by agonists of Gq-protein-coupled receptors, such as histamine. Recent works have provided evidence that inhibition of vascular Kv7 channels may trigger vessel contractions. In this study, we investigated how Kv7 activity modulates the histamine-induced contractions in "healthy" and metabolic syndrome (MetS) pig right coronary arteries (CAs). We performed isometric tension and immunohistochemical studies with domestic, lean Ossabaw, and MetS Ossabaw pig CAs. We found that neither the Kv7.2/Kv7.4/Kv7.5 activator ML213 nor the general Kv7 inhibitor XE991 altered the tension of CA rings under preload, indicating that vascular Kv7 channels are likely inactive in the preloaded rings. Conversely, ML213 potently dilated histamine-pre-contracted CAs, suggesting that Kv7 channels are activated during histamine applications and yet partially inhibited by histamine. Immunohistochemistry analysis revealed strong Kv7.4 immunostaining in the medial and intimal layers of the CA wall, whereas Kv7.5 immunostaining intensity was strong in the intimal but weak in the medial layers. The medial Kv7 immunostaining was significantly weaker in MetS Ossabaw CAs as compared to lean Ossabaw or domestic CAs. Consistently, histamine-pre-contracted MetS Ossabaw CAs exhibited attenuated ML213-dependent dilations. In domestic pig CAs, where medial Kv7 immunostaining intensity was stronger, histamine-induced contractions spontaneously decayed to ~31% of the peak amplitude within 4 minutes. Oppositely, in Ossabaw CAs, where Kv7 immunostaining intensity was weaker, the histamine-induced contractions were more sustained. XE991 pretreatment significantly slowed the decay rate of histamine-induced contractions in domestic CAs, supporting the hypothesis that increased Kv7 activity correlates with a faster rate of histamine-induced contraction decay. Alternatively, XE991 significantly decreased the amplitude of bradykinin-dependent dilations in pre-contracted CAs

  11. Single-Step Generation of Conditional Knockout Mouse Embryonic Stem Cells

    Directory of Open Access Journals (Sweden)

    Matyas Flemr

    2015-07-01

    Full Text Available Induction of double-strand DNA breaks (DSBs by engineered nucleases, such as CRISPR/Cas9 or transcription activator-like effector nucleases (TALENs, stimulates knockin of exogenous DNA fragments via homologous recombination (HR. However, the knockin efficiencies reported so far have not allowed more complex in vitro genome modifications such as, for instance, simultaneous integration of a DNA fragment at two distinct genomic sites. We developed a reporter system to enrich for cells with engineered nuclease-assisted HR events. Using this system in mouse embryonic stem cells (mESCs, we achieve single-step biallelic and seamless integration of two loxP sites for Cre recombinase-mediated inducible gene knockout, as well as biallelic endogenous gene tagging with high efficiency. Our approach reduces the time and resources required for conditional knockout mESC generation dramatically.

  12. Generation of knockout rabbits using transcription activator-like effector nucleases.

    Science.gov (United States)

    Wang, Yu; Fan, Nana; Song, Jun; Zhong, Juan; Guo, Xiaogang; Tian, Weihua; Zhang, Quanjun; Cui, Fenggong; Li, Li; Newsome, Philip N; Frampton, Jon; Esteban, Miguel A; Lai, Liangxue

    2014-01-01

    Zinc-finger nucleases and transcription activator-like effector nucleases are novel gene-editing platforms contributing to redefine the boundaries of modern biological research. They are composed of a non-specific cleavage domain and a tailor made DNA-binding module, which enables a broad range of genetic modifications by inducing efficient DNA double-strand breaks at desired loci. Among other remarkable uses, these nucleases have been employed to produce gene knockouts in mid-size and large animals, such as rabbits and pigs, respectively. This approach is cost effective, relatively quick, and can produce invaluable models for human disease studies, biotechnology or agricultural purposes. Here we describe a protocol for the efficient generation of knockout rabbits using transcription activator-like effector nucleases, and a perspective of the field.

  13. Efficient gene knockout in goats using CRISPR/Cas9 system.

    Directory of Open Access Journals (Sweden)

    Wei Ni

    Full Text Available The CRISPR/Cas9 system has been adapted as an efficient genome editing tool in laboratory animals such as mice, rats, zebrafish and pigs. Here, we report that CRISPR/Cas9 mediated approach can efficiently induce monoallelic and biallelic gene knockout in goat primary fibroblasts. Four genes were disrupted simultaneously in goat fibroblasts by CRISPR/Cas9-mediated genome editing. The single-gene knockout fibroblasts were successfully used for somatic cell nuclear transfer (SCNT and resulted in live-born goats harboring biallelic mutations. The CRISPR/Cas9 system represents a highly effective and facile platform for targeted editing of large animal genomes, which can be broadly applied to both biomedical and agricultural applications.

  14. Gentamicin Blocks the ACh-Induced BK Current in Guinea Pig Type II Vestibular Hair Cells by Competing with Ca2+ at the l-Type Calcium Channel

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    Hong Yu

    2014-04-01

    Full Text Available Type II vestibular hair cells (VHCs II contain big-conductance Ca2+-dependent K+ channels (BK and L-type calcium channels. Our previous studies in guinea pig VHCs II indicated that acetylcholine (ACh evoked the BK current by triggering the influx of Ca2+ ions through l-type Ca2+ channels, which was mediated by M2 muscarinic ACh receptor (mAChRs. Aminoglycoside antibiotics, such as gentamicin (GM, are known to have vestibulotoxicity, including damaging effects on the efferent nerve endings on VHCs II. This study used the whole-cell patch clamp technique to determine whether GM affects the vestibular efferent system at postsynaptic M2-mAChRs or the membrane ion channels. We found that GM could block the ACh-induced BK current and that inhibition was reversible, voltage-independent, and dose-dependent with an IC50 value of 36.3 ± 7.8 µM. Increasing the ACh concentration had little influence on GM blocking effect, but increasing the extracellular Ca2+ concentration ([Ca2+]o could antagonize it. Moreover, 50 µM GM potently blocked Ca2+ currents activated by (--Bay-K8644, but did not block BK currents induced by NS1619. These observations indicate that GM most likely blocks the M2 mAChR-mediated response by competing with Ca2+ at the l-type calcium channel. These results provide insights into the vestibulotoxicity of aminoglycoside antibiotics on mammalian VHCs II.

  15. Altered expression and localization of hippocampal A-type potassium channel subunits in the pilocarpine-induced model of temporal lobe epilepsy.

    Science.gov (United States)

    Monaghan, M M; Menegola, M; Vacher, H; Rhodes, K J; Trimmer, J S

    2008-10-15

    Altered ion channel expression and/or function may contribute to the development of certain human epilepsies. In rats, systemic administration of pilocarpine induces a model of human temporal lobe epilepsy, wherein a brief period of status epilepticus (SE) triggers development of spontaneous recurrent seizures that appear after a latency of 2-3 weeks. Here we investigate changes in expression of A-type voltage-gated potassium (Kv) channels, which control neuronal excitability and regulate action potential propagation and neurotransmitter release, in the pilocarpine model of epilepsy. Using immunohistochemistry, we examined the expression of component subunits of somatodendritic (Kv4.2, Kv4.3, KChIPl and KChIP2) and axonal (Kv1.4) A-type Kv channels in hippocampi of pilocarpine-treated rats that entered SE. We found that Kv4.2, Kv4.3 and KChIP2 staining in the molecular layer of the dentate gyrus changes from being uniformly distributed across the molecular layer to concentrated in just the outer two-thirds. We also observed a loss of KChIP1 immunoreactive interneurons, and a reduction of Kv4.2 and KChIP2 staining in stratum radiatum of CA1. These changes begin to appear 1 week after pilocarpine treatment and persist or are enhanced at 4 and 12 weeks. As such, these changes in Kv channel distribution parallel the acquisition of recurrent spontaneous seizures as observed in this model. We also found temporal changes in Kv1.4 immunoreactivity matching those in Timm's stain, being expanded in stratum lucidum of CA3 and in the inner third of the dentate molecular layer. Among pilocarpine-treated rats, changes were only observed in those that entered SE. These changes in A-type Kv channel expression may contribute to hyperexcitability of dendrites in the associated hippocampal circuits as observed in previous studies of the effects of pilocarpine-induced SE.

  16. Stereoselective Blockage of Quinidine and Quinine in the hERG Channel and the Effect of Their Rescue Potency on Drug-Induced hERG Trafficking Defect

    Directory of Open Access Journals (Sweden)

    Meng Yan

    2016-09-01

    Full Text Available Diastereoisomers of quinidine and quinine are used to treat arrhythmia and malaria, respectively. It has been reported that both drugs block the hERG (human ether-a-go-go-related gene potassium channel which is essential for myocardium repolarization. Abnormality of repolarization increases risk of arrhythmia. The aim of our research is to study and compare the impacts of quinidine and quinine on hERG. Results show that both drugs block the hERG channel, with quinine 14-fold less potent than quinidine. In addition, they presented distinct impacts on channel dynamics. The results imply their stereospecific block effect on the hERG channel. However, F656C-hERG reversed this stereoselectivity. The mutation decreases affinity of the two drugs with hERG, and quinine was more potent than quinidine in F656C-hERG blockage. These data suggest that F656 residue contributes to the stereoselective pocket for quinidine and quinine. Further study demonstrates that both drugs do not change hERG protein levels. In rescue experiments, we found that they exert no reverse effect on pentamidine- or desipramine-induced hERG trafficking defect, although quinidine has been reported to rescue trafficking-deficient pore mutation hERG G601S based on the interaction with F656. Our research demonstrated stereoselective effects of quinidine and quinine on the hERG channel, and this is the first study to explore their reversal potency on drug-induced hERG deficiency.

  17. Kv3.3 channels harbouring a mutation of spinocerebellar ataxia type 13 alter excitability and induce cell death in cultured cerebellar Purkinje cells.

    Science.gov (United States)

    Irie, Tomohiko; Matsuzaki, Yasunori; Sekino, Yuko; Hirai, Hirokazu

    2014-01-01

    The cerebellum plays crucial roles in controlling sensorimotor functions. The neural output from the cerebellar cortex is transmitted solely by Purkinje cells (PCs), whose impairment causes cerebellar ataxia. Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominant disease, and SCA13 patients exhibit cerebellar atrophy and cerebellar symptoms. Recent studies have shown that missense mutations in the voltage-gated K(+) channel Kv3.3 are responsible for SCA13. In the rodent brain, Kv3.3 mRNAs are expressed most strongly in PCs, suggesting that the mutations severely affect PCs in SCA13 patients. Nevertheless, how these mutations affect the function of Kv3.3 in PCs and, consequently, the morphology and neuronal excitability of PCs remains unclear. To address these questions, we used lentiviral vectors to express mutant mouse Kv3.3 (mKv3.3) channels harbouring an R424H missense mutation, which corresponds to the R423H mutation in the Kv3.3 channels of SCA13 patients, in mouse cerebellar cultures. The R424H mutant-expressing PCs showed decreased outward current density, broadened action potentials and elevated basal [Ca(2+)]i compared with PCs expressing wild-type mKv3.3 subunits or those expressing green fluorescent protein alone. Moreover, expression of R424H mutant subunits induced impaired dendrite development and cell death selectively in PCs, both of which were rescued by blocking P/Q-type Ca(2+) channels in the culture conditions. We therefore concluded that expression of R424H mutant subunits in PCs markedly affects the function of endogenous Kv3 channels, neuronal excitability and, eventually, basal [Ca(2+)]i, leading to cell death. These results suggest that PCs in SCA13 patients also exhibit similar defects in PC excitability and induced cell death, which may explain the pathology of SCA13.

  18. Differences in the effects of four TRPV1 channel antagonists on lipopolysaccharide-induced cytokine production and COX-2 expression in murine macrophages.

    Science.gov (United States)

    Ninomiya, Yuki; Tanuma, Sei-Ichi; Tsukimoto, Mitsutoshi

    2017-03-11

    Sepsis is a systemic inflammatory response syndrome triggered by lipopolysaccharide (LPS), an outer membrane component of gram-negative bacteria, and cytokine production via LPS-induced macrophage activation is deeply involved in its pathogenesis. Effective therapy of sepsis has not yet been established. However, it was reported that transient receptor potential vanilloid 1 (TRPV1) channel antagonist capsazepine (CPZ; a capsaicin analogue) attenuates sepsis in a murine model [Ang et al., PLoS ONE 6(9) (2011) e24535; J. Immunol. 187 (2011) 4778-4787]. Here, we profiled the effects of four TRPV1 channel antagonists, AMG9810, SB366791, BCTC and CPZ, on the release of IL-6, IL-1β and IL-18, and on expression of cyclooxygenase 2 (COX-2) in LPS-activated macrophages. Treatment of murine macrophage J774.1 cells or BALB/c mouse-derived intraperitoneal immune cells with LPS induced pro-inflammatory cytokines production and COX-2 expression. Pretreatment with AMG9810 or CPZ significantly suppressed the release of IL-6, IL-1β and IL-18, and COX-2 expression, whereas SB366791 and BCTC were less effective. These results support a role of TRPV1 channel in macrophage activation, but also indicate that only a subset of TRPV1 channel antagonists may be effective in suppressing inflammatory responses. These results suggest that at least some TRPV1 channel antagonists, such as AMG9810 and CPZ, may be candidate anti-inflammatory agents for treatment of sepsis.

  19. K(+)-induced stimulation of K+ secretion involves activation of the IsK channel in vestibular dark cells.

    Science.gov (United States)

    Wangemann, P; Shen, Z; Liu, J

    1996-10-01

    Vestibular dark cells in the inner ear secrete K+ from perilymph containing 4 mM K+ to endolymph containing 145 mM K+. Sensory transduction causes K+ to flow from endolymph to perilymph, thus threatening the homeostasis of the perilymphatic K+ concentration which is crucial for maintaining sensory transduction since the basolateral membranes of the sensory cells and adjacent neuronal elements need to be protected from K(+)-induced depolarization. The present study addresses the questions (1) whether increases in the perilymphatic K+ concentration by as little as 1 mM are sufficient to stimulate KCl uptake across the basolateral membrane of vestibular dark cells, (2) whether K(+)-induced stimulation of KCl uptake causes stimulation of the IsK channel in the apical membrane, and (3) whether the rate of transepithelial K+ secretion depends on the perilymphatic (basolateral) K+ concentration when the apical side of the epithelium is bathed with a solution containing 145 mM K+, as in vivo. Uptake of KCl was monitored by measuring cell height as an indicator for cell volume. The current (IIsK), conductance (gIsK) and inactivation time constant (tau IsK) of the IsK channel as well as the apparent reversal potential of the apical membrane (Vr) were obtained with the cell-attached macro-patch technique. Vr was corrected for the membrane voltage previously measured with microelectrodes. The rate of transepithelial K+ secretion JK was obtained as equivalent short circuit current from measurements of the transepithelial voltage (Vt) and resistance (Rt) measured in the micro-Ussing chamber. Cell height of vestibular dark cells was 7.2 microns (average). Elevations of the extracellular K+ concentration from 3.5 to 4.5 mM caused cell swelling with an initial rate of cell height change of 11 nm/s. With 3.6 mM K+ in the pipette IIsK was outwardly directed and elevation of the extracellular K+ concentration from 3.6 to 25 mM caused an increase of IIsK from 12 to 65 pA, gIsK from 152

  20. Role of TRPV1 channels of the dorsal periaqueductal gray in the modulation of nociception and open elevated plus maze-induced antinociception in mice.

    Science.gov (United States)

    Mascarenhas, Diego Cardozo; Gomes, Karina Santos; Nunes-de-Souza, Ricardo Luiz

    2015-10-01

    Recent findings have identified the presence of transient receptor potential vanilloid-1 (TRPV1) channels within the dorsal portion of the periaqueductal gray (dPAG), suggesting their involvement in the control of pain and environmentally-induced antinociception. Environmentally, antinociception may be achieved through the use of an open elevated plus maze (oEPM, an EPM with 4 open arms), a highly aversive environmental situation. Here, we investigated the role of these TRPV1 channels within the dPAG in the modulation of a tonic pain and in the oEPM-induced antinociception. Male Swiss mice, under the nociceptive effect of 2.5% formalin injected into the right hind paw, received intra-dPAG injections of the TRPV1 agonist (capsaicin: 0, 0.01, 0.1 or 1.0 nmol/0.2 μL; Experiment 1) or antagonist (capsazepine: 0, 10 or 30 nmol/0.2 μL; Experiment 2) or combined injections of capsazepine (30 nmol) and capsaicin (1.0 nmol) (Experiment 3) and the time spent licking the formalin-injected paw was recorded. In Experiment 4, mice received intra-dPAG capsazepine (0 or 30 nmol) and were exposed to the oEPM or to a control situation, an enclosed EPM (eEPM; an EPM with 4 enclosed arms). Results showed that while capsaicin (1 nmol) decreased the time spent licking the formalin-injected paw, capsazepine did not change nociceptive response. Capsazepine (30 nmol) blocked pain inhibition induced by capsaicin and mildly attenuated the oEPM-induced antinociception. Our results revealed an important role of TRPV1 channels within the dPAG in the modulation of pain and in the phenomenon known as fear-induced antinociception in mice.

  1. Hydroxyproline-induced Helical Disruption in Conantokin Rl-B Affects Subunit-selective Antagonistic Activities toward Ion Channels of N-Methyl-d-aspartate Receptors.

    Science.gov (United States)

    Kunda, Shailaja; Yuan, Yue; Balsara, Rashna D; Zajicek, Jaroslav; Castellino, Francis J

    2015-07-17

    Conantokins are ~20-amino acid peptides present in predatory marine snail venoms that function as allosteric antagonists of ion channels of the N-methyl-d-aspartate receptor (NMDAR). These peptides possess a high percentage of post-/co-translationally modified amino acids, particularly γ-carboxyglutamate (Gla). Appropriately spaced Gla residues allow binding of functional divalent cations, which induces end-to-end α-helices in many conantokins. A smaller number of these peptides additionally contain 4-hydroxyproline (Hyp). Hyp should prevent adoption of the metal ion-induced full α-helix, with unknown functional consequences. To address this disparity, as well as the role of Hyp in conantokins, we have solved the high resolution three-dimensional solution structure of a Gla/Hyp-containing 18-residue conantokin, conRl-B, by high field NMR spectroscopy. We show that Hyp(10) disrupts only a small region of the α-helix of the Mn(2+)·peptide complex, which displays cation-induced α-helices on each terminus of the peptide. The function of conRl-B was examined by measuring its inhibition of NMDA/Gly-mediated current through NMDAR ion channels in mouse cortical neurons. The conRl-B displays high inhibitory selectivity for subclasses of NMDARs that contain the functionally important GluN2B subunit. Replacement of Hyp(10) with N(8)Q results in a Mg(2+)-complexed end-to-end α-helix, accompanied by attenuation of NMDAR inhibitory activity. However, replacement of Hyp(10) with Pro(10) allowed the resulting peptide to retain its inhibitory property but diminished its GluN2B specificity. Thus, these modified amino acids, in specific peptide backbones, play critical roles in their subunit-selective inhibition of NMDAR ion channels, a finding that can be employed to design NMDAR antagonists that function at ion channels of distinct NMDAR subclasses.

  2. Amyloid precursor protein modulates Nav1.6 sodium channel currents through a Go-coupled JNK pathway

    Science.gov (United States)

    Li, Shao; Wang, Xi; Ma, Quan-Hong; Yang, Wu-lin; Zhang, Xiao-Gang; Dawe, Gavin S.; Xiao, Zhi-Cheng

    2016-01-01

    Amyloid precursor protein (APP), commonly associated with Alzheimer’s disease, also marks axonal degeneration. In the recent studies, we demonstrated that APP aggregated at nodes of Ranvier (NORs) in myelinated central nervous system (CNS) axons and interacted with Nav1.6. However, the physiological function of APP remains unknown. In this study, we described reduced sodium current densities in APP knockout hippocampal neurons. Coexpression of APP or its intracellular domains containing a VTPEER motif with Nav1.6 sodium channels in Xenopus oocytes resulted in an increase in peak sodium currents, which was enhanced by constitutively active Go mutant and blocked by a dominant negative mutant. JNK and CDK5 inhibitor attenuated increases in Nav1.6 sodium currents induced by overexpression of APP. Nav1.6 sodium currents were increased by APPT668E (mutant Thr to Glu) and decreased by T668A (mutant Thr to ALa) mutant, respectively. The cell surface expression of Nav1.6 sodium channels in the white matter of spinal cord and the spinal conduction velocity is decreased in APP, p35 and JNK3 knockout mice. Therefore, APP modulates Nav1.6 sodium channels through a Go-coupled JNK pathway, which is dependent on phosphorylation of APP at Thr668. PMID:28008944

  3. Cooperative gating between ion channels.

    Science.gov (United States)

    Choi, Kee-Hyun

    2014-01-01

    Cooperative gating between ion channels, i.e. the gating of one channel directly coupled to the gating of neighboring channels, has been observed in diverse channel types at the single-channel level. Positively coupled gating could enhance channel-mediated signaling while negative coupling may effectively reduce channel gating noise. Indeed, the physiological significance of cooperative channel gating in signal transduction has been recognized in several in vivo studies. Moreover, coupled gating of ion channels was reported to be associated with some human disease states. In this review, physiological roles for channel cooperativity and channel clustering observed in vitro and in vivo are introduced, and stimulation-induced channel clustering and direct channel cross linking are suggested as the physical mechanisms of channel assembly. Along with physical clustering, several molecular mechanisms proposed as the molecular basis for functional coupling of neighboring channels are covered: permeant ions as a channel coupling mediator, concerted channel activation through the membrane, and allosteric mechanisms. Also, single-channel analysis methods for cooperative gating such as the binomial analysis, the variance analysis, the conditional dwell time density analysis, and the maximum likelihood fitting analysis are reviewed and discussed.

  4. BK channels regulate sinoatrial node firing rate and cardiac pacing in vivo.

    Science.gov (United States)

    Lai, Michael H; Wu, Yuejin; Gao, Zhan; Anderson, Mark E; Dalziel, Julie E; Meredith, Andrea L

    2014-11-01

    Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels play prominent roles in shaping muscle and neuronal excitability. In the cardiovascular system, BK channels promote vascular relaxation and protect against ischemic injury. Recently, inhibition of BK channels has been shown to lower heart rate in intact rodents and isolated hearts, suggesting a novel role in heart function. However, the underlying mechanism is unclear. In the present study, we recorded ECGs from mice injected with paxilline (PAX), a membrane-permeable BK channel antagonist, and examined changes in cardiac conduction. ECGs revealed a 19 ± 4% PAX-induced reduction in heart rate in wild-type but not BK channel knockout (Kcnma1(-/-)) mice. The heart rate decrease was associated with slowed cardiac pacing due to elongation of the sinus interval. Action potential firing recorded from isolated sinoatrial node cells (SANCs) was reduced by 55 ± 15% and 28 ± 9% by application of PAX (3 μM) and iberiotoxin (230 nM), respectively. Furthermore, baseline firing rates from Kcnma1(-/-) SANCs were 33% lower than wild-type SANCs. The slowed firing upon BK current inhibition or genetic deletion was due to lengthening of the diastolic depolarization phase of the SANC action potential. Finally, BK channel immunoreactivity and PAX-sensitive currents were identified in SANCs with HCN4 expression and pacemaker current, respectively, and BK channels cloned from SANCs recapitulated similar activation as the PAX-sensitive current. Together, these data localize BK channels to SANCs and demonstrate that loss of BK current decreases SANC automaticity, consistent with slowed sinus pacing after PAX injection in vivo. Furthermore, these findings suggest BK channels are potential therapeutic targets for disorders of heart rate.

  5. Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance, Ca(2+)-Activated K(+) Channels In Vitro.

    Science.gov (United States)

    Su, Fang; Guo, An-Chen; Li, Wei-Wei; Zhao, Yi-Long; Qu, Zheng-Yi; Wang, Yong-Jun; Wang, Qun; Zhu, Yu-Lan

    2017-02-01

    Increasing evidence suggests that low to moderate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca(2+)-activated K(+) channel (BKCa) α-subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) compared with controls. Preconditioning with low-dose ethanol (10 mmol/L) increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca(2+) levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol preconditioning was antagonized by a BKCa channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol. The above results indicated that low-dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca(2+) and preventing neuronal apoptosis, and this is mediated by BKCa channel activation.

  6. Effect of nitric oxide-induced tyrosine phosphorylation of calcium-activated potassium channel α subunit on vascular hyporesponsiveness in rats

    Institute of Scientific and Technical Information of China (English)

    ZHOU Rong; LIU Liang-ming; HU De-yao

    2005-01-01

    Objective: To study the effect of nitric oxide-induced tyrosine phosphorylation of large-conductance calcium-activated potassium (BKCa) channel α subunit on vascular hyporesponsiveness in rats. Methods: A total of 46 Wistar rats of either sex, weighing 250 g±20 g, were used in this study. Models of vascular hyporesponsiveness induced by hemorrhagic shock (30 mm Hg for 2 hours) in vivo and by L-arginine in vitro were established respectively. The vascular responsiveness of isolated superior mesenteric arteries to norepinephrine was observed. Tyrosine phosphorylation of BKCa α subunit was evaluated with methods of immunoprecipitation and Western blotting. Results: In the smooth muscle cells of the superior mesenteric arteries, the expression of BKCa α subunit tyrosine phosphorylation increased following hemorrhagic shock, and L-arginine could induce BKCa channel α subunit tyrosine phosphorylation in a time- and dose-dependent manner. L-NAME (Nω-nitro-L-arginine-methyl-ester), a nitric oxide synthetase inhibitor, could partly restore the decreased vasoresponsiveness of the superior mesenteric arteries after hemorrhagic shock in rats. Down-regulating the protein tyrosine phosphorylation with genistein, a widely-used special protein tyrosine kinase inhibitor, could partly improve the decreased vasoresponsiveness of the superior mesenteric arteries induced by L-arginine in vitro, while up-regulating the protein tyrosine phosphorylation with Na3VO4, a protein tyrosine phosphatase inhibitor, could further decrease the nitric oxide-induced vascular hyporesponsiveness, which could be partly ameliorated by 0.1 mmol/L tetrabutylammonium chloride (TEA), a selective BKCa inhibitor at this concentration. Conclusions: Nitric oxide can induce the tyrosine phosphorylation of BKCa α subunit, which influences the vascular hyporesponsiveness in hemorrhagic shock rats or induced by L-arginine in vitro.

  7. Endothelial transient receptor potential conical channel (TRPC)-3 activation induces vasogenic edema formation in the rat piriform cortex following status epilepticus.

    Science.gov (United States)

    Ryu, Hea Jin; Kim, Ji-Eun; Kim, Yeon-Joo; Kim, Ji-Yang; Kim, Won I L; Choi, So-Yeon; Kim, Min-Ju; Kang, Tae-Cheon

    2013-05-01

    Transient receptor potential canonical channel (TRPC) is a nonselective cation channel permeable to Ca(2+), which express in many cell types, including neurons. However the alterations in TRPC receptor expressions in response to status epilepticus (SE) have not been explored. Therefore, the present study was designated to elucidate the roles of TRPC3 in neuronal death and vasogenic edema within the rat piriform cortex (PC) following SE. In non-SE animals, TRPC3 immunoreactivity was abundantly detected in the PC. Following SE, TRPC3 immunoreactivity was increased in neurons. Furthermore, TRPC3 expression was detected in endothelial cells that did not contain it in non-SE animals. Loss of SMI-71 (a blood-brain barrier antigen) immunoreactivity was also observed in TRPC3 positive endothelial cells. In addition, FJB positive neurons and vasogenic edema were noticeably detected in the PC. To directly determine whether TRPC3 activation is correlated to SE-induced vasogenic edema formation and neuronal damages in the PC, the effect of Pyr-3 (a TRPC3 antagonist) on SE-induced insults were investigated. Pyr-3 infusion effectively attenuated vasogenic edema in the PC as compared to the vehicle. Therefore, our findings indicate that TRPC3 activation/overexpression induced by SE may involve BBB disruption and neuronal damages in the rat PC following SE. Therefore, the present study was TRPC3 may play an important role in SE-induced vasogenic edema formation through BBB disruptions in the rat PC.

  8. Targeted gene knockout in chickens mediated by TALENs

    OpenAIRE

    Park, Tae Sub; Lee, Hong Jo; Kim, Ki Hyun; Kim, Jin-Soo; Han, Jae Yong

    2014-01-01

    Targeted gene knockout by editing specific loci in genome has revolutionized the field of functional genomics. Transcription activator-like effector nucleases (TALENs) are representative next-generation platforms for customized genomic editing in transgenic animals, as well as cultured cells in vitro. In this study, in combination with chicken primordial germ cell line with germ-line transmission capacity, we generated the ovalbumin gene knockout chickens by TALEN-mediated gene targeting. Our...

  9. Methylphenidate restores novel object recognition in DARPP-32 knockout mice.

    Science.gov (United States)

    Heyser, Charles J; McNaughton, Caitlyn H; Vishnevetsky, Donna; Fienberg, Allen A

    2013-09-15

    Previously, we have shown that Dopamine- and cAMP-regulated phosphoprotein of 32kDa (DARPP-32) knockout mice required significantly more trials to reach criterion than wild-type mice in an operant reversal-learning task. The present study was conducted to examine adult male and female DARPP-32 knockout mice and wild-type controls in a novel object recognition test. Wild-type and knockout mice exhibited comparable behavior during the initial exploration trials. As expected, wild-type mice exhibited preferential exploration of the novel object during the substitution test, demonstrating recognition memory. In contrast, knockout mice did not show preferential exploration of the novel object, instead exhibiting an increase in exploration of all objects during the test trial. Given that the removal of DARPP-32 is an intracellular manipulation, it seemed possible to pharmacologically restore some cellular activity and behavior by stimulating dopamine receptors. Therefore, a second experiment was conducted examining the effect of methylphenidate. The results show that methylphenidate increased horizontal activity in both wild-type and knockout mice, though this increase was blunted in knockout mice. Pretreatment with methylphenidate significantly impaired novel object recognition in wild-type mice. In contrast, pretreatment with methylphenidate restored the behavior of DARPP-32 knockout mice to that observed in wild-type mice given saline. These results provide additional evidence for a functional role of DARPP-32 in the mediation of processes underlying learning and memory. These results also indicate that the behavioral deficits in DARPP-32 knockout mice may be restored by the administration of methylphenidate.

  10. Using engineered endonucleases to create knockout and knockin zebrafish models

    OpenAIRE

    Bedell, Victoria M.; Ekker, Stephen C.

    2015-01-01

    Over the last few years, the technology to create targeted knockout and knockin zebrafish animals has exploded. We have gained the ability to create targeted knockouts through the use of zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR associated system (CRISPR/Cas). Furthermore, using the high-efficiency TALEN system, we were able to create knockin zebrafish using a single-stranded DNA ...

  11. The mechanism of gentisic acid-induced relaxation of the guinea pig isolated trachea: the role of potassium channels and vasoactive intestinal peptide receptors

    Directory of Open Access Journals (Sweden)

    J.F. Cunha

    2001-03-01

    Full Text Available We examined some of the mechanisms by which the aspirin metabolite and the naturally occurring metabolite gentisic acid induced relaxation of the guinea pig trachea in vitro. In preparations with or without epithelium and contracted by histamine, gentisic acid caused concentration-dependent and reproducible relaxation, with mean EC50 values of 18 µM and Emax of 100% (N = 10 or 20 µM and Emax of 92% (N = 10, respectively. The relaxation caused by gentisic acid was of slow onset in comparison to that caused by norepinephrine, theophylline or vasoactive intestinal peptide (VIP. The relative rank order of potency was: salbutamol 7.9 > VIP 7.0 > gentisic acid 4.7 > theophylline 3.7. Gentisic acid-induced relaxation was markedly reduced (24 ± 7.0, 43 ± 3.9 and 78 ± 5.6% in preparations with elevated potassium concentration in the medium (20, 40 or 80 mM, respectively. Tetraethylammonium (100 µM, a nonselective blocker of the potassium channels, partially inhibited the relaxation response to gentisic acid, while 4-AP (10 µM, a blocker of the voltage potassium channel, inhibited gentisic acid-induced relaxation by 41 ± 12%. Glibenclamide (1 or 3 µM, at a concentration which markedly inhibited the relaxation induced by the opener of ATP-sensitive K+ channels, levcromakalim, had no effect on the relaxation induced by gentisic acid. Charybdotoxin (0.1 or 0.3 µM, a selective blocker of the large-conductance Ca2+-activated K+ channels, caused rightward shifts (6- and 7-fold of the gentisic acid concentration-relaxation curve. L-N G-nitroarginine (100 µM, a NO synthase inhibitor, had no effect on the relaxant effect of gentisic acid, and caused a slight displacement to the right in the relaxant effect of the gentisic acid curve at 300 µM, while methylene blue (10 or 30 µM or ODQ (1 µM, the inhibitors of soluble guanylate cyclase, all failed to affect gentisic acid-induced relaxation. D-P-Cl-Phe6,Leu17[VIP] (0.1 µM, a VIP receptor antagonist

  12. Amyloid-β induces synaptic dysfunction through G protein-gated inwardly rectifying potassium channels in the fimbria-CA3 hippocampal synapse

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    Mauricio O. Nava-Mesa

    2013-07-01

    Full Text Available Last evidences suggest that, in Alzheimer's disease (AD early stage, Amyloid-β (Aβ peptide induces an imbalance between excitatory and inhibitory neurotransmission systems resulting in the functional impairment of neural networks. Such alterations are particularly important in the septohippocampal system where learning and memory processes take place depending on accurate oscillatory activity tuned at fimbria-CA3 synapse. Here, the acute effects of Aβ on CA3 pyramidal neurons and their synaptic activation from septal part of the fimbria were studied in rats. A triphasic postsynaptic response defined by an excitatory potential (EPSP followed by both early and late inhibitory potentials (IPSP was evoked. The EPSP was glutamatergic acting on ionotropic receptors. The early IPSP was blocked by GABAA antagonists whereas the late IPSP was removed by GABAB antagonists. Aβ perfusion induced recorded cells to depolarize, increase their input resistance and decrease the late IPSP. Aβ action mechanism was localized at postsynaptic level and most likely linked to GABAB-related ion channels conductance decrease. In addition, it was found that the specific pharmacological modulation of the GABAB receptor effector, G-protein-coupled inward rectifier potassium (GirK channels, mimicked all Aβ effects previously described. Thus, our findings suggest that Aβ altering GirK channels conductance in CA3 pyramidal neurons might have a key role in the septohippocampal activity dysfunction observed in AD.

  13. Hydrogen sulfide attenuates gastric mucosal injury induced by restraint water-immersion stress via activation of KATP channel and NF-κB dependent pathway

    Science.gov (United States)

    Sun, Hong-Zhao; Zheng, Shan; Lu, Kai; Hou, Feng-Tian; Bi, Jie-Xue; Liu, Xue-Lian; Wang, Shan-Shan

    2017-01-01

    AIM To explore the effect of hydrogen sulfide (H2S) on restraint water-immersion stress (RWIS)-induced gastric lesions in rats and the influence of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway on such an effect. METHODS Male Wistar rats were randomly divided into a control group, a physiological saline (PS) group, a sodium hydrosulfide (NaHS) group, a glibenclamide (Gl) group, Gl plus NaHS group, a pyrrolidine dithiocarbamate (PDTC) group, and a PDTC plus NaHS group. Gastric mucosal injury was induced by RWIS for 3 h in rats, and gastric mucosal damage was analyzed after that. The PS, NaHS (100 μmol/kg body weight), Gl (100 μmol/kg body weight), Gl (100 μmol/kg or 150 μmol/kg body weight) plus NaHS (100 μmol/kg body weight), PDTC (100 μmol/kg body weight), and PDTC (100 μmol/kg body weight) plus NaHS (100 μmol/kg body weight) were respectively injected intravenously before RWIS. RESULTS RWIS induced serious gastric lesions in the rats in the PS pretreatment group. The pretreatment of NaHS (a H2S donor) significantly reduced the damage induced by RWIS. The gastric protective effect of the NaHS during RWIS was attenuated by PDTC, an NF-κB inhibitor, and also by glibenclamide, an ATP-sensitive potassium channel blocker, in a dose-dependent manner. CONCLUSION These results suggest that exogenous H2S plays a protective role against RWIS injury in rats, possibly through modulation of KATP channel opening and the NF-κB dependent pathway. PMID:28104983

  14. Characterization of a critical role for CFTR chloride channels in cardioprotection against ischemia/reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Sunny Yang XIANG; Linda L YE; LI-lu Marie DUAN; Li-hui LIU; Zhi-dong GE; John A AUCHAMPACH; Garrett J GROSS; Dayue Darrel DUAN

    2011-01-01

    Aim: To further characterize the functional role of cystic fibrosis transmembrane conductance regulator (CFTR) in early and late (second window) ischemic preconditioning (IPC)- and postcondtioning (POC)-mediated cardioprotection against ischemia/reperfusion (I/R) injury.Methods: CFTR knockout (CFTR-/-) mice and age- and gender-matched wild-type (CFTR+/+) and heterozygous (CFTR+/-) mice were used.In in vivo studies, the animals were subjected to a 30-min coronary occlusion followed by a 40-min reperfusion. In ex vivo (isolate heart) studies, a 45-min global ischemia was applied. To evaluate apoptosis, the level of activated caspase 3 and TdT-mediated dUTP-X nick end labeling (TUNEL) were examined.Results: In the in vivo I/R models, early IPC significantly reduced the myocardial infarct size in wild-type (CFTR+/+) (from 40.4%±5.3% to 10.4%±2.0%, n=8, P<0.001) and heterozygous (CFTR+/-) littermates (from 39.4%±2.4% to 15.4%±5.1%, n=6, P<0.001) but failed to protect CFTR knockout (CFTR-/-) mice from I/R induced myocardial infarction (46.9%±6.2% vs 55.5%±7.8%, n=6, P>0.5). Similar results were observed in the in vivo late IPC experiments. Furthermore, in both in vivo and ex vivo I/R models, POC significantly reduced myocardial infarction in wild-type mice, but not in CFTR knockout mice. In ex vivo I/R models, targeted inactivation of CFTRgene abolished the protective effects of IPC against I/R-induced apoptosis.Conclusion: These results provide compelling evidence for a critical role for CFTR Cl- channels in IPC- and POC-mediated cardioprotection against I/R-induced myocardial injury.

  15. Locomotor activity, ultrasonic vocalization and oxytocin levels in infant CD38 knockout mice.

    Science.gov (United States)

    Liu, Hong-Xiang; Lopatina, Olga; Higashida, Chiharu; Tsuji, Takahiro; Kato, Ichiro; Takasawa, Shin; Okamoto, Hiroshi; Yokoyama, Shigeru; Higashida, Haruhiro

    2008-12-19

    Oxytocin (OT), a neurohormone involved in reproduction, plays a critical role in social behavior in a wide range of mammalian species from rodents to humans. The role of CD38 in regulating OT secretion for social behavior has been demonstrated in adult mice, but has not been examined in pups or during development. Separation from the dam induces stress in 7-day-old mouse pups. During such isolation, locomotor activity was higher in CD38 knockout (CD38(-/-)) pups than in wild-type (CD38(+/+)) or heterozygous (CD38(+/-)) controls. The number of ultrasonic vocalizations was lower in CD38(-/-) pups than in CD38(+/+) pups. However, the difference between the two genotypes was less severe than that in OT knockout or OT receptor knockout mice. To explain this, we measured plasma OT levels. The level was not lower in CD38(-/-) pups during the period 1-3 weeks after birth, but was significantly reduced after weaning (>3 weeks). ADP-ribosyl cyclase activities in the hypothalamus and pituitary were markedly lower from 1 week after birth in CD38(-/-) mice and were consistently lower thereafter to the adult stage (2 months old). These results showed that the reduced severity of behavioral abnormalities in CD38(-/-) pups was due to partial compensation by the high level of plasma OT.

  16. APP knockout mice experience acute mortality as the result of ischemia.

    Directory of Open Access Journals (Sweden)

    Maya A Koike

    Full Text Available The incidence of Alzheimer's disease increases in people who have had an ischemic episode. Furthermore, APP expression is increased following ischemic or hypoxic conditions, as is the production of the Aβ peptide. To address the question of why APP and Aβ are increased in hypoxic and ischemic conditions we induced an ischemic episode in APP knockout mice (APP-/- and BACE1 knockout mice (BACE-/-. We find that both APP-/- and BACE-/- mice have a dramatically increased risk of mortality as a result of cerebral ischemia. Furthermore, APP knockout mice have reduced cerebral blood flow in response to hypoxia, while wild-type mice maintain or increase cerebral blood flow to the same conditions. The transcription factor, serum response factor (SRF, and calcium-binding molecule, calsequestrin, both involved in vascular regulation, are significantly altered in the brains of APP-/- mice compared to wild type controls. These results show that APP regulates cerebral blood flow in response to hypoxia, and that it, and its cleavage fragments, are crucial for rapid adaptation to ischemic conditions.

  17. Mechanism for attenuated outward conductance induced by mutations in the cytoplasmic pore of Kir2.1 channels

    Science.gov (United States)

    Chang, Hsueh-Kai; Iwamoto, Masayuki; Oiki, Shigetoshi; Shieh, Ru-Chi

    2015-12-01

    Outward currents through Kir2.1 channels regulate the electrical properties of excitable cells. These currents are subject to voltage-dependent attenuation by the binding of polyamines to high- and low-affinity sites, which leads to inward rectification, thereby controlling cell excitability. To examine the effects of positive charges at the low-affinity site in the cytoplasmic pore on inward rectification, we studied a mutant Kir channel (E224K/H226E) and measured single-channel currents and streaming potentials (Vstream), the latter provide the ratio of water to ions queued in a single-file permeation process in the selectivity filter. The water-ion coupling ratio was near one at a high K+ concentration ([K+]) for the wild-type channel and increased substantially as [K+] decreased. On the other hand, fewer ions occupied the selectivity filter in the mutant at all [K+]. A model for the Kir channel involving a K+ binding site in the wide pore was introduced. Model analyses revealed that the rate constants associated with the binding and release to and from the wide-pore K+ binding site was modified in the mutant. These effects lead to the reduced contribution of a conventional two-ion permeation mode to total conductance, especially at positive potentials, thereby inward rectification.

  18. Role of BK(Ca) Potassium Channels in the Mechanisms of Modulatory Effects of IL-10 on Hypoxia-Induced Changes in Activity of Hippocampal Neurons.

    Science.gov (United States)

    Levin, S G; Konakov, M V; Godukhin, O V

    2016-03-01

    We studied the contribution of large conductance Ca(2+)-activated potassium channels (BKCa) in the mechanisms of neuromodulatory effects of anti-inflammatory cytokine IL-10 on hypoxiainduced changes in activity of CA1 pyramidal neurons in rat hippocampus. We used the method of registration of population spikes from CA1 pyramidal neurons in hippocampal slices before, during, and after exposure to short-term episodes of hypoxia. Selective blocker (iberiotoxin) and selective activator of BKCa (BMS-191011) were used to evaluate the contribution of these channels in the mechanisms of suppressive effects of IL-10 on changes in neuronal activity during hypoxia and development of post-hypoxic hyperexcitability. It was shown that BKCa are involved in the modulatory effects of IL-10 on hypoxia-induced suppression of activity of CA1 pyramidal neurons in the hippocampus and development of post-hypoxic hyperexcitability in these neurons.

  19. Metamizol acts as an ATP sensitive potassium channel opener to inhibit the contracting response induced by angiotensin II but not to norepinephrine in rat thoracic aorta smooth muscle.

    Science.gov (United States)

    Valenzuela, Fermín; García-Saisó, Sebastián; Lemini, Cristina; Ramírez-Solares, Rafael; Vidrio, Horacio; Mendoza-Fernández, Víctor

    2005-08-01

    Clinically metamizol (MZ) has been related to alteration on haemodynamic parameters and modifications on blood pressure in humans when administered intravenously. These effects have been observed at MZ therapeutic doses. Experimentally, MZ is able to induce relaxation on several types of vascular smooth muscles and modulates the contraction induced by phenylephrine. However, the mechanism underlying the MZ effects on vascular reactivity is not clear. Potassium channels (K) present on vascular smooth muscle cells closely regulate the vascular reactivity and membrane potential. There are four described types of K in vascular tissue: K voltage sensitive (K(V)), K calcium sensitive (K(Ca)2+), K ATP sensitive (K(ATP) and K inward rectification (K(IR), voltage sensitive). The aim of this work was to investigate MZ effects on angiotensin II (AT II) and noradrenaline (NA) induced contraction and to evaluate the K participation on MZ modulating effect on vascular smooth muscle contraction, using isometric and patch clamp techniques. MZ induces relaxation in a concentration dependent manner. Furthermore, MZ strongly inhibits in a concentration dependent fashion the contraction induced by AT II. However, MZ inhibition on NA induced contraction was moderated compared with that observed on AT II. MZ effects on AT II induced contraction was blocked by glybenclamide (a specific K(ATP) blocker, 3 microM, *p < 0.01). In patch clamp experiments, MZ (3 mM) induces an increase on potassium current (K+) mediated by K(ATP) in similar way as diazoxide (a specific K(ATP) opener, 3 microM). Our results suggest that MZ induces relaxation and inhibits contraction induced by AT II acting as a K(ATP) opener.

  20. Assessment of 5-HT7 Receptor Agonists Selectivity Using Nociceptive and Thermoregulation Tests in Knockout versus Wild-Type Mice

    Directory of Open Access Journals (Sweden)

    Alex Brenchat

    2012-01-01

    Full Text Available No study has ever examined the effect of 5-HT7 receptor agonists on nociception by using 5-HT7 receptor knockout mice. Basal sensitivity to noxious heat stimuli and formalin-induced nociception in both phase I and II of the formalin test did not differ in 5-HT7 receptor knockout mice and paired wild-type controls. Similarly, there was no significant difference in basal body temperature between both genotypes. Subcutaneous administration of 5-HT7 receptor agonists AS-19 (10 mg/kg, E-57431 (10 mg/kg, and E-55888 (20 mg/kg significantly reduced formalin-induced licking/biting behavior during the phase II of the test in wild-type but not in 5-HT7 receptor knockout mice. At these active analgesic doses, none of the three 5-HT7 receptor agonists modified the basal body temperature neither in wild-type nor in 5-HT7 receptor knockout mice. However, a significant decrease in body temperature was observed at a higher dose (20 mg/kg of AS-19 and E-57431 in both genotypes. Our data strongly suggest that the 5-HT7 receptor agonists AS-19, E-57431, and E-55888 produce antinociception in the formalin test by activating 5-HT7 receptors. These results also strengthen the idea that the 5-HT7 receptor plays a role in thermoregulation, but by acting in concert with other receptors.

  1. Inhibition of the K+ channel K(Ca3.1 reduces TGF-β1-induced premature senescence, myofibroblast phenotype transition and proliferation of mesangial cells.

    Directory of Open Access Journals (Sweden)

    Rong-Guo Fu

    Full Text Available OBJECTIVE: K(Ca3.1 channel participates in many important cellular functions. This study planned to investigate the potential involvement of K(Ca3.1 channel in premature senescence, myofibroblast phenotype transition and proliferation of mesangial cells. METHODS & MATERIALS: Rat mesangial cells were cultured together with TGF-β1 (2 ng/ml and TGF-β1 (2 ng/ml + TRAM-34 (16 nM separately for specified times from 0 min to 60 min. The cells without treatment served as controls. The location of K(Ca3.1 channels in mesangial cells was determined with Confocal laser microscope, the cell cycle of mesangial cells was assessed with flow cytometry, the protein and mRNA expression of K(Ca3.1, α-smooth muscle actin (α-SMA and fibroblast-specific protein-1 (FSP-1 were detected with Western blot and RT-PCR. One-way analysis of variance (ANOVA and Student-Newman-Keuls-q test (SNK-q were used to do statistical analysis. Statistical significance was considered at P<0.05. RESULTS: Kca3.1 channels were located in the cell membranes and/or in the cytoplasm of mesangial cells. The percentage of cells in G0-G1 phase and the expression of K(ca3.1, α-SMA and FSP-1 were elevated under the induction of TGF-β1 when compared to the control and decreased under the induction of TGF-β1+TRAM-34 when compared to the TGF-β1 induced (P<0.05 or P<0.01. CONCLUSION: Targeted disruption of K(Ca3.1 inhibits TGF-β1-induced premature aging, myofibroblast-like phenotype transdifferentiation and proliferation of mesangial cells.

  2. Blockade of Ca2+-permeable AMPA/kainate channels decreases oxygen-glucose deprivation-induced Zn2+ accumulation and neuronal loss in hippocampal pyramidal neurons.

    Science.gov (United States)

    Yin, Hong Z; Sensi, Stefano L; Ogoshi, Fumio; Weiss, John H

    2002-02-15

    Synaptic release of Zn2+ and its translocation into postsynaptic neurons probably contribute to neuronal injury after ischemia or epilepsy. Studies in cultured neurons have revealed that of the three major routes of divalent cation entry, NMDA channels, voltage-sensitive Ca2+ channels (VSCCs), and Ca2+-permeable AMPA/kainate (Ca-A/K) channels, Ca-A/K channels exhibit the highest permeability to exogenously applied Zn2+. However, routes through which synaptically released Zn2+ gains entry to postsynaptic neurons have not been characterized in vivo. To model ischemia-induced Zn2+ movement in a system approximating the in vivo situation, we subjected mouse hippocampal slice preparations to controlled periods of oxygen and glucose deprivation (OGD). Timm's staining revealed little reactive Zn2+ in CA1 and CA3 pyramidal neurons of slices exposed in the presence of O2 and glucose. However, 15 min of OGD resulted in marked labeling in both regions. Whereas strong Zn2+ labeling persisted if both the NMDA antagonist MK-801 and the VSCC blocker Gd3+ were present during OGD, the presence of either the Ca-A/K channel blocker 1-naphthyl acetyl spermine (NAS) or the extracellular Zn2+ chelator Ca2+ EDTA substantially decreased Zn2+ accumulation in pyramidal neurons of both subregions. In parallel experiments, slices were subjected to 5 min OGD exposures as described above, followed 4 hr later by staining with the cell-death marker propidium iodide. As in the Timm's staining experiments, substantial CA1 or CA3 pyramidal neuronal damage occurred despite the presence of MK-801 and Gd3+, whereas injury was decreased by NAS or by Ca2+ EDTA (in CA1).

  3. Microclimate-induced Lateral Channel Migration as a Driver for Hillslope Asymmetry in Semi-arid Landscapes

    Science.gov (United States)

    Richardson, P. W.; Perron, J. T.; Miller, S. R.

    2014-12-01

    North-facing slopes in semi-arid regions of the northern hemisphere are commonly steeper than south-facing slopes, whereas the converse is observed in the southern hemisphere. In the absence of a structural cause, the most common explanations for topographic asymmetry ultimately invoke aspect-related microclimate. Landscapes with asymmetric topography are therefore potential natural laboratories for investigating the sensitivity of surface processes to climate. However, the specific mechanisms driving asymmetry are not well understood, and studies using asymmetric topography to investigate landscape climate sensitivity may have to consider multiple origins of the asymmetry. Two leading hypotheses have emerged. One states that small differences in microclimate cause differences in the efficiency of erosional processes on slopes with different aspect. The more efficiently eroding slope erodes faster until the resulting slope asymmetry compensates for the difference in erosional efficiency. According to the other hypothesis, the difference in erosional efficiency is not sufficient to create the observed topographic asymmetry. Instead, sediment aggradation at the foot of the more quickly eroding slope forces lateral channel migration and undercutting of the opposing slope. These two explanations for topographic asymmetry predict different trajectories of long-term landscape evolution - sustained migration of asymmetric valleys would drive stream capture and drainage reorganization, whereas the mechanism without lateral channel migration would not - but there is no existing test capable of distinguishing between them. We develop such a test using a landscape evolution model that simulates different asymmetry-forming mechanisms, including asymmetric runoff production, channel incision threshold, soil creep, and lateral channel migration. For the case of topographic asymmetry produced by lateral channel migration, the model predicts that north-facing hilltops should be

  4. The role of potassium channels in the nitric oxide-induced relaxation of human airway smooth muscle of passively sensitization by serum from allergic asthmatic patients

    Institute of Scientific and Technical Information of China (English)

    Tao Ye; Yongjian Xu; Zhenxiang Zhang; Xiansheng Liu; Zhao Yang; Baoan Gao

    2006-01-01

    Objective: To investigate the role of large Ca2+-activated, delayed-rectifier and ATP-sensitive potassium channel in regulating the relaxation induced by nitric oxide (NO) in normal and passively sensitized human airway smooth muscle (HASM) with serum from asthmatic patients. Methods: The effects of NO or/and potassium channel blockers on the tensions of normal and passively sensitized HASM were measured by using nitric oxide donor and potassium blockers, with the isometric tension recording technique. Results: Showed that (1)In the control group and passively sensitized group, Kv blocker (4-AP) cause concentration-dependent augmentation in the contraction induced by histamine (1 ×10-4 mol/L), (P < 0.05), but Glib (1 × 10-2 mol/L)and TEA (1×10-3 mol/L) have no significant effects on the contraction induced by histamine (1×10-4 mol/L). The maximum tension induced by histamine in passively sensitized group is higher than that in the control group (P < 0.05). (2) NO-donor Sodium Nitroprusside (SNP) bring about significant relaxation in normal and passively sensitized HASM rings (P < 0.05). Relaxations of passively sensitized airway rings [ (29.4 ± 3.3)% ] were significant less than those of normal HASM rings [ (44.1 ± 10.2)% ], (P <0.05).(3) Glib(1×10-2 mol/L)have no significant effect on the relaxations induced by SNP(1×10-4 mol/L). 4-AP(1×10-2 mol/L) inhibited relaxation induced by SNP (1×10-4 mol/L), (P < 0.01). TEA (1×10-3 mol/L) inhibited relaxation induced by SNP (1×10-4mol/L) (P < 0.05), and the inhibiting effect in passively sensitized HASM rings were significant less than in normal HASM, (P <0.05). Conclusion: It was concluded that SNP(NO-donor) relaxed the contraction of HASM partly via BKca channel opening. In passively sensitized HASM in vitro, the relaxation of SNP decreased compared with control group, which might be associated with the down-regulating activity of BKca in passively sensitized HASM.

  5. Augmented activity of the pelvic nerve afferent mediated by TRP channels in dextran sulfate sodium (DSS)-induced colitis of rats.

    Science.gov (United States)

    Makimura, Yukitoshi; Ito, Koichi; Kuwahara, Masayoshi; Tsubone, Hirokazu

    2012-08-01

    Enteritis has been recognized as a major symptom in domestic animals and human patients suffering from feed and food poisonings. The aim of the present study was to clarify the excitatory mechanism of the pelvic nerve afferent which may influence the occurrence of enteritis in response to nociceptive chemical stimuli of the colon in normal and abnormal rats with colitis induced by dextran sulfate sodium (DSS). The pelvic nerve afferent activity was markedly increased by colonic instillation of solution (0.5 ml) of acetic acid (5-25%) and capsaicin (100 μg/ml). The nerve activity was augmented by colonic instillation of capsaicin to a greater extent in rats with DSS-induced colitis than in normal control rats. This augmented activity by capsaicin was more prominent at one day (DSS-1) than at 8 day (DSS-8) after the administration of DSS. The increased nerve activity caused by capsaicin in DSS-1 and DSS-8 was significantly inhibited by pretreatment with ruthenium red, which is a nonselective inhibitor of TRP channels of unmyelinated C-fibers (nociceptors). In conclusion, it was elucidated that the nociceptive function of the pelvic nerve was largely elevated at one day after DSS-induced colitis and such increased function was mostly mediated by TRP channels.

  6. Immunohistochemical investigation of voltage-gated potassium channel-interacting protein 1 in normal rat brain and Pentylenettrazole-induced seizures

    Institute of Scientific and Technical Information of China (English)

    Tao SU; Ai-Hua LUO; Wen-Dong CONG; Wei-Wen SUN; Wei-Yi DENG; Qi-Hua ZHAO; Zhuo-Hua ZHANG; Wei-Ping LIAO

    2006-01-01

    Objective To explore the possible role of voltage-gated potassium channel-interacting protein 1 (KChIP1) in the pathogenesis of epilepsy. Methods Sprague Dawley female adult rats were treated with pentylenettrazole (PTZ) to develop acute and chronic epilepsy models. The approximate coronal sections of normal and epilepsy rat brain were processed for immunohistochemistry. Double-labeling confocal microscopy was used to determine the coexistence of KChIP1 and gamma-aminobutyric acid (GABA). Results KChIP1 was expressed abundantly throughout adult rat brain.KChIP1 is highly co-localize with GABA transmitter in hippocampus and cerebral cortex. In the acute PTZ-induced convulsive rats, the number of KChIP1-postive cells was significantly increased especially in the regions of CA 1 and CA3 (P < 0.05); whereas the chronic PTZ-induced convulsive rats were found no changes. The number of GABA-labeled and co-labeled neurons in the hippocampus appeared to have no significant alteration responding to the epilepsy-genesis treatments. Conclusion KChIP1 might be involved in the PTZ-induced epileptogenesis process as a regulator to neuronal excitability through influencing the properties of potassium channels. KChIP1 is preferentially expressed in GABAergic neurons, but its changes did not couple with GABA in the epileptic models.

  7. Involvement of large-conductance Ca2+-activated K+ channels in chloroquine-induced force alterations in pre-contracted airway smooth muscle.

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    Ming-Yu Wei

    Full Text Available The participation of large-conductance Ca2+ activated K+ channels (BKs in chloroquine (chloro-induced relaxation of precontracted airway smooth muscle (ASM is currently undefined. In this study we found that iberiotoxin (IbTx, a selective inhibitor of BKs and chloro both completely blocked spontaneous transient outward currents (STOCs in single mouse tracheal smooth muscle cells, which suggests that chloro might block BKs. We further found that chloro inhibited Ca2+ sparks and caffeine-induced global Ca2+ increases. Moreover, chloro can directly block single BK currents completely from the intracellular side and partially from the extracellular side. All these data indicate that the chloro-induced inhibition of STOCs is due to the blockade of chloro on both BKs and ryanodine receptors (RyRs. We also found that low concentrations of chloro resulted in additional contractions in tracheal rings that were precontracted by acetylcholine (ACH. Increases in chloro concentration reversed the contractile actions to relaxations. In the presence of IbTx or paxilline (pax, BK blockers, chloro-induced contractions were inhibited, although the high concentrations of chloro-induced relaxations were not affected. Taken together, our results indicate that chloro blocks BKs and RyRs, resulting in abolishment of STOCs and occurrence of contraction, the latter will counteract the relaxations induced by high concentrations of chloro.

  8. Excitotoxic death induced by released glutamate in depolarized primary cultures of mouse cerebellar granule cells is dependent on GABAA receptors and niflumic acid-sensitive chloride channels.

    Science.gov (United States)

    Babot, Zoila; Cristòfol, Rosa; Suñol, Cristina

    2005-01-01

    Excitotoxic neuronal death has been linked to neurological and neurodegenerative diseases. Several studies have sought to clarify the involvement of Cl(-) channels in neuronal excitotoxicity using either N-methyl-D-aspartic acid (NMDA) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate/kainic acid agonists. In this work we induced excitotoxic death in primary cultures of cerebellar granule cells by means of endogenously released glutamate. Excitotoxicity was provoked by exposure to high extracellular K(+) concentrations ([K(+)](o)) for 5 min. Under these conditions, a Ca(2+)-dependent release of glutamate was evoked. When extracellular glutamate concentration rose to between 2 and 4 microM, cell viability was significantly reduced by 30-40%. The NMDA receptor antagonists (MK-801 and D-2-amino-5-phosphonopentanoic acid) prevented cell death. Exposure to high [K(+)](o) produced a (36)Cl(-) influx which was significantly reduced by picrotoxinin. In addition, the GABA(A) receptor antagonists (bicuculline, picrotoxinin and SR 95531) protected cells from high [K(+)](o)-triggered excitotoxicity and reduced extracellular glutamate concentration. The Cl(-) channel blockers niflumic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid also exerted a neuroprotective effect and reduced extracellular glutamate concentration, even though they did not reduce high [K(+)](o)-induced (36)Cl(-) influx. Primary cultures of cerebellar granule cells also contain a population of GABAergic neurons that released GABA in response to high [K(+)](o). Chronic treatment of primary cultures with kainic acid abolished GABA release and rendered granule cells insensitive to high [K(+)](o) exposure, even though NMDA receptors were functional. Altogether, these results demonstrate that, under conditions of membrane depolarization, low micromolar concentrations of extracellular glutamate might induce an excitotoxic process through both NMDA and GABA(A) receptors and niflumic acid-sensitive Cl

  9. Bidirectional regulation of dendritic voltage-gated potassium channels by the fragile X mental retardation protein.

    Science.gov (United States)

    Lee, Hye Young; Ge, Woo-Ping; Huang, Wendy; He, Ye; Wang, Gordon X; Rowson-Baldwin, Ashley; Smith, Stephen J; Jan, Yuh Nung; Jan, Lily Yeh

    2011-11-17

    How transmitter receptors modulate neuronal signaling by regulating voltage-gated ion channel expression remains an open question. Here we report dendritic localization of mRNA of Kv4.2 voltage-gated potassium channel, which regulates synaptic plasticity, and its local translational regulation by fragile X mental retardation protein (FMRP) linked to fragile X syndrome (FXS), the most common heritable mental retardation. FMRP suppression of Kv4.2 is revealed by elevation of Kv4.2 in neurons from fmr1 knockout (KO) mice and in neurons expressing Kv4.2-3'UTR that binds FMRP. Moreover, treating hippocampal slices from fmr1 KO mice with Kv4 channel blocker restores long-term potentiation induced by moderate stimuli. Surprisingly, recovery of Kv4.2 after N-methyl-D-aspartate receptor (NMDAR)-induced degradation also requires FMRP, likely due to NMDAR-induced FMRP dephosphorylation, which turns off FMRP suppression of Kv4.2. Our study of FMRP regulation of Kv4.2 deepens our knowledge of NMDAR signaling and reveals a FMRP target of potential relevance to FXS.

  10. Inhibition of mitochondrial permeability transition pore contributes to the neuroprotection induced by activation of mitochondrial ATP-sensitive potassium channel

    Institute of Scientific and Technical Information of China (English)

    Li-pingWU; FangSHEN; QiangXIA

    2004-01-01

    AIM: To investigate whether the neuroprotection via activating mitochondrial ATP-sensitive potassium channel (mitoKTP) is mediated by the inhibition of mitochondrial permeability transition pore (MPTP). METHODS: Adult male Sprague-Dawleyrats were undergoing 90 min of middle cerebral artery occlusion(MCAO) by introducing a nylon monofilament through the external

  11. The molecular mechanism of toxin-induced conformational changes in a potassium channel : relation to C-type inactivation

    NARCIS (Netherlands)

    Zachariae, U.; Schneider, R.; Velisetty, P.; Lange, A.; Seeliger, D.; Wacker, S.J.; Karimi-Nejad, Y.; Vriend, G.; Becker, S.; Pongs, O.; Baldus, M.; Groot, B.L. de

    2008-01-01

    Recently, a solid-state NMR study revealed that scorpion toxin binding leads to conformational changes in the selectivity filter of potassium channels. The exact nature of the conformational changes, however, remained elusive. We carried out all-atom molecular dynamics simulations that enabled us to

  12. Role of the KATP channel in the protective effect of nicorandil on cyclophosphamide-induced lung and testicular toxicity in rats

    OpenAIRE

    Ahmed, Lamiaa A.; El-Maraghy, Shohda A.; Rizk, Sherine M.

    2015-01-01

    This study is the first to investigate the role of the KATP channel in the possible protection mediated by nicorandil against cyclophosphamide-induced lung and testicular toxicity in rats. Animals received cyclophosphamide (150 mg/kg/day, i.p.) for 2 consecutive days and then were untreated for the following 5 days. Nicorandil (3 mg/kg/day, p.o.) was administered starting from the day of cyclophosphamide injection with or without glibenclamide (5 mg/kg/day, p.o.). Nicorandil administration si...

  13. Volume regulated anion channel currents of rat hippocampal neurons and their contribution to oxygen-and-glucose deprivation induced neuronal death.

    Directory of Open Access Journals (Sweden)

    Huaqiu Zhang

    Full Text Available Volume-regulated anion channels (VRAC are widely expressed chloride channels that are critical for the cell volume regulation. In the mammalian central nervous system, the physiological expression of neuronal VRAC and its role in cerebral ischemia are issues largely unknown. We show that hypoosmotic medium induce an outwardly rectifying chloride conductance in CA1 pyramidal neurons in rat hippocampal slices. The induced chloride conductance was sensitive to some of the VRAC inhibitors, namely, IAA-94 (300 µM and NPPB (100 µM, but not to tamoxifen (10 µM. Using oxygen-and-glucose deprivation (OGD to simulate ischemic conditions in slices, VRAC activation appeared after OGD induced anoxic depolarization (AD that showed a progressive increase in current amplitude over the period of post-OGD reperfusion. The OGD induced VRAC currents were significantly inhibited by inhibitors for glutamate AMPA (30 µM NBQX and NMDA (40 µM AP-5 receptors in the OGD solution, supporting the view that induction of AD requires an excessive Na(+-loading via these receptors that in turn to activate neuronal VRAC. In the presence of NPPB and DCPIB in the post-OGD reperfusion solution, the OGD induced CA1 pyramidal neuron death, as measured by TO-PRO-3-I staining, was significantly reduced, although DCPIB did not appear to be an effective neuronal VRAC blocker. Altogether, we show that rat hippocampal pyramidal neurons express functional VRAC, and ischemic conditions can initial neuronal VRAC activation that may contribute to ischemic neuronal damage.

  14. Antidiuretic effect of hydrochlorothiazide in lithium-induced nephrogenic diabetes insipidus is associated with upregulation of aquaporin-2, Na-Cl co-transporter, and epithelial sodium channel.

    Science.gov (United States)

    Kim, Gheun-Ho; Lee, Jay Wook; Oh, Yun Kyu; Chang, Hye Ryun; Joo, Kwon Wook; Na, Ki Young; Earm, Jae-Ho; Knepper, Mark A; Han, Jin Suk

    2004-11-01

    Thiazides have been used in patients with nephrogenic diabetes insipidus (NDI) to decrease urine volume, but the mechanism by which it produces the paradoxic antidiuretic effect remains unclear. Previous studies have reported that downregulation of aquaporin-2 (AQP2) is important for the development of lithium-induced (Li-induced) polyuria and that hydrochlorothiazide (HCTZ) increases renal papillary osmolality and Na(+) concentration in Brattleboro rats. For elucidating the molecular basis of the antidiuretic action of HCTZ in diabetes insipidus, whether administration of HCTZ may affect the expression of AQP2 and major renal Na(+) transporters in Li-induced NDI rats was investigated, using semiquantitative immunoblotting and immunohistochemistry. After feeding male Sprague-Dawley rats Li chloride-containing rat diet for 4 wk, HCTZ or vehicle was infused subcutaneously via osmotic minipump. Urine output was significantly decreased by HCTZ treatment, whereas it was not changed in vehicle-treated rats. Urine osmolality was also higher in HCTZ-treated rats than in vehicle-treated rats. Semiquantitative immunoblotting using whole-kidney homogenates revealed that HCTZ treatment caused a significant partial recovery in AQP2 abundance from Li-induced downregulation. AQP2 immunohistochemistry showed compatible findings with the immunoblot results in both cortex and medulla. The abundances of thiazide-sensitive NaCl co-transporter and alpha-epithelial sodium channel were increased by HCTZ treatment. Notably, HCTZ treatment induced a shift in molecular weight of gamma-epithelial sodium channel from 85 to 70 kD, consistent with previously demonstrated aldosterone stimulation. The upregulation of AQP2 and distal renal Na(+) transporters in response to HCTZ treatment may account for the antidiuretic action of HCTZ in NDI.

  15. An Upregulation in the Expression of Vanilloid Transient Potential Channels 2 Enhances Hypotonicity-Induced Cytosolic Ca2+ Rise in Human Induced Pluripotent Stem Cell Model of Hutchinson Gillford Progeria

    Science.gov (United States)

    Ho, Jenny Chung-Yee; Siu, Chung-Wah; Cheung, Sin-Ying; Tang, Nelson L.; Yu, Shan; Tse, Hung-Fat; Yao, Xiaoqiang

    2014-01-01

    Hutchinson-Gillford Progeria Syndrome (HGPS) is a fatal genetic disorder characterized by premature aging in multiple organs including the skin, musculoskeletal and cardiovascular systems. It is believed that an increased mechanosensitivity of HGPS cells is a causative factor for vascular cell death and vascular diseases in HGPS patients. However, the exact mechanism is unknown. Transient receptor potential (TRP) channels are cationic channels that can act as cellular sensors for mechanical stimuli. The aim of this present study was to examine the expression and functional role of TRP channels in human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from the patients with HGPS. The mRNA and protein expression of TRP channels in HGPS and control (IMR90) iPSC-ECs were examined by semi-quantitative RT-PCRs and immunoblots, respectively. Hypotonicity-induced cytosolic Ca2+ ([Ca2+]i) rise in iPSC-ECs was measured by confocal microscopy. RT-PCRs and immunoblots showed higher expressional levels of TRPV2 in iPSC-ECs from HGPS patients than those from normal individuals. In functional studies, hypotonicity induced a transient [Ca2+]i rise in iPSC-ECs from normal individuals but a sustained [Ca2+]i elevation in iPSC-ECs from HGPS patients. A nonselective TRPV inhibitor, ruthenium red (RuR, 20 µM), and a specific TRPV2 channel inhibitor, tranilast (100 µM), abolished the sustained phase of hypotonicity-induced [Ca2+]i rise in iPSC-ECs from HGPS patients, and also markedly attenuated the transient phase of the [Ca2+]i rise in these cells. Importantly, a short 10 min hypotonicity treatment caused a substantial increase in caspase 8 activity in iPSC-ECs from HGPS patients but not in cells from normal individuals. Tranilast could also inhibit the hypotonicity-induced increase in caspase 8 activity. Taken together, our data suggest that an up-regulation in TRPV2 expression causes a sustained [Ca2+]i elevation in HGPS-iPSC-ECs under hypotonicity, consequently

  16. An upregulation in the expression of vanilloid transient potential channels 2 enhances hypotonicity-induced cytosolic Ca²⁺ rise in human induced pluripotent stem cell model of Hutchinson-Gillford Progeria.

    Directory of Open Access Journals (Sweden)

    Chun-Yin Lo

    Full Text Available Hutchinson-Gillford Progeria Syndrome (HGPS is a fatal genetic disorder characterized by premature aging in multiple organs including the skin, musculoskeletal and cardiovascular systems. It is believed that an increased mechanosensitivity of HGPS cells is a causative factor for vascular cell death and vascular diseases in HGPS patients. However, the exact mechanism is unknown. Transient receptor potential (TRP channels are cationic channels that can act as cellular sensors for mechanical stimuli. The aim of this present study was to examine the expression and functional role of TRP channels in human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs from the patients with HGPS. The mRNA and protein expression of TRP channels in HGPS and control (IMR90 iPSC-ECs were examined by semi-quantitative RT-PCRs and immunoblots, respectively. Hypotonicity-induced cytosolic Ca²⁺ ([Ca²⁺](i rise in iPSC-ECs was measured by confocal microscopy. RT-PCRs and immunoblots showed higher expressional levels of TRPV2 in iPSC-ECs from HGPS patients than those from normal individuals. In functional studies, hypotonicity induced a transient [Ca²⁺](i rise in iPSC-ECs from normal individuals but a sustained [Ca²⁺](i elevation in iPSC-ECs from HGPS patients. A nonselective TRPV inhibitor, ruthenium red (RuR, 20 µM, and a specific TRPV2 channel inhibitor, tranilast (100 µM, abolished the sustained phase of hypotonicity-induced [Ca²⁺](i rise in iPSC-ECs from HGPS patients, and also markedly attenuated the transient phase of the [Ca²⁺](i rise in these cells. Importantly, a short 10 min hypotonicity treatment caused a substantial increase in caspase 8 activity in iPSC-ECs from HGPS patients but not in cells from normal individuals. Tranilast could also inhibit the hypotonicity-induced increase in caspase 8 activity. Taken together, our data suggest that an up-regulation in TRPV2 expression causes a sustained [Ca²⁺](i elevation in HGPS

  17. An upregulation in the expression of vanilloid transient potential channels 2 enhances hypotonicity-induced cytosolic Ca²⁺ rise in human induced pluripotent stem cell model of Hutchinson-Gillford Progeria.

    Science.gov (United States)

    Lo, Chun-Yin; Tjong, Yung-Wui; Ho, Jenny Chung-Yee; Siu, Chung-Wah; Cheung, Sin-Ying; Tang, Nelson L; Yu, Shan; Tse, Hung-Fat; Yao, Xiaoqiang

    2014-01-01

    Hutchinson-Gillford Progeria Syndrome (HGPS) is a fatal genetic disorder characterized by premature aging in multiple organs including the skin, musculoskeletal and cardiovascular systems. It is believed that an increased mechanosensitivity of HGPS cells is a causative factor for vascular cell death and vascular diseases in HGPS patients. However, the exact mechanism is unknown. Transient receptor potential (TRP) channels are cationic channels that can act as cellular sensors for mechanical stimuli. The aim of this present study was to examine the expression and functional role of TRP channels in human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from the patients with HGPS. The mRNA and protein expression of TRP channels in HGPS and control (IMR90) iPSC-ECs were examined by semi-quantitative RT-PCRs and immunoblots, respectively. Hypotonicity-induced cytosolic Ca²⁺ ([Ca²⁺](i)) rise in iPSC-ECs was measured by confocal microscopy. RT-PCRs and immunoblots showed higher expressional levels of TRPV2 in iPSC-ECs from HGPS patients than those from normal individuals. In functional studies, hypotonicity induced a transient [Ca²⁺](i) rise in iPSC-ECs from normal individuals but a sustained [Ca²⁺](i) elevation in iPSC-ECs from HGPS patients. A nonselective TRPV inhibitor, ruthenium red (RuR, 20 µM), and a specific TRPV2 channel inhibitor, tranilast (100 µM), abolished the sustained phase of hypotonicity-induced [Ca²⁺](i) rise in iPSC-ECs from HGPS patients, and also markedly attenuated the transient phase of the [Ca²⁺](i) rise in these cells. Importantly, a short 10 min hypotonicity treatment caused a substantial increase in caspase 8 activity in iPSC-ECs from HGPS patients but not in cells from normal individuals. Tranilast could also inhibit the hypotonicity-induced increase in caspase 8 activity. Taken together, our data suggest that an up-regulation in TRPV2 expression causes a sustained [Ca²⁺](i) elevation in HGPS

  18. Wip1 knockout inhibits the proliferation and enhances the migration of bone marrow mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yiting [College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095 (China); State Key Laboratory of Animal Nutrition and Key Laboratory of Farm Animal Genetic Resources and Germplasm Innovation of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193 (China); Liu, Lan [State Key Laboratory of Animal Nutrition and Key Laboratory of Farm Animal Genetic Resources and Germplasm Innovation of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193 (China); Sheng, Ming [College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095 (China); Xiong, Kai [Department of Veterinary Clinical and Animal Sciences, University of Copenhagen, Grønnegårdsvej 7, 1870 Frederiksberg C (Denmark); Huang, Lei; Gao, Qian; Wei, Jingliang; Wu, Tianwen; Yang, Shulin [State Key Laboratory of Animal Nutrition and Key Laboratory of Farm Animal Genetic Resources and Germplasm Innovation of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193 (China); Liu, Honglin, E-mail: liuhonglinnjau@163.com [College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095 (China); Mu, Yulian, E-mail: muyulian76@iascaas.net.cn [State Key Laboratory of Animal Nutrition and Key Laboratory of Farm Animal Genetic Resources and Germplasm Innovation of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193 (China); Li, Kui [State Key Laboratory of Animal Nutrition and Key Laboratory of Farm Animal Genetic Resources and Germplasm Innovation of Ministry of Agriculture, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193 (China)

    2015-06-10

    Mesenchymal stem cells (MSCs), a unique population of multipotent adult progenitor cells originally found in bone marrow (BM), are extremely useful for multifunctional therapeutic approaches. However, the growth arrest and premature senescence of MSCs in vitro prevent the in-depth characterization of these cells. In addition, the regulatory factors involved in MSCs migration remain largely unknown. Given that protein phosphorylation is associated with the processes of MSCs proliferation and migration, we focused on wild-type p53-inducible phosphatase-1 (Wip1), a well-studied modulator of phosphorylation, in this study. Our results showed that Wip1 knockout significantly inhibited MSCs proliferation and induced G2-phase cell-cycle arrest by reducing cyclinB1 expression. Compared with WT-MSCs, Wip1{sup −/−} MSCs displayed premature growth arrest after six passages in culture. Transwell and scratch assays revealed that Wip1{sup −/−} MSCs migrate more effectively than WT-MSCs. Moreover, the enhanced migratory response of Wip1{sup −/−} MSCs may be attributed to increases in the induction of Rac1-GTP activity, the pAKT/AKT ratio, the rearrangement of filamentous-actin (f-actin), and filopodia formation. Based on these results, we then examined the effect of treatment with a PI3K/AKT and Rac1 inhibitor, both of which impaired the migratory activity of MSCs. Therefore, we propose that the PI3K/AKT/Rac1 signaling axis mediates the Wip1 knockout-induced migration of MSCs. Our findings indicate that the principal function of Wip1 in MSCs transformation is the maintenance of proliferative capacity. Nevertheless, knocking out Wip1 increases the migratory capacity of MSCs. This dual effect of Wip1 provides the potential for purposeful routing of MSCs. - Highlights: • Wip1 knockout inhibited MSCs proliferation through reducing cyclinB1 expression. • Wip1{sup −/−} MSCs displayed premature growth arrest in vitro after six passages. • Knocking out Wip1

  19. Claudin-2 knockout by TALEN-mediated gene targeting in MDCK cells: claudin-2 independently determines the leaky property of tight junctions in MDCK cells.

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    Shinsaku Tokuda

    Full Text Available Tight junctions (TJs regulate the movements of substances through the paracellular pathway, and claudins are major determinants of TJ permeability. Claudin-2 forms high conductive cation pores in TJs. The suppression of claudin-2 expression by RNA interference in Madin-Darby canine kidney (MDCK II cells (a low-resistance strain of MDCK cells was shown to induce a three-fold increase in transepithelial electrical resistance (TER, which, however, was still lower than in high-resistance strains of MDCK cells. Because RNA interference-mediated knockdown is not complete and only reduces gene function, we considered the possibility that the remaining claudin-2 expression in the knockdown study caused the lower TER in claudin-2 knockdown cells. Therefore, we investigated the effects of claudin-2 knockout in MDCK II cells by establishing claudin-2 knockout clones using transcription activator-like effector nucleases (TALENs, a recently developed genome editing method for gene knockout. Surprisingly, claudin-2 knockout increased TER by more than 50-fold in MDCK II cells, and TER values in these cells (3000-4000 Ω·cm2 were comparable to those in the high-resistance strains of MDCK cells. Claudin-2 re-expression restored the TER of claudin-2 knockout cells dependent upon claudin-2 protein levels. In addition, we investigated the localization of claudin-1, -2, -3, -4, and -7 at TJs between control MDCK cells and their respective knockout cells using their TALENs. Claudin-2 and -7 were less efficiently localized at TJs between control and their knockout cells. Our results indicate that claudin-2 independently determines the 'leaky' property of TJs in MDCK II cells and suggest the importance of knockout analysis in cultured cells.

  20. Fibronectin-induced VEGF receptor and calcium channel transactivation stimulate GLUT-1 synthesis and trafficking through PPARγ and TC10 in mouse embryonic stem cells.

    Science.gov (United States)

    Suh, Han Na; Han, Ho Jae

    2013-05-01

    Extracellular matrix (ECM) mediates interactions between integrin and growth factor receptor (GFR) or ion channel. Although this crosstalk promotes integration of the downstream signal pathways and then regulates cellular function, the effect of ECM on glucose transporter (GLUT) in stem cells has not been elucidated. Therefore, we examined the effect of fibronectin on GLUT-1 expression, trafficking, and its related signal pathways in mouse embryonic stem cells (mESCs). Fibronectin increased 2-deoxyglucose (DG) uptake and GLUT-1 protein expression that were blocked by transcription or translation inhibitors. Integrin α5β1-bound fibronectin increased 2-DG uptake through cluster formation with vascular endothelial growth factor receptor (VEGFR) 2, and then activated Ras and PI3K/Akt. In another pathway, integrin α5β1 displayed structural and functional interactions with calcium channels, and stimulated 2-DG uptake through calcium influx and PKC activation. Akt and PKC-induced PPARγ phosphorylation enhanced the decreased expression of PPARγ protein, and subsequently increased GLUT-1 protein synthesis and 2-DG uptake. Fibronectin stimulated TC10 activity and cytoskeleton (F-actin) rearrangement, followed by GLUT-1 trafficking. In conclusion, integrin-bound fibronectin stimulates GLUT-1 synthesis through VEGFR2/Ras/PI3K/Akt and calcium channel/Ca(2+)/PKC, which are merged at PPARγ and GLUT-1 trafficking through TC10 and F-actin.

  1. Blockade by NIP-142, an antiarrhythmic agent, of carbachol-induced atrial action potential shortening and GIRK1/4 channel.

    Science.gov (United States)

    Matsuda, Tomoyuki; Ito, Mie; Ishimaru, Sayoko; Tsuruoka, Noriko; Saito, Tomoaki; Iida-Tanaka, Naoko; Hashimoto, Norio; Yamashita, Toru; Tsuruzoe, Nobutomo; Tanaka, Hikaru; Shigenobu, Koki

    2006-08-01

    Mechanisms for the atria-specific action potential-prolonging action of NIP-142 ((3R*,4S*)-4-cyclopropylamino-3,4-dihydro-2,2-dimethyl-6-(4-methoxyphenylacetylamino)-7-nitro-2H-1-benzopyran-3-ol), a benzopyran compound that terminates experimental atrial arrhythmia, was examined. In isolated guinea-pig atrial tissue, NIP-142 reversed the shortening of action potential duration induced by either carbachol or adenosine. These effects were mimicked by tertiapin, but not by E-4031. NIP-142 concentration-dependently blocked the human G protein-coupled inwardly rectifying potassium channel current (GIRK1/4 channel current) expressed in HEK-293 cells with an EC50 value of 0.64 microM. At higher concentrations, NIP-142 blocked the human ether a go-go related gene (HERG) channel current with an EC50 value of 44 microM. In isolated guinea-pig papillary muscles, NIP-142 had no effect on the negative inotropic effect of carbachol under beta-adrenergic stimulation, indicating lack of effect on the muscarinic receptor and Gi protein. These results suggest that NIP-142 directly inhibits the acetylcholine-activated potassium current.

  2. Effects of L-type Ca2+ channel antagonists on in vitro excystment of Paragonimus ohirai metacercariae induced by sodium cholate.

    Science.gov (United States)

    Ikeda, Teruaki

    2006-09-01

    The inhibitory effects of L-type Ca2+ channel antagonists on Na cholate-induced in vitro excystment (CIIE) of Paragonimus ohirai metacercariae were studied. At concentrations of 10 microM, nicardipine and nimodipine inhibited CIIE completely and by approximately 92%, respectively. Nitrendipine and (+/-)-verapamil inhibited CIIE by about one half and one third, respectively. Nifedipine and diltiazem did not inhibit CIIE significantly. At higher concentrations, nitrendipine at 20 microM completely inhibited CIIE, and (+/-)-verapamil at 40 microM inhibited CIIE by 93%. Nifedipine and diltiazem inhibited CIIE only slightly and little, respectively, even at 40 microM. Complete inhibition by nicardipine at 10 microM required preincubation of metacercariae with the antagonist for 15 min. The inhibitory effects of nicardipine and nimodipine were reversible, and most of the nimodipine-treated metacercariae could excyst within 1 h after being washed, but the nicardipine-treated ones started to excyst 1 h after washing. Nicardipine suppressed the active movement of encysted juveniles evoked by Na cholate, whereas nimodipine did not suppress this significantly. These results suggested that L-type Ca2+ channels appeared to be involved in CIIE of P. ohirai metacercariae and that the inhibitory effect of the channels was due primarily to factors other than the inhibition of muscular activity, probably involving the secretion and release of enzymes lytic against the metacercarial cyst wall.

  3. Calcium current homeostasis and synaptic deficits in hippocampal neurons from Kelch-like 1 knockout mice

    Directory of Open Access Journals (Sweden)

    Paula Patricia Perissinotti

    2015-01-01

    Full Text Available Kelch-like 1 (KLHL1 is a neuronal actin-binding protein that modulates voltage-gated CaV2.1 (P/Q-type and CaV3.2 (α1H T-type calcium channels; KLHL1 knockdown experiments (KD cause down-regulation of both channel types and altered synaptic properties in cultured rat hippocampal neurons (Perissinotti et al., 2014. Here, we studied the effect of ablation of KLHL1 on calcium channel function and synaptic properties in cultured hippocampal neurons from KLHL1 knockout (KO mice. Western blot data showed the P/Q-type channel α1A subunit was less abundant in KO hippocampus compared to wildtype (WT; and PQ-type calcium currents were smaller in KO neurons than WT during early days in vitro, although this decrease was compensated for at late stages by increases in L-type calcium current. In contrast, T-type currents did not change in culture. However, biophysical properties and western blot analysis revealed a differential contribution of T-type channel isoforms in the KO, with CaV3.2 α1H subunit being down-regulated and CaV3.1 α1G up-regulated. Synapsin I levels were reduced in the KO hippocampus; cultured neurons displayed a concomitant reduction in synapsin I puncta and decreased miniature excitatory postsynaptic current (mEPSC frequency. In summary, genetic ablation of the calcium channel modulator resulted in compensatory mechanisms to maintain calcium current homeostasis in hippocampal KO neurons; however, synaptic alterations resulted in a reduction of excitatory synapse number, causing an imbalance of the excitatory-inhibitory synaptic input ratio favoring inhibition.

  4. The low PLC-δ1 expression in cystic fibrosis bronchial epithelial cells induces upregulation of TRPV6 channel activity.

    Science.gov (United States)

    Vachel, Laura; Norez, Caroline; Jayle, Christophe; Becq, Frédéric; Vandebrouck, Clarisse

    2015-01-01

    Increase of Ca(2+) influx in Cystic Fibrosis (CF) cells has been reported to be related to Transient Receptor Potential Canonical (TRPC6) channel, which is implicated in a functional coupling with Cystic Fibrosis Transmembrane conductance Regulator (CFTR). Several members of the Transient Receptor Potential Vanilloid (TRPV) channels family have already been described as emerging target for respiratory diseases. Two specific isoforms, TRPV5 and TRPV6 are of particular interest in the context of CF Ca(2+) homeostasis as they are highly selective toward Ca(2+) and constitutively activated. Thus, we investigated the involvement of these channels in Ca(2+) influx in CF and non-CF human bronchial epithelial cell lines. 16HBE14o-, CFBE41o- cell lines, primary human airway epithelial cells (hAEC) and freshly isolated human airway epithelial cells from CF and non-CF individuals were used. We showed that both channels are expressed in CF and non-CF cells and constitutive Ca(2+) influx was significantly higher (85%) in cells from CF individuals compared to cells from non-CF ones. Using the selective inhibitor of TRPV6 channel SOR-C27 and a siRNA strategy, our results revealed that TRPV6 was mostly involved in the increase of Ca(2+) influx. TRPV6 channel is negatively regulated by the PLC-PIP2 pathway. We measured the Ca(2+) influx in the presence of the non-specific PLC inhibitor, U73122, in non-CF human bronchial epithelial cells. Ca(2+) influx was increased by 33% with U73122 and this increase was largely reduced in the presence of SOR-C27. PLC inhibition in CF cells by U73122 had no effect on Ca(2+) influx. These results showed that PLC-PIP2 pathway is dysregulated in CF cells and leads to the increase of TRPV6 activity. The regulation of TRPV6 by PLC-PIP2 pathway implicates the specific PLC isoform, PLC-δ1. Immunoblot experiments revealed that expression of PLC-δ1 was decreased by 70% in CF cells. TRPV6 activity was normalized but not the level of expression of PLC-δ1

  5. Gene expression profile of sodium channel subunits in the anterior cingulate cortex during experimental paclitaxel-induced neuropathic pain in mice

    Directory of Open Access Journals (Sweden)

    Willias Masocha

    2016-11-01

    Full Text Available Paclitaxel, a chemotherapeutic agent, causes neuropathic pain whose supraspinal pathophysiology is not fully understood. Dysregulation of sodium channel expression, studied mainly in the periphery and spinal cord level, contributes to the pathogenesis of neuropathic pain. We examined gene expression of sodium channel (Nav subunits by real time polymerase chain reaction (PCR in the anterior cingulate cortex (ACC at day 7 post first administration of paclitaxel, when mice had developed paclitaxel-induced thermal hyperalgesia. The ACC was chosen because increased activity in the ACC has been observed during neuropathic pain. In the ACC of vehicle-treated animals the threshold cycle (Ct values for Nav1.4, Nav1.5, Nav1.7, Nav1.8 and Nav1.9 were above 30 and/or not detectable in some samples. Thus, comparison in mRNA expression between untreated control, vehicle-treated and paclitaxel treated animals was done for Nav1.1, Nav1.2, Nav1.3, Nav1.6, Nax as well as Navβ1–Navβ4. There were no differences in the transcript levels of Nav1.1–Nav1.3, Nav1.6, Nax, Navβ1–Navβ3 between untreated and vehicle-treated mice, however, vehicle treatment increased Navβ4 expression. Paclitaxel treatment significantly increased the mRNA expression of Nav1.1, Nav1.2, Nav1.6 and Nax, but not Nav1.3, sodium channel alpha subunits compared to vehicle-treated animals. Treatment with paclitaxel significantly increased the expression of Navβ1 and Navβ3, but not Navβ2 and Navβ4, sodium channel beta subunits compared to vehicle-treated animals. These findings suggest that during paclitaxel-induced neuropathic pain (PINP there is differential upregulation of sodium channels in the ACC, which might contribute to the increased neuronal activity observed in the area during neuropathic pain.

  6. Gene expression profile of sodium channel subunits in the anterior cingulate cortex during experimental paclitaxel-induced neuropathic pain in mice

    Science.gov (United States)

    2016-01-01

    Paclitaxel, a chemotherapeutic agent, causes neuropathic pain whose supraspinal pathophysiology is not fully understood. Dysregulation of sodium channel expression, studied mainly in the periphery and spinal cord level, contributes to the pathogenesis of neuropathic pain. We examined gene expression of sodium channel (Nav) subunits by real time polymerase chain reaction (PCR) in the anterior cingulate cortex (ACC) at day 7 post first administration of paclitaxel, when mice had developed paclitaxel-induced thermal hyperalgesia. The ACC was chosen because increased activity in the ACC has been observed during neuropathic pain. In the ACC of vehicle-treated animals the threshold cycle (Ct) values for Nav1.4, Nav1.5, Nav1.7, Nav1.8 and Nav1.9 were above 30 and/or not detectable in some samples. Thus, comparison in mRNA expression between untreated control, vehicle-treated and paclitaxel treated animals was done for Nav1.1, Nav1.2, Nav1.3, Nav1.6, Nax as well as Navβ1–Navβ4. There were no differences in the transcript levels of Nav1.1–Nav1.3, Nav1.6, Nax, Navβ1–Navβ3 between untreated and vehicle-treated mice, however, vehicle treatment increased Navβ4 expression. Paclitaxel treatment significantly increased the mRNA expression of Nav1.1, Nav1.2, Nav1.6 and Nax, but not Nav1.3, sodium channel alpha subunits compared to vehicle-treated animals. Treatment with paclitaxel significantly increased the expression of Navβ1 and Navβ3, but not Navβ2 and Navβ4, sodium channel beta subunits compared to vehicle-treated animals. These findings suggest that during paclitaxel-induced neuropathic pain (PINP) there is differential upregulation of sodium channels in the ACC, which might contribute to the increased neuronal activity observed in the area during neuropathic pain. PMID:27896032

  7. Effects of Akt1 gene knockout on pain behaviour induced by chronic constriction injury of sciatic nerve in mice%Akt1基因敲除对坐骨神经结扎小鼠痛行为的影响

    Institute of Scientific and Technical Information of China (English)

    隽立芹; 薄靳华; 马正良; 顾小萍

    2014-01-01

    目的 探讨Akt1基因敲除对坐骨神经结扎小鼠痛行为学的影响.方法 C57BL/6雄性小鼠随机分为Akt1基因敲除组(KO组,n=12)和野生组(WT组,n=12).在小鼠右侧制作坐骨神经慢性挤压(chronic constriction injury,CCI)模型,测试术前1d和术后1d、3d、5d、7d、10d、14d、17d、21 d的机械缩足阈值(paw withdrawal mechanical threshold,PWMT)和热缩足潜伏期(paw withdrawal thermal latency,PWTL).结果 KO组和WT组小鼠的两侧PWMT基础值[右侧:(0.89±0.15)g,(0.87±0.15)g;左侧:(0.97 ±0.19)g,(1.05±0,14)g,P>0.05]和PWTL[右侧:(7.64±0.71)s,(7.56±0.68)s;左侧:(7.67±0.6)s,(7.64±0.64)s,P>0.05]差异无统计学意义.术后各测试时间点KO组/WT组小鼠右侧的PWMT和PWTL与其基础值相比均明显减低(P<0.05),KO组左侧PWMT和PWTL与WT组小鼠相比差异无统计学意义(P>0.05),但是KO组右侧PWMT和PWTL较WT组明显降低(P<0.05).结论 Akt1基因敲除后会加重小鼠坐骨神经结扎所诱发的神经病理性疼痛.%Objective To investigate the effects of Aktl gene knockout on pain behavior induced by chronic constriction injury model of sciatic nerve (CCI).Methods C57BL/6 male mice were randomly divided into Akt1 knockout group (KO group,n=12),wild type group(WT group,n=12).All mice were made model of CCI in the right sciatic nerve.Each mouse received tests of the paw withdrawal mechanical threshold (PWMT) and the paw withdrawal thermal latency(PWTL) at the times of 1d before and 1 d,3 d,5 d,7 d,10 d,14 d,17 d,21 d after surgery.Results For both KO group and WT group,the basic values of PMWT(right(0.89±0.15)g,(0.87±0.15)g; left(0.97±0.19) g,(1.05±0.14) g,P>0.05) and PWTL(right (7.64±0.71) s,(7.56±0.68) s ;left: (7.67±0.6) s,(7.64±0.64) s,P>0.05) showed no significantly statistical difference.Compared with WT group and the basic value,PWMT and PWTL were significantly decreased after surgery in KO group (P<0.05).The PWMT and P WTL of the left paw in KO group

  8. Invariant mass spectroscopy of 17C via one-neutron knockout reaction from 18C

    Science.gov (United States)

    Kim, Sunji; Samurai Collaboration

    2014-09-01

    The nuclei away from the β-stability line are expected to have exotic nuclear structures. For example, the ground states of neutron-rich carbon isotopes, 15C, 17C, and 19C, have been predicted to be 5/2+ states in the naive shell model. However, they were identified as 1/2+, 3/2+, and 1/2+, respectively, due to the halo structure and/or nuclear deformation. To understand the properties of the valence orbit relative to the inner orbit in those neutron-rich carbon isotopes, the study of the negative parity states is decisive. The present study focuses on the low-lying negative parity states in 17C above the neutron decay threshold. The experiment was performed for the C(18C,17C*) one-neutron knockout reaction channel at 250 MeV/nucleon using the SAMURAI spectrometer at RIKEN-RIBF, during the first physics runs of the apparatus. The nucleon knockout reaction utilizing the secondary beams in inverse kinematics has become recognized as a sensitive tool for spectroscopy of the nuclei far from the β-stability line. In the presentation, details of the measurement and analysis will be reported together with new results on the low-lying negative parity states in 17C.

  9. Observing a model ion channel gating action in model cell membranes in real time in situ: membrane potential change induced alamethicin orientation change.

    Science.gov (United States)

    Ye, Shuji; Li, Hongchun; Wei, Feng; Jasensky, Joshua; Boughton, Andrew P; Yang, Pei; Chen, Zhan

    2012-04-11

    Ion channels play crucial roles in transport and regulatory functions of living cells. Understanding the gating mechanisms of these channels is important to understanding and treating diseases that have been linked to ion channels. One potential model peptide for studying the mechanism of ion channel gating is alamethicin, which adopts a split α/3(10)-helix structure and responds to changes in electric potential. In this study, sum frequency generation vibrational spectroscopy (SFG-VS), supplemented by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), has been applied to characterize interactions between alamethicin (a model for larger channel proteins) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayers in the presence of an electric potential across the membrane. The membrane potential difference was controlled by changing the pH of the solution in contact with the bilayer and was measured using fluorescence spectroscopy. The orientation angle of alamethicin in POPC lipid bilayers was then determined at different pH values using polarized SFG amide I spectra. Assuming that all molecules adopt the same orientation (a δ distribution), at pH = 6.7 the α-helix at the N-terminus and the 3(10)-helix at the C-terminus tilt at about 72° (θ(1)) and 50° (θ(2)) versus the surface normal, respectively. When pH increases to 11.9, θ(1) and θ(2) decrease to 56.5° and 45°, respectively. The δ distribution assumption was verified using a combination of SFG and ATR-FTIR measurements, which showed a quite narrow distribution in the angle of θ(1) for both pH conditions. This indicates that all alamethicin molecules at the surface adopt a nearly identical orientation in POPC lipid bilayers. The localized pH change in proximity to the bilayer modulates the membrane potential and thus induces a decrease in both the tilt and the bend angles of the two helices in alamethicin. This is the first reported application of SFG

  10. Retigabine, a Kv7.2/Kv7.3-Channel Opener, Attenuates Drug-Induced Seizures in Knock-In Mice Harboring Kcnq2 Mutations.

    Science.gov (United States)

    Ihara, Yukiko; Tomonoh, Yuko; Deshimaru, Masanobu; Zhang, Bo; Uchida, Taku; Ishii, Atsushi; Hirose, Shinichi

    2016-01-01

    The hetero-tetrameric voltage-gated potassium channel Kv7.2/Kv7.3, which is encoded by KCNQ2 and KCNQ3, plays an important role in limiting network excitability in the neonatal brain. Kv7.2/Kv7.3 dysfunction resulting from KCNQ2 mutations predominantly causes self-limited or benign epilepsy in neonates, but also causes early onset epileptic encephalopathy. Retigabine (RTG), a Kv7.2/ Kv7.3-channel opener, seems to be a rational antiepileptic drug for epilepsies caused by KCNQ2 mutations. We therefore evaluated the effects of RTG on seizures in two strains of knock-in mice harboring different Kcnq2 mutations, in comparison to the effects of phenobarbital (PB), which is the first-line antiepileptic drug for seizures in neonates. The subjects were heterozygous knock-in mice (Kcnq2Y284C/+ and Kcnq2A306T/+) bearing the Y284C or A306T Kcnq2 mutation, respectively, and their wild-type (WT) littermates, at 63-100 days of age. Seizures induced by intraperitoneal injection of kainic acid (KA, 12mg/kg) were recorded using a video-electroencephalography (EEG) monitoring system. Effects of RTG on KA-induced seizures of both strains of knock-in mice were assessed using seizure scores from a modified Racine's scale and compared with those of PB. The number and total duration of spike bursts on EEG and behaviors monitored by video recording were also used to evaluate the effects of RTG and PB. Both Kcnq2Y284C/+ and Kcnq2A306T/+ mice showed significantly more KA-induced seizures than WT mice. RTG significantly attenuated KA-induced seizure activities in both Kcnq2Y284C/+ and Kcnq2A306T/+ mice, and more markedly than PB. This is the first reported evidence of RTG ameliorating KA-induced seizures in knock-in mice bearing mutations of Kcnq2, with more marked effects than those observed with PB. RTG or other Kv7.2-channel openers may be considered as first-line antiepileptic treatments for epilepsies resulting from KCNQ2 mutations.

  11. Retigabine, a Kv7.2/Kv7.3-Channel Opener, Attenuates Drug-Induced Seizures in Knock-In Mice Harboring Kcnq2 Mutations.

    Directory of Open Access Journals (Sweden)

    Yukiko Ihara

    Full Text Available The hetero-tetrameric voltage-gated potassium channel Kv7.2/Kv7.3, which is encoded by KCNQ2 and KCNQ3, plays an important role in limiting network excitability in the neonatal brain. Kv7.2/Kv7.3 dysfunction resulting from KCNQ2 mutations predominantly causes self-limited or benign epilepsy in neonates, but also causes early onset epileptic encephalopathy. Retigabine (RTG, a Kv7.2/ Kv7.3-channel opener, seems to be a rational antiepileptic drug for epilepsies caused by KCNQ2 mutations. We therefore evaluated the effects of RTG on seizures in two strains of knock-in mice harboring different Kcnq2 mutations, in comparison to the effects of phenobarbital (PB, which is the first-line antiepileptic drug for seizures in neonates. The subjects were heterozygous knock-in mice (Kcnq2Y284C/+ and Kcnq2A306T/+ bearing the Y284C or A306T Kcnq2 mutation, respectively, and their wild-type (WT littermates, at 63-100 days of age. Seizures induced by intraperitoneal injection of kainic acid (KA, 12mg/kg were recorded using a video-electroencephalography (EEG monitoring system. Effects of RTG on KA-induced seizures of both strains of knock-in mice were assessed using seizure scores from a modified Racine's scale and compared with those of PB. The number and total duration of spike bursts on EEG and behaviors monitored by video recording were also used to evaluate the effects of RTG and PB. Both Kcnq2Y284C/+ and Kcnq2A306T/+ mice showed significantly more KA-induced seizures than WT mice. RTG significantly attenuated KA-induced seizure activities in both Kcnq2Y284C/+ and Kcnq2A306T/+ mice, and more markedly than PB. This is the first reported evidence of RTG ameliorating KA-induced seizures in knock-in mice bearing mutations of Kcnq2, with more marked effects than those observed with PB. RTG or other Kv7.2-channel openers may be considered as first-line antiepileptic treatments for epilepsies resulting from KCNQ2 mutations.

  12. Blockade of L-type calcium channel in myocardium and calcium-induced contractions of vascular smooth muscle by by CPU 86017

    Institute of Scientific and Technical Information of China (English)

    De-zai DAI; Hui-juan HU; Jing ZHAO; Xue-mei HAO; Dong-mei YANG; Pei-ai ZHOU; Cai-hong WU

    2004-01-01

    AIM: To assess the blockade by CPU 86017 on the L-type calcium channels in the myocardium and on the Ca2+related contractions of vascular smooth muscle. METHODS: The whole-cell patch-clamp was applied to investigate the blocking effect of CPU 86017 on the L-type calcium current in isolated guinea pig myocytes and contractions by KC1 or phenylephrine (Phe) of the isolated rat tail arteries were measured. RESULTS: Suppression of the L-type current of the isolated myocytes by CPU 86017 was moderate, in time- and concentration-dependent manner and with no influence on the activation and inactivation curves. The IC50 was 11.5 μmol/L. Suppressive effect of CPU 86017 on vaso-contractions induced by KC1 100 mmol/L, phenylephrine I μmol/Lin KH solution (phase 1),Ca2+ free KH solution ( phase 2), and by addition of CaCI2 into Ca2+-free KH solution (phase 3) were observed. The IC50 to suppress vaso-contractions by calcium entry via the receptor operated channel (ROC) and Voltage-dependent channel (VDC) was 0.324 μmol/L and 16.3 μmol/L, respectively. The relative potency of CPU 86017 to suppress vascular tone by Ca2+ entry through ROC and VDC is 1/187 of prazosin and 1/37 of verapamil, respectively.CONCLUSION: The blocking effects of CPU 86017 on the L-type calcium channel of myocardium and vessel are moderate and non-selective. CPU 86017 is approximately 50 times more potent in inhibiting ROC than VDC.

  13. Age- and location-dependent differences in store depletion-induced h-channel plasticity in hippocampal pyramidal neurons

    OpenAIRE

    Clemens, Ann M.; Johnston, Daniel

    2013-01-01

    Disruptions of endoplasmic reticulum (ER) Ca2+ homeostasis are heavily linked to neuronal pathology. Depletion of ER Ca2+ stores can result in cellular dysfunction and potentially cell death, although adaptive processes exist to aid in survival. We examined the age and region dependence of one postulated, adaptive response to ER store-depletion (SD), hyperpolarization-activated cation-nonspecific (h)-channel plasticity in neurons of the dorsal and ventral hippocampus (DHC and VHC, respectivel...

  14. Artepillin C, a major ingredient of Brazilian propolis, induces a pungent taste by activating TRPA1 channels.

    Directory of Open Access Journals (Sweden)

    Taketoshi Hata

    Full Text Available Brazilian green propolis is a popular health supplement because of its various biological properties. The ethanol extract of Brazilian green propolis (EEBP is characteristic for its herb-like smell and unique pungent taste. However, the ingredients responsible for its pungency have not yet been identified. This study provides the first evidence that artepillin C is the main pungent ingredient in EEBP and that it potently activates human transient receptor potential ankyrin 1 (TRPA1 channels. EEBP was fractionated using column chromatography with a step gradient elution of an ethanol-water solution, and the fractions having the pungent taste were determined by sensory tests. HPLC analysis revealed that the pungent fraction was composed primarily of artepillin C, a prenylated derivative of cinnamic acid. Artepillin C was also identified as the pungent compound of EEBP by organoleptic examiners. Furthermore, the effects of artepillin C and other cinnamic acids found in EEBP on TRPA1 channels were examined by calcium imaging and plate reader-based assays in human TRPA1-expressing cells to investigate the molecular mechanisms underlying their pungent tastes. Artepillin C and baccharin activated the TRPA1 channel strongly, whereas drupanin caused a slight activation and p-coumaric acid showed no activation. Because the EC(50 values of artepillin C, baccharin, and allyl isothiocyanate were 1.8 µM, 15.5 µM, and 6.2 µM, respectively, artepillin C was more potent than the typical TRPA1 agonist allyl isothiocyanate. These findings strongly indicate that artepillin C is the main pungent ingredient in EEBP and stimulates a pungent taste by activating TRPA1 channels.

  15. Lack of potassium channel induces proliferation and survival causing increased neurogenesis and two-fold hippocampus enlargement

    DEFF Research Database (Denmark)

    Almgren, Malin; Persson, Ann-Sophie; Fenghua, Chen

    2007-01-01

    The megencephaly mice show dramatic progressive increase in brain size and seizures. The overgrowth affects primarily the hippocampus and ventral cortex. The phenotype originates from a mutation in the Shaker-like voltage-gated potassium channel Kv1.1 brain, which results in a malfunctioning prot...... of age. This phenotype is a result, at least in DG, from increased proliferation, neurogenesis, and enhanced general hippocampal cell survival. Udgivelsesdato: 2007-null...

  16. Parathyroid Hormone Induces Bone Cell Motility and Loss of Mature Osteocyte Phenotype through L-Calcium Channel Dependent and Independent Mechanisms.

    Directory of Open Access Journals (Sweden)

    Matthew Prideaux

    Full Text Available Parathyroid Hormone (PTH can exert both anabolic and catabolic effects on the skeleton, potentially through expression of the PTH type1 receptor (PTH1R, which is highly expressed in osteocytes. To determine the cellular and molecular mechanisms responsible, we examined the effects of PTH on osteoblast to osteocyte differentiation using primary osteocytes and the IDG-SW3 murine cell line, which differentiate from osteoblast to osteocyte-like cells in vitro and express GFP under control of the dentin matrix 1 (Dmp1 promoter. PTH treatment resulted in an increase in some osteoblast and early osteocyte markers and a decrease in mature osteocyte marker expression. The gene expression profile of PTH-treated Day 28 IDG-SW3 cells was similar to PTH treated primary osteocytes. PTH treatment induced striking changes in the morphology of the Dmp1-GFP positive cells in IDG-SW3 cultures and primary cells from Dmp1-GFP transgenic mice. The cells changed from a more dendritic to an elongated morphology and showed increased cell motility. E11/gp38 has been shown to be important for cell migration, however, deletion of the E11/gp38/podoplanin gene had no effect on PTH-induced motility. The effects of PTH on motility were reproduced using cAMP, but not with protein kinase A (PKA, exchange proteins activated by cAMP (Epac, protein kinase C (PKC or phosphatidylinositol-4,5-bisphosphonate 3-kinase (Pi3K agonists nor were they blocked by their antagonists. However, the effects of PTH were mediated through calcium signaling, specifically through L-type channels normally expressed in osteoblasts but decreased in osteocytes. PTH was shown to increase expression of this channel, but decrease the T-type channel that is normally more highly expressed in osteocytes. Inhibition of L-type calcium channel activity attenuated the effects of PTH on cell morphology and motility but did not prevent the downregulation of mature osteocyte marker expression. Taken together, these

  17. Suppression of peripheral pain by blockade of Cav2.2 channels in nociceptors induces RANKL and impairs recovery from inflammatory arthritis

    Science.gov (United States)

    Baddack, Uta; Frahm, Silke; Antolin-Fontes, Beatriz; Grobe, Jenny; Lipp, Martin; Müller, Gerd; Ibañez-Tallon, Ines

    2015-01-01

    Objective A hallmark of rheumatoid arthritis (RA) is the chronic pain that accompanies the inflammation and joint deformation. Patients with RA rate pain relief with highest priority, however, few studies have addressed the efficacy and safety of therapies directed specifically towards pain pathways. The conotoxin MVIIA (Prialt/Ziconotide) is used in humans to alleviate persistent pain syndromes because it specifically blocks the CaV2.2 voltage-gated calcium channel, which mediates the release of neurotransmitters and proinflammatory mediators from peripheral nociceptor nerve terminals. The purpose of this study was to investigate whether block of CaV2.2 can suppress arthritic pain, and to examine the progression of induced arthritis during persistent CaV2.2 blockade. Methods Transgenic mice (Tg-MVIIA) expressing a membrane-tethered form of the ω-conotoxin MVIIA, under the control of a nociceptor-specific gene, were employed. These mice were subjected to unilateral induction of joint inflammation using the Antigen- and Collagen-Induced Arthritis (ACIA) model. Results We observed that CaV2.2-blockade mediated by t-MVIIA effectively suppressed arthritis-induced pain; however, in contrast to their wild-type littermates, which ultimately regained use of their injured joint as inflammation subsides, Tg-MVIIA mice showed continued inflammation with an up-regulation of the osteoclast activator RANKL and concomitant joint and bone destruction. Conclusion Altogether, our results indicate that alleviation of peripheral pain by blockade of CaV2.2- mediated calcium influx and signaling in nociceptor sensory neurons, impairs recovery from induced arthritis and point to the potentially devastating effects of using CaV2.2 channel blockers as analgesics during inflammation. PMID:25733371

  18. Potentiation of Opioid-Induced Analgesia by L-Type Calcium Channel Blockers: Need for Clinical Trial in Cancer Pain

    Directory of Open Access Journals (Sweden)

    S Basu Ray

    2008-01-01

    Full Text Available Previous reports indicate that the analgesic effect of opioids is due to both closure of specific voltage-gated calcium channels (N- and P/Q-types and opening of G protein-coupled inwardly rectifying potassium channels (GIRKs in neurons concerned with transmission of pain. However, administration of opioids leads to unacceptable levels of side effects, particularly at high doses. Thus, current research is directed towards simultaneously targeting other voltage-gated calcium channels (VGCCs like the L-type VGCCs or even other cell signaling mechanisms, which would aug-ment opioid-mediated analgesic effect without a concurrent increase in the side effects. Unfortunately, the results of these studies are often conflicting considering the different experimental paradigms (variable drug selection and their doses and also the specific pain test used for studying analgesia adopted by researchers. The present review focuses on some of the interesting findings regarding the analgesic effect of Opioids + L-VGCC blockers and suggests that time has come for a clinical trial of this combination of drugs in the treatment of cancer pain.

  19. Quantifying noise-induced stability of a cortical fast-spiking cell model with Kv3-channel-like current.

    Science.gov (United States)

    Tateno, T; Robinson, H P C

    2007-01-01

    Population oscillations in neural activity in the gamma (>30 Hz) and higher frequency ranges are found over wide areas of the mammalian cortex. Recently, in the somatosensory cortex, the details of neural connections formed by several types of GABAergic interneurons have become apparent, and they are believed to play a significant role in generating these oscillations through synaptic and gap-junctional interactions. However, little is known about the mechanism of how such oscillations are maintained stably by particular interneurons and by their local networks, in a noisy environment with abundant synaptic inputs. To obtain more insight into this, we studied a fast-spiking (FS)-cell model including Kv3-channel-like current, which is a distinctive feature of these cells, from the viewpoint of nonlinear dynamical systems. To examine the specific role of the Kv3-channel in determining oscillation properties, we analyzed basic properties of the FS-cell model, such as the bifurcation structure and phase resetting curves (PRCs). Furthermore, to quantitatively characterize the oscillation stability under noisy fluctuations mimicking small fast synaptic inputs, we applied a recently developed method from random dynamical system theory to estimate Lyapunov exponents, both for the original four-dimensional dynamics and for a reduced one-dimensional phase-equation on the circle. The results indicated that the presence of the Kv3-channel-like current helps to regulate the stability of noisy neural oscillations and a transient-period length to stochastic attractors.

  20. One-neutron knockout from Ne24-28 isotopes

    CERN Document Server

    Rodriguez-Tajes, C; Caamano, M; Faestermann, T; Cortina-Gil, D; Zhukov, M; Simon, H; Nilsson, T; Borge, M J G; Alvarez-Pol, H; Winkler, M; Prochazka, A; Nociforo, C; Weick, H; Kanungo, R; Perez-Loureiro, D; Kurtukian, T; Suemmerer, K; Eppinger, K; Perea, A; Chatillon, A; Maierbeck, P; Benlliure, J; Pascual-Izarra, C; Gernhaeuser, R; Geissel, H; Aumann, T; Kruecken, R; Larsson, K; Tengblad, O; Benjamim, E; Jonson, B; Casarejos, E

    2010-01-01

    One-neutron knockout reactions of Ne24-28 in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, Ne-27 and Ne-28, are dominated by a configuration in which a s(1/2) neutron is coupled to an excited state of the Ne-26 and Ne-27 core, respectively. (C) 2010 Elsevier B.V. All rights reserved.

  1. Generation of conditional knockout alleles for PRL-3.

    Science.gov (United States)

    Yan, Hong; Kong, Dong; Ge, Xiaomei; Gao, Xiang; Han, Xiao

    2011-11-01

    Phosphatase of regenerating liver-3 (PRL-3) is a member of the protein tyrosine phosphatase (PTP) superfamily and is highly expressed in cancer metastases. For better understanding of the role of PRL-3 in tumor metastasis, we applied a rapid and efficient method for generating PRL-3 floxed mice and investigated its phenotypes. A BAC retrieval strategy was applied to construct the PRL-3 conditional gene-targeting vector. Exon 4 was selected for deletion to generate a nonfunctional prematurely terminated short peptide as it will cause a frame-shift mutation. Conditional knockout PRL-3 mice were generated by using the Cre-loxP system and were validated by Southern blot and RT-PCR analysis. Further analysis revealed the phenotype characteristics of PRL-3 knockout mice and wildtype mice. In this study, we successfully constructed the PRL-3 conditional knockout mice, which will be helpful to clarify the roles of PRL-3 and the mechanisms in tumor metastasis.

  2. Zn(2+) induces hyperpolarization by activation of a K(+) channel and increases intracellular Ca(2+) and pH in sea urchin spermatozoa.

    Science.gov (United States)

    Beltrán, Carmen; Rodríguez-Miranda, Esmeralda; Granados-González, Gisela; García de De la Torre, Lucia; Nishigaki, Takuya; Darszon, Alberto

    2014-10-01

    Zinc (Zn(2+)) has been recently recognized as a crucial element for male gamete function in many species although its detailed mechanism of action is poorly understood. In sea urchin spermatozoa, Zn(2+) was reported as an essential trace ion for efficient sperm motility initiation and the acrosome reaction by modulating intracellular pH (pHi). In this study we found that submicromolar concentrations of free Zn(2+) change membrane potential (Em) and increase the concentration of intracellular Ca(2+) ([Ca(2+)]i) and cAMP in Lytechinus pictus sperm. Our results indicate that the Zn(2+) response in sperm of this species mainly involves an Em hyperpolarization caused by K(+) channel activation. The pharmacological profile of the Zn(2+)-induced hyperpolarization indicates that the cGMP-gated K(+) selective channel (tetraKCNG/CNGK), which is crucial for speract signaling, is likely a main target for Zn(2+). Considering that Zn(2+) also induces [Ca(2+)]i fluctuations, our observations suggest that Zn(2+) activates the signaling cascade of speract, except for an increase in cGMP, and facilitates sperm motility initiation upon spawning. These findings provide new insights about the role of Zn(2+) in male gamete function.

  3. Berberine Reduces cAMP-Induced Chloride Secretion in T84 Human Colonic Carcinoma Cells through Inhibition of Basolateral KCNQ1 Channels.

    LENUS (Irish Health Repository)

    Alzamora, Rodrigo

    2011-01-01

    Berberine is a plant alkaloid with multiple pharmacological actions, including antidiarrhoeal activity and has been shown to inhibit Cl(-) secretion in distal colon. The aims of this study were to determine the molecular signaling mechanisms of action of berberine on Cl(-) secretion and the ion transporter targets. Monolayers of T84 human colonic carcinoma cells grown in permeable supports were placed in Ussing chambers and short-circuit current measured in response to secretagogues and berberine. Whole-cell current recordings were performed in T84 cells using the patch-clamp technique. Berberine decreased forskolin-induced short-circuit current in a concentration-dependent manner (IC(50) 80 ± 8 μM). In apically permeabilized monolayers and whole-cell current recordings, berberine inhibited a cAMP-dependent and chromanol 293B-sensitive basolateral membrane K(+) current by 88%, suggesting inhibition of KCNQ1 K(+) channels. Berberine did not affect either apical Cl(-) conductance or basolateral Na(+)-K(+)-ATPase activity. Berberine stimulated p38 MAPK, PKCα and PKA, but had no effect on p42\\/p44 MAPK and PKCδ. However, berberine pre-treatment prevented stimulation of p42\\/p44 MAPK by epidermal growth factor. The inhibitory effect of berberine on Cl(-) secretion was partially blocked by HBDDE (∼65%), an inhibitor of PKCα and to a smaller extent by inhibition of p38 MAPK with SB202190 (∼15%). Berberine treatment induced an increase in association between PKCα and PKA with KCNQ1 and produced phosphorylation of the channel. We conclude that berberine exerts its inhibitory effect on colonic Cl(-) secretion through inhibition of basolateral KCNQ1 channels responsible for K(+) recycling via a PKCα-dependent pathway.

  4. Berberine Reduces cAMP-Induced Chloride Secretion in T84 Human Colonic Carcinoma Cells through Inhibition of Basolateral KCNQ1 Channels.

    LENUS (Irish Health Repository)

    Alzamora, Rodrigo

    2012-02-01

    Berberine is a plant alkaloid with multiple pharmacological actions, including antidiarrhoeal activity and has been shown to inhibit Cl(-) secretion in distal colon. The aims of this study were to determine the molecular signaling mechanisms of action of berberine on Cl(-) secretion and the ion transporter targets. Monolayers of T84 human colonic carcinoma cells grown in permeable supports were placed in Ussing chambers and short-circuit current measured in response to secretagogues and berberine. Whole-cell current recordings were performed in T84 cells using the patch-clamp technique. Berberine decreased forskolin-induced short-circuit current in a concentration-dependent manner (IC(50) 80 +\\/- 8 muM). In apically permeabilized monolayers and whole-cell current recordings, berberine inhibited a cAMP-dependent and chromanol 293B-sensitive basolateral membrane K(+) current by 88%, suggesting inhibition of KCNQ1 K(+) channels. Berberine did not affect either apical Cl(-) conductance or basolateral Na(+)-K(+)-ATPase activity. Berberine stimulated p38 MAPK, PKCalpha and PKA, but had no effect on p42\\/p44 MAPK and PKCdelta. However, berberine pre-treatment prevented stimulation of p42\\/p44 MAPK by epidermal growth factor. The inhibitory effect of berberine on Cl(-) secretion was partially blocked by HBDDE ( approximately 65%), an inhibitor of PKCalpha and to a smaller extent by inhibition of p38 MAPK with SB202190 ( approximately 15%). Berberine treatment induced an increase in association between PKCalpha and PKA with KCNQ1 and produced phosphorylation of the channel. We conclude that berberine exerts its inhibitory effect on colonic Cl(-) secretion through inhibition of basolateral KCNQ1 channels responsible for K(+) recycling via a PKCalpha-dependent pathway.

  5. Berberine reduces cAMP-induced chloride secretion in T84 human colonic carcinoma cells through inhibition of basolateral KCNQ1 channels

    Directory of Open Access Journals (Sweden)

    Rodrigo eAlzamora

    2011-06-01

    Full Text Available Berberine is a plant alkaloid with multiple pharmacological actions, including antidiarrhoeal activity and has been shown to inhibit Cl- secretion in distal colon. The aims of this study were to determine the molecular signalling mechanisms of action of berberine on Cl- secretion and the ion transporter targets. Monolayers of T84 human colonic carcinoma cells grown in permeable supports were placed in Ussing chambers and short-circuit current measured in response to secretagogues and berberine. Whole-cell current recordings were performed in T84 cells using the patch-clamp technique. Berberine decreased forskolin-induced short-circuit current in a concentration-dependent manner (IC50 80  8 M. In apically permeabilized monolayers and whole-cell current recordings, berberine inhibited a cAMP-dependent and chromanol 293B-sensitive basolateral membrane K+ current by 88%, suggesting inhibition of KCNQ1 K+ channels. Berberine did not affect either apical Cl- conductance or basolateral Na+-K+-ATPase activity. Berberine stimulated p38 MAPK, PKC and PKA, but had no effect on p42/p44 MAPK and PKC. However, berberine pre-treatment prevented stimulation of p42/p44 MAPK by epidermal growth factor. The inhibitory effect of berberine on Cl- secretion was partially blocked by HBDDE (65 %, an inhibitor of PKC and to a smaller extent by inhibition of p38 MAPK with SB202190 (15 %. Berberine treatment induced an increase in association between PKC and PKA with KCNQ1 and produced phosphorylation of the channel. We conclude that berberine exerts its inhibitory effect on colonic Cl- secretion through inhibition of basolateral KCNQ1 channels responsible for K+ recycling via a PKC-dependent pathway.

  6. Anti-arrhythmic effect of diosgenin in reperfusion-induced myocardial injury in a rat model: activation of nitric oxide system and mitochondrial KATP channel.

    Science.gov (United States)

    Badalzadeh, Reza; Yousefi, Bahman; Majidinia, Maryam; Ebrahimi, Hadi

    2014-11-01

    This study was designed to investigate the anti-arrhythmic effect of diosgenin preconditioning in myocardial reperfusion injury in rat, focusing on the involvement of the nitric oxide (NO) system and mitochondrial ATP-dependent potassium (mitoKATP) channels in this scenario. After isolation of the hearts of male Wister rats, the study was conducted in an isolated buffer-perfused heart model. Global ischemia (for 30 min) was induced by interruption of the aortic supply, which was followed by 90-min reperfusion. Throughout the experiment, the electrocardiograms of hearts were monitored using three golden surface electrodes connected to a data acquisition system. Arrhythmias were assessed based on the Lambeth convention and were categorized as number, duration and incidence of ventricular tachycardia (VT), ventricular fibrillation (VF), and premature ventricular complexes (PVC), and arrhythmic score. Additionally, lactate dehydrogenase (LDH) levels in coronary effluent were estimated colorimetrically. Diosgenin pre-administration for 20 min before ischemia reduced the LDH release into the coronary effluent, as compared with control hearts (P PVC, VT and VF, a reduced duration and incidence of VT and VF, and less severe arrhythmia at reperfusion phase, in comparison with controls. Blocking the mitoKATP channels using 5-hydroxydecanoate as well as inhibiting the NO system through prior administration of L-NAME significantly reduced the positive effects of diosgenin. Our finding showed that pre-administration of diosgenin could provide cardioprotection through anti-arrhythmic effects against ischemia-reperfusion (I/R) injury in isolated rat hearts. In addition, mitoKATP channels and NO system may be the key players in diosgenin-induced cardioprotective mechanisms.

  7. CD8 Knockout Mice Are Protected from Challenge by Vaccination with WR201, a Live Attenuated Mutant of Brucella melitensis

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    Samuel L. Yingst

    2013-01-01

    Full Text Available CD8+ T cells have been reported to play an important role in defense against B. abortus infection in mouse models. In the present report, we use CD8 knockout mice to further elucidate the role of these cells in protection from B. melitensis infection. Mice were immunized orally by administration of B. melitensis WR201, a purine auxotrophic attenuated vaccine strain, then challenged intranasally with B. melitensis 16M. In some experiments, persistence of WR201 in the spleens of CD8 knockout mice was slightly longer than that in the spleens of normal mice. However, development of anti-LPS serum antibody, antigen-induced production of γ-interferon (IFN-γ by immune splenic lymphocytes, protection against intranasal challenge, and recovery of nonimmunized animals from intranasal challenge were similar between normal and knockout animals. Further, primary Brucella infection was not exacerbated in perforin knockout and Fas-deficient mice and these animals’ anti-Brucella immune responses were indistinguishable from those of normal mice. These results indicate that CD8+ T cells do not play an essential role as either cytotoxic cells or IFN-γ producers, yet they do participate in a specific immune response to immunization and challenge in this murine model of B. melitensis infection.

  8. Using engineered endonucleases to create knockout and knockin zebrafish models.

    Science.gov (United States)

    Bedell, Victoria M; Ekker, Stephen C

    2015-01-01

    Over the last few years, the technology to create targeted knockout and knockin zebrafish animals has exploded. We have gained the ability to create targeted knockouts through the use of zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR associated system (CRISPR/Cas). Furthermore, using the high-efficiency TALEN system, we were able to create knockin zebrafish using a single-stranded DNA (ssDNA) protocol described here. Through the use of these technologies, the zebrafish has become a valuable vertebrate model and an excellent bridge between the invertebrate and mammalian model systems for the study of human disease.

  9. Generating double knockout mice to model genetic intervention for diabetic cardiomyopathy in humans.

    Science.gov (United States)

    Chavali, Vishalakshi; Nandi, Shyam Sundar; Singh, Shree Ram; Mishra, Paras Kumar

    2014-01-01

    Diabetes is a rapidly increasing disease that enhances the chances of heart failure twofold to fourfold (as compared to age and sex matched nondiabetics) and becomes a leading cause of morbidity and mortality. There are two broad classifications of diabetes: type1 diabetes (T1D) and type2 diabetes (T2D). Several mice models mimic both T1D and T2D in humans. However, the genetic intervention to ameliorate diabetic cardiomyopathy in these mice often requires creating double knockout (DKO). In order to assess the therapeutic potential of a gene, that specific gene is either overexpressed (transgenic expression) or abrogated (knockout) in the diabetic mice. If the genetic mice model for diabetes is used, it is necessary to create DKO with transgenic/knockout of the target gene to investigate the specific role of that gene in pathological cardiac remodeling in diabetics. One of the important genes involved in extracellular matrix (ECM) remodeling in diabetes is matrix metalloproteinase-9 (Mmp9). Mmp9 is a collagenase that remains latent in healthy hearts but induced in diabetic hearts. Activated Mmp9 degrades extracellular matrix (ECM) and increases matrix turnover causing cardiac fibrosis that leads to heart failure. Insulin2 mutant (Ins2+/-) Akita is a genetic model for T1D that becomes diabetic spontaneously at the age of 3-4 weeks and show robust hyperglycemia at the age of 10-12 weeks. It is a chronic model of T1D. In Ins2+/- Akita, Mmp9 is induced. To investigate the specific role of Mmp9 in diabetic hearts, it is necessary to create diabetic mice where Mmp9 gene is deleted. Here, we describe the method to generate Ins2+/-/Mmp9-/- (DKO) mice to determine whether the abrogation of Mmp9 ameliorates diabetic cardiomyopathy.

  10. Comprehensive behavioral phenotyping of ryanodine receptor type 3 (RyR3) knockout mice: decreased social contact duration in two social interaction tests.

    Science.gov (United States)

    Matsuo, Naoki; Tanda, Koichi; Nakanishi, Kazuo; Yamasaki, Nobuyuki; Toyama, Keiko; Takao, Keizo; Takeshima, Hiroshi; Miyakawa, Tsuyoshi

    2009-01-01

    Dynamic regulation of the intracellular Ca2+ concentration is crucial for various neuronal functions such as synaptic transmission and plasticity, and gene expression. Ryanodine receptors (RyRs) are a family of intracellular calcium release channels that mediate calcium-induced calcium release from the endoplasmic reticulum. Among the three RyR isoforms, RyR3 is preferentially expressed in the brain especially in the hippocampus and striatum. To investigate the behavioral effects of RyR3 deficiency, we subjected RyR3 knockout (RyR3-/-) mice to a battery of behavioral tests. RyR3-/- mice exhibited significantly decreased social contact duration in two different social interaction tests, where two mice can freely move and make contacts with each other. They also exhibited hyperactivity and mildly impaired prepulse inhibition and latent inhibition while they did not show significant abnormalities in motor function and working and reference memory tests. These results indicate that RyR3 has an important role in locomotor activity and social behavior.

  11. Comprehensive behavioral phenotyping of ryanodine receptor type3 (RyR3 knockout mice: Decreased social contact duration in two social interaction tests

    Directory of Open Access Journals (Sweden)

    Naoki Matsuo

    2009-05-01

    Full Text Available Dynamic regulation of the intracellular Ca2+ concentration is crucial for various neuronal functions such as synaptic transmission and plasticity, and gene expression. Ryanodine receptors (RyRs are a family of intracellular calcium release channels that mediate calcium-induced calcium release (CICR from the endoplasmic reticulum. Among the three RyR isoforms, RyR3 is preferentially expressed in the brain especially in the hippocampus and striatum. To investigate the behavioral effects of RyR3 deficiency, we subjected RyR3 knockout (RyR3-/- mice to a battery of behavioral tests. RyR3-/- mice exhibited significantly decreased social contact duration in two different social interaction tests, where two mice can freely move and make contacts with each other. They also exhibited hyperactivity and mildly impaired prepulse inhibition and latent inhibition while they did not show significant abnormalities in motor function and working and reference memory tests. These results suggest that RyR3 has an important role in locomotor activity and social behavior.

  12. Cav1.2, but not Cav1.3, L-type calcium channel subtype mediates nicotine-induced conditioned place preference in miceo.

    Science.gov (United States)

    Liu, Yudan; Harding, Meghan; Dore, Jules; Chen, Xihua

    2017-04-03

    Nicotine use is one of the most common forms of drug addiction. Although L-type calcium channels (LTCCs) are involved in nicotine addiction, the contribution of the two primary LTCC subtypes (Cav1.2 and 1.3) is unknown. This study aims to determine the contribution of these two LTCC subtypes to nicotine-induced conditioned place preference (CPP) responses by using transgenic mouse models that do not express Cav1.3 (Cav1.3(-/-)) or contain a mutation in the dihydropyridine (DHP) site of the Cav1.2 (Cav1.2DHP(-/-)). We found a hyperbolic dose dependent nicotine (0.1-1mg/kg; 0.5mg/kg optimum) effect on place preference in wild type (WT) mice, that could be prevented by the DHP LTCC blocker nifedipine pretreatment. Similarly, Cav1.3(-/-) mice showed nicotine-induced place preference which was antagonized by nifedipine. In contrast, nifedipine pretreatment of Cav1.2DHP(-/-) mice had no effect on nicotine-induced CPP responses, suggesting an involvement of Cav1.2 subtype in the nicotine-induced CPP response. Nifedipine alone failed to produce either conditioned place aversion or CPP in WT mice. These results collectively indicate Cav1.2, but not Cav1.3 LTCC subtype regulates, at least in part, the reinforcing effects of nicotine use.

  13. RhoA knockout fibroblasts lose tumor-inhibitory capacity in vitro and promote tumor growth in vivo

    Science.gov (United States)

    Alkasalias, Twana; Alexeyenko, Andrey; Hennig, Katharina; Danielsson, Frida; Lebbink, Robert Jan; Fielden, Matthew; Turunen, S. Pauliina; Lehti, Kaisa; Kashuba, Vladimir; Madapura, Harsha S.; Bozoky, Benedek; Lundberg, Emma; Balland, Martial; Guvén, Hayrettin; Klein, George; Gad, Annica K. B.; Pavlova, Tatiana

    2017-01-01

    Fibroblasts are a main player in the tumor-inhibitory microenvironment. Upon tumor initiation and progression, fibroblasts can lose their tumor-inhibitory capacity and promote tumor growth. The molecular mechanisms that underlie this switch have not been defined completely. Previously, we identified four proteins overexpressed in cancer-associated fibroblasts and linked to Rho GTPase signaling. Here, we show that knocking out the Ras homolog family member A (RhoA) gene in normal fibroblasts decreased their tumor-inhibitory capacity, as judged by neighbor suppression in vitro and accompanied by promotion of tumor growth in vivo. This also induced PC3 cancer cell motility and increased colony size in 2D cultures. RhoA knockout in fibroblasts induced vimentin intermediate filament reorganization, accompanied by reduced contractile force and increased stiffness of cells. There was also loss of wide F-actin stress fibers and large focal adhesions. In addition, we observed a significant loss of α-smooth muscle actin, which indicates a difference between RhoA knockout fibroblasts and classic cancer-associated fibroblasts. In 3D collagen matrix, RhoA knockout reduced fibroblast branching and meshwork formation and resulted in more compactly clustered tumor-cell colonies in coculture with PC3 cells, which might boost tumor stem-like properties. Coculturing RhoA knockout fibroblasts and PC3 cells induced expression of proinflammatory genes in both. Inflammatory mediators may induce tumor cell stemness. Network enrichment analysis of transcriptomic changes, however, revealed that the Rho signaling pathway per se was significantly triggered only after coculturing with tumor cells. Taken together, our findings in vivo and in vitro indicate that Rho signaling governs the inhibitory effects by fibroblasts on tumor-cell growth. PMID:28174275

  14. 钙激活性氯离子通道与高肺血流性肺动脉高压%Ca2+-activated Cl- channels and pulmonary hypertension induced by high pulmonary blood flow

    Institute of Scientific and Technical Information of China (English)

    陈传斯; 庞玉生

    2012-01-01

    Pulmonary hypertension induced by high pulmonary blood flow involves a variety of complex mecha -nisms, including endothelial damage , pulmonary artery smooth muscle relaxation - contraction disorder and vascular remod -eling. Besides, the factor of ion channels in pulmonary artery smooth muscle cells is also highly correlated to vasoconstric -tion. In recent years , many studies have shown that activation of Ca - activated Cl channels is responsible for the membrane depolarization of pulmonary artery smooth muscle cells , and plays an important role in the regulation of vascular tone and vasoconstriction. This article reviews the biophysical and pharmacological characteristics of Ca - activated Cl channels as well as the influence of Ca - activated Cl channels in high pulmonary blood flow - induced pulmonary hyperten -sion.

  15. Monitoring channel head erosion processes in response to an artificially induced abrupt base level change using time-lapse photography

    Science.gov (United States)

    Nichols, M. H.; Nearing, M.; Hernandez, M.; Polyakov, V. O.

    2016-07-01

    Gullies that terminate at a vertical-wall are ubiquitous throughout arid and semiarid regions. Multi-year assessments of gully evolution and headcut advance are typically accomplished using traditional ground surveys and aerial photographs, with much recent research focused on integrating data collected at very high spatial resolutions using new techniques such as aerial surveys with blimps or kites and ground surveys with LiDar scanners. However, knowledge of specific processes that drive headcut advance is limited due to inadequate observation and documentation of flash floods and subsequent erosion that can occur at temporal resolutions not captured through repeat surveys. This paper presents a method for using very-high temporal resolution ground-based time-lapse photography to capture short-duration flash floods and gully head evolution in response. In 2004, a base level controlling concrete weir was removed from the outlet of a 1.29 ha semiarid headwater drainage on the Walnut Gulch Experimental Watershed in southeastern Arizona, USA. During the ten year period from 2004 to 2014 the headcut migrated upchannel a total of 14.5 m reducing the contributing area at the headwall by 9.5%. Beginning in July 2012, time-lapse photography was employed to observe event scale channel evolution dynamics. The most frequent erosion processes observed during three seasons of time-lapse photography were plunge pool erosion and mass wasting through sidewall or channel headwall slumping that occurred during summer months. Geomorphic change during the ten year period was dominated by a single piping event in August 2014 that advanced the channel head 7.4 m (51% of the overall advance) and removed 11.3 m3 of sediment. High temporal resolution time-lapse photography was critical for identifying subsurface erosion processes, in the absence of time-lapse images piping would not have been identified as an erosion mechanism responsible for advancing the gully headwall at this site.

  16. ZO-1 knockout by TALEN-mediated gene targeting in MDCK cells: involvement of ZO-1 in the regulation of cytoskeleton and cell shape.

    Directory of Open Access Journals (Sweden)

    Shinsaku Tokuda

    Full Text Available ZO-1, ZO-2 and ZO-3 are tight junction-associated scaffold proteins that bind to transmembrane proteins of tight junctions and the underlying cytoskeleton. ZO-1 is involved in the regulation of cytoskeletal organization, but its detailed molecular mechanism is less well understood. Gene knockout is an ideal method to investigate the functions of proteins that might have redundant functions such as ZO proteins, when compared with methods such as RNA interference-mediated suppression of gene expression. In this study we applied transcription activator-like effector nucleases (TALENs, a recently developed genome editing method for gene knockout, and established ZO-1 knockout clones in Madin-Darby canine kidney (MDCK cells. ZO-1 knockout induced striking changes in myosin organization at cell-cell contacts and disrupted the localization of tight junction proteins; these findings were previously unseen in studies of ZO-1 knockdown by RNA interference. Rescue experiments revealed that trace ZO-1 expression reversed these changes while excessive ZO-1 expression induced an intensive zigzag shape of cell-cell junctions. These results suggest a role for ZO-1 in the regulation of cytoskeleton and shape of cell-cell junctions in MDCK cells and indicate the advantage of knockout analysis in cultured cells.

  17. 肌肉特异性糖皮质激素受体基因敲除对慢性肾脏病骨骼肌消耗的影响%Muscle specific glucocorticoids receptor gene knockout rescue muscle atrophy induced by CKD

    Institute of Scientific and Technical Information of China (English)

    王会玲; 丁婷婷; 许烨; 张金元

    2012-01-01

    Objective: The endogenous glucocorticoids ( GC) is required for activation of muscle protein degradation in chronic kidney disease (CKD) related protein energy wasting. We studied the muscle wasting in a muscle specific glucocorticoids receptor knockout mouse ( MGRKO) with CKD model. We hypothesis the MGRKO could suppress muscle atrophy. Methodology: MGRKO and lox/lox mice CKD model was made by 5/6 nephroctomy, and the sham was regarded as control (CTL). The serum corticosteroid hormone was measured by ELISA. The bodyweight and Tibia Anterior (TA) muscle weight were measured. The TA muscle size of was observed under microscope and calculated with software. The expression of Atrogin-1 ( Muscle Atrophy Fbox-1) and MuRF-1 ( Muscle RING finger 1) was measured by Q-PCR and western blot. We also analyzed the signaling pathway of Akt/FoxOl. Results: The levels of serum BUN and corticosteroids were increased dramatically in lox/lox-CKD and MGRKO-CKD, but no differences between two groups. The bodyweight and TA muscle weight in the lox/lox-CKD was lower than that in the lox/lox- CTL L; but no difference between the MGKO-CTL and MGKO-CKD. The cross-sectional area of muscle fibers in the MGRKO-CKD was smaller, and the shrinkages of fibers sizes caused leftward shift in fiber size distribution was obvious in lox/lox-CKD, but only mild change in ' MGRKO + CKD mice's muscle. The level of Atrogin-1 and MuRF-1 was increased dramatically, and the Akt/FoxOlsignaling pathway was abnormal which showed the level of phosphorylated Akt/FoxOl repressive simultaneously in lox/lox-CKD (P< 0.001). Whereas, the Atrogin-1 mRNA showed a mild higher ( P < 0. 05 ), the MuRF-1 mRNA 'showed no difference, and the Akt/FoxOl signaling abnormal was unconspicuous in the MGKO-CKD, which showed suppresses insulin/ IGF-1 stimulation of Akt/FoxOl activities. The MGRKO could resist to this abnormal, hence, ameliorate CKD induced muscle wasting. Conclusion: Endogenous Glucocorticoids ( GC) may play an

  18. Downregulation of Kv4.2 and Kv4.3 channel gene expression in right ventricular hypertrophy induced by monocrotaline in rat

    Institute of Scientific and Technical Information of China (English)

    Tian-tai ZHANG; Bing CUI; De-zai DAI

    2004-01-01

    AIM: To investigate the differences in gene expression of transient outward potassium ion channel between the free wall of right ventricle, free wall of left ventricle, and the septum in monocrotaline (MCT)-induced right ventricular hypertrophy of rat. METHODS: Twenty rats were randomly divided into two groups: a single injection of monocrotaline (MCT) 60 mg/kg (model) or saline (control). Four weeks later, hemodynamic parameters were measured and the gene expression of Ito channels were detected by semi-quantitative RT-PCR. RESUITS: After 28 d, the right ventricular systolic pressure and central venous pressure were remarkably elevated by 128 % and 533 % in the MCT-treated group, accompanied by an overt right ventricle (RV) remodeling. The difference of mRNA expression of Kv1.4 was not significant in free wall of RV, left ventricle (LV), and septum in MCT group compared with control group. In contrast, mRNA of Ky4.2 and Ky4.3 in the free wall of RV in MCT-induced rat was dramatically decreased by 45.2 % and 51.1% vs control, however, in free wall of LV and septum, no difference was found. In addition, mRNA expression level of Ky4.2 in control rat was significantly lower in septum than that in free wall of RV and LV. CONCLUSION: Expression of Kv1.4. Ky4.2, and Kv4.3 differs between regions in normal rat hearts. The down-regulation of Ky4 family gene expression of Ito contributed to the pathophysiological changes in ventricular hypertrophy and pulmonary hypertension induced by MCT.

  19. Effect of P2X7 receptor knockout on AQP-5 expression of type I alveolar epithelial cells.

    Directory of Open Access Journals (Sweden)

    Georg Ebeling

    Full Text Available P2X7 receptors, ATP-gated cation channels, are specifically expressed in alveolar epithelial cells. The pathophysiological function of this lung cell type, except a recently reported putative involvement in surfactant secretion, is unknown. In addition, P2X7 receptor-deficient mice show reduced inflammation and lung fibrosis after exposure with bleomycin. To elucidate the role of the P2X7 receptor in alveolar epithelial type I cells we characterized the pulmonary phenotype of P2X7 receptor knockout mice by using immunohistochemistry, western blot analysis and real-time RT PCR. No pathomorphological signs of fibrosis were found. Results revealed, however, a remarkable loss of aquaporin-5 protein and mRNA in young knockout animals. Additional in vitro experiments with bleomycin treated precision cut lung slices showed a greater sensitivity of the P2X7 receptor knockout mice in terms of aquaporin-5 reduction as wild type animals. Finally, P2X7 receptor function was examined by using the alveolar epithelial cell lines E10 and MLE-12 for stimulation experiments with bleomycin. The in vitro activation of P2X7 receptor was connected with an increase of aquaporin-5, whereas the inhibition of the receptor with oxidized ATP resulted in down regulation of aquaporin-5. The early loss of aquaporin-5 which can be found in different pulmonary fibrosis models does not implicate a specific pathogenetic role during fibrogenesis.

  20. MAO A knockout attenuates adrenocortical response to various kinds of stress.

    Science.gov (United States)

    Popova, Nina K; Maslova, Larissa N; Morosova, Ekaterina A; Bulygina, Veta V; Seif, Isabelle

    2006-02-01

    The effect of a lack of the gene encoding monoamine oxidase A (MAO A) in transgenic Tg 8 mice on the corticosterone response to restraint, cold, water deprivation-induced, or social acute stress as well as chronic variable stress was studied. It was found that Tg 8 mice with genetic MAO A knockout and wild-type C3H/HeJ (C3H) strain showed similar plasma corticosterone resting level. MAO A knockout mice differed from C3H mice by attenuated response to restraint (60 min), cold (4 degrees C, 60 min), and water deprivation (48 h) as well as to a chronic (15 days) variable stress. No difference between Tg 8 and C3H strains in the response to psychosocial stress (encounters for 30 min of six previously isolated mice) has been found. ACTH administration to dexamethasone-pretreated mice produced a similar corticosterone effect in Tg 8 and C3H mice, indicating that the decreased stress response in MAO A-deficient mice was due rather to the central mechanisms regulating stress-induced ACTH release than to adrenocortical responsiveness to ACTH.

  1. Multiphysics simulation of ion concentration polarization induced by a surface-patterned nanoporous membrane in single channel devices.

    Science.gov (United States)

    Jia, Mingjie; Kim, Taesung

    2014-10-21

    Microfluidic devices utilize ion concentration polarization (ICP) phenomena for a variety of applications, but a comprehensive understanding of the generation of ICP is still necessary. Recently, the emergence of a novel single channel ICP (SC-ICP) device has stimulated further research on the mechanism of ICP generation, so that we developed a 2-D model of an SC-ICP device that integrates a nanoporous membrane on the bottom surface of the channel, allowing bulk flow over the membrane. We solved a set of coupled governing equations with appropriate boundary conditions to explore ICP numerically. As a result, we not only showed that the simulation results held a strong qualitative agreement with experimental results, but also found the distribution of ion concentrations in the SC-ICP device that has never been reported in previous studies. We confirmed again that the electrophoretic mobility (EPM) of counterions in the membrane is the most dominant factor determining the generation and strength of ICP, whereas the charge density of the membrane was dominant to the ICP strength only when a high EPM value was assumed. From the viewpoint of practical applications, an SC-ICP device with a long membrane under low buffer strength showed enhanced performance in the preconcentration of charged molecules. Therefore, we believe that the simulation results could not only provide sharp insight into ICP phenomena but also predict and optimize the performance of SC-ICP devices in various microfluidic applications.

  2. The Computational Complexity of the Parallel Knock-Out Problem

    NARCIS (Netherlands)

    Broersma, H.J.; Johnson, M.; Paulusma, D.; Stewart, I.A.; Correa, J.R.; Hevia, A.; Kiwi, M.

    2006-01-01

    We consider computational complexity questions related to parallel knock-out schemes for graphs. In such schemes, in each round, each remaining vertex of a given graph eliminates exactly one of its neighbours. We show that the problem of whether, for a given graph, such a scheme can be found that el

  3. The mammalian gene function resource: The International Knockout Mouse Consortium

    NARCIS (Netherlands)

    A. Bradley (Allan); K. Anastassiadis (Konstantinos); A. Ayadi (Abdelkader); J.F. Battey (James); C. Bell (Cindy); M.-C. Birling (Marie-Christine); J. Bottomley (Joanna); S.D.M. Brown (Steve); F. Bürger (Friederike); C.J. Bult (Carol); W. Bushell (Wendy); F.S. Collins (Francis); C. Desaintes (Christian); B. Doe (Brendan); E. Aris (Economides); J.T. Eppig (Janan); R.H. Finnell (Richard); C. Fletcher (Colin); M. Fray (Martin); D. Frendewey (David); R.H. Friedel (Roland); F.G. Grosveld (Frank); J. Hansen; Y. Hérault (Yann); G. Hicks (Geoffrey); A. Hörlein (Andreas); C. Houghton (Catherine); M. Hrabé De Angelis (Martin); D. Huylebroeck (Danny); V. Iyer (Vivek); P.J. de Jong (Pieter); J.A. Kadin (James); C. Kaloff (Cornelia); K. Kennedy (Karen); M. Koutsourakis (Manousos); K.C. Kent Lloyd (K.); S. Marschall (Susan); J. Mason (Jeremy); C. McKerlie (Colin); M.P. McLeod (Michael); H. von Melchner (Harald); M. Moore (Matt); A.O. Mujica (Alejandro); A. Nagy (Andras); M. Nefedov (Mikhail); L.M. Nutter (Lauryl); G. Pavlovic (Guillaume); J.L. Peterson (Jane); I. Pollock; R. Ramirez-Solis (Ramiro); D.E. Rancourt (Derrick); M. Raspa (Marcello); J.E. Remacle (Jacques); M. Ringwald (Martin); B. Rosen (Barry); N. Rosenthal (Nadia); J. Rossant (Janet); P. Ruiz Noppinger (Patricia); S. Ryder; J.Z. Schick (Joel Zupicich); F. Schnütgen (Frank); C.J. Schofield (Christopher); C. Seisenberger (Claudia); M. Selloum (Mohammed); E.M. Simpson (Elizabeth); W.C. Skarnes (William); D. Smedley (Damian); W.L. Stanford (William); A. Francis Stewart (A.); K. Stone (Kevin); K. Swan (Kate); H. Tadepally (Hamsa); J.L. Teboul (Jean Louis); G.P. Tocchini-Valentini (Glauco); D. Valenzuela (David); A.P. West (Anthony); K.-I. Yamamura (Ken-Ichi); Y. Yoshinaga (Yuko); M. Wurst (Martin)

    2012-01-01

    textabstractIn 2007, the International Knockout Mouse Consortium (IKMC) made the ambitious promise to generate mutations in virtually every protein-coding gene of the mouse genome in a concerted worldwide action. Now, 5 years later, the IKMC members have developed highthroughput gene trapping and, i

  4. Threshold Energies for Single Carbon Knockout from Polycyclic Aromatic Hydrocarbons

    CERN Document Server

    Stockett, M H; Chen, T; de Ruette, N; Giacomozzi, L; Wolf, M; Schmidt, H T; Zettergren, H; Cederquist, H

    2015-01-01

    We have measured absolute cross sections for ultrafast (fs) single-carbon knockout from Polycyclic Aromatic Hydrocarbon (PAH) cations as functions of He-PAH center-of-mass collision energy in the range 10-200 eV. Classical Molecular Dynamics (MD) simulations cover this range and extend up to 10$^5$ eV. The shapes of the knockout cross sections are well described by a simple analytical expression yielding experimental and MD threshold energies of $E_{th}^{Exp}=32.5\\pm 0.4$ eV and $E_{th}^{MD}=41.0\\pm 0.3$ eV, respectively. These are the first measurements of knockout threshold energies for molecules isolated \\emph{in vacuo}. We further deduce semi-empirical (SE) and MD displacement energies --- \\emph{i.e.} the energy transfers to the PAH molecules at the threshold energies for knockout --- of $T_{disp}^{SE}=23.3\\pm 0.3$ eV and $T_{disp}^{MD}=27.0\\pm 0.3$ eV. The semi-empirical results compare favorably with measured displacement energies for graphene $T_{disp}=23.6$ eV [Meyer \\emph{et al.} Phys. Rev Lett. \\tex...

  5. Role of acid-sensing ion channel 3 in sub-acute-phase inflammation

    Directory of Open Access Journals (Sweden)

    Chen Chien-Ju

    2009-01-01

    Full Text Available Abstract Background Inflammation-mediated hyperalgesia involves tissue acidosis and sensitization of nociceptors. Many studies have reported increased expression of acid-sensing ion channel 3 (ASIC3 in inflammation and enhanced ASIC3 channel activity with pro-inflammatory mediators. However, the role of ASIC3 in inflammation remains inconclusive because of conflicting results generated from studies of ASIC3 knockout (ASIC3-/- or dominant-negative mutant mice, which have shown normal, decreased or increased hyperalgesia during inflammation. Results Here, we tested whether ASIC3 plays an important role in inflammation of subcutaneous tissue of paw and muscle in ASIC3-/- mice induced by complete Freund's adjuvant (CFA or carrageenan by investigating behavioral and pathological responses, as well as the expression profile of ion channels. Compared with the ASIC3+/+ controls, ASIC3-/- mice showed normal thermal and mechanical hyperalgesia with acute (4-h intraplantar CFA- or carrageenan-induced inflammation, but the hyperalgesic effects in the sub-acute phase (1–2 days were milder in all paradigms except for thermal hyperalgesia with CFA-induced inflammation. Interestingly, carrageenan-induced primary hyperalgesia was accompanied by an ASIC3-dependent Nav1.9 up-regulation and increase of tetrodotoxin (TTX-resistant sodium currents. CFA-inflamed muscle did not evoke hyperalgesia in ASIC3-/- or ASIC3+/+ mice, whereas carrageenan-induced inflammation in muscle abolished mechanical hyperalgesia in ASIC3-/- mice, as previously described. However, ASIC3-/- mice showed attenuated pathological features such as less CFA-induced granulomas and milder carrageenan-evoked vasculitis as compared with ASIC3+/+ mice. Conclusion We provide a novel finding that ASIC3 participates in the maintenance of sub-acute-phase primary hyperalgesia in subcutaneous inflammation and mediates the process of granuloma formation and vasculitis in intramuscular inflammation.

  6. Activation of ATP-sensitive potassium channel by iptakalim normalizes stress-induced HPA axis disorder and depressive behaviour by alleviating inflammation and oxidative stress in mouse hypothalamus.

    Science.gov (United States)

    Zhao, Xiao-Jie; Zhao, Zhan; Yang, Dan-Dan; Cao, Lu-Lu; Zhang, Ling; Ji, Juan; Gu, Jun; Huang, Ji-Ye; Sun, Xiu-Lan

    2017-02-01

    Stress-induced disturbance of the hypothalamic-pituitary-adrenal (HPA) axis is strongly implicated in incidence of mood disorders. A heightened neuroinflammatory response and oxidative stress play a fundamental role in the dysfunction of the HPA axis. We have previously demonstrated that iptakalim (Ipt), a new ATP-sensitive potassium (K-ATP) channel opener, could prevent oxidative injury and neuroinflammation against multiple stimuli-induced brain injury. The present study was to demonstrate the impacts of Ipt in stress-induced HPA axis disorder and depressive behavior. We employed 2 stress paradigms: 8 weeks of continuous restraint stress (chronic restraint stress, CRS) and 2h of restraint stress (acute restraint stress, ARS), to mimic both chronic stress and severe acute stress. Prolonged (4 weeks) and short-term (a single injection) Ipt treatment was administered 30min before each stress paradigm. We found that HPA axis was altered after stress, with different responses to CRS (lower ACTH and CORT, higher AVP, but normal CRH) and ARS (higher CRH, ACTH and CORT, but normal AVP). Both prolonged and short-term Ipt treatment normalized stress-induced HPA axis disorders and abnormal behaviors in mice. CRS and ARS up-regulated mRNA levels of inflammation-related molecules (TNFα, IL-1β, IL-6 and TLR4) and oxidative stress molecules (gp91phox, iNOS and Nrf2) in the mouse hypothalamus. Double immunofluorescence showed CRS and ARS increased microglia activation (CD11b and TNFα) and oxidative stress in neurons (NeuN and gp91phox), which were alleviated by Ipt. Therefore, the present study reveals that Ipt could prevent against stress-induced HPA axis disorders and depressive behavior by alleviating inflammation and oxidative stress in the hypothalamus.

  7. Poly I:C induces an antiviral state against Ictalurid Herpesvirus 1 and Mx1 transcription in the channel catfish (Ictalurus punctatus).

    Science.gov (United States)

    Plant, Karen P; Harbottle, Heather; Thune, Ronald L

    2005-01-01

    In vivo studies were carried out to investigate the protective effect of the interferon inducer poly I:C against channel catfish virus (CCV). Channel catfish were stimulated by intraperitoneal injection of 50 microg of poly I:C or PBS at various days prior to immersion challenge with CCV. Mortality in the poly I:C group was significantly reduced from 70% to 3% at day 1 compared to the PBS controls. Mortality increased at day 3 but was still significantly different from the PBS controls. Mx1 transcription was significantly higher only at day 1. In an additional study Mx1 transcription was monitored in the liver, kidney, gills, spleen, and intestine at various time points post-stimulation with either poly I:C or CCV. Mx1 mRNA was significantly elevated in all organs only at day 1 post-injection with poly I:C. In response to CCV, Mx1 transcription was not significantly elevated until day 3 post-challenge, but remained elevated in certain organs until day 7.

  8. Effects of Arecoline on Calcium Channel Currents and Caffeine-induced Calcium Release in Isolated Single Ventricular Myocyte of Guinea Pig

    Institute of Scientific and Technical Information of China (English)

    林先明; 李真; 胡本容; 夏国瑾; 姚伟星; 向继洲

    2002-01-01

    Summary: The effects of Arecoline (Are) on calcium mobilization were investigated. In isolatedsingle ventricular myocyte of guinea pig, patch clamp whole cell recording techniques were used torecord the current of L-type calcium channel and cytosolic Ca2+ level ([Ca2+]i) labeled with fluo-rescence probe Fluo-3/AM was measured under a laser scanning confocal microscope. Results re-vealed that Are (3-100 μmol/L) could inhibit L-type calcium current in a concentration-depen-dent manner and the value of IC50 was 33. 73μmol/L (n= 5). In the absence of extracellular calci-um, the resting levels of [Ca2+]i was not affected by Are (n=6, P>0. 05), but pretreatmentwith Are (30 μmol/L) could significantly inhibit the [Ca2+]i elevation induced by caffeine (10mmol/L, n = 6, P < 0. 01). It was concluded that Are could inhibit not only calcium influxthrough L-type calcium channel but also calcium release from sarcoplasmic reticulum.

  9. p21{sup WAF1/Cip1/Sdi1} knockout mice respond to doxorubicin with reduced cardiotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Terrand, Jerome; Xu, Beibei; Morrissy, Steve; Dinh, Thai Nho [Department of Pharmacology,College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724 (United States); Williams, Stuart [Biomedical Engineering Program, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724 (United States); Chen, Qin M., E-mail: qchen@email.arizona.edu [Department of Pharmacology,College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson, AZ 85724 (United States)

    2011-11-15

    Doxorubicin (Dox) is an antineoplastic agent that can cause cardiomyopathy in humans and experimental animals. As an inducer of reactive oxygen species and a DNA damaging agent, Dox causes elevated expression of p21{sup WAF1/Cip1/Sdi1} (p21) gene. Elevated levels of p21 mRNA and p21 protein have been detected in the myocardium of mice following Dox treatment. With chronic treatment of Dox, wild type (WT) animals develop cardiomyopathy evidenced by elongated nuclei, mitochondrial swelling, myofilamental disarray, reduced cardiac output, reduced ejection fraction, reduced left ventricular contractility, and elevated expression of ANF gene. In contrast, p21 knockout (p21KO) mice did not show significant changes in the same parameters in response to Dox treatment. In an effort to understand the mechanism of the resistance against Dox induced cardiomyopathy, we measured levels of antioxidant enzymes and found that p21KO mice did not contain elevated basal or inducible levels of glutathione peroxidase and catalase. Measurements of 6 circulating cytokines indicated elevation of IL-6, IL-12, IFN{gamma} and TNF{alpha} in Dox treated WT mice but not p21KO mice. Dox induced elevation of IL-6 mRNA was detected in the myocardium of WT mice but not p21KO mice. While the mechanism of the resistance against Dox induced cardiomyopathy remains unclear, lack of inflammatory response may contribute to the observed cardiac protection in p21KO mice. -- Highlights: Black-Right-Pointing-Pointer Doxorubicin induces p21 elevation in the myocardium. Black-Right-Pointing-Pointer Doxorubicin causes dilated cardiomyopathy in wild type mice. Black-Right-Pointing-Pointer p21 Knockout mice are resistant against doxorubicin induced cardiomyopathy. Black-Right-Pointing-Pointer Lack of inflammatory response correlates with the resistance in p21 knockout mice.

  10. Flow-Induced New Channels of Energy Exchange in Multi-Scale Plasma Dynamics – Revisiting Perturbative Hybrid Kinetic-MHD Theory

    Science.gov (United States)

    Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go

    2016-01-01

    It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle’s Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas. PMID:27160346

  11. Coupled-channels effects in elastic scattering and near-barrier fusion induced by