Sample records for cardiac sarcoplasmic reticulum

  1. Digoxin activates sarcoplasmic reticulum Ca(2+)-release channels: a possible role in cardiac inotropy.



    1. The effect of digoxin on rapid 45Ca2+ efflux from cardiac and skeletal sarcoplasmic reticulum (SR) vesicles was investigated. Additionally the interaction of digoxin with single cardiac and skeletal muscle SR Ca(2+)-release channels incorporated into planar phospholipid bilayers and held under voltage clamp was determined. 2. Digoxin (1 nM) increased the initial rate and amount of Ca(2+)-induced release of 45Ca2+ from cardiac SR vesicles, passively loaded with 45CaCl2, at an extravesicular...

  2. Down-regulation of the cardiac sarcoplasmic reticulum ryanodine channel in severely food-restricted rats

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    V.A. Vizotto


    Full Text Available We have shown that myocardial dysfunction induced by food restriction is related to calcium handling. Although cardiac function is depressed in food-restricted animals, there is limited information about the molecular mechanisms that lead to this abnormality. The present study evaluated the effects of food restriction on calcium cycling, focusing on sarcoplasmic Ca2+-ATPase (SERCA2, phospholamban (PLB, and ryanodine channel (RYR2 mRNA expressions in rat myocardium. Male Wistar-Kyoto rats, 60 days old, were submitted to ad libitum feeding (control rats or 50% diet restriction for 90 days. The levels of left ventricle SERCA2, PLB, and RYR2 were measured using semi-quantitative RT-PCR. Body and ventricular weights were reduced in 50% food-restricted animals. RYR2 mRNA was significantly decreased in the left ventricle of the food-restricted group (control = 5.92 ± 0.48 vs food-restricted group = 4.84 ± 0.33, P < 0.01. The levels of SERCA2 and PLB mRNA were similar between groups (control = 8.38 ± 0.44 vs food-restricted group = 7.96 ± 0.45, and control = 1.52 ± 0.06 vs food-restricted group = 1.53 ± 0.10, respectively. Down-regulation of RYR2 mRNA expressions suggests that chronic food restriction promotes abnormalities in sarcoplasmic reticulum Ca2+ release.

  3. Crosstalk between mitochondrial and sarcoplasmic reticulum Ca2+ cycling modulates cardiac pacemaker cell automaticity.

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    Yael Yaniv

    Full Text Available BACKGROUND: Mitochondria dynamically buffer cytosolic Ca(2+ in cardiac ventricular cells and this affects the Ca(2+ load of the sarcoplasmic reticulum (SR. In sinoatrial-node cells (SANC the SR generates periodic local, subsarcolemmal Ca(2+ releases (LCRs that depend upon the SR load and are involved in SANC automaticity: LCRs activate an inward Na(+-Ca(2+ exchange current to accelerate the diastolic depolarization, prompting the ensemble of surface membrane ion channels to generate the next action potential (AP. OBJECTIVE: To determine if mitochondrial Ca(2+ (Ca(2+ (m, cytosolic Ca(2+ (Ca(2+ (c-SR-Ca(2+ crosstalk occurs in single rabbit SANC, and how this may relate to SANC normal automaticity. RESULTS: Inhibition of mitochondrial Ca(2+ influx into (Ru360 or Ca(2+ efflux from (CGP-37157 decreased [Ca(2+](m to 80 ± 8% control or increased [Ca(2+](m to 119 ± 7% control, respectively. Concurrent with inhibition of mitochondrial Ca(2+ influx or efflux, the SR Ca(2+ load, and LCR size, duration, amplitude and period (imaged via confocal linescan significantly increased or decreased, respectively. Changes in total ensemble LCR Ca(2+ signal were highly correlated with the change in the SR Ca(2+ load (r(2 = 0.97. Changes in the spontaneous AP cycle length (Ru360, 111 ± 1% control; CGP-37157, 89 ± 2% control in response to changes in [Ca(2+](m were predicted by concurrent changes in LCR period (r(2 = 0.84. CONCLUSION: A change in SANC Ca(2+ (m flux translates into a change in the AP firing rate by effecting changes in Ca(2+ (c and SR Ca(2+ loading, which affects the characteristics of spontaneous SR Ca(2+ release.

  4. Digoxin activates sarcoplasmic reticulum Ca(2+)-release channels: a possible role in cardiac inotropy. (United States)

    McGarry, S J; Williams, A J


    1. The effect of digoxin on rapid 45Ca2+ efflux from cardiac and skeletal sarcoplasmic reticulum (SR) vesicles was investigated. Additionally the interaction of digoxin with single cardiac and skeletal muscle SR Ca(2+)-release channels incorporated into planar phospholipid bilayers and held under voltage clamp was determined. 2. Digoxin (1 nM) increased the initial rate and amount of Ca(2+)-induced release of 45Ca2+ from cardiac SR vesicles, passively loaded with 45CaCl2, at an extravesicular [Ca2+] of 0.1 microM. The efflux in the presence and absence of digoxin was inhibited at pM extravesicular Ca2+ and blocked by 5 mM Mg2+. 3. To elucidate the mechanism of action of digoxin, single-channel recording was used. Digoxin (1-20 nM) increased single-channel open probability (Po) when added to the cytosolic but not the luminal face of the cardiac channel in the presence of sub-maximally activating Ca2+ (0.1 microM-10 microM) with an EC50 of 0.91 nM at 10 microM Ca2+. The mechanisms underlying the action of digoxin appear to be concentration-dependent. The activation observed at 1 nM digoxin appears to be consistent with the sensitization of the channel to the effects of Ca2+. At higher concentrations the drug appears to interact synergistically with Ca2+ to produce values of Po considerably greater than those seen with Ca2+ as the sole activating ligand. 4. Digoxin had no effect on single-channel conductance or the Ca2+/Tris permeability ratio. In channels activated by digoxin the Po was decreased by Mg2+. Single-channels were characteristically modified to along lasting open, but reduced, conductance state when 100 nM ryanodine was added to the cytosolic side of the channel.5. Activation of the cardiac SR Ca2+-release channel was observed with similar concentrations of digitoxin, however, higher concentrations of ouabain were required to increase PO. In contrast, a steroid which is not positively inotropic, chlormadinone acetate, had no effect on either cardiac or

  5. Spontaneous Ca2+ release from the sarcoplasmic reticulum limits Ca2+- dependent twitch potentiation in individual cardiac myocytes. A mechanism for maximum inotropy in the myocardium



    We hypothesized that the occurrence of spontaneous Ca2+ release from the sarcoplasmic reticulum (SR), in diastole, might be a mechanism for the saturation of twitch potentiation common to a variety of inotropic perturbations that increase the total cell Ca. We used a videomicroscopic technique in single cardiac myocytes to quantify the amplitude of electrically stimulated twitches and to monitor the occurrence of the mechanical manifestation of spontaneous SR Ca2+ release, i.e., the spontaneo...

  6. Effects of Mg2+ on Ca2+ handling by the sarcoplasmic reticulum in skinned skeletal and cardiac muscle fibres. (United States)

    Kabbara, A A; Stephenson, D G


    The influence of myoplasmic Mg2+ (0.05-10 mM) on Ca2+ accumulation (net Ca2+ flux) and Ca2+ uptake (pump-driven Ca2+ influx) by the intact sarcoplasmic reticulum (SR) was studied in skinned fibres from the toad iliofibularis muscle (twitch portion), rat extensor digitorum longus (EDL) muscle (fast twitch), rat soleus muscle (slow twitch) and rat cardiac trabeculae. Ca2+ accumulation was optimal between 1 and 3 mM Mg2+ in toad fibres and reached a plateau between 1 and 10 mM Mg2+ in the rat EDL fibres and between 3 and 10 mM Mg2+ in the rat cardiac fibres. In soleus fibres, optimal Ca2+ accumulation occurred at 10 mM Mg2+. The same trend was obtained with all preparations at 0.3 and 1 microM Ca2+. Experiments with 2,5-di-(tert-butyl)-1,4-benzohydroquinone, a specific inhibitor of the Ca2+ pump, revealed a marked Ca2+ efflux from the SR of toad iliofibularis fibres in the presence of 0.2 microM Ca2+ and 1 mM Mg2+. Further experiments indicated that the SR Ca2+ leak could be blocked by 10 microM ruthenium red without affecting the SR Ca2+ pump and this allowed separation between SR Ca2+ uptake and SR Ca2+ accumulation. At 0.3 microM Ca2+, Ca2+ uptake was optimal with 1 mM Mg2+ in the toad iliofibularis and rat EDL fibres and between 1 and 10 mM Mg2+ in the rat soleus and trabeculae preparations. At higher [Ca2+] (1 microM), Ca2+ uptake was optimal with 1 mM Mg2+ in the iliofibularis fibres and between 1 and 3 mM Mg2+ in the EDL fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Phospholamban Modulates the Functional Coupling between Nucleotide Domains in Ca-ATPase Oligomeric Complexes in Cardiac Sarcoplasmic Reticulum

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    Chen, L.; Yao, Qing; Soares, Thereza A.; Squier, Thomas C.; Bigelow, Diana J.


    Oligomeric interactions between Ca-ATPase polypeptide chains and their modulation by phospholamban (PLB) were measured in native cardiac sarcoplasmic reticulum (SR) microsomes. Progressive modification of Lys514 with fluorescein-5-isothiocyanate (FITC), which physically blocks access to the nucleotide binding site by ATP, demonstrates that Ca-ATPase active sites function independently of one another prior to the phosphorylation of PLB. However, upon PKA-dependent phosphorylation of PLB, a second-order dependence between enzyme activity and the fraction of active sites is observed, consistent with a dimeric functional complex. Complementary distance measurements were made using FITC or 5-iodoacetamido-fluorescein (IAF) bound to Cys674 within the N- or P-domains respectively, to detect structural coupling within oligomeric complexes. Accompanying the phosphorylation of PLB, neighboring Ca-ATPase polypeptide chains exhibit a 4 ± 2 Å decrease in the proximity between FITC sites within the N-domain and a 9 ± 3 Å increase in the proximity between IAF sites within P-domains. Thus, the phosphorylation of PLB induces spatial rearrangements between the N- and P-domain elements of proximal Ca-ATPase polypeptide chains which restore functional interactions between neighboring polypeptide chains and, in turn, result in increased rates of catalytic turnover. These results are interpreted in terms of a structural model, calculated through optimization of shape complementarity, desolvation, and electrostatic energies, which suggests a dimeric arrangement of Ca-ATPase polypeptide chains through the proximal association of N-domains. We suggest that the phosphorylation of PLB acts to release constraints involving interdomain subunit interactions that enhance catalytically important N-domain motions.

  8. Conducting and voltage-dependent behaviors of potassium ion channels reconstituted from diaphragm sarcoplasmic reticulum: comparison with the cardiac isoform. (United States)

    Picher, M; Decrouy, A; Rousseau, E


    Sarcoplasmic reticulum (SR) K+ channels from canine diaphragm were studied upon fusion of longitudinal and junctional membrane vesicles into planar lipid bilayers (PLB). The large-conductance cation selective channel (gamma(max) = 250 pS; Km = 33 mM) displays long-lasting open events which are much more frequent at positive than at negative voltages. A major subconducting state about 45% of the fully-open state current amplitude was occasionally observed at all voltages. The voltage-dependence of the open probability displays a sigmoid relationship that was fitted by the Boltzmann equation and expressed in terms of thermodynamic parameters, namely the free energy (delta Gi) and the effective gating charge (Zs): delta Gi = 0.27 kcal/mol and Zs = -1.19 in 250 mM potassium gluconate (K-gluconate). Kinetic analyses also confirmed the voltage-dependent gating behavior of this channel, and indicate the implication of at least two open and three closed states. The diaphragm SR K+ channel shares several biophysical properties with the cardiac isoform: g = 180 pS, delta Gi = 0.75 kcal/mol, Zs = -1.45 in 150 mM K-gluconate, and a similar sigmoid P(o)/voltage relationship. Little is known about the regulation of the diaphragm and cardiac SR K+ channels. The conductance and gating of these channels were not influenced by physiological concentrations of Ca2+ (0.1 microM-1 mM) or Mg2+ (0.25-1 mM), as well as by cGMP (25-100 microM), lemakalim (1-100 microM), glyburide (up to 10 microM) or charybdotoxin (45-200 nM), added either to the cis or to the trans chamber. The apparent lack of biochemical or pharmacological modulation of these channels implies that they are not related to any of the well characterized surface membrane K+ channels. On the other hand, their voltage sensitivity strongly suggests that their activity could be modulated by putative changes in SR membrane potential that might occur during calcium fluxes.

  9. Luteolin improves cardiac dysfunction in heart failure rats by regulating sarcoplasmic reticulum Ca2+-ATPase 2a (United States)

    Hu, Wenjing; Xu, Tongda; Wu, Pei; Pan, Defeng; Chen, Junhong; Chen, Jing; Zhang, Buchun; Zhu, Hong; Li, Dongye


    We previously found that luteolin (Lut) appeared to improve the contractility of cardiomyocytes during ischemia/reperfusion in rats. The enhancement was associated with the alteration in sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a). This finding prompted us to consider if the mechanism worked in heart failure (HF). We studied the regulation of SERCA2a by Lut in failing cardiomyocytes and intact heart of rats. Improvement of contractility and the mechanisms centered on SERCA2a were studied in isolated cardiomyocytes and intact heart. We found that Lut significantly improved contractility and Ca2+ transients, ameliorated expression, activity and stability of SERCA2a and upregulated expression of small ubiquitin-related modifier (SUMO) 1, which is a newfound SERCA2a regulator. Lut also increased phosphorylation of protein kinase B (Akt), phospholaban (PLB) and sumoylation of SERCA2a, specificity protein 1 (Sp1). Transcriptions of SUMO1 and SERCA2a were concurrently increased. Inhibition of posphatidylinositol 3 kinase/Akt (PI3K/Akt) pathway and SERCA2a activity both markedly abolished Lut-induced benefits in vitro and in vivo. Lut upregulated the expression ratio of Bcl-2/Bax, caspase-3/cleaved-Caspase3. Meanwhile, Lut ameliorated the myocardium fibrosis of HF. These discoveries provide an important potential therapeutic strategy that Lut targeted SERCA2a SUMOylation related to PI3K/Akt-mediated regulations on rescuing the dysfunction of HF.

  10. Short-term effects of β2-AR blocker ICI 118,551 on sarcoplasmic reticulum SERCA2a and cardiac function of rats with heart failure. (United States)

    Gong, Haibin; Li, Yanfei; Wang, Lei; Lv, Qian; Wang, Xiuli


    The study was conducted to examine the effects of ICI 118,551 on the systolic function of cardiac muscle cells of rats in heart failure and determine the molecular mechanism of selective β2-adrenergic receptor (β2-AR) antagonist on these cells. The chronic heart failure model for rats was prepared through abdominal aortic constriction and separate cardiac muscle cells using the collagenase digestion method. The rats were then divided into Sham, HF and HF+ICI 50 nM goups and cultivated for 48 h. β2-AR, Gi/Gs and sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) protein expression levels in the cardiac muscle cells were evaluated by western blotting and changes in the systolic function of cardiac muscle cells based on the boundary detection system of contraction dynamics for individual cells was measured. The results showed that compared with the Sham group, the survival rate, percentage of basic contraction and maximum contraction amplitude percentage of cardiac muscle cells with heart failure decreased, Gi protein expression increased while Gs and SERCA2a protein expression decreased. Compared with the HF group, the maximum contraction amplitude percentage of cardiac muscle cells in group HF+ICI 50 nM decreased, the Gi protein expression level increased while the SERCA2a protein expression level decreased. Following the stimulation of Ca(2+) and ISO, the maximum contraction amplitude percentage of cardiac muscle cells in the HF+ICI 50 nM group was lower than that in group HF. This indicated that ICI 118,551 has negative inotropic effects on cardiac muscle cells with heart failure, which may be related to Gi protein. Systolic function of cardiac muscle cells with heart failure can therefore be reduced by increasing Gi protein expression and lowering SERCA2a protein expression.

  11. Decavanadate interactions with sarcoplasmic reticulum calcium pump



    Although not stable, once formed, decameric vanadate (V10) disintegration is in general slow enough to allow the study of its effects even in the micromolar range. Besides, it may become inaccessible to decomposition due to their specific interaction upon target proteins such as the Ca2+-ATPase from sarcoplasmic reticulum (SR). Characterization of the vanadate solutions and interactions with compounds containing phosphate as well as with the SR Ca2+-ATPase was analysed by 51V NMR spectr...

  12. Ameliorated stress related proteins are associated with improved cardiac function by sarcoplasmic reticulum calcium ATPase gene transfer in heart failure

    Institute of Scientific and Technical Information of China (English)

    Zhi-Qing Fu; Xiao-Ying Li; Xiao-Chun Lu; Ya-Fei Mi; Tao Liu; Wei-Hua Ye


    Background Previous studies showed that overexpression of sarco-endoplasmic reticulum calcium ATPase (SERCA2a) in a variety of heart failure (HF) models was associated with greatly enhanced cardiac performance. However, it still undefined the effect of SERCA2a overexpression on the systemic inflammatory response and neuro-hormonal factors. Methods A rapid right ventricular pacing model of experimental HF was used in beagles. Then the animals underwent recombinant adeno-associated virus 1 (rAAV1) mediated gene transfection by direct intra-myocardium injection. HF animals were randomized to receive the SERCA2a gene, enhanced green fluorescent protein (control) gene, or equivalent phosphate buffered saline. Thirty days after gene delivery, the cardiac function was evaluated by echocardiographic testing. The protein level of SERCA2a was measured by western blotting. The proteomic analysis of left ventricular (LV) sample was determined using two-dimensional (2-D) gel electrophoresis and MALDI-TOF-MS. The serum levels of the systemic inflammatory and neuro-hormonal factors were assayed using radioimmunoassay kits. Results The cardiac function improved after SERCA- 2a gene transfer due to the significantly increased SERCA2a protein level. Beagles treated with SERCA2a had significantly decreased serum levels of the inflammatory markers (interleukin-6 and tumor necrosis factor-α) and neuro-hormonal factors (brain natriuretic peptide, endothelin-1 and angiotensin Ⅱ) compared with HF animals. The myocardial proteomic analysis showed that haptoglobin heavy chain, heat shock protein (alpha-crystallin-related, B6) were down-regulated, and galectin-1 was up-regulated in SERCA2a group compared with HF group, companied by up-regulated contractile proteins and NADH dehydrogenase. Conclusions These findings demonstrate that regional intramyocardial injections of rAAV1-SERCA2a vectors may improve global LV function, correlating with reverse activation of the systemic inflammatory

  13. Cardiac function improved by sarcoplasmic reticulum Ca2+-ATPase overexpression in a heart failure model induced by chronic myocardial ischemia

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    Wei XIN


    Full Text Available Objective Chronic myocardial ischemia(CMI has become an important cause of heart failure(HF.The aim of present study was to examine the effects of Sarco-endoplasmic reticulum calcium ATPase(SERCA2a gene transfer in HF model in large animal induced by CMI.Methods HF was reproduced in minipigs by ligating the initial segment of proximal left anterior descending(LAD coronary artery with an ameroid constrictor to produce progressive vessel occlusion and ischemia.After confirmation of myocardial perfusion defect and cardiac function impairment by SPECT and echocardiography in the model,animals were divided into 4 groups: HF group;HF+enhanced green fluorescent protein(EGFP group;HF+SERCA2a group;and sham operation group as control.rAAV1-EGFP and rAAV1-SERCA2a(1×1012 vg for each animal were directly and intramyocardially injected to the animals of HF+EGFP and HF+SERCA2a groups.Sixty days after the gene transfer,the expression of SERCA2a at the protein level was examined by Western blotting and immunohistochemistry,the changes in cardiac function were determined by echocardiographic and hemodynamic analysis,and the changes in serum inflammatory and neuro-hormonal factors(including BNP,TNF-a,IL-6,ET-1 and Ang II were determined by radioimmunoassay.Results Sixty days after gene transfer,LVEF,Ev/Av and ±dp/dtmax increased significantly(P < 0.05,along with an increase of SERCA2a protein expression in the ischemic myocardium(PP < 0.05,accompanied by a significant decrease of inflammatory and neural-hormonal factors(PP < 0.05 in HF+SERCA2a group as compared with HF/HF+EGFP group.Conclusions Overexpression of SERCA2a may significantly improve the cardiac function of the ischemic myocardium of HF model induced by CMI and reverse the activation of neural-hormonal factors,implying that it has a potential therapeutic significance in CMI related heart failure.

  14. Improvement in cardiac function after sarcoplasmic reticulum Ca2+-ATPase gene transfer in a beagle heart failure model

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    MI Ya-fei; LI Xiao-ying; TANG Li-jiang; LU Xiao-chun; FU Zhi-qing; YE Wei-hua


    Background Heart failure (HF) is a major cause of morbidity and mortality worldwide, but current treatment modalities cannot reverse the underlying pathological state of the heart. Gene-based therapies are emerging as promising therapeutic modalities in HF patients. Our previous studies have shown that recombinant adeno-associated viral (rAAV) gene transfer of Sarco-endoplasmic reticulum calcium ATPase (SERCA2a) can be effective in treating rats with chronic heart failure (CHF). The aim of this study was to examine the effects of SERCA2a gene transfer in a large HF animal model.Methods HF was induced in beagles by rapid right ventricular pacing (230 beats/min) for 30 days. A reduced rate ventricular pacing (180 beats/min) was continued for another 30 days. The beagles were assigned to four groups: (a) control group (n=4); (b) HF group (n=4); (c) enhanced green fluorescent protein group (n=4); and (d) SERCA2.a group (n=4). rAAVl-EGFP (lx1012 μg) and rAAVl-SERCA2a (lx1012 μg) were delivered intramyocardially. SERCA2.a expression was assessed by Western blotting and immunohistochemistry.Results Following 30 days of SERCA2a gene transfer in HF beagles its protein expression was significantly higher than in the HF group than in the control group (P <0.05). Heart function improved along with the increase in SERCA2a expression. Left ventricular systolic function significantly improved, including the ejection fraction, left ventricular systolic pressure, maximal rate of rise of left ventricular pressure (+dp/dtmax), and the maximal rate of decline of left ventricular pressure (-dp/dtmax) (P <0.05). Left ventricular end-diastole pressure significantly decreased (P <0.05). The expression of SERCA2a in the myocardial tissue was higher in the SERCA2a group than in the HF group (P<0.05). Conclusions Intramyocardial injection of rAAVl-SERCA2a can improve the cardiac function in beagles induced with HE We expect further studies on SERCA2a's long-term safety, efficacy, dosage

  15. Nitric oxide-dependent activation of CaMKII increases diastolic sarcoplasmic reticulum calcium release in cardiac myocytes in response to adrenergic stimulation.

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    Jerry Curran

    Full Text Available Spontaneous calcium waves in cardiac myocytes are caused by diastolic sarcoplasmic reticulum release (SR Ca(2+ leak through ryanodine receptors. Beta-adrenergic (β-AR tone is known to increase this leak through the activation of Ca-calmodulin-dependent protein kinase (CaMKII and the subsequent phosphorylation of the ryanodine receptor. When β-AR drive is chronic, as observed in heart failure, this CaMKII-dependent effect is exaggerated and becomes potentially arrhythmogenic. Recent evidence has indicated that CaMKII activation can be regulated by cellular oxidizing agents, such as reactive oxygen species. Here, we investigate how the cellular second messenger, nitric oxide, mediates CaMKII activity downstream of the adrenergic signaling cascade and promotes the generation of arrhythmogenic spontaneous Ca(2+ waves in intact cardiomyocytes. Both SCaWs and SR Ca(2+ leak were measured in intact rabbit and mouse ventricular myocytes loaded with the Ca-dependent fluorescent dye, fluo-4. CaMKII activity in vitro and immunoblotting for phosphorylated residues on CaMKII, nitric oxide synthase, and Akt were measured to confirm activity of these enzymes as part of the adrenergic cascade. We demonstrate that stimulation of the β-AR pathway by isoproterenol increased the CaMKII-dependent SR Ca(2+ leak. This increased leak was prevented by inhibition of nitric oxide synthase 1 but not nitric oxide synthase 3. In ventricular myocytes isolated from wild-type mice, isoproterenol stimulation also increased the CaMKII-dependent leak. Critically, in myocytes isolated from nitric oxide synthase 1 knock-out mice this effect is ablated. We show that isoproterenol stimulation leads to an increase in nitric oxide production, and nitric oxide alone is sufficient to activate CaMKII and increase SR Ca(2+ leak. Mechanistically, our data links Akt to nitric oxide synthase 1 activation downstream of β-AR stimulation. Collectively, this evidence supports the hypothesis

  16. Discontinuity of sarcoplasmic reticulum in the mid-sarcomere region in flight muscle of dragonflies. (United States)

    de Eguileor, M; Valvassori, R; Lanzavecchia, G


    The sarcoplasmic reticulum organization of dragonfly flight muscles is analyzed, with particular reference to the doubling existing at H-band level. This doubling could be explained as a consequence of a regular discontinuity in the sarcoplasmic reticulum covering myofibrils. In each sarcomere, two sleeves of the sarcoplasmic reticulum seem to overlap forming a telescopic system which can slide outside each other during the lengthening and shortening movements of the fiber.

  17. Affi-gel blue treatment simplifies the protein composition of sarcoplasmic reticulum vesicles. (United States)

    Papp, S; Dux, L; Martonosi, A


    Sarcoplasmic reticulum vesicles isolated by conventional techniques usually contain, in addition to the recognized sarcoplasmic reticulum components, several other proteins (phosphorylase, myosin, glyceraldehyde-3-phosphate dehydrogenase, etc.) in variable amounts; these proteins complicate the interpretation of chemical modification data. Incubation of sarcoplasmic reticulum vesicles with Affi-Gel blue particles for 1-4 h at 2 degrees C, followed by sedimentation of the Affi-Gel in a clinical centrifuge, simplifies the protein composition by selective adsorption of the accessory proteins, and improves the consistency of the preparations. The Affi-Gel blue treatment is recommended as part of the standard procedure for the isolation of sarcoplasmic reticulum vesicles.

  18. Enhanced sarcoplasmic reticulum Ca(2+) release following intermittent sprint training

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    Ørtenblad, Niels; Lunde, Per; Levin, Kasper


    To evaluate the effect of intermittent sprint training on sarcoplasmic reticulum (SR) function, nine young men performed a 5 wk high-intensity intermittent bicycle training, and six served as controls. SR function was evaluated from resting vastus lateralis muscle biopsies, before and after...... the training period. Intermittent sprint performance (ten 8-s all-out periods alternating with 32-s recovery) was enhanced 12% (P training. The 5-wk sprint training induced a significantly higher (P ...-977) arbitrary units Ca(2+). g protein(-1). min(-1) (after). The relative SR density of functional ryanodine receptors (RyR) remained unchanged after training; there was, however, a 48% (P

  19. Dynamic Changes in Sarcoplasmic Reticulum Structure in Ventricular Myocytes

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    Amanda L. Vega


    sarcoplasmic reticulum (SR and the sarcolemma where Ca2+ release is activated. Here, we tested the hypothesis that the SR is a structurally inert organelle in ventricular myocytes. Our data suggest that rather than being static, the SR undergoes frequent dynamic structural changes. SR boutons expressing functional ryanodine receptors moved throughout the cell, approaching or moving away from the sarcolemma of ventricular myocytes. These changes in SR structure occurred in the absence of changes in [Ca2+] during EC coupling. Microtubules and the molecular motors dynein and kinesin 1(Kif5b were important regulators of SR motility. These findings support a model in which the SR is a motile organelle capable of molecular motor protein-driven structural changes.

  20. Interactions of vanadate oligomers with sarcoplasmic reticulum Ca(2+)-ATPase. (United States)

    Aureliano, M; Mdeira, V M


    Upon addition of sarcoplasmic reticulum (SR), the line width of tetrameric vanadate signal of 51V-NMR spectra narrowed in the presence of ATP and Ca2+, whereas monomeric vanadate line widths were broadened. Thus, ATP decreases the affinity of the enzyme for tetravanadate whereas it induces the interaction with monomeric vanadate. In the presence of Ca2+ it was observed that tetrameric and decameric vanadate bind to SR ATPase whereas monomeric vanadate only binds to SR when ATP is present. However, decameric vanadate clearly differs from vanadate oligomers present in monovanadate solutions in preventing the accumulation of Ca2+ by sarcoplasmic reticulum (SR) vesicles coupled to ATP hydrolysis. Mg2+ increased the inhibitory effect promoted by decavanadate whereas a slight enhancement of Ca2+ uptake was observed in the presence of monovanadate. For 5 mM Mg2+, a nominal 2 mM vanadium 'decavanadate' solution containing about 190 to 200 microM decameric and less than 100 microM monomeric species depressed the rate of Ca2+ uptake by 50% whereas a nominal 2 mM monovanadate solution containing about 662 microM monomeric, 143 microM dimeric and 252 microM tetrameric species had no effect on the rate of Ca2+ accumulation. However, 2 mM 'decavanadate' inhibits by 75% the SR Ca(2+)-ATPase activity whereas the presence of 2 mM 'monovanadate' produces an inhibitory effect below 50%. Therefore, the Ca:ATP stoichiometry of Ca2+ transport is enhanced by monovanadate. In the presence of oxalate, inhibition of SR Ca(2+)-ATPase activity by these solutions is enhanced to 97% and 86% whereas in the presence of the ionophore lasalocid, the inhibitory values were 87% and 19% for 2 mM decavanadate and 2 mM monovanadate solutions, respectively. Apparently, the increase of vesicular Ca2+ concentration counteracts monovanadate inhibition of SR Ca(2+)-ATPase activity but it does not significantly affect decavanadate inhibition.

  1. Biochemical and morphological characterization of light and heavy sarcoplasmic reticulum vesicles

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    Campbell, K.P.


    Light and heavy sarcoplasmic reticulum vesicles isolated from rabbit leg muscle have been used in a study of chloride-induced calcium release. The biochemical and morphological data indicate that light sarcoplasmic reticulum vesicles are derived from the longitudinal reticulum and heavy sarcoplasmic reticulum vesicles are derived from the terminal cisternae of the sarcoplasmic reticulum. The light and heavy sarcoplasmic reticulum vesicles were both able to accumulate calcium in the presence of ATP to amounts greater than 100 nmoles Ca/sup + +/ per mg of protein in less than one minute. Light and heavy sarcoplasmic reticulum vesicles each had a biphasic time course of calcium uptake. The initial uptake was followed by a rapid release after approximately one minute, of 30 to 40% of the accumulated calcium, which was then followed by a slower phase of calcium accumulation. Results indicate that the chloride induced release of calcium may be acting by two mechanisms, osmotic swelling and depolarization. The release of calcium from the light SR vesicles is probably due to osmotic swelling and the release of calcium from the heavy SR vesicles is probably due to depolarization.

  2. Association of cardiac injury with iron-increased oxidative and nitrative modifications of the SERCA2a isoform of sarcoplasmic reticulum Ca(2+)-ATPase in diabetic rats. (United States)

    Li, Xueli; Li, Wenliang; Gao, Zhonghong; Li, Hailing


    The role of iron in the etiology of diabetes complications is not well established. Thus, this study was performed to test whether the iron-induced increase of oxidative/nitrative damage is involved in SERCA2a-related diabetic heart complication. Four randomly divided groups of rats were used: normal control group; iron overload group; diabetes group, and diabetic plus iron overload group. Iron supplementation stimulated cardiomyocyte hypertrophy and led to an increase in cardiac protein carbonyls, nitrotyrosine (3-NT) formation, and iNOS protein expression, thus resulting in abnormal myocardium calcium homeostasis of diabetic rats. The levels of SECA2a oxidation/nitration were significantly increased in the iron overload diabetic rats, along with a decrease in SECA2a expression and activity. In order to elucidate the possible role of iron in SERCA2a dysfunction, the effects of iron (Fe(3+) or hemin) on peroxynitrite (ONOO(-)) induced SERCA2a oxidation and nitration were further investigated in vitro. It was found that tyrosine nitration played more important role in SERCA2a inactivation than thiol oxidation. These results present a potential mechanism in which iron exacerbates the diabetes-induced oxidative/nitrative modification of SERCA2a, which may cause functional deficits in the myocyte associated with diabetic cardiac dysfunction. Our findings may help to further understand the role of iron in the pathogenesis of diabetic complications.

  3. The changes of cardioelectrical activity of rat with myocardial infarction receiving sarcoplasmic reticulum Ca2+-ATPase gene modified bone marrow stem cell transplantation by microelectrode array technology

    Institute of Scientific and Technical Information of China (English)



    Objective Therapy effects and cardiac electrical activity comparison of bone marrow stem cells (BMSCs) transplantation and sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) gene modified BMSCs transplantation after acute myocardial infarction(AMI) in rats.Methods Rats with AMI were divided

  4. Biochemical and morphological characterization of light and heavy sarcoplasmic reticulum vesicles

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Kevin Peter


    Light (30 to 32.5% sucrose) and heavy (38.5 to 42% sucrose) sarcoplasmic reticulum vesicles (LSR,HSR) were isolated from rabbit leg muscle using a combination of differential centrifugation and isopycnic zonal ultracentrifugation. Thin-section electron microscopy of LSR vesicles reveals empty vesicles of various sizes and shapes whereas the HSR vesicles appear as rounded vesicles of uniform size filled with electron dense material, similar to that seen in the terminal cisternae of the sarcoplasmic reticulum. The sucrose HSR vesicles have an additional morphological feature which appears as membrane projections that resemble the SR feet. The freeze-fracture morphology of either type of SR reveals an asymmetric distribution of intramembraneous particles in the same orientation and distribution as the sarcoplasmic reticulum in vivo. Biochemical studies were made on the content of Ca, Mg, ATPase, and protein of the vesicles and phosphorylation of the vesicles. The biochemical and morphological data indicate that the LSR is derived from the longitudinal sarcoplasmic reticulum and the HSR is derived from the terminal cisternae of the sarcoplasmic reticulum, contains junctional SR membrane and has three unique proteins (calsequestrin, an intrinsic 30,000 dalton protein and a 9000 dalton proteolipid).

  5. CaMKII inhibition targeted to the sarcoplasmic reticulum inhibits frequency dependent acceleration of relaxation and Ca2+ current facilitation


    Picht, Eckard; DeSantiago, Jaime; Huke, Sabine; Kaetzel, Marcia A.; Dedman, John R.; Bers, Donald M.


    Cardiac Ca2+/calmodulin-dependent protein kinase II (CaMKII) in heart has been implicated in Ca2+ current (ICa) facilitation, enhanced sarcoplasmic reticulum (SR) Ca2+ release and frequency dependent acceleration of relaxation (FDAR) via enhanced SR Ca2+ uptake. However, questions remain about how CaMKII may work in these three processes. Here we tested the role of CaM-KII in these processes using transgenic mice (SR-AIP) that express four concatenated repeats of the CaMKII inhibitory peptide...

  6. Effect of losartan on sarcoplasmic reticulum Ca2+ handing proteins in heart failure rabbit

    Institute of Scientific and Technical Information of China (English)



    Objective To investigate the effects of losartan on mRNA expression of myocardial sarcoplasmic reticulum calcium handling proteins (SERCA2, RyR2 and PLB) and the role of which in prevention of chronic heart failure in rabbit. Methods After chronic heart failure was

  7. Reduced sarcoplasmic reticulum content of releasable Ca2+ in rat soleus muscle fibres after eccentric contractions

    DEFF Research Database (Denmark)

    Nielsen, J S; Sahlin, K; Ørtenblad, N


    AIM: The purpose was to evaluate the effects of fatiguing eccentric contractions (EC) on calcium (Ca2+) handling properties in mammalian type I muscles. We hypothesized that EC reduces both endogenous sarcoplasmic reticulum (SR) content of releasable Ca2+ (eSRCa2+) and myofibrillar Ca2+ sensitivity...

  8. Effects of boldine on mouse diaphragm and sarcoplasmic reticulum vesicles isolated from skeletal muscle. (United States)

    Kang, J J; Cheng, Y W


    The effects of boldine [(S)-2,9-dihydroxy-1,10-dimethoxyaporphine], a major alkaloid in the leaves and bark of boldo (Peumus boldus Mol.), on skeletal muscle were studied using mouse diaphragm and isolated sarcoplasmic reticulum membrane vesicles. Boldine, at 10-200 microM, has little effect on the muscle-evoked twitches; however, the ryanodine-induced contracture was potentiated dose-dependently. At higher concentrations of 300 microM, boldine by itself induced muscle contracture of two phases, which were caused by the influx of extracellular Ca2+ and induction of Ca2+ release from the internal Ca2+ storage site, the sarcoplasmic reticulum, respectively. When tested with isolated sarcoplasmic reticulum membrane vesicles, boldine dose-dependently induced Ca2+ release from actively loaded sarcoplasmic reticulum vesicles isolated from skeletal muscle of rabbit or rat which was inhibited by ruthenium red, suggesting that the release was through the Ca2+ release channel, also known as the ryanodine receptor. Boldine also dose-dependently increased apparent [3H]-ryanodine binding with the EC50 value of 50 microM. In conclusion, we have shown that boldine could sensitize the ryanodine receptor and induce Ca2+ release from the internal Ca2+ storage site of skeletal muscle.

  9. Ion pathways in the sarcoplasmic reticulum Ca2+-ATPase. (United States)

    Bublitz, Maike; Musgaard, Maria; Poulsen, Hanne; Thøgersen, Lea; Olesen, Claus; Schiøtt, Birgit; Morth, J Preben; Møller, Jesper Vuust; Nissen, Poul


    The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) is a transmembrane ion transporter belonging to the P(II)-type ATPase family. It performs the vital task of re-sequestering cytoplasmic Ca(2+) to the sarco/endoplasmic reticulum store, thereby also terminating Ca(2+)-induced signaling such as in muscle contraction. This minireview focuses on the transport pathways of Ca(2+) and H(+) ions across the lipid bilayer through SERCA. The ion-binding sites of SERCA are accessible from either the cytoplasm or the sarco/endoplasmic reticulum lumen, and the Ca(2+) entry and exit channels are both formed mainly by rearrangements of four N-terminal transmembrane α-helices. Recent improvements in the resolution of the crystal structures of rabbit SERCA1a have revealed a hydrated pathway in the C-terminal transmembrane region leading from the ion-binding sites to the cytosol. A comparison of different SERCA conformations reveals that this C-terminal pathway is exclusive to Ca(2+)-free E2 states, suggesting that it may play a functional role in proton release from the ion-binding sites. This is in agreement with molecular dynamics simulations and mutational studies and is in striking analogy to a similar pathway recently described for the related sodium pump. We therefore suggest a model for the ion exchange mechanism in P(II)-ATPases including not one, but two cytoplasmic pathways working in concert.

  10. Minor sarcoplasmic reticulum membrane components that modulate excitation–contraction coupling in striated muscles (United States)

    Treves, Susan; Vukcevic, Mirko; Maj, Marcin; Thurnheer, Raphael; Mosca, Barbara; Zorzato, Francesco


    In striated muscle, activation of contraction is initiated by membrane depolarisation caused by an action potential, which triggers the release of Ca2+ stored in the sarcoplasmic reticulum by a process called excitation–contraction coupling. Excitation–contraction coupling occurs via a highly sophisticated supramolecular signalling complex at the junction between the sarcoplasmic reticulum and the transverse tubules. It is generally accepted that the core components of the excitation–contraction coupling machinery are the dihydropyridine receptors, ryanodine receptors and calsequestrin, which serve as voltage sensor, Ca2+ release channel, and Ca2+ storage protein, respectively. Nevertheless, a number of additional proteins have been shown to be essential both for the structural formation of the machinery involved in excitation–contraction coupling and for its fine tuning. In this review we discuss the functional role of minor sarcoplasmic reticulum protein components. The definition of their roles in excitation–contraction coupling is important in order to understand how mutations in genes involved in Ca2+ signalling cause neuromuscular disorders. PMID:19403606

  11. Lipogenesis mitigates dysregulated sarcoplasmic reticulum calcium uptake in muscular dystrophy. (United States)

    Paran, Christopher W; Zou, Kai; Ferrara, Patrick J; Song, Haowei; Turk, John; Funai, Katsuhiko


    Muscular dystrophy is accompanied by a reduction in activity of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) that contributes to abnormal Ca(2+) homeostasis in sarco/endoplasmic reticulum (SR/ER). Recent findings suggest that skeletal muscle fatty acid synthase (FAS) modulates SERCA activity and muscle function via its effects on SR membrane phospholipids. In this study, we examined muscle's lipid metabolism in mdx mice, a mouse model for Duchenne muscular dystrophy (DMD). De novo lipogenesis was ~50% reduced in mdx muscles compared to wildtype (WT) muscles. Gene expressions of lipogenic and other ER lipid-modifying enzymes were found to be differentially expressed between wildtype (WT) and mdx muscles. A comprehensive examination of muscles' SR phospholipidome revealed elevated phosphatidylcholine (PC) and PC/phosphatidylethanolamine (PE) ratio in mdx compared to WT mice. Studies in primary myocytes suggested that defects in key lipogenic enzymes including FAS, stearoyl-CoA desaturase-1 (SCD1), and Lipin1 are likely contributing to reduced SERCA activity in mdx mice. Triple transgenic expression of FAS, SCD1, and Lipin1 (3TG) in mdx myocytes partly rescued SERCA activity, which coincided with an increase in SR PE that normalized PC/PE ratio. These findings implicate a defect in lipogenesis to be a contributing factor for SERCA dysfunction in muscular dystrophy. Restoration of muscle's lipogenic pathway appears to mitigate SERCA function through its effects on SR membrane composition.

  12. Effect of Zn2+ ions on ryanodine binding to sarcoplasmic reticulum of striated muscles in the presence of pyrithione

    Institute of Scientific and Technical Information of China (English)

    Hong XIE; Ke-ying CHEN; Pei-hong ZHU


    AIM: To explore whether the differential effects of Zn2+ on ryanodine binding to the sarcoplasmic reticulum (SR)of skeletal and cardiac muscles resulted from different permeability of the SR to Zn2+. METHODS: [3H]ryanodine binding assays were performed to examine the effect of Zn2+ on ryanodine binding to the SR in the presence of pyrithione sodium (PyNa), a specific Zn2+ ionophore. RESULTS: As a control, PyNa up to 50 μmol/L did not induce any effect on ryanodine binding to the SR of cardiac muscle. But PyNa 1-100 μmol/L increased ryanodine binding in skeletal muscle with maximum binding (222.2 %+20.9 % of the control) and inhibited ryanodine binding to 50 % of the control at about 500 μrnol/L. In the presence of PyNa 10 and 50 μmol/L the dose-dependence of the effect of Zn2+ in cardiac muscle was still monophasic and not changed by PyNa, while the biphasic effect of Zn2+in skeletal muscle became monophasic. CONCLUSION: Different permeability of the SR to Zn2+ may account for the differential effects of Zn2+on ryanodine binding in skeletal and cardiac muscles. PyNa is not a strictly specific Zn2+ ionophore.

  13. Cellular mechanisms of reduced sarcoplasmic reticulum Ca2+ content in L-thyroxin-induced rat ventricular hypertrophy

    Institute of Scientific and Technical Information of China (English)

    Lai-jing SONG; Guan-lei WANG; Jie LIU; Qin-ying QIU; Jing-hua OU; Yong-yuan GUAN


    Aim:To examine how the sarcoplasmic reticulum (SR) Ca2+ content changes and the underlying mechanism in L-thyroxin-induced cardiac hypertrophy. Methods:Echocardiography was used to confirm the establishment of the cardiac hypertro-phy model. The confocal microscopy and fluorescent indicator Fluo-3 was ap-plied to examine the intracellular Ca2+ concentration ([Ca2+]I), the Ca2+ sparks, and the caffeine-induced Ca2+ transient in freshly isolated cardiac ventricular myocytes. The activity of sarcolemmal and SR Ca2+-ATPase 2a (SERCA2a) in the ventricular tissue was also measured, respectively. Results:L-thyroxin (1 mg/kg injection for 10 d) induces left ventricular cardiac hypertrophy with normal myocardial function. The decreased caffeine-induced Ca2+ transient in the Ca2+-free solution was detected. The spontaneous Ca2+ sparks in hypertrophied myocytes occurred more frequently than in normal cells, with similar duration and spatial spread, but smaller amplitude. Then the basal [Ca2+]I increase was observed in quiescent left ventricular myocytes from hyperthyroidism rats. The activity of sarcolemmal and SR Ca2+-ATPase was decreased in the hypertrophied ventricle tissue. Conclusion:The results suggested that the reduced SR Ca2+ content may be associated with an increased Ca2+ leak and reduced SERCA2a activity, contributing to abnormal intracellular Ca2+ handling during hypertrophy in hyperthyroidism rats.

  14. Vanadate oligomer inhibition of passive and active Ca2+ translocation by the Ca2+ pump of sarcoplasmic reticulum. (United States)

    Aureliano, M


    'Monovanadate' containing mainly monomeric, dimeric and tetrameric vanadate species or 'decavanadate', containing mainly decameric vanadate species inhibits the passive and the active efflux of Ca2+ through the sarcoplasmic reticulum calcium pump. When the efflux of Ca2+ by sarcoplasmic reticulum vesicles is not associated with ATP synthesis both vanadate solutions inhibit the passive efflux of Ca2+. However, only 'decavanadate' exerts noticeable effects when the efflux of Ca2+ is associated with ATP synthesis being the active efflux of Ca2+ almost completely inhibited by decameric species concentration as low as 40 microM.

  15. Conformational changes in the (Ca2+ + Mg2+)-ATPase of sarcoplasmic reticulum detected using phosphorescence polarization. (United States)

    Restall, C J; Coke, M; Murray, E K; Chapman, D


    The technique of time-averaged phosphorescence has been used to study the interaction of calcium ions and ATP with the (Ca2+ + Mg2+)-ATPase in sarcoplasmic reticulum vesicles. The presence of excess calcium ions was found to cause a 20% decrease in the phosphorescence emission anisotropy. This is interpreted as being due to a conformational change in the protein and is supported by data from time-resolved phosphorescence measurements which also show a lowering of the anisotropy. This change in the decay of the emission anisotropy is associated with only minor changes in the rotational relaxation time of the protein and is again suggestive of a conformational change in the protein. In some cases ATP was also observed to lower the time-averaged phosphorescence anisotropy possibly via an interaction with the low-affinity regulatory site of the protein.

  16. Biochemical and morphological characterization of light and heavy sarcoplasmic reticulum vesicles. Volume I

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Kevin Peter


    Light (30 to 32.5% sucrose) and heavy (38.5 to 42% sucrose) sarcoplasmic reticulum vesicles (LSR, HSR) were isolated from rabbit leg muscle. They were then diluted and washed with sucrose or KCl and referred to as sucrose or KCl washed vesicles. Thin-section electron microscopy of LSR vesicles reveals empty vesicles of various sizes and shapes where as the HSR vesicles appear as rounded vesicles of uniform size filled with electron dense material. The LSR consists of predominantly Ca/sup 2 +/ + Mg/sup 2 +/ ATPase (80 to 90%), a small amount of the high affinity Ca binding protein (5%), and a 5000 dalton proteolipid. The sucrose HSR vesicles contain the Ca/sup 2 +/ + Mg/sup 2 +/ ATPase (50%), Calsequestrin (25%), high affinity Ca binding protein (5%), one extrinsic 34,000 dalton protein (3%), one intrinsic 30,000 dalton protein (3%), a 9000 dalton proteolipid, and a 5000 dalton proteolipid. The sucrose--washed HSR vesicles contain greater than three times the calcium content of the sucrose washed LSR vesicles where as the KCl--washed vesicles contain less than 15 nmoles Ca/sup 2 +//mg of protein each. The light and heavy sarcoplasmic reticulum vesicles were both able to accumulate calcium in the presence of ATP. Exchange of methanesulfonate for chloride resulted in the release of calcium from both the light and heavy SR vesicles. Sucrose causes a slight inhibition of chloride--induced calcium release from the heavy SR vesicles but it greatly reduces the release of calcium from the light SR vesicles. Sodium dantrolene (20 uM) has no effect on the release of calcium from the light SR vesicles but it inhibits the release of calcium from the heavy SR vesicles. The results indicate that the chloride--induced release of calcium may be acting by two mechanisms, osmotic swelling and depolarization.

  17. H+ countertransport and electrogenicity of the sarcoplasmic reticulum Ca2+ pump in reconstituted proteoliposomes. (United States)

    Yu, X; Carroll, S; Rigaud, J L; Inesi, G


    The Ca2+ transport adenosine triphosphatase of sarcoplasmic reticulum was reconstituted in unilamellar liposomes prepared by reverse-phase evaporation. The size of the resulting proteoliposomes was similar to that of native sarcoplasmic reticulum vesicles, but their protein content was much lower, with a protein/lipid ratio (wt/wt) of 1:40-160, as compared with 1:1 in the native membrane. The proteoliposomes sustained adenosine triphosphate-dependent Ca2+ uptake at rates proportional to the protein content (1-2 mumol Ca2+/mg protein/min), reaching asymptotic levels corresponding to a lumenal calcium concentration of 10-20 mM. The low permeability of the proteoliposomes permitted direct demonstration of Ca2+/H+ countertransport and electrogenicity by parallel measurements in the same experimental system. Countertransport of one H+ per one Ca2+ was demonstrated, and inhibition of the Ca2+ pump by lumenal alkalinization was relieved by the H+ ionophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone. Consistent with the countertransport stoichiometry, net positive charge displacement was produced by Ca2+ transport, as revealed by a rapid oxonol VI absorption rise. The initial rise and the following steady-state level of oxonol absorption were highest when SO4(2-) was the prevalent anion and lowest in the presence of the lipophilic anion SCN-. The influence of anions was attributed to potential driven counterion compensation. The absorption rise was rapidly collapsed by addition of valinomycin in the presence of K+. Experimentation with Ca2+ and H+ ionophores was consistent with a primary role of Ca2+ and H+ in net charge displacement. The estimated value of the steady-state electrical potential observed under optimal conditions was approximately 50 mV and was accounted for by the estimated charge transfer associated with Ca2+ and H+ countertransport under the same conditions.

  18. Functional properties of human embryonic stem cell-derived cardiomyocytes: intracellular Ca2+ handling and the role of sarcoplasmic reticulum in the contraction. (United States)

    Dolnikov, Katya; Shilkrut, Mark; Zeevi-Levin, Naama; Gerecht-Nir, Sharon; Amit, Michal; Danon, Asaf; Itskovitz-Eldor, Joseph; Binah, Ofer


    Since cardiac transplantation is limited by the small availability of donor organs, regeneration of the diseased myocardium by cell transplantation is an attractive therapeutic modality. To determine the compatibility of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) (7 to 55 days old) with the myocardium, we investigated their functional properties regarding intracellular Ca2+ handling and the role of the sarcoplasmic reticulum in the contraction. The functional properties of hESC-CMs were investigated by recording simultaneously [Ca2+]i transients and contractions. Additionally, we performed Western blot analysis of the Ca2+-handling proteins SERCA2, calsequestrin, phospholamban, and Na+/Ca2+ exchanger (NCX). Our major findings are, first, that hESC-CMs displayed temporally related [Ca2+]i transients and contractions, negative force-frequency relations, and lack of post-rest potentiation. Second, ryanodine, thapsigargin, and caffeine did not affect the [Ca2+]i transient and contraction, indicating that at this developmental stage, contraction depends on transsarcolemmal Ca2+ influx rather than on sarcoplasmic reticulum Ca2+ release. Third, in agreement with the notion that a voltage-dependent Ca2+ current is present in hESC-CMs and contributes to the mechanical function, verapamil completely blocked contraction. Fourth, whereas hESC-CMs expressed SERCA2 and NCX at levels comparable to those of the adult porcine myocardium, calsequestrin and phospholamban were not expressed. Our study shows for the first time that functional properties related to intracellular Ca2+ handling of hESC-CMs differ markedly from the adult myocardium, probably due to immature sarcoplasmic reticulum capacity.

  19. Cylindrical Spirals in Skeletal Muscles Originate From the Longitudinal Sarcoplasmic Reticulum. (United States)

    Xu, Jing-Wen; Liu, Fu-Chen; Li, Wei; Zhao, Yu-Ying; Zhao, Dan-Dan; Luo, Yue-Bei; Lu, Jian-Qiang; Yan, Chuan-Zhu


    Cylindrical spirals (CSs) are rare but distinct subsarcolemmal accumulations in skeletal muscle fibers. To date, CSs have been reported in only 16 patients with a variety of neuromuscular conditions. The origin and composition of CSs are unknown, although there are some morphologic similarities between CSs and tubular aggregates (TAs). To clarify the nature of CSs, we characterized the sarcoplasmic reticulum (SR) and other intracellular membrane system proteins in CSs of muscle biopsies from 2 adult Chinese siblings. Immunohistochemical studies revealed subsarcolemmal immunoreactivity for sarco/endoplasmic reticulum Ca2þ-ATPase 1 (SERCA 1) in the longitudinal SR, but no immunoreactivity for calsequestrin in the terminal cisternae or type 1 ryanodine receptor (RYR1) in the junctional SR. Muscles biopsied from 2 patients with TAs showed immunoreactivity not only for SERCA1 but also for other SR proteins, including calsequestrin and RYR1. CSs exhibited no immunoreactivity for the Golgi apparatus marker GM130, the nuclear membrane emerin, desmin, the autophagosome marker LC3, the lysosomal membrane marker LAMP2, dystrophin, or myosin. Our results suggest CSs may originate only from the longitudinal SR, whereas TAs are composed of both the junctional and longitudinal SR. Immunochemical staining with antibodies against calsequestrin and RYR1 help to distinguish these 2 pathological alterations.

  20. Disturbances of the sarcoplasmic reticulum and transverse tubular system in 24-h electrostimulated fast-twitch skeletal muscle

    DEFF Research Database (Denmark)

    Frías, J A; Cadefau, J A; Prats, C;


    -migration of terminal cisternae and t-tubules from R3 to R4, indicating the presence of triads. This density change may be associated with calcium overload of the sarcoplasmic reticulum, since total calcium rose three- to fourfold in stimulated muscle homogenates. These changes correlate well with ultrastructural...... damage to longitudinal sarcoplasmic reticulum and swelling of t-tubules revealed by electron microscopy. The ultrastructural changes observed here reflect exercise-induced damage of membrane systems that might severely compromise muscle function. Since this process is reversible, we suggest that it may......Chronic low-frequency stimulation of rabbit tibialis anterior muscle over a 24-h period induces a conspicuous loss of isometric tension that is unrelated to muscle energy metabolism (J.A. Cadefau, J. Parra, R. Cusso, G. Heine, D. Pette, Responses of fatigable and fatigue-resistant fibres of rabbit...

  1. Preliminary investigation of sequence-independent DNA binding proteins in rat skeletal muscle sarcoplasmic reticulum and their function

    Institute of Scientific and Technical Information of China (English)

    赵文; 姜志胜; 倪菊华; 陈光慧; 刘乃奎; 汤健; 贾弘褆; 唐朝枢


    To observe the binding of plasmid DNA to non-nuclear DNA binding proteins in sar-coplasmic reticulum (SR) and the effects of this binding on SR function, sarcoplasmic reticulum proteins in rat skeletal muscle were isolated by differential centrifuge and sucrose density-gradient centrifuge. The results showed that there are two sequence-independent DNA binding proteins in SR proteins, the molecular weights of which are 83 and 58 ku, respectively. Ca2+ uptake and release of SR were remarkably promoted by the binding of plasmid DNA to DNA binding proteins in SR, the mechanism is probably through increasing of Ca2+-ATPase activity in SR and changing of character of Ca2+ release channel ryanodine receptors induced by the binding. These results suggest that there exist DNA binding proteins in SR and its binding to DNA may affect Ca2+ transport of SR.

  2. Preliminary investigation of sequence-independent DNA binding proteins in rat skeletal muscle sarcoplasmic reticulum and their function

    Institute of Scientific and Technical Information of China (English)


    To observe the binding of plasmid DNA to non-nuclear DNA binding proteins in sarcoplasmic reticulum (SR) and the effects of this binding on SR function, sarcoplasmic reticulum proteins in rat skeletal muscle were isolated by differential centrifuge and sucrose density-gradient centrifuge. The results showed that there are two sequence-independent DNA binding proteins in SR proteins, the molecular weights of which are 83 and 58 ku, respectively. Ca2+ uptake and release of SR were remarkably promoted by the binding of plasmid DNA to DNA binding proteins in SR, the mechanism is probably through increasing of Ca2+-ATPase activity in SR and changing of character of Ca2+ release channel ryanodine receptors induced by the binding. These results suggest that there exist DNA binding proteins in SR and its binding to DNA may affect Ca2+ transport of SR.

  3. Biphasic decay of the Ca transient results from increased sarcoplasmic reticulum Ca leak (United States)

    Sankaranarayanan, Rajiv; Li, Yatong; Greensmith, David J.; Eisner, David A.


    Key points Ca leak from the sarcoplasmic reticulum through the ryanodine receptor (RyR) reduces the amplitude of the Ca transient and slows its rate of decay.In the presence of β‐adrenergic stimulation, RyR‐mediated Ca leak produces a biphasic decay of the Ca transient with a fast early phase and a slow late phase.Two forms of Ca leak have been studied, Ca‐sensitising (induced by caffeine) and non‐sensitising (induced by ryanodine) and both induce biphasic decay of the Ca transient.Only Ca‐sensitising leak can be reversed by traditional RyR inhibitors such as tetracaine.Ca leak can also induce Ca waves. At low levels of leak, waves occur. As leak is increased, first biphasic decay and then slowed monophasic decay is seen. The level of leak has major effects on the shape of the Ca transient. Abstract In heart failure, a reduction in Ca transient amplitude and contractile dysfunction can by caused by Ca leak through the sarcoplasmic reticulum (SR) Ca channel (ryanodine receptor, RyR) and/or decreased activity of the SR Ca ATPase (SERCA). We have characterised the effects of two forms of Ca leak (Ca‐sensitising and non‐sensitising) on calcium cycling and compared with those of SERCA inhibition. We measured [Ca2+]i with fluo‐3 in voltage‐clamped rat ventricular myocytes. Increasing SR leak with either caffeine (to sensitise the RyR to Ca activation) or ryanodine (non‐sensitising) had similar effects to SERCA inhibition: decreased systolic [Ca2+]i, increased diastolic [Ca2+]i and slowed decay. However, in the presence of isoproterenol, leak produced a biphasic decay of the Ca transient in the majority of cells while SERCA inhibition produced monophasic decay. Tetracaine reversed the effects of caffeine but not of ryanodine. When caffeine (1 mmol l−1) was added to a cell which displayed Ca waves, the wave frequency initially increased before waves disappeared and biphasic decay developed. Eventually (at higher caffeine concentrations), the

  4. Alteration of Sarcoplasmic Reticulum Ca2+ Release in Skeletal Muscle from Calpain 3-Deficient Mice

    Directory of Open Access Journals (Sweden)

    Govindan Dayanithi


    Full Text Available Mutations of Ca2+-activated proteases (calpains cause muscular dystrophies. Nevertheless, the specific role of calpains in Ca2+ signalling during the onset of dystrophies remains unclear. We investigated Ca2+ handling in skeletal cells from calpain 3-deficient mice. [Ca2+]i responses to caffeine, a ryanodine receptor (RyR agonist, were decreased in −/− myotubes and absent in −/− myoblasts. The −/− myotubes displayed smaller amplitudes of the Ca2+ transients induced by cyclopiazonic acid in comparison to wild type cells. Inhibition of L-type Ca2+ channels (LCC suppressed the caffeine-induced [Ca2+]i responses in −/− myotubes. Hence, the absence of calpain 3 modifies the sarcoplasmic reticulum (SR Ca2+ release, by a decrease of the SR content, an impairment of RyR signalling, and an increase of LCC activity. We propose that calpain 3-dependent proteolysis plays a role in activating support proteins of intracellular Ca2+ signalling at a stage of cellular differentiation which is crucial for skeletal muscle regeneration.

  5. Calcium handling by the sarcoplasmic reticulum during oscillatory contractions of skinned skeletal muscle fibres. (United States)

    Szentesi, P; Zaremba, R; Stienen, G J


    Isometric ATP consumption and force were investigated in mechanically skinned fibres from iliofibularis muscle of Xenopus laevis. Measurements were performed at different [Ca2+], in the presence and absence of caffeine (5 nM). In weakly Ca2+-buffered solutions without caffeine, spontaneous oscillations in force and ATPase activity occurred. The repetition frequency was [Ca2+]-and temperature-dependent. The Ca2+ threshold (+/- SEM) for the oscillations corresponded to a pCa of 6.5 +/- 0.1. The maximum ATP consumption associated with calcium uptake by the sarcoplasmic reticulum (SR) reached during the oscillations was similar to the activity under steady-state conditions at saturating calcium concentrations in the presence of caffeine. Maximum activity was reached when the force relaxation was almost complete. The calculated amount of Ca2+ taken up by the SR during a complete cycle corresponded to 5.4 +/ 0.4 mmol per litre cell volume. In strongly Ca2+-buffered solutions, caffeine enhanced the calcium sensitivity of the contractile apparatus and, at low calcium concentrations, SR Ca uptake. These results suggest that when the SR is heavily loaded by net Ca uptake, there is a massive calcium-induced calcium release. Subsequent net Ca uptake by the SR then gives rise to the periodic nature of the calcium transient.

  6. Vanadate oligoanions interact with the proton ejection by the Ca2+ pump of sarcoplasmic reticulum. (United States)

    Aureliano, M; Madeira, V M


    Decameric vanadate differs from other oligomeric vanadate species in inhibiting Ca2+ uptake and H+ ejection promoted by sarcoplasmic reticulum ATPase. A decavanadate solution, 2 mM in total vanadium, containing about 200 microM decameric species, inhibits by about 50% the uptake of Ca2+ and by 75% the H+ ejection, whereas 2 mM nominal monovanadate slightly increases the uptake of Ca2+ and inhibits the ejection of H+ by 25%. Moreover, decavanadate linearly increases the Ca2+/H+ ratio, whereas monovanadate mimicks decavanadate behavior only at concentrations up to 1.2 mM. For higher concentrations of monovanadate, this effect is reversed probably due to the formation of metavanadates, namely tetravandate. It is concluded that Ca2+ uptake is tightly coupled to proton ejection through molecular events that are sensitive to the interaction of vanadate species. Apparently, the stoichiometry is variable and modulated by molecular events involved in vanadate interaction suggesting alterations in the energetic coupling associated with Ca2+ translocation.

  7. Thyroid hormones differentially affect sarcoplasmic reticulum function in rat atria and ventricles. (United States)

    Kaasik, A; Minajeva, A; Paju, K; Eimre, M; Seppet, E K


    The present study was undertaken to compare the effects of hypothyroidism and hyperthyroidism on sarcoplasmic reticulum (SR) Ca(2+)-pump activity, together with assessment of the functional role of SR in providing activator Ca2+ under these altered thyroid states. In response to a shift from hypothyroid to hyperthyroid state, a 10 fold and 2 fold increase in SR Ca(2+)-pump activity in atria and ventricles, respectively, were observed. This was associated with the 8-9 fold increases in atrial contractility (+dT/dt) and relaxation (-dT/dt), but only with a 3-4 fold increase in their ventricular counterparts. Also, the recirculation fraction of activator Ca2+ (RFA) increased to a far greater extent in atria (4 fold) than in papillary muscles, and the relative increment in inhibition of developed tension by ryanodine became 3 times larger in atria than in papillary muscles. A positive force-frequency relationship (FFR) was observed in hypothyroid atria, whereas the hyperthyroid atria, hypothyroid and hyperthyroid papillary muscles showed a negative FFR. These results suggest the greater role of transsarcolemmal (SL) Ca2+ and smaller role of SR Ca2+ in activating contraction in hypothyroid atria compared to other preparations. Thyroid hormones decrease the contribution of SL and increase that of SR in providing activator Ca2+ to the greater extent in atria than in ventricles. This effect of thyroid hormones is based on larger stimulation of SR Ca(2+)-pump in atria compared to ventricles.

  8. Matching of sarcoplasmic reticulum and contractile properties in rat fast- and slow-twitch muscle fibres. (United States)

    Trinh, Huong H; Lamb, Graham D


    1. The twitch characteristics (fast-twitch or slow-twitch) of skeletal muscle fibres are determined not only by the contractile apparatus properties of the fibre, but also by the time-course of Ca2+ release and re-uptake by the sarcoplasmic reticulum (SR). The present study examined, in individual fibres from non-transforming muscle of the rat, whether particular SR properties are matched to the contractile apparatus properties of the fibre, in particular in the case of fibres with fast-twitch contractile apparatus located in a slow-twitch muscle, namely the soleus. 2. Force was recorded in single, mechanically skinned fibres from extensor digitorum longus (EDL), gastrocnemius, peroneus longus and soleus muscles. Using repeated cycles in which the SR was emptied of all releasable Ca2+ and then reloaded, it was possible to determine the relative amount of Ca2+ present in the SR endogenously, the maximum SR capacity and the rate of Ca2+ loading. The sensitivity of the contractile apparatus to Ca2+ and Sr2+ was used to classify the fibres as fast-twitch (FT), slow-twitch (ST) or mixed (< 3% of the fibres examined) and thereby identify the likely troponin C and myosin heavy chain types present. 3. There was no significant difference in SR properties between the groups of FT fibres obtained from the four different muscles, including soleus. Despite some overlap in the SR properties of individual fibres between the FT and ST groups, the properties of the FT fibres in all four muscles studied were significantly different from those of the ST and mixed fibres. 4. In general, in FT fibres the SR had a larger capacity and the endogenous Ca2+ content was a relatively lower percentage of maximum compared with ST fibres. Importantly, in terms of their SR properties, FT fibres from soleus muscle more closely resembled FT fibres from other muscles than they did ST fibres from soleus muscle.

  9. Interactions of vanadium(V)-citrate complexes with the sarcoplasmic reticulum calcium pump. (United States)

    Aureliano, Manuel; Tiago, Teresa; Gândara, Ricardo M C; Sousa, Andrea; Moderno, A; Kaliva, M; Salifoglou, A; Duarte, Rui O; Moura, José J G


    Among the biotargets interacting with vanadium is the calcium pump from the sarcoplasmic reticulum (SR). To this end, initial research efforts were launched with two vanadium(V)-citrate complexes, namely (NH(4))(6)[V(2)O(4)(C(6)H(4)O(7))(2)].6H(2)O and (NH(4))(6)[V(2)O(2)(O(2))(2)(C(6)H(4)O(7))(2)].4H(2)O, potentially capable of interacting with the SR calcium pump by combining kinetic studies with (51)V NMR spectroscopy. Upon dissolution in the reaction medium (concentration range: 4-0.5mM), both vanadium(V):citrate (VC) and peroxovanadium(V):citrate (PVC) complexes are partially converted into vanadate oligomers. A 1mM solution of the PVC complex, containing 184microM of the PVC complex, 94microM oxoperoxovanadium(V) (PV) species, 222microM monomeric (V1), 43microM dimeric (V2) and 53microM tetrameric (V4) species, inhibits Ca(2+) accumulation by 75 %, whereas a solution of the VC complex of the same vanadium concentration, containing 98microM of the VC complex, 263microM monomeric (V1), 64microM dimeric (V2) and 92microM tetrameric (V4) species inhibits the calcium pump activity by 33 %. In contrast, a 1 mM metavanadate solution, containing 460microM monomeric (V1), 90.2microM dimeric (V2) and 80microM tetrameric (V4) species, has no effect on Ca(2+) accumulation. The NMR signals from the VC complex (-548.0ppm), PVC complex (-551.5ppm) and PV (-611.1ppm) are broadened upon SR vesicle addition (2.5mg/ml total protein). The relative order for the half width line broadening of the NMR signals, which reflect the interaction with the protein, was found to be V4>PVC>VC>PV>V2=V1=1, with no effect observed for the V1 and V2 signals. Putting it all together the effects of two vanadium(V)-citrate complexes on the modulation of calcium accumulation and ATP hydrolysis by the SR calcium pump reflected the observed variable reactivity into the nature of key species forming upon dissolution of the title complexes in the reaction media.

  10. Effects of prior exercise and a low-carbohydrate diet on muscle sarcoplasmic reticulum function during cycling in women. (United States)

    Duhamel, T A; Green, H J; Perco, J G; Ouyang, J


    The effects of exercise and diet on sarcoplasmic reticulum Ca(2+)-cycling properties in female vastus lateralis muscle were investigated in two groups of women following four different conditions. The conditions were 4 days of a low-carbohydrate (Lo CHO) and glycogen-depleting exercise plus a Lo CHO diet (Ex + Lo CHO) (experiment 2) and 4 days of normal CHO (Norm CHO) and glycogen-depleting exercise plus Norm CHO (Ex + Norm CHO) (experiment 1). Peak aerobic power (Vo2peak)) was 38.1 +/- 1.4 (SE); n = 9 and 35.6 +/- 1.4; n = 9, respectively. Sarcoplasmic reticulum properties measured in vitro in homogenates (micromol.g protein(-1).min(-1)) indicated exercise-induced reductions (P 30, 60 min > fatigue), Ca(2+) uptake (0 > 30 > 60 min, fatigue), and Ca(2+) release, both phase 1 (0, 30 > 60 min, fatigue) and phase 2 (0 > 30, 60 min, fatigue; 30 min > fatigue) in Norm CHO. Exercise was without effect in altering the Hill slope (n(H)), defined as the slope of relationship between Ca(2+)-ATPase activity and Ca(2+) concentration. No differences were observed between Norm CHO and Ex+Norm CHO. Compared with Norm CHO, Lo CHO resulted in a lower (P cycling and that, with the exception of Ca(2+) release, a glycogen-depleting session of exercise before Lo CHO can reverse the effects.

  11. Phosphorylation of anchoring protein by calmodulin protein kinase associated to the sarcoplasmic reticulum of rabbit fast-twitch muscle. (United States)

    Damiani, E; Sacchetto, R; Margreth, A


    Regulatory phosphorylation of phospholamban and of SR Ca(2+)-ATPase SERCA2a isoform by endogenous CaM-K II in slow-twitch skeletal and cardiac sarcoplasmic reticulum (SR) is well documented, but much less is known of the exact functional role of CaM K II in fast-twitch muscle SR. Recently, it was shown that RNA splicing of brain-specific alpha CaM K II, gives rise to a truncated protein (alpha KAP), consisting mainly of the association domain, serving to anchor CaM K II to SR membrane in rat skeletal muscle [Bayer, K.-U., et al. (1998) EMBO J. 19, 5598-5605]. In the present study, we searched for the presence of alpha KAP in sucrose-density purified SR membrane fractions from representative fast-twitch and slow-twitch limb muscles, both of the rabbit and the rat, using immunoblot techniques and antibody directed against the association domain of alpha CaM K II. Putative alpha KAP was immunodetected as a 23-kDa electrophoretic component on SDS-PAGE of the isolated SR from fast-twitch but not from slow-twitch muscle, and was further identified as a specific substrate of endogenous CaM K II, in the rabbit. Immunodetected, (32)P-labeled, non-calmodulin binding protein, behaved as a single 23-kDa protein species under several electrophoretic conditions. The 23-kDa protein, with defined properties, was isolated as a complex with 60-kDa delta CaM K II isoform, by sucrose-density sedimentation analysis. Moreover, we show here that putative alphaKAP, in spite of its inability to bind CaM in ligand blot overlay, co-eluted with delta CaM K II from CaM-affinity columns. That raises the question of whether CaM K II-mediated phosphorylation of alpha KAP and triadin together might be involved in a molecular signaling pathway important for SR Ca(2+)-release in fast-twitch muscle SR.

  12. Sarcoplasmic reticulum calcium ATPase interactions with decaniobate, decavanadate, vanadate, tungstate and molybdate. (United States)

    Fraqueza, Gil; Ohlin, C André; Casey, William H; Aureliano, Manuel


    Over the last few decades there has been increasing interest in oxometalate and polyoxometalate applications to medicine and pharmacology. This interest arose, at least in part, due to the properties of these classes of compounds as anti-cancer, anti-diabetic agents, and also for treatment of neurodegenerative diseases, among others. However, our understanding of the mechanism of action would be improved if biological models could be used to clarify potential toxicological effects in main cellular processes. Sarcoplasmic reticulum (SR) vesicles, containing a large amount of Ca(2+)-ATPase, an enzyme that accumulates calcium by active transport using ATP, have been suggested as a useful model to study the effects of oxometalates on calcium homeostasis. In the present article, it is shown that decavanadate, decaniobate, vanadate, tungstate and molybdate, all inhibited SR Ca(2+)-ATPase, with the following IC(50) values: 15, 35, 50, 400 μM and 45 mM, respectively. Decaniobate (Nb(10)), is the strongest P-type enzyme inhibitor, after decavanadate (V(10)). Atomic-absorption spectroscopy (AAS) analysis, indicates that decavanadate binds to the protein with a 1:1 decavanadate:Ca(2+)-ATPase stoichiometry. Furthermore, V(10) binds with similar extension to all the protein conformations, which occur during calcium translocation by active transport, namely E1, E1P, E2 and E2P, as analysed by AAS. In contrast, it was confirmed that the binding of monomeric vanadate (H(2)VO(4)(2-); V(1)) to the calcium pump is favoured only for the E2 and E2P conformations of the ATPase, whereas no significant amount of vanadate is bound to the E1 and E1P conformations. Scatchard plot analysis, confirmed a 1:1 ratio for decavanadate-Ca(2+)-ATPase, with a dissociation constant, k(d) of 1 μM(-1). The interaction of decavanadate V(10)O(28)(6-) (V(10)) with Ca(2+)-ATPase is prevented by the isostructural and isoelectronic decaniobate Nb(10)O(28)(6-) (Nb(10)), whereas no significant effects were

  13. Effects of simvastatin on cardiac performance and expression of sarcoplasmic reticular calcium regulatory proteins in rat heart

    Institute of Scientific and Technical Information of China (English)

    Xia ZHENG; Shen-jiang HU


    Aim: To investigate the effect of simvastatin on the cardiac contractile function and the alteration of gene and protein expression of the sarcoplasmic calcium regulatory proteins, including sarcoplasmic reticulum Ca2+-ATPase (SERCA),phospholamban (PLB), and ryanodine receptor 2 (RyR2) in rat hearts. Methods:Langendorff-perfused rat hearts were subjected to 60-min perfusion with different concentrations of simvastatin (1, 3, 10, 30, or 100 μmol/L), and the parameters of cardiac function such as left ventricular developed pressure (LVDP), +dp/dtmax,and -dp/dtmax were determined. The cultured neonatal rat ventricular cardiomyocytes were incubated with simvastatin (1, 3, 10, 30, and 100 μmol/L) for 1 h or 24 h.The levels of SERCA, PLB, and RyR2 expression were measured by reverse transcription-polymerase chain reaction and Western blot. Cytotoxic effect of simvastatin on ventricular cardiomyocytes was assessed by the MTT colorimetric assay.Results: LVDP, +dp/dtmax, and -dp/dtmax of hearts were increased significantly after treatment with simvastatin 3, 10, and 30 μmol/L. In simvastatin-treated isolated hearts, the levels of mRNA expression of SERCA and RyR2 were elevated compared with the control (P<0.05), while the mRNA expression of PLB did not change. After the cultured neonatal rat ventricular cardiomyocytes were incubated with 3, 10, 30, and 100 μmol/L simvastatin for 1 h, SERCA and RyR2 mRNA expressions of cardiomyocytes rose, but there was no alteration in protein expressions. However, with the elongation of simvastatin treatment to 24 h, the protein expression of SERCA and RyR2 were also elevated. Additionally,simvastatin (1-30 μmol/L) had no influence on cell viability of cultured cardiac myocytes, but simvastatin 100 μmol/L inhibited the cell viability. Conclusion:Simvastatin improved cardiac performance accompanied by the elevation of SERCA and RyR2 gene and protein expression.

  14. A novel artificial microRNA expressing AAV vector for phospholamban silencing in cardiomyocytes improves Ca2+ uptake into the sarcoplasmic reticulum.

    Directory of Open Access Journals (Sweden)

    Tobias Gröβl

    Full Text Available In failing rat hearts, post-transcriptonal inhibition of phospholamban (PLB expression by AAV9 vector-mediated cardiac delivery of short hairpin RNAs directed against PLB (shPLBr improves both impaired SERCA2a controlled Ca2+ cycling and contractile dysfunction. Cardiac delivery of shPLB, however, was reported to cause cardiac toxicity in canines. Thus we developed a new AAV vector, scAAV6-amiR155-PLBr, expressing a novel engineered artificial microRNA (amiR155-PLBr directed against PLB under control of a heart-specific hybrid promoter. Its PLB silencing efficiency and safety were compared with those of an AAV vector expressing shPLBr (scAAV6-shPLBr from an ubiquitously active U6 promoter. Investigations were carried out in cultured neonatal rat cardiomyocytes (CM over a period of 14 days. Compared to shPLBr, amiR155-PLBr was expressed at a significantly lower level, resulting in delayed and less pronounced PLB silencing. Despite decreased knockdown efficiency of scAAV6-amiR155-PLBr, a similar increase of the SERCA2a-catalyzed Ca2+ uptake into sarcoplasmic reticulum (SR vesicles was observed for both the shPLBr and amiR155-PLBr vectors. Proteomic analysis confirmed PLB silencing of both therapeutic vectors and revealed that shPLBr, but not the amiR155-PLBr vector, increased the proinflammatory proteins STAT3, STAT1 and activated STAT1 phosphorylation at the key amino acid residue Tyr701. Quantitative RT-PCR analysis detected alterations in the expression of several cardiac microRNAs after treatment of CM with scAAV6-shPLBr and scAAV6-amiR155-PLBr, as well as after treatment with its related amiR155- and shRNAs-expressing control AAV vectors. The results demonstrate that scAAV6-amiR155-PLBr is capable of enhancing the Ca2+ transport function of the cardiac SR PLB/SERCA2a system as efficiently as scAAV6-shPLBr while offering a superior safety profile.

  15. Effect of chloride on Ca2+ release from the sarcoplasmic reticulum of mechanically skinned skeletal muscle fibres. (United States)

    Coonan, J R; Lamb, G D


    The effect of intracellular Cl- on Ca2+ release in mechanically skinned fibres of rat extensor digitorum longus (EDL) and toad iliofibularis muscles was examined under physiological conditions of myoplasmic [Mg2+] and [ATP] and sarcoplasmic reticulum (SR) Ca2+ loading. Both in rat and toad fibres, the presence of 20 mM Cl- in the myoplasm increased Ca2+ leakage from the SR at pCa (i.e. -log10 [Ca2+]) 6.7, but not at pCa 8. Ca2+ uptake was not significantly affected by the presence of Cl-. This Ca2+-dependent effect of Cl- on Ca2+ leakage was most likely due to a direct action on the ryanodine receptor/Ca2+ release channel, and could influence channel sensitivity and the resting [Ca2+] in muscle fibres in vivo. In contrast to this effect, acute addition of 20 mM Cl- to the myoplasm caused a 40-50% reduction in Ca2+ release in response to a low caffeine concentration both in toad and rat fibres. One possible explanation for this latter effect is that the addition of Cl- induces a potential across the SR (lumen negative) which might reduce Ca2+ release via several different mechanisms.

  16. Effects of thapsigargin and cyclopiazonic acid on the sarcoplasmic reticulum Ca2+ pump of skinned fibres from frog skeletal muscle. (United States)

    Du, G G; Ashley, C C; Lea, T J


    Thapsigargin has been reported to inhibit ATP-dependent Ca2+ uptake by isolated sarcoplasmic reticulum (SR) vesicles of vertebrate skeletal muscle fibres at nanomolar concentrations. There have been no reports confirming this effect in skinned muscle fibre preparations. We have examined the ability of thapsigargin to inhibit the uptake of Ca2+ by the SR in mechanically skinned fibres of frog iliofibularis muscles, using the size of the caffeine-induced contracture to assess the Ca2+ content of the SR. The SR was first depleted of Ca2+ and then reloaded for 1 min at pCa 6.2 in the presence and absence of thapsigargin. When 5 min were allowed for diffusion, a thapsigargin concentration of at least 131 microM was required to inhibit Ca2+ loading by 50%. In contrast, another SR Ca2+ uptake inhibitor, cyclopiazonic acid, was more effective, producing 50% inhibition at 7.0 microM and total inhibition at 50 microM. When cyclopiazonic acid (100 microM) was applied after, rather than during, Ca2+ loading, the caffeine-induced contracture was not changed. Thapsigargin (300 microM), on the other hand, caused some reduction in the peak amplitude of the caffeine-induced contracture when applied after Ca2+ loading. The poor effectiveness of thapsigargin in the skinned fibres, compared with in SR vesicles, is attributed to its slow diffusion into the skinned fibres, perhaps as a result of binding to myofibrillar components.

  17. Drug action of benzocaine on the sarcoplasmic reticulum Ca-ATPase from fast-twitch skeletal muscle. (United States)

    Di Croce, D; Trinks, P W; Grifo, M B; Takara, D; Sánchez, G A


    The effect of the local anesthetic benzocaine on sarcoplasmic reticulum membranes isolated from fast-twitch muscles was tested. The effects on Ca-ATPase activity, calcium binding and uptake, phosphoenzyme accumulation and decomposition were assessed using radioisotopic methods. The calcium binding to the Ca-ATPase was noncompetitively inhibited, and the enzymatic activity decreased in a concentration-dependent manner (IC50 47.1 mM). The inhibition of the activity depended on the presence of the calcium ionophore calcimycin and the membrane protein concentration. The pre-exposure of the membranes to benzocaine enhanced the enzymatic activity in the absence of calcimycin, supporting the benzocaine permeabilizing effect, which was prevented by calcium. Benzocaine also interfered with the calcium transport capability by decreasing the maximal uptake (IC50 40.3 mM) without modification of the calcium affinity for the ATPase. It inhibited the phosphorylation of the enzyme, and at high benzocaine concentration, the dephosphorylation step became rate-limiting as suggested by the biphasic profile of phosphoenzyme accumulation at different benzocaine concentrations. The data reported in this paper revealed a complex pattern of inhibition involving two sites for interaction with low and high benzocaine concentrations. It is concluded that benzocaine not only exerts an indirect action on the membrane permeability to calcium but also affects key steps of the Ca-ATPase enzymatic cycle.

  18. Short and long range functions of amino acids in the transmembrane region of the sarcoplasmic reticulum ATPase. A mutational study. (United States)

    Chen, L; Sumbilla, C; Lewis, D; Zhong, L; Strock, C; Kirtley, M E; Inesi, G


    Mutational analysis of several amino acids in the transmembrane region of the sarcoplasmic reticulum ATPase was performed by expressing wild type ATPase and 32 site-directed mutants in COS-1 cells followed by functional characterization of the microsomal fraction. Four different phenotype characteristics were observed in the mutants: (a) functions similar to those sustained by the wild type ATPase; (b) Ca2+ transport inhibited to a greater extent than ATPase hydrolytic activity; (c) inhibition of transport and hydrolytic activity in the presence of high levels of phosphorylated enzyme intermediate; and (d) total inhibition of ATP utilization by the enzyme while retaining the ability to form phosphoenzyme by utilization of P(i). Analysis of experimental observations and molecular models revealed short and long range functions of several amino acids within the transmembrane region. Short range functions include: (a) direct involvement of five amino acids in Ca2+ binding within a channel formed by clustered transmembrane helices M4, M5, M6, and M8; (b) roles of several amino acids in structural stabilization of the helical cluster for optimal channel function; and (c) a specific role of Lys297 in sealing the distal end of the channel, suggesting that the M4 helix rotates to allow vectorial flux of Ca2+ upon enzyme phosphorylation. Long range functions are related to the influence of several transmembrane amino acids on phosphorylation reactions with ATP or P(i), transmitted to the extramembranous region of the ATPase in the presence or in the absence of Ca2+.

  19. Modulation of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase activity and oxidative modification during the development of adjuvant arthritis. (United States)

    Strosova, Miriam K; Karlovska, Janka; Zizkova, Petronela; Kwolek-Mirek, Magdalena; Ponist, Silvester; Spickett, Corinne M; Horakova, Lubica


    Adjuvant arthritis (AA) was induced by intradermal administration of Mycobacterium butyricum to the tail of Lewis rats. In sarcoplasmic reticulum (SR) of skeletal muscles, we investigated the development of AA. SR Ca(2+)-ATPase (SERCA) activity decreased on day 21, suggesting possible conformational changes in the transmembrane part of the enzyme, especially at the site of the calcium binding transmembrane part. These events were associated with an increased level of protein carbonyls, a decrease in cysteine SH groups, and alterations in SR membrane fluidity. There was no alteration in the nucleotide binding site at any time point of AA, as detected by a FITC fluorescence marker. Some changes observed on day 21 appeared to be reversible, as indicated by SERCA activity, cysteine SH groups, SR membrane fluidity, protein carbonyl content and fluorescence of an NCD-4 marker specific for the calcium binding site. The reversibility may represent adaptive mechanisms of AA, induced by higher relative expression of SERCA, oxidation of cysteine, nitration of tyrosine and presence of acidic phospholipids such as phosphatidic acid. Nitric oxide may regulate cytoplasmic Ca(2+) level through conformational alterations of SERCA, and decreasing levels of calsequestrin in SR may also play regulatory role in SERCA activity and expression.

  20. Protective and inhibitory effects of various types of amphipols on the Ca2+-ATPase from sarcoplasmic reticulum: a comparative study. (United States)

    Picard, Martin; Dahmane, Tassadite; Garrigos, Manuel; Gauron, Carole; Giusti, Fabrice; le Maire, Marc; Popot, Jean-Luc; Champeil, Philippe


    Amphipols are amphipathic polymers designed to replace or supplement detergents in membrane protein solution studies. Previous work has suggested both advantages and disadvantages to the use of a polyacrylate-based amphipol, A8-35, for studying the sarcoplasmic reticulum Ca2+-ATPase (SERCA1a). We investigated this issue further using a set of four amphipols with different chemical structures. Previous size exclusion chromatography experiments had shown that A8-35 and SERCA1a/A8-35 complexes aggregate under certain conditions. We show here that aggregation can be prevented by omitting calcium from buffers or by using a sulfonated version of A8-35. A8-35 had previously been shown to protect Ca2+-ATPase from irreversible denaturation, while inhibiting its activity in a reversible manner. We show here that the other three amphipols tested also display these properties and that all four amphipols slow down backward calcium dissociation from the nonphosphorylated solubilized enzyme, a priori an unrelated step. As this calcium dissociation involves the opening up of the bundle of transmembrane ATPase segments, the slowing of this process may indicate that multipoint attachment of the polymers to the hydrophobic transmembrane surface damps protein dynamics ("Gulliver" effect). Damping might be the reason why amphipols also simultaneously protect membrane proteins against irreversible denaturation and may inhibit the activity of those of them that display large rearrangements of their transmembrane surface during their catalytic cycle.

  1. 3-Bromopyruvate inhibits calcium uptake by sarcoplasmic reticulum vesicles but not SERCA ATP hydrolysis activity. (United States)

    Jardim-Messeder, Douglas; Camacho-Pereira, Juliana; Galina, Antonio


    3-Bromopyruvate (3BrPA) is an antitumor agent that alkylates the thiol groups of enzymes and has been proposed as a treatment for neoplasias because of its specific reactivity with metabolic energy transducing enzymes in tumor cells. In this study, we show that the sarco/endoplasmic reticulum calcium (Ca(2+)) ATPase (SERCA) type 1 is one of the target enzymes of 3BrPA activity. Sarco/endoplasmic reticulum vesicles (SRV) were incubated in the presence of 1mM 3BrPA, which was unable to inhibit the ATPase activity of SERCA. However, Ca(2+)-uptake activity was significantly inhibited by 80% with 150 μM 3BrPA. These results indicate that 3BrPA has the ability to uncouple the ATP hydrolysis from the calcium transport activities. In addition, we observed that the inclusion of 2mM reduced glutathione (GSH) in the reaction medium with different 3BrPA concentrations promoted an increase in 40% in ATPase activity and protects the inhibition promoted by 3BrPA in calcium uptake activity. This derivatization is accompanied by a decrease of reduced cysteine (Cys), suggesting that GSH and 3BrPA increases SERCA activity and transport by pyruvylation and/or S-glutathiolation mediated by GSH at a critical Cys residues of the SERCA.

  2. 姜黄素对心力衰竭兔肌浆网钙泵表达的影响%Effects of curcumin on sarcoplasmic reticulum Ca~(2+) -ATPase in rabbits with heart failure

    Institute of Scientific and Technical Information of China (English)

    张艳; 林国生; 包明威; 武欣迎; 王澈; 杨波


    group.Compared with the control groups (Groups 3 and 4),the heart/body weight ratio was significantly increased in the heart failure-curcumin group (Group 1) and the heart failure-placebo group (Group 2,all P<0.05),but the ratio was significantly lower in heart failure-curcumin group than in heart failure-placebo group (P<0.05).The degree of heart failure was decreased by curcumin.Activity and mRNA and protein expression for sarcoplasmic reticulum Ca~(2+) -ATPase were significantly reduced in the heart failure-placebo group and which could be significantly attenuated by curcumin (all P<0.05).Conclusion Curoumin could improve cardiac function via upregulating the expression of sarcoplasmic reticulum Ca~(2+) -ATPas in this model.

  3. Role of SERCA and the sarcoplasmic reticulum calcium content on calcium waves propagation in rat ventricular myocytes. (United States)

    Salazar-Cantú, Ayleen; Pérez-Treviño, Perla; Montalvo-Parra, Dolores; Balderas-Villalobos, Jaime; Gómez-Víquez, Norma L; García, Noemí; Altamirano, Julio


    In Ca(2+)-overloaded ventricular myocytes, SERCA is crucial to steadily achieve the critical sarcoplasmic reticulum (SR) Ca(2+) level to trigger and sustain Ca(2+) waves, that propagate at constant rate (ʋwave). High luminal Ca(2+) sensitizes RyR2, thereby increasing Ca(2+) sparks frequency, and the larger RyR2-mediated SR Ca(2+) flux (dF/dt) sequentially activates adjacent RyR2 clusters. Recently, it was proposed that rapid SERCA Ca(2+) reuptake, ahead of the wave front, further sensitizes RyR2, increasing ʋwave. Nevertheless, this is controversial because rapid cytosolic Ca(2+) removal could instead impair RyR2 activation. We assessed whether rapid SR Ca(2+) uptake enhances ʋwave by changing SERCA activity (ҡDecay) over a large range (∼175%). We used normal (Ctrl) and hyperthyroid rat (HT; reduced phospholamban by ∼80%) myocytes treated with thapsigargin or isoproterenol (ISO). We found that ʋwave and dF/dt had a non-linear dependency with ҡDecay, while Ca(2+) waves amplitude was largely unaffected. Furthermore, SR Ca(2+) also showed a non-linear dependency with ҡDecay, however, the relationships ʋwave vs. SR Ca(2+) and ʋwave vs. dF/dt were linear, suggesting that high steady state SR Ca(2+) determines ʋwave, while rapid SERCA Ca(2+) uptake does not. Finally, ISO did not increase ʋwave in HT cells, therefore, ISO-enhanced ʋwave in Ctrl depended on high SR Ca(2+).

  4. Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation

    Directory of Open Access Journals (Sweden)

    Lu Fang-hao


    Full Text Available Abstract Communication between the SR (sarcoplasmic reticulum, SR and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM. Although it has been demonstrated that CaR (calcium sensing receptor activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re, the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

  5. Calcium-sensing receptors regulate cardiomyocyte Ca2+ signaling via the sarcoplasmic reticulum-mitochondrion interface during hypoxia/reoxygenation. (United States)

    Lu, Fang-hao; Tian, Zhiliang; Zhang, Wei-hua; Zhao, Ya-jun; Li, Hu-lun; Ren, Huan; Zheng, Hui-shuang; Liu, Chong; Hu, Guang-xia; Tian, Ye; Yang, Bao-feng; Wang, Rui; Xu, Chang-qing


    Communication between the SR (sarcoplasmic reticulum, SR) and mitochondria is important for cell survival and apoptosis. The SR supplies Ca2+ directly to mitochondria via inositol 1,4,5-trisphosphate receptors (IP3Rs) at close contacts between the two organelles referred to as mitochondrion-associated ER membrane (MAM). Although it has been demonstrated that CaR (calcium sensing receptor) activation is involved in intracellular calcium overload during hypoxia/reoxygenation (H/Re), the role of CaR activation in the cardiomyocyte apoptotic pathway remains unclear. We postulated that CaR activation plays a role in the regulation of SR-mitochondrial inter-organelle Ca2+ signaling, causing apoptosis during H/Re. To investigate the above hypothesis, cultured cardiomyocytes were subjected to H/Re. We examined the distribution of IP3Rs in cardiomyocytes via immunofluorescence and Western blotting and found that type 3 IP3Rs were located in the SR. [Ca2+]i, [Ca2+]m and [Ca2+]SR were determined using Fluo-4, x-rhod-1 and Fluo 5N, respectively, and the mitochondrial membrane potential was detected with JC-1 during reoxygenation using laser confocal microscopy. We found that activation of CaR reduced [Ca2+]SR, increased [Ca2+]i and [Ca2+]m and decreased the mitochondrial membrane potential during reoxygenation. We found that the activation of CaR caused the cleavage of BAP31, thus generating the pro-apoptotic p20 fragment, which induced the release of cytochrome c from mitochondria and the translocation of bak/bax to mitochondria. Taken together, these results reveal that CaR activation causes Ca2+ release from the SR into the mitochondria through IP3Rs and induces cardiomyocyte apoptosis during hypoxia/reoxygenation.

  6. Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca2+ leak after one session of high-intensity interval exercise. (United States)

    Place, Nicolas; Ivarsson, Niklas; Venckunas, Tomas; Neyroud, Daria; Brazaitis, Marius; Cheng, Arthur J; Ochala, Julien; Kamandulis, Sigitas; Girard, Sebastien; Volungevičius, Gintautas; Paužas, Henrikas; Mekideche, Abdelhafid; Kayser, Bengt; Martinez-Redondo, Vicente; Ruas, Jorge L; Bruton, Joseph; Truffert, Andre; Lanner, Johanna T; Skurvydas, Albertas; Westerblad, Håkan


    High-intensity interval training (HIIT) is a time-efficient way of improving physical performance in healthy subjects and in patients with common chronic diseases, but less so in elite endurance athletes. The mechanisms underlying the effectiveness of HIIT are uncertain. Here, recreationally active human subjects performed highly demanding HIIT consisting of 30-s bouts of all-out cycling with 4-min rest in between bouts (≤3 min total exercise time). Skeletal muscle biopsies taken 24 h after the HIIT exercise showed an extensive fragmentation of the sarcoplasmic reticulum (SR) Ca(2+) release channel, the ryanodine receptor type 1 (RyR1). The HIIT exercise also caused a prolonged force depression and triggered major changes in the expression of genes related to endurance exercise. Subsequent experiments on elite endurance athletes performing the same HIIT exercise showed no RyR1 fragmentation or prolonged changes in the expression of endurance-related genes. Finally, mechanistic experiments performed on isolated mouse muscles exposed to HIIT-mimicking stimulation showed reactive oxygen/nitrogen species (ROS)-dependent RyR1 fragmentation, calpain activation, increased SR Ca(2+) leak at rest, and depressed force production due to impaired SR Ca(2+) release upon stimulation. In conclusion, HIIT exercise induces a ROS-dependent RyR1 fragmentation in muscles of recreationally active subjects, and the resulting changes in muscle fiber Ca(2+)-handling trigger muscular adaptations. However, the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes, which may explain why HIIT is less effective in this group.

  7. Structural dynamics and topology of phosphorylated phospholamban homopentamer reveal its role in the regulation of calcium transport in sarcoplasmic reticulum (United States)

    Vostrikov, Vitaly V.; Mote, Kaustubh R.; Verardi, Raffaello; Veglia, Gianluigi


    Phospholamban (PLN) inhibits the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA), thereby regulating cardiac diastole. In membranes, PLN assembles into homopentamers that in both the phosphorylated and non-phosphorylated states have been proposed to form ion-selective channels. Here, we determined the structure of the phosphorylated pentamer using a combination of solution and solid-state nuclear magnetic resonance methods. We found that the pinwheel architecture of the homopentamer is preserved upon phosphorylation, with each monomer having an L-shaped conformation of each monomer. The TM domains form a hydrophobic pore of approximately 24 Å long, and 2 Å in diameter, which is inconsistent with canonical Ca2+ selective channels. Phosphorylation, however, enhances the conformational dynamics of the cytoplasmic region of PLN, causing the partial unwinding of the amphipathic helix. We propose that PLN oligomers act as storage for active monomers, keeping SERCA function within a physiological window. PMID:24207128

  8. Sarcoplasmic reticulum calcium release compared in slow-twitch and fast-twitch fibres of mouse muscle. (United States)

    Baylor, S M; Hollingworth, S


    Experiments were carried out to compare the amplitude and time course of Ca2+ release from the sarcoplasmic reticulum (SR) in intact slow-twitch and fast-twitch mouse fibres. Individual fibres within small bundles were injected with furaptra, a low-affinity, rapidly responding Ca2+ indicator. In response to a single action potential at 16 degrees C, the peak amplitude and half-duration of the change in myoplasmic free [Ca2+] (Delta[Ca2+]) differed significantly between fibre types (slow-twitch: peak amplitude, 9.4 +/- 1.0 microM (mean +/- S.E.M.); half-duration, 7.7 +/- 0.6 ms; fast-twitch: peak amplitude 18.5 +/- 0.5 microM; half-duration, 4.9 +/- 0.3 ms). SR Ca2+ release was estimated from Delta[Ca2+] with a computational model that calculated Ca2+ binding to the major myoplasmic Ca2+ buffers (troponin, ATP and parvalbumin); buffer concentrations and reaction rate constants were adjusted to reflect fibre-type differences. In response to an action potential, the total concentration of released Ca2+ (Delta[CaT]) and the peak rate of Ca2+ release ((d/dt)Delta[CaT]) differed about 3-fold between the fibre types (slow-twitch: Delta[CaT], 127 +/- 7 microM; (d/dt)Delta[CaT], 70 +/- 6 microM ms-1; fast-twitch: Delta[CaT], 346 +/- 6 microM; (d/dt)Delta[CaT], 212 +/- 4 microM ms-1). In contrast, the half-duration of (d/dt)Delta[CaT] was very similar in the two fibre types (slow-twitch, 1.8 +/- 0.1 ms; fast-twitch, 1.6 +/- 0.0 ms). When fibres were stimulated with a 5-shock train at 67 Hz, the peaks of (d/dt)Delta[CaT] in response to the second and subsequent shocks were much smaller than that due to the first shock; the later peaks, expressed as a fraction of the amplitude of the first peak, were similar in the two fibre types (slow-twitch, 0.2-0.3; fast-twitch, 0.1-0.3). The results support the conclusion that individual SR Ca2+ release units function similarly in slow-twitch and fast-twitch mammalian fibres.

  9. Effect of saponin treatment on the sarcoplasmic reticulum of rat, cane toad and crustacean (yabby) skeletal muscle. (United States)

    Launikonis, B S; Stephenson, D G


    1. Mechanically skinned fibres from skeletal muscles of the rat, toad and yabby were used to investigate the effect of saponin treatment on sarcoplasmic reticulum (SR) Ca2+ loading properties. The SR was loaded submaximally under control conditions before and after treatment with saponin and SR Ca2+ was released with caffeine. 2. Treatment with 10 micrograms ml-1 saponin greatly reduced the SR Ca2+ loading ability of skinned fibres from the extensor digitorum longus muscle of the rat with a rate constant of 0.24 min-1. Saponin concentrations up to 150 micrograms ml-1 and increased exposure time up to 30 min did not further reduce the SR Ca2+ loading ability of the SR, which indicates that the inhibitory action of 10-150 micrograms ml-1 saponin is not dose dependent. The effect of saponin was also not dependent on the state of polarization of the transverse-tubular system. 3. Treatment with saponin at concentrations up to 100 micrograms ml-1 for 30 min did not affect the Ca2+ loading ability of SR in skinned skeletal muscle fibres from the twitch portion of the toad iliofibularis muscle but SR Ca2+ loading ability decreased markedly with a time constant of 0.22 min-1 in the presence of 150 micrograms ml-1 saponin. 4. The saponin dependent increase in permeability could be reversed in both rat and toad fibres by short treatment with 6 microM Ruthenium Red, a potent SR Ca2+ channel blocker, suggesting that saponin does affect the SR Ca2+ channel properties in mammalian and anuran skeletal muscle. 5. Treatment of skinned fibres of long sarcomere length (> 6 microns) from the claw muscle of the yabby (a freshwater decapod crustacean) with 10 micrograms ml-1 saponin for 30 min abolished the ability of the SR to load Ca2+, indicating that saponin affects differently the SR from skeletal muscles of mammals, anurans and crustaceans. 6. It is concluded that at relatively low concentrations, saponin causes inhibition of the skeletal SR Ca2+ loading ability in a species

  10. Interaction of phosphatidic acid and phosphatidylserine with the Ca2+-ATPase of sarcoplasmic reticulum and the mechanism of inhibition. (United States)

    Dalton, K A; East, J M; Mall, S; Oliver, S; Starling, A P; Lee, A G


    The sarcoplasmic reticulum of skeletal muscle contains anionic phospholipids as well as the zwitterionic phosphatidylcholine and phosphatidylethanolamine. Here we study the effects of anionic phospholipids on the activity of the Ca2+-ATPase purified from the membrane. Reconstitution of the Ca2+-ATPase into dioleoylphosphatidylserine [di(C18:1)PS] or dioleoylphosphatidic acid [di(C18:1)PA] leads to a decrease in ATPase activity. Measurements of the quenching of the tryptophan fluorescence of the ATPase by brominated phospholipids give a relative binding constant for the anionic lipids compared with dioleoylphosphatidylcholine close to 1 and suggest that phosphatidic acid only binds to the ATPase at the bulk lipid sites around the ATPase. Addition of di(C18:1)PS or di(C18:1)PA to the ATPase in the short-chain dimyristoleoylphosphatidylcholine [di(C14:1)PC] reverse the effects of the short-chain lipid on ATPase activity and on Ca2+ binding, as revealed by the response of tryptophan fluorescence intensity to Ca2+ binding. It is concluded that the lipid headgroup and lipid fatty acyl chains have separate effects on the function of the ATPase. The anionic phospholipids have no significant effect on Ca2+ binding to the ATPase; the level of Ca2+ binding to the ATPase, the affinity of binding and the rate of dissociation of Ca2+ are unchanged by reconstitution into di(C18:1)PA. The major effect of the anionic lipids is a reduction in the maximal level of binding of MgATP. This is attributed to the formation of oligomers of the Ca2+-ATPase, in which only one molecule of the ATPase can bind MgATP dimers in di(C18:1)PS and trimers or tetramers in di(C18:1)PA. The rates of phosphorylation and dephosphorylation for the proportion of the ATPase still able to bind ATP are unaffected by reconstitution. Larger changes were observed in the level of phosphorylation of the ATPase by Pi, which became very low in the anionic phospholipids. The fluorescence response to Mg2+ for the ATPase

  11. Sarcoplasmic reticulum calcium mobilization in right ventricular pressure-overload hypertrophy in the ferret: relationships to diastolic dysfunction and a negative treppe. (United States)

    Gwathmey, J K; Morgan, J P


    In a model of right-ventricular pressure-overload hypertrophy (POH) in the ferret, action potential duration (to 90% repolarization) was found to be significantly longer (228 +/- 11 vs 314 +/- 12 ms) with no change in amplitude (85 +/- 3 vs 85 +/- 2 mV) or resting membrane potential (-79 +/- 1.5 vs -79 +/- 1 mV) for control and POH, respectively. Peak sarcoplasmic reticulum Ca2+ release (expressed as the logarithm of the fractional luminescence, -4.2 +/- 0.1 vs -4.4 +/- 0.3) and resting calcium concentrations (-5.5 +/- 0.1 vs -5.7 +/- 0.1) were not different between the two groups (control vs POH respectively). Muscles from control and POH animals demonstrated a positive force/interval relationship in the presence of physiological extracellular [Ca2+]. However, unlike muscles from control animals, muscles from animals with POH subjected to increasing frequencies of contraction in the presence of increased extracellular [Ca2+] demonstrated further impairment of diastolic relaxation and a negative treppe. Exposure of muscles from POH animals to isoproterenol returned the slowed Ca2+ uptake by the sarcoplasmic reticulum as detected with aequorin to control values, although the relaxation phase of the isometric twitch remained prolonged compared to non-hypertrophied muscles. Exposure to milrinone also abbreviated the time course of the intracellular Ca2+ transient, but did not return it to that seen in normal myocardium. The exposure of non-hypertrophied isolated muscles to caffeine resulted in similar prolongation of the isometric twitch duration to that seen in hypertrophied myocardium. Results of these experiments suggest that impaired muscle relaxation in POH reflects changes at the level of the myofilaments. Thus, although slowed intracellular calcium mobilization contributes to diastolic relaxation abnormalities, it can not be the sole factor responsible for the slowed relaxation as has been suggested.

  12. S100A1: A Regulator of Striated Muscle Sarcoplasmic Reticulum Ca2+ Handling, Sarcomeric, and Mitochondrial Function

    Directory of Open Access Journals (Sweden)

    Mirko Völkers


    S100A1 has further been detected at different sites within the cardiac sarcomere indicating potential roles in myofilament function. More recently, a study reported a mitochondrial location of S100A1 in cardiomyocytes. Additionally, normalizing the level of S100A1 protein by means of viral cardiac gene transfer in animal heart failure models resulted in a disrupted progression towards cardiac failure and enhanced survival. This brief review is confined to the physiological and pathophysiological relevance of S100A1 in cardiac and skeletal muscle Ca2+ handling with a particular focus on its potential as a molecular target for future therapeutic interventions.

  13. Interaction between endoplasmic/sarcoplasmic reticulum stress (ER/SR stress), mitochondrial signaling and Ca(2+) regulation in airway smooth muscle (ASM). (United States)

    Delmotte, Philippe; Sieck, Gary C


    Airway inflammation is a key aspect of diseases such as asthma. Several inflammatory cytokines (e.g., TNFα and IL-13) increase cytosolic Ca(2+) ([Ca(2+)]cyt) responses to agonist stimulation and Ca(2+) sensitivity of force generation, thereby enhancing airway smooth muscle (ASM) contractility (hyper-reactive state). Inflammation also induces ASM proliferation and remodeling (synthetic state). In normal ASM, the transient elevation of [Ca(2+)]cyt induced by agonists leads to a transient increase in mitochondrial Ca(2+) ([Ca(2+)]mito) that may be important in matching ATP production with ATP consumption. In human ASM (hASM) exposed to TNFα and IL-13, the transient increase in [Ca(2+)]mito is blunted despite enhanced [Ca(2+)]cyt responses. We also found that TNFα and IL-13 induce reactive oxidant species (ROS) formation and endoplasmic/sarcoplasmic reticulum (ER/SR) stress (unfolded protein response) in hASM. ER/SR stress in hASM is associated with disruption of mitochondrial coupling with the ER/SR membrane, which relates to reduced mitofusin 2 (Mfn2) expression. Thus, in hASM it appears that TNFα and IL-13 result in ROS formation leading to ER/SR stress, reduced Mfn2 expression, disruption of mitochondrion-ER/SR coupling, decreased mitochondrial Ca(2+) buffering, mitochondrial fragmentation, and increased cell proliferation.

  14. Determination of the ATP Affinity of the Sarcoplasmic Reticulum Ca(2+)-ATPase by Competitive Inhibition of [γ-(32)P]TNP-8N3-ATP Photolabeling. (United States)

    Clausen, Johannes D; McIntosh, David B; Woolley, David G; Andersen, Jens Peter


    The photoactivation of aryl azides is commonly employed as a means to covalently attach cross-linking and labeling reagents to proteins, facilitated by the high reactivity of the resultant aryl nitrenes with amino groups present in the protein side chains. We have developed a simple and reliable assay for the determination of the ATP binding affinity of native or recombinant sarcoplasmic reticulum Ca(2+)-ATPase, taking advantage of the specific photolabeling of Lys(492) in the Ca(2+)-ATPase by [γ-(32)P]2',3'-O-(2,4,6-trinitrophenyl)-8-azido-adenosine 5'-triphosphate ([γ-(32)P]TNP-8N3-ATP) and the competitive inhibition by ATP of the photolabeling reaction. The method allows determination of the ATP affinity of Ca(2+)-ATPase mutants expressed in mammalian cell culture in amounts too minute for conventional equilibrium binding studies. Here, we describe the synthesis and purification of the [γ-(32)P]TNP-8N3-ATP photolabel, as well as its application in ATP affinity measurements.

  15. Cyclopiazonic Acid Is Complexed to a Divalent Metal Ion When Bound to the Sarcoplasmic Reticulum Ca2+-ATPase

    DEFF Research Database (Denmark)

    Laursen, Mette; Bublitz, Maike; Moncoq, Karine;


    Abstract: We have determined the structure of the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) in an E2.P-i-like form stabilized as a complex with MgF42-, an ATP analog, adenosine 5'-(beta,gamma-methylene) triphosphate (AMPPCP), and cyclopiazonic acid (CPA). The structure determined at 2.......5 angstrom resolution leads to a significantly revised model of CPA binding when compared with earlier reports. It shows that a divalent metal ion is required for CPA binding through coordination of the tetramic acid moiety at a characteristic kink of the M1 helix found in all P-type ATPase structures, which...... is expected to be part of the cytoplasmic cation access pathway. Our model is consistent with the biochemical data on CPA function and provides new measures in structure-based drug design targeting Ca2+-ATPases, e. g. from pathogens. We also present an extended structural basis of ATP modulation pinpointing...

  16. Sarcoplasmic reticulum calcium ATPase is inhibited by organic vanadium coordination compounds: pyridine-2,6-dicarboxylatodioxovanadium(V), BMOV, and an amavadine analogue. (United States)

    Aureliano, Manuel; Henao, Fernando; Tiago, Teresa; Duarte, Rui O; Moura, J J G; Baruah, Bharat; Crans, Debbie C


    The general affinity of the sarcoplasmic reticulum (SR) Ca (2+)-ATPase was examined for three different classes of vanadium coordination complexes including a vanadium(V) compound, pyridine-2,6-dicarboxylatodioxovanadium(V) (PDC-V(V)), and two vanadium(IV) compounds, bis(maltolato)oxovanadium(IV) (BMOV), and an analogue of amavadine, bis( N-hydroxylamidoiminodiacetato)vanadium(IV) (HAIDA-V(IV)). The ability of vanadate to act either as a phosphate analogue or as a transition-state analogue with enzymes' catalysis phosphoryl group transfer suggests that vanadium coordination compounds may reveal mechanistic preferences in these classes of enzymes. Two of these compounds investigated, PDC-V(V) and BMOV, were hydrolytically and oxidatively reactive at neutral pH, and one, HAIDA-V(IV), does not hydrolyze, oxidize, or otherwise decompose to a measurable extent during the enzyme assay. The SR Ca (2+)-ATPase was inhibited by all three of these complexes. The relative order of inhibition was PDC-V(V) > BMOV > vanadate > HAIDA-V(IV), and the IC 50 values were 25, 40, 80, and 325 microM, respectively. Because the observed inhibition is more potent for PDC-V(V) and BMOV than that of oxovanadates, the inhibition cannot be explained by oxovanadate formation during enzyme assays. Furthermore, the hydrolytically and redox stable amavadine analogue HAIDA-V(IV) inhibited the Ca (2+)-ATPase less than oxovanadates. To gauge the importance of the lipid environment, studies of oxidized BMOV in microemulsions were performed and showed that this system remained in the aqueous pool even though PDC-V(V) is able to penetrate lipid interfaces. These findings suggest that the hydrolytic properties of these complexes may be important in the inhibition of the calcium pump. Our results show that two simple coordination complexes with known insulin enhancing effects can invoke a response in calcium homeostasis and the regulation of muscle contraction through the SR Ca (2+)-ATPase.

  17. Biphasic contractions induced by milrinone at low temperature in ferret ventricular muscle: role of the sarcoplasmic reticulum and transmembrane calcium influx. (United States)

    Malecot, C O; Bers, D M; Katzung, B G


    The effects of milrinone were studied in ferret papillary muscle stimulated at various rates and temperatures from 23 degrees to 36 degrees C. In voltage-clamp experiments, 50 micrograms/ml (0.237 mM) milrinone induced a 2.1-fold increase in calcium current at 28 degrees or 36 degrees C. At 50 micrograms/ml, milrinone transiently increased contractility in all muscles at 28 degrees C, but its steady-state effect was either increased (+50%) or decreased (-24.7%) steady-state twitch amplitude. A negative inotropic effect always occurred below 27 degrees C. Milrinone decreased the total twitch duration and split the twitch into two components (P1 and P2) in the absence of any evidence of aberrant conduction. Increasing milrinone concentration from 50 to 300 micrograms/ml decreased P1 and increased P2. Ryanodine (100 mM) or caffeine (10 mM) suppressed P1. Contractions elicited after 30 seconds of rest were also biphasic in the presence of milrinone, but not in its absence. P2 of post-rest contraction was increased by caffeine or calcium (10 mM) and decreased by cobalt (2 mM) when drugs were applied at the beginning of the rest. Ryanodine and caffeine also suppressed P1 of post-rest contraction. The evidence suggests that P1 may be caused by Ca release from the sarcoplasmic reticulum and P2 by increased Ca influx during the action potential via the calcium channel. It is also suggested that P2 may be present under control conditions, but to a lesser extent, and masked by a large P1.

  18. Inhibition of the sarcoplasmic reticulum Ca2+ pump with thapsigargin to estimate the contribution of Na+-Ca2+ exchange to ventricular myocyte relaxation

    Directory of Open Access Journals (Sweden)

    Bassani R.A.


    Full Text Available Relaxation in the mammalian ventricle is initiated by Ca2+ removal from the cytosol, which is performed by three main transport systems: sarcoplasmic reticulum Ca2+-ATPase (SR-A, Na+-Ca2+ exchanger (NCX and the so-called slow mechanisms (sarcolemmal Ca2+-ATPase and mitochondrial Ca2+ uptake. To estimate the relative contribution of each system to twitch relaxation, SR Ca2+ accumulation must be selectively inhibited, usually by the application of high caffeine concentrations. However, caffeine has been reported to often cause changes in membrane potential due to NCX-generated inward current, which compromises the reliability of its use. In the present study, we estimated integrated Ca2+ fluxes carried by SR-A, NCX and slow mechanisms during twitch relaxation, and compared the results when using caffeine application (Cf-NT and an electrically evoked twitch after inhibition of SR-A with thapsigargin (TG-TW. Ca2+ transients were measured in 20 isolated adult rat ventricular myocytes with indo-1. For transients in which one or more transporters were inhibited, Ca2+ fluxes were estimated from the measured free Ca2+ concentration and myocardial Ca2+ buffering characteristics. NCX-mediated integrated Ca2+ flux was significantly higher with TG-TW than with Cf-NT (12 vs 7 µM, whereas SR-dependent flux was lower with TG-TW (77 vs 81 µM. The relative participations of NCX (12.5 vs 8% with TG-TW and Cf-NT, respectively and SR-A (85 vs 89.5% with TG-TW and Cf-NT, respectively in total relaxation-associated Ca2+ flux were also significantly different. We thus propose TG-TW as a reliable alternative to estimate NCX contribution to twitch relaxation in this kind of analysis.

  19. PARM-1 is an endoplasmic reticulum molecule involved in endoplasmic reticulum stress-induced apoptosis in rat cardiac myocytes.

    Directory of Open Access Journals (Sweden)

    Koji Isodono

    Full Text Available To identify novel transmembrane and secretory molecules expressed in cardiac myocytes, signal sequence trap screening was performed in rat neonatal cardiac myocytes. One of the molecules identified was a transmembrane protein, prostatic androgen repressed message-1 (PARM-1. While PARM-1 has been identified as a gene induced in prostate in response to castration, its function is largely unknown. Our expression analysis revealed that PARM-1 was specifically expressed in hearts and skeletal muscles, and in the heart, cardiac myocytes, but not non-myocytes expressed PARM-1. Immunofluorescent staining showed that PARM-1 was predominantly localized in endoplasmic reticulum (ER. In Dahl salt-sensitive rats, high-salt diet resulted in hypertension, cardiac hypertrophy and subsequent heart failure, and significantly stimulated PARM-1 expression in the hearts, with a concomitant increase in ER stress markers such as GRP78 and CHOP. In cultured cardiac myocytes, PARM-1 expression was stimulated by proinflammatory cytokines, but not by hypertrophic stimuli. A marked increase in PARM-1 expression was observed in response to ER stress inducers such as thapsigargin and tunicamycin, which also induced apoptotic cell death. Silencing PARM-1 expression by siRNAs enhanced apoptotic response in cardiac myocytes to ER stresses. PARM-1 silencing also repressed expression of PERK and ATF6, and augmented expression of CHOP without affecting IRE-1 expression and JNK and Caspase-12 activation. Thus, PARM-1 expression is induced by ER stress, which plays a protective role in cardiac myocytes through regulating PERK, ATF6 and CHOP expression. These results suggested that PARM-1 is a novel ER transmembrane molecule involved in cardiac remodeling in hypertensive heart disease.

  20. Decavanadate, decaniobate, tungstate and molybdate interactions with sarcoplasmic reticulum Ca(2+)-ATPase: quercetin prevents cysteine oxidation by vanadate but does not reverse ATPase inhibition. (United States)

    Fraqueza, Gil; Batista de Carvalho, Luís A E; Marques, M Paula M; Maia, Luisa; Ohlin, C André; Casey, William H; Aureliano, Manuel


    Recently we demonstrated that the decavanadate (V(10)) ion is a stronger Ca(2+)-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V(10) interaction is not affected by any of the protein conformations that occur during the process of calcium translocation (i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the present study, we further explore this subject, and we can now show that the decaniobate ion, [Nb(10) = Nb(10)O(28)](6-), is a useful tool in deducing the interaction and the non-competitive Ca(2+)-ATPase inhibition by the decavanadate ion [V(10) = V(10)O(28)](6-). Moreover, decavanadate and vanadate induce protein cysteine oxidation whereas no effects were detected for the decaniobate, tungstate or molybdate ions. The presence of the antioxidant quercetin prevents cysteine oxidation, but not ATPase inhibition, by vanadate or decavanadate. Definitive V(IV) EPR spectra were observed for decavanadate in the presence of sarcoplasmic reticulum Ca(2+)-ATPase, indicating a vanadate reduction at some stage of the protein interaction. Raman spectroscopy clearly shows that the protein conformation changes that are induced by V(10), Nb(10) and vanadate are different from the ones induced by molybdate and tungstate monomer ions. Here, Mo and W cause changes similar to those by phosphate, yielding changes similar to the E1P protein conformation. The putative reduction of vanadium(V) to vanadium(IV) and the non-competitive binding of the V(10) and Nb(10) decametalates may explain the differences in the Raman spectra compared to those seen in the presence of molybdate or tungstate. Putting it all together, we suggest that the ability of V(10) to inhibit the Ca(2+)-ATPase may be at least in part due to the process of vanadate reduction and associated protein cysteine oxidation. These

  1. Calcium buffering properties of sarcoplasmic reticulum and calcium-induced Ca(2+) release during the quasi-steady level of release in twitch fibers from frog skeletal muscle. (United States)

    Fénelon, Karine; Lamboley, Cédric R H; Carrier, Nicole; Pape, Paul C


    Experiments were performed to characterize the properties of the intrinsic Ca(2+) buffers in the sarcoplasmic reticulum (SR) of cut fibers from frog twitch muscle. The concentrations of total and free calcium ions within the SR ([Ca(T)](SR) and [Ca(2+)](SR)) were measured, respectively, with the EGTA/phenol red method and tetramethylmurexide (a low affinity Ca(2+) indicator). Results indicate SR Ca(2+) buffering was consistent with a single cooperative-binding component or a combination of a cooperative-binding component and a linear binding component accounting for 20% or less of the bound Ca(2+). Under the assumption of a single cooperative-binding component, the most likely resting values of [Ca(2+)](SR) and [Ca(T)](SR) are 0.67 and 17.1 mM, respectively, and the dissociation constant, Hill coefficient, and concentration of the Ca-binding sites are 0.78 mM, 3.0, and 44 mM, respectively. This information can be used to calculate a variable proportional to the Ca(2+) permeability of the SR, namely d[Ca(T)](SR)/dt ÷ [Ca(2+)](SR) (denoted release permeability), in experiments in which only [Ca(T)](SR) or [Ca(2+)](SR) is measured. In response to a voltage-clamp step to -20 mV at 15°C, the release permeability reaches an early peak followed by a rapid decline to a quasi-steady level that lasts ~50 ms, followed by a slower decline during which the release permeability decreases by at least threefold. During the quasi-steady level of release, the release amplitude is 3.3-fold greater than expected from voltage activation alone, a result consistent with the recruitment by Ca-induced Ca(2+) release of 2.3 SR Ca(2+) release channels neighboring each channel activated by its associated voltage sensor. Release permeability at -60 mV increases as [Ca(T)](SR) decreases from its resting physiological level to ~0.1 of this level. This result argues against a release termination mechanism proposed in mammalian muscle fibers in which a luminal sensor of [Ca(2+)](SR) inhibits

  2. Cytoplasmic nanojunctions between lysosomes and sarcoplasmic reticulum are required for specific calcium signaling [v1; ref status: indexed,

    Directory of Open Access Journals (Sweden)

    Nicola Fameli


    Full Text Available Herein we demonstrate how nanojunctions between lysosomes and sarcoplasmic reticulum (L-SR junctions serve to couple lysosomal activation to regenerative, ryanodine receptor-mediated cellular Ca2+ waves. In pulmonary artery smooth muscle cells (PASMCs it has been proposed that nicotinic acid adenine dinucleotide phosphate (NAADP triggers increases in cytoplasmic Ca2+ via L-SR junctions, in a manner that requires initial Ca2+ release from lysosomes and subsequent Ca2+-induced Ca2+ release (CICR via ryanodine receptor (RyR subtype 3 on the SR membrane proximal to lysosomes. L-SR junction membrane separation has been estimated to be < 400 nm and thus beyond the resolution of light microscopy, which has restricted detailed investigations of the junctional coupling process. The present study utilizes standard and tomographic transmission electron microscopy to provide a thorough ultrastructural characterization of the L-SR junctions in PASMCs. We show that L-SR nanojunctions are prominent features within these cells and estimate that the junctional membrane separation and extension are about 15 nm and 300 nm, respectively. Furthermore, we develop a quantitative model of the L-SR junction using these measurements, prior kinetic and specific Ca2+ signal information as input data. Simulations of NAADP-dependent junctional Ca2+ transients demonstrate that the magnitude of these signals can breach the threshold for CICR via RyR3. By correlation analysis of live cell Ca2+ signals and simulated Ca2+ transients within L-SR junctions, we estimate that “trigger zones” comprising 60–100 junctions are required to confer a signal of similar magnitude. This is compatible with the 110 lysosomes/cell estimated from our ultrastructural observations. Most importantly, our model shows that increasing the L-SR junctional width above 50 nm lowers the magnitude of junctional [Ca2+] such that there is a failure to breach the threshold for CICR via RyR3. L

  3. αB-Crystallin R120G variant causes cardiac arrhythmias and alterations in the expression of Ca(2+) -handling proteins and endoplasmic reticulum stress in mice. (United States)

    Jiao, Qibin; Sanbe, Atsushi; Zhang, Xingwei; Liu, Jun-Ping; Minamisawa, Susumu


    Mutations of αB-crystallin (CryαB), a small heat shock protein abundantly expressed in cardiac and skeletal muscles, are known to cause desmin-related myopathies. The CryαB R120G allele has been linked to a familial desminopathy and, in transgenic mice, causes a sudden death at about 28 weeks of age. To investigate the mechanisms of the sudden cardiac arrest of CryαB R120G transgenic mice, we prepared protein samples from left ventricular tissues of two different age groups (10 and 28 weeks) and examined Ca(2+) -handling proteins. Expression of sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) 2, phospholamban, ryanodine receptor 2 and calsequestrin 2 was significantly decreased in 28- versus 10-week-old CryαB R120G transgenic mice. In addition, low heart rate variability, including heart rate, total power and low frequency, was observed and continuous electrocardiogram monitoring revealed cardiac arrhythmias, such as ventricular tachycardia, atrioventricular block and atrial flutter, in 28-week-old CryαB R120G transgenic mice. In contrast, expression of endoplasmic reticulum (ER) degradation enhancing α-mannosidase-like protein, inositol requirement 1 and X-box binding protein 1 were increased significantly in 28- versus 10-week-old CryαBR120G transgenic mice, suggesting that the CryαBR120G transgenic mice exhibit increased ER stress compared with wild-type mice. Together, the data suggest that the CryαB R120G dominant variant induces ER stress and impairs Ca(2+) regulation, leading to ageing-related cardiac dysfunction, arrhythmias and decreased autonomic tone with shortened lifespan.

  4. 精-甘-天冬-丝氨酸对脓毒性休克大鼠心肌肌浆网钙转运的影响%Effects of Arg-Gly-Asp-Ser on Ca2 + transport of myocardial sarcoplasmic reticulum in rat septic shock

    Institute of Scientific and Technical Information of China (English)

    吉勇; 赵明; 齐鹰; 董林旺; 吴立玲; 彭师奇; 苏静怡


    To study the effects of Arg-Gly-Asp-Ser (RGDS), a synthetic short peptide of fibrinogen degradation, on the Ca2 + transport function of cardiac sarcoplasmic reticulum in rat septic shock.4 h and 14 h after cecal ligation and puncture (CLP) operation on rats. Highly purified membrane of sarcoplasmic reticulum (SR) was prepared from rat hearts. Assays were made of ATP-dependent Ca2 + uptake by cardiac SR and [3H] ryanodine binding to SR. RESULTS: The initial rate and the capacity of SR Ca2 + uptake were increased by 104 % (P<0.01) and 12 % (P<0.05), respectively, paralleled by an increase in Ca2 +-ATPase activity and a decrease in calcium accumulation of myo- cardium of septic rats, whereas the Bmax and Kd values of Ca2+ activated [3H]ryanodine binding to SR were unaffected after RGDS administration. CONCLUTIONS: The results indicated that RGDS have cardioprotective effects of maintaining Ca2+ homeostasis of cardiac myocytes by enhancing SR Ca2 + uptake in rat septic shock.%探讨一种人工合成的纤维蛋白原降解肽片段RGDS对脓毒性休克大鼠心肌肌浆网钙转运功能的影响.方法:大鼠盲肠结扎穿孔术后4 h和14 h分两次尾静脉注射RGDS 5 μmol·kg-1.制备大鼠心肌肌浆网(SR)膜;测定SR Ca2+摄取和[3H]ryanodine受体结合功能.结果:RGDS组大鼠心肌SR摄Ca2+率及摄Ca2+量分别较休克组提高104%(P<0.01)和12%(P<0.05),而心肌SR钙释放通道-[3H]ryanodine受体结合Bmax和Ka值没有明显变化.同时RGDS还可以减轻休克大鼠心肌组织钙聚积.结论:RGDS提高休克大鼠心肌SR Ca2+摄取功能,维持心肌细胞钙稳态,具有心肌保护作用.

  5. Disruption of calpain reduces lipotoxicity-induced cardiac injury by preventing endoplasmic reticulum stress (United States)

    Li, Shengcun; Zhang, Lulu; Ni, Rui; Cao, Ting; Zheng, Dong; Xiong, Sidong; Greer, Peter A.; Fan, Guo-Chang; Peng, Tianqing


    Diabetes and obesity are prevalent in westernized countries. In both conditions, excessive fatty acid uptake by cardiomyocytes induces cardiac lipotoxicity, an important mechanism contributing to diabetic cardiomyopathy. This study investigated the effect of calpain disruption on cardiac lipotoxicity. Cardiac-specific capns1 knockout mice and their wild-type littermates (male, age of 4 weeks) were fed a high fat diet (HFD) or normal diet for 20 weeks. HFD increased body weight, altered blood lipid profiles and impaired glucose tolerance comparably in both capns1 knockout mice and their wild-type littermates. Calpain activity, cardiomyocyte cross-sectional areas, collagen deposition and triglyceride were significantly increased in HFD-fed mouse hearts, and these were accompanied by myocardial dysfunction and up-regulation of hypertrophic and fibrotic collagen genes as well as pro-inflammatory cytokines. These effects of HFD were attenuated by disruption of calpain in capns1 knockout mice. Mechanistically, deletion of capns1 in HFD-fed mouse hearts and disruption of calpain with calpain inhibitor-III, silencing of capn1, or deletion of capns1 in palmitate-stimulated cardiomyocytes prevented endoplasmic reticulum stress, apoptosis, cleavage of caspase-12 and junctophilin-2, and pro-inflammatory cytokine expression. Pharmacological inhibition of endoplasmic reticulum stress diminished palmitate-induced apoptosis and pro-inflammatory cytokine expression in cardiomyocytes. In summary, disruption of calpain prevents lipotoxicity-induced apoptosis in cardiomyocytes and cardiac injury in mice fed a HFD. The role of calpain is mediated, at least partially, through endoplasmic reticulum stress. Thus, calpain/endoplasmic reticulum stress may represent a new mechanism and potential therapeutic targets for cardiac lipotoxicity. PMID:27523632

  6. Salubrinal Alleviates Pressure Overload-Induced Cardiac Hypertrophy by Inhibiting Endoplasmic Reticulum Stress Pathway (United States)

    Rani, Shilpa; Sreenivasaiah, Pradeep Kumar; Cho, Chunghee; Kim, Do Han


    Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit (p-eIF2)-α, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal (0.5 mg·kg−1·day−1) alleviated cardiac hypertrophy and tissue fibrosis. Salubrinal also alleviated hypertrophic growth in endothelin 1 (ET1)-treated NRVMs. Therefore, the present results suggest that salubrinal may be a potentially efficacious drug for treating pathological cardiac remodeling. PMID:28152298

  7. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum. (United States)

    Loy, Ryan E; Orynbayev, Murat; Xu, Le; Andronache, Zoita; Apostol, Simona; Zvaritch, Elena; MacLennan, David H; Meissner, Gerhard; Melzer, Werner; Dirksen, Robert T


    The type 1 isoform of the ryanodine receptor (RYR1) is the Ca(2+) release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation-contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1(I4898T) mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca(2+) content, and RYR1 Ca(2+) release channel function using adult heterozygous Ryr1(I4895T/+) knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca(2+) content, both electrically evoked and 4-chloro-m-cresol-induced Ca(2+) release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4-6-mo-old IT/+ mice. The sensitivity of the SR Ca(2+) release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca(2+) permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca(2+) release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca(2+) ion permeation.

  8. Sarcoplasmic Reticulum Ca2+ Cycling Protein Phosphorylation in a Physiologic Ca2+ Milieu Unleashes a High-Power, Rhythmic Ca2+ Clock in Ventricular Myocytes: Relevance to Arrhythmias and Bio-Pacemaker Design (United States)

    Sirenko, Syevda; Maltsev, Victor A; Maltseva, Larissa A; Yang, Dongmei; Lukyanenko, Yevgeniya; Vinogradova, Tatiana; Jones, Larry; Lakatta, Edward G.


    Basal phosphorylation of sarcoplasmic reticulum (SR) Ca2+ proteins is high in sinoatrial nodal cells (SANC), which generate partially synchronized, spontaneous, rhythmic, diastolic local Ca2+ releases (LCRs), but low in ventricular myocytes (VM), which exhibit rare diastolic, stochastic SR-generated Ca2+ sparks. We tested the hypothesis that in a physiologic Ca2+ milieu, and independent of increased Ca2+ influx, an increase in basal phosphorylation of SR Ca2+ cycling proteins will convert stochastic Ca2+ sparks into periodic, high-power Ca2+ signals of the type that drives SANC normal automaticity. We measured phosphorylation of SR-associated proteins, phospholamban (PLB) and ryanodine receptors (RyR), and spontaneous local Ca2+ release characteristics (LCR) in permeabilized single, rabbit VM in physiologic [Ca2+], prior to and during inhibition of protein phosphatase (PP) and phosphodiesterase (PDE), or addition of exogenous cAMP, or in the presence of an antibody (2D12), that specifically inhibits binding of the PLB to SERCA-2. In the absence of the aforementioned perturbations, VM could only generate stochastic local Ca2+ releases of low power and low amplitude, as assessed by confocal Ca2+ imaging and spectral analysis. When the kinetics of Ca2+ pumping into the SR were increased by an increase in PLB phosphorylation (via PDE and PP inhibition or addition of cAMP) or by 2D12, self-organized, “clock-like” local Ca2+ releases, partially synchronized in space and time (Ca2+ wavelets), emerged, and the ensemble of these rhythmic local Ca2+ wavelets generated a periodic high-amplitude Ca2+ signal. Thus, a Ca2+ clock is not specific to pacemaker cells, but can also be unleashed in VM when SR Ca2+ cycling increases and spontaneous local Ca2+ release becomes partially synchronized. This unleashed Ca2+ clock that emerges in a physiological Ca2+ milieu in VM has two faces, however: it can provoke ventricular arrhythmias; or if harnessed, can be an important feature

  9. 心肺复苏后心功能障碍与心肌内质网Ca2+调控蛋白表达关系的研究%The relationship between sarcoplasmic reticulum Ca2+modulation proteins and postresuscitation myocardial dysfunction

    Institute of Scientific and Technical Information of China (English)

    黄煜; 何庆


    Objective To investigate the relationship between sarcoplasmic reticulum Ca2+modulation proteins and postresuscitation myocardial dysfunction. Methods Thirty-eight SPF male Sprague-Dawley (SD) rats were randomly divided into control group(n=12)and cardiac arrest(CA)group(n=26). CA was induced by intravenous bolus of potassium chloride(40μg/g),and cardiopulmonary resuscitation(CPR)was conducted 8 minutes later. No CA was induced in control group except catheter placement for monitoring cardiopulmonary parameters after anesthesia. Invasive hemodynamic parameters were monitored for 1 hour after CPR. Echocardiogram was performed to evaluate cardiac function. Myocardial samples were harvested 5 minutes and 1 hour after restoration of spontaneous circulation (ROSC),and sarcoplasmic reticulum Ca2+ ATPase (SERCA2a),phosphorylated phospholamban (p-PLB) and rynodine receptor(RyR)were determined by Western Blot. Results ROSC rate of CA group was 92.3%(24/26),and mean recovery time was (68 ±39)seconds. Cardiac function was significantly impaired in CA group at 1 hour after resuscitation, and ejection fraction, fraction shortening (FS), the maximal rate of left ventricular pressure increase/decline (±dp/dt max)were significantly decreased compared with those in control group 〔ejection fraction:0.548±0.060 vs. 0.809±0.043,F=71.692,P=0.000;FS:(34.4±4.4)%vs. (46.0±3.5)%,F=55.443,P=0.000;+dp/dt max(mmHg/s):4 718±743 vs. 7 098±394,P0.05). Conclusions The impairment of the p-PLB is closely related to postresuscitation myocardial dysfunction.%目的探讨心肌内质网Ca2+调控蛋白表达与心肺复苏(CPR)后心功能障碍的关系。方法38只SPF级雄性SD大鼠按随机数字表法分为对照组(12只)和心搏骤停组(26只)。静脉弹丸式注射氯化钾40μg/g诱导心搏骤停,8 min后进行CPR;对照组大鼠仅麻醉后置管并监测指标,不诱导心搏骤停。在复苏后进行有创血流动力学监测1 h,采用超声心动

  10. Mechanism of ghrelin in improving cardiac function by inhibiting endoplasmic reticulum stress in rats with acute myocardial infarctio

    Directory of Open Access Journals (Sweden)

    Min CAI


    Full Text Available Objective  To establish the rat model of acute myocardial infarction (AMI, and to explore the mechanism of ghrelin in improving cardiac function through inhibiting endoplasmic reticulum stress (ERS. Methods  AMI model was reproduced in 18 adult male Sprague-Dawley rats (220±20g by ligation of the left anterior descending coronary artery. Four days after the reproduction of the model, 14 survived rats with AMI were randomly divided into two groups (7 each: model group, animals were subcutaneously (sc injected with normal saline only; treatment group, animals were given ghrelin (100μg/kg twice a day (12h interval for two weeks. In addition, a sham-operated group was set up (Sham operation+saline, n=8. Two weeks later, the cardiac function was examined by echocardiography (UCG, the morphological changes in myocardial tissue were observed with hematoxylin-eosin (HE staining, the levels of LDH and CK-MB were determined by ELISA, and the expressions of glucose-regulated protein 78 (GRP-78 and C/EBP homologous protein (CHOP were assessed by Western blotting. Results  AMI model was successfully reproduced in SD rats. Compared with the rats in sham group, those in model group showed poor cardiac function (P < 0.05, HE staining revealed loosening of tissue and edema, ELISA revealed elevation of serum LDH and CK-MB levels (P < 0.05, and up regulation of expressions of GRP-78 and CHOP protein (P < 0.05. While compared with model group, rats in treatment group showed better cardiac function (P < 0.05, tissue loosening and edema were alleviated, the levels of serum LDH and CK-MB lowered (P < 0.05, and inhibition of the expressions of GRP-78 and CHOP protein (P < 0.05. Conclusion  Ghrelin may improve the cardiac function by in hibiting ERS, thus ameliorating the myocardial damage caused by AMI.

  11. Effect of downhill exercise on sarcoplasmic reticulum function in rat skeletal muscle%下坡运动对大鼠骨骼肌肌浆网功能的影响

    Institute of Scientific and Technical Information of China (English)

    陈万; Ruell PA; Thompson MW


    To investigate the effect of downhill(eccentric)exercise(ECE)on sarcoplasmic reticulum(SR) Ca2+-ATPase activity,Ca2+ uptake and release in rat skeletal muscle,in terms of both magnitude and time course.In addition,ionophore stimulation was determined to assess vesicle integrity by measuring the ratio of calciumdependent ATPase activities in the presence and absence of A23187.Method:Adult male SD rats were randomly assigned to control and ECE groups.The ECE rats were sacrificed at the Oth,4th,24th,48th,72nd and 144th h following ECE(n=7).The ECE protocol consisted of 90min continuous downhill exercise(-16 deg;15m·min-1).Red vastus muscles were sampled separately for each group and muscle homogenates were prepared.The rates of SR Ca2+-ATPase activity.Ca2+uptake and release were measured in vitro.Result:SR Ca2+uptake was significantly lower(P<0.05)compared with control values[19.25+1.38 nmol·min-1·(mg protein)-1],by 29% and 36% immediately and 4h after ECE,respectively,and remained depressed(P<0.05)24h following ECE.SR Ca2+ release was also significantly lower(P<0.05)compared with control values[31.06±2.36 nmol·min-1·(mg protein)-1],by 37% and 39% immediately and 4h after ECE,respectively,and remained depressed(P<0.05)24h following ECE.SR Ca2+-ATPaseactivity measured with ionophore was 31% lower(P<0.05)4h after ECE,and remained lower(P<0.05)24h following ECE.The ratio of Ca2+-ATPase activities in the presence and absence of A23187 was not significantly changed following ECE,indicating that membrane integrity was not altered by the exercise.Conclusion:The present remits suggest that a bout of low-intensity,prolonged downhill exereise results in a long-lasting depression of SR function that is not fully restored after two days of recovery,which may underlie some muscle functional impairments induced by ECE.These changes could be the results of stress from sarcomere length inhomogeneities during eccentric contractions.%目的:观测研究下坡(离心)

  12. Sarcoplasmic phospholamban protein is involved in the mechanisms of postresuscitation myocardial dysfunction and the cardioprotective effect of nitrite during resuscitation.

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    Yu Huang

    Full Text Available OBJECTIVES: Sarcoplasmic reticulum (SR Ca(2+-handling proteins play an important role in myocardial dysfunction after acute ischemia/reperfusion injury. We hypothesized that nitrite would improve postresuscitation myocardial dysfunction by increasing nitric oxide (NO generation and that the mechanism of this protection is related to the modulation of SR Ca(2+-handling proteins. METHODS: We conducted a randomized prospective animal study using male Sprague-Dawley rats. Cardiac arrest was induced by intravenous bolus of potassium chloride (40 µg/g. Nitrite (1.2 nmol/g or placebo was administered when chest compression was started. No cardiac arrest was induced in the sham group. Hemodynamic parameters were monitored invasively for 90 minutes after the return of spontaneous circulation (ROSC. Echocardiogram was performed to evaluate cardiac function. Myocardial samples were harvested 5 minutes and 1 hour after ROSC. RESULTS: Myocardial function was significantly impaired in the nitrite and placebo groups after resuscitation, whereas cardiac function (i.e., ejection fraction and fractional shortening was significantly greater in the nitrite group than in the placebo group. Nitrite administration increased the level of nitric oxide in the myocardium 5 min after resuscitation compared to the other two groups. The levels of phosphorylated phospholamban (PLB were decreased after resuscitation, and nitrite increased the phosphorylation of phospholamban compared to the placebo. No significant differences were found in the expression of sarcoplasmic reticulum Ca(2+ ATPase (SERCA2a and ryanodine receptors (RyRs. CONCLUSIONS: postresuscitation myocardial dysfunction is associated with the impairment of PLB phosphorylation. Nitrite administered during resuscitation improves postresuscitation myocardial dysfunction by preserving phosphorylated PLB protein during resuscitation.

  13. 肌浆网钙ATP酶基因转导对慢性心力衰竭犬心肌蛋白质组影响的初步研究%Overexpression of sarcoplasmic reticulum calcium ATPase induced hemodynamic and proteomic changes in a dog model of heart failure

    Institute of Scientific and Technical Information of China (English)

    付治卿; 李小鹰; 刘秀华; 孙胜; 刘涛; 米亚非; 周声安; 叶卫华; 王青松


    handling,myofibrils,and energy production in this dog model of chronic heart failure.%目的 分析心肌肌浆网Ca2+-ATP酶(sarcoplasmic reticulum Ca2+ ATPase 2a,SERCA2a)基因转导对慢性心力衰竭(HF)犬心肌蛋白质组的影响,探讨SERCA2a基因转导改善心功能的机制.方法 快速右心室起搏建立HF犬模型并随机分为HF组、HF+绿色荧光蛋白(enhanced green fluorescent pmtein,EGFP)组、HF+SERCA2a组.后两组分别向心肌内注射携带EGFP和SERCA2a基因的rAAV载体.于基因转导30 d时停止起搏后进行超声心动图和血流动力学检查并制备心室肌双向电泳蛋白样品和心肌双向电泳图谱,图像分析软件分析蛋白表达差异点,MALDI-TOF-MS数据库搜索鉴定蛋白质.结果 基因转导30 d时,HF+SERCA2a组犬的症状、超声心动图和血流动力学指标与HF+EGFP组相比有显著好转(P<0.05);与对照组相比差异无统计学意义(P>0.05).挑选SERCA2a基因转导后表达量发生明显改变的10个蛋白点进行分析,经质谱鉴定分别为心肌收缩相关蛋白、线粒体能量代谢酶类和应激相关蛋白.结论 以rAAV为载体介导SERCA2a基因转导能够改善HF犬心脏的收缩和舒张功能,其可能的机制是恢复了心肌收缩相关蛋白正常表型或正常表达量,增加了心肌能量的产生,改变了应激相关蛋白的表达.

  14. Clofibrate, calcium and cardiac muscle. (United States)

    Fairhurst, A S; Wickie, G; Peabody, T


    The anti-hyperlipidemic drug clofibrate produces negative inotropic effects and arrythmias in isolated perfused rabbit heart Langendorff preparations. In electrically stimulated rat left atria, clofibrate produces negative inotropic effects, the speed of onset and extent of which are decreased by raising the Ca concentration of the bathing medium. Sensitivity of isolated rat atria to clofibrate is not increased when the tissues are stimulated under slow Ca channel conditions, in which the tissues are activated by either isoproterenol or dibutyryl cyclic AMP, although sensitivity to clofibrate is decreased when atria are exposed to increasing concentrations of norepinephrine. Increasing the stimulation frequency of isolated guinea-pig atria to produce a positive treppe also decreases the inhibitory effect of clofibrate, while in rat atria the typical negative treppe is altered towards a positive treppe in presence of clofibrate. The effects of paired electrical stimulation are not diminished by the drug, suggesting that Ca release from the sarcoplasmic reticulum is not affected by clofibrate, although the drug inhibits the rate of Ca uptake by isolated cardiac sarcoplasmic reticulum and mitochondria. These results suggest that clofibrate has multiple effects on Ca functions in cardiac muscle.

  15. Characterization of Post-Translational Modifications to Calsequestrins of Cardiac and Skeletal Muscle

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    Kevin M. Lewis


    Full Text Available Calsequestrin is glycosylated and phosphorylated during its transit to its final destination in the junctional sarcoplasmic reticulum. To determine the significance and universal profile of these post-translational modifications to mammalian calsequestrin, we characterized, via mass spectrometry, the glycosylation and phosphorylation of skeletal muscle calsequestrin from cattle (B. taurus, lab mice (M. musculus and lab rats (R. norvegicus and cardiac muscle calsequestrin from cattle, lab rats and humans. On average, glycosylation of skeletal calsequestrin consisted of two N-acetylglucosamines and one mannose (GlcNAc2Man1, while cardiac calsequestrin had five additional mannoses (GlcNAc2Man6. Skeletal calsequestrin was not phosphorylated, while the C-terminal tails of cardiac calsequestrin contained between zero to two phosphoryls, indicating that phosphorylation of cardiac calsequestrin may be heterogeneous in vivo. Static light scattering experiments showed that the Ca2+-dependent polymerization capabilities of native bovine skeletal calsequestrin are enhanced, relative to the non-glycosylated, recombinant isoform, which our crystallographic studies suggest may be due to glycosylation providing a dynamic “guiderail”-like scaffold for calsequestrin polymerization. Glycosylation likely increases a polymerization/depolymerization response to changing Ca2+ concentrations, and proper glycosylation, in turn, guarantees both effective Ca2+ storage/buffering of the sarcoplasmic reticulum and localization of calsequestrin (Casq at its target site.

  16. SR-targeted CaMKII inhibition improves SR Ca2+ handling, but accelerates cardiac remodeling in mice overexpressing CaMKIIδC


    Huke, Sabine; DeSantiago, Jaime; Kaetzel, Marcia A.; Mishra, Shikha; Brown, Joan H.; Dedman, John R.; Bers, Donald M.


    Cardiac myocyte overexpression of CaMKIIδC leads to cardiac hypertrophy and heart failure (HF) possibly caused by altered myocyte Ca2+ handling. A central defect might be the marked CaMKII-induced increase in diastolic sarcoplasmic reticulum (SR) Ca2+ leak which decreases SR Ca2+ load and Ca2+ transient amplitude. We hypothesized that inhibition of CaMKII near the SR membrane would decrease the leak, improve Ca2+ handling and prevent the development of contractile dysfunction and HF. To test ...

  17. Ion channelopathy and hyperphosphorylation contributing to cardiac arrhythmias

    Institute of Scientific and Technical Information of China (English)

    De-zai DAI; Feng YU


    The occurrence of cardiac arrhythmias is related to the abnormality of ion channels not only in sarcolemma but also in the sarcoplasmic reticulum, which regulates the process of calcium release and up-take intracellularly. Patterns of ion channelopathy in the sarcolemma can be divided into single channel disorder from gene mutations and multiple channels disorder in a diseased hypertrophied heart. Abnormal RyR2, FKBP12.6, SERCA2a, and PLB are also involved in the initiation of cardiac arrhythmias. Maladjustment by hyperphosphorylation on the ion channels in the sarcolemma and RyR2-FKBP12.6 and SERCA2a-PLB is discussed. Hyperphosphorylation, which is the main abnormality upstream to ion channels, can be targeted for suppressing the deterioration of ion channelopathy in terms of new drug discovery in the treatment and prevention of malignant cardiac arrhythmias.

  18. LPCES对慢性低压缺氧兔颏舌肌肌球蛋白重链和SR Ca2+摄取-释放动力学的影响%Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia

    Institute of Scientific and Technical Information of China (English)

    刘熙; 刘刚; 张妮; 欧娜; 张鹏


    Objective To identify the effect of chronic electrical stimulation at a lower physiological frequency on the expressions of myosin heavy chain (MHC) isoforms and kinetics of sarcoplasmic reticulum (SR) Ca2 + uptake/release in the genioglossus of rabbits exposed to chronic hypoxia. Methods Twenty-four adult rabbits were randomized into control group ( A), chronic hypoxia group ( B ), 2.5 Hz electrical stimulation group (C) and (2.5 + 40) Hz electrical stimulation group (low frequency plus physical frequency, D).After the rabbits from group B, C and D had been fed with free access to food and water in a hypoxia cabin ( simulating 5 000 m altitude) in 10 h a day for 4 weeks, the rabbits in group C and D received electrical stimulation in their genioglossus at a frequency of 2.5 Hz and (2.5 +40) Hz respectively in 10 h per day for 14 d,while those in group B received no electrical stimulation. Expressions of MHC isoforms in the genioglossus of rabbits in 4 groups were detected by Western blotting, and Fura-2 fluorophotometry was used to assay the kinetics changes of SR Ca2 + uptake-release. Restlts The expression level of MHC l a was significantly higher while that of MHC I was significantly lower in group B than that in group A (P < 0.05 ). Meanwhile,the genioglossus SR Ca2+ uptake/release velocity in group B was significantly decreased compared with that in group A ( P < 0. 05 ). The expression levels of MHC Ⅱ a and MHC I in group C and D after electrical stimulation were significantly higher, while those of MHC Ⅱ b, especially in group D, were significantly lower than those in group B (P < 0.05 ). The genioglossus SR Ca2+ uptake/release velocity in group C and D, especially in group D, was significantly increased compared with that in group B ( P < 0.05 ). No significant difference was found in expression levels of MHC Ⅱ a and MHC I between group C and D after electrical stimulation ( P > 0.05). Conclusion MHC Ⅱb in the genioglossus of rabbits with

  19. Targeted Deletion of MicroRNA-22 Promotes Stress-Induced Cardiac Dilation and Contractile Dysfunction (United States)

    Gurha, Priyatansh; Abreu-Goodger, Cei; Wang, Tiannan; Ramirez, Maricela O.; Drumond, Ana L.; van Dongen, Stijn; Chen, Yuqing; Bartonicek, Nenad; Enright, Anton J.; Lee, Brendan; Kelm, Robert J.; Reddy, Anilkumar K.; Taffet, George E.; Bradley, Allan; Wehrens, Xander H.; Entman, Mark L.; Rodriguez, Antony


    Background Delineating the role of microRNAs (miRNAs) in the posttranscriptional gene regulation offers new insights into how the heart adapts to pathological stress. We developed a knockout of miR-22 in mice and investigated its function in the heart. Methods and Results Here, we show that miR-22–deficient mice are impaired in inotropic and lusitropic response to acute stress by dobutamine. Furthermore, the absence of miR-22 sensitized mice to cardiac decompensation and left ventricular dilation after long-term stimulation by pressure overload. Calcium transient analysis revealed reduced sarcoplasmic reticulum Ca2+ load in association with repressed sarcoplasmic reticulum Ca2+ ATPase activity in mutant myocytes. Genetic ablation of miR-22 also led to a decrease in cardiac expression levels for Serca2a and muscle-restricted genes encoding proteins in the vicinity of the cardiac Z disk/titin cytoskeleton. These phenotypes were attributed in part to inappropriate repression of serum response factor activity in stressed hearts. Global analysis revealed increased expression of the transcriptional/translational repressor purine-rich element binding protein B, a highly conserved miR-22 target implicated in the negative control of muscle expression. Conclusion These data indicate that miR-22 functions as an integrator of Ca2+ homeostasis and myofibrillar protein content during stress in the heart and shed light on the mechanisms that enhance propensity toward heart failure. PMID:22570371

  20. Evidence against inhibition of sarcoplasmic reticulum Ca2 + -pump as mechanism of H202-induced contraction of rat aorta%肌浆网钙泵的抑制不参与过氧化氢诱导的大鼠主动脉收缩

    Institute of Scientific and Technical Information of China (English)

    沈建中; 郑秀凤; 魏尔清; 關超然


    目的:研究肌浆网钙泵抑制是否参与H2O2诱导的大 鼠主动脉收缩反应。方法:离体主动脉环张力实验 比较H2O2及钙泵特异性抑制剂环匹阿尼酸(CPA)缩 血管效应及其信号机制的差异。结果:H2O2和CPA 均收缩去内皮主动脉环,但H2O2触发快速短暂相位 相收缩,而CPA诱导缓慢持续的张力相收缩。在无 钙液中,仅CPA 30 μmol/L而非H2O2 30μmol/L预 处理取消苯肾上腺素10 μmol/L缩血管效应。Thap- sigargin 30 μmol/L诱导最大收缩反应时,仅H2O2能 使血管环进一步收缩。另外,P2受体拮抗剂 suramin、RB-2(各100μmol/L)以及多种酶抑制剂包 括PLC、PKC、PLA2、COX和蛋白质酪氨酸激酶均 能抑制H2O2而非CPA诱导的缩血管效应,但2-APB 50μmol/L对两者都有抑制作用。结论:肌浆网钙 泵抑制不是H2O2收缩大鼠去内皮主动脉的机制。%AIM: To test whether inhibition of sarcoplasmic reticulum (SR) Ca2+ -pump is involved in H2O2-induced contraction of endothelium-denuded rat aorta. METH ODS: Isometric tension recording of H2O2 and cyclopia zonic acid (CPA)-induced contractions of rat aortic rings were compared in the absence or presence of various pharmacological tools to discriminate their signaling path ways involved. RESULTS: Both H2O2 and CPA con tracted rat aortic rings, but with different contractile pat terns. H2O2 triggered a fast and phasic contraction, whereas CPA elicited a slow and sustained contraction. In Ca 2 +-free medium, pretreatment of aortic tings with CPA 30 μmol/L but not with H2O2 30 μmol/L nearly abolished phenylephrine (10 μmol/L)-induced contrac tion. In addition, upon the maximal contraction induced by thapsigargin 30 μ r mol/L, H2O2 but not CPA further contracted aortic rings. On the other hand, H2O2 (30 μmoL/L)- but not CPA (10 μmol/L)-induced contraction could be inhibited by suramin and RB-2 (each 100 μmol/L), two P2-purinoceptor antagonists. Further more, although

  1. 大鼠 H9c2心肌细胞缺氧/复氧损伤模型肌浆网钙调控相关蛋白表达及当归补血汤的干预作用%Danggui Buxue Decoction on expression of sarcoplasmic reticulum calcium regulatory protein in H9c2 myocardial cell model with hypoxia/reoxygenation damage

    Institute of Scientific and Technical Information of China (English)

    周春刚; 汤加; 李卿; 徐辰; 张志斌


    Objective To establish the model of hypoxia / reoxygenation damage in H9c2 rat myocardial cell and observe the expression of myocardial sarcoplasmic reticulum calcium regulatory protein and the effect of Danggui Bux-ue Decoction on calcium overload in H9c2 cells with hypoxia / reoxygenation injury. Methods JC-1 staining was used to detect the mitochondrial membrane potential by flow cytometry,Fluo-3 AM calcium fluorescence probe for the detection of intracellular calcium concentration,The expression level of sarcoplasmic reticulum Ca transport ATP en-zyme(SERCA2a),L type calcium channel(CAV1. 3),ryanodine receptor(RyR1,RyR2),phospholamban(PLB), calsequestrin(CASQ)mRNA were detected by RT-PCR. Results Compared with the normal control group,the early apoptosis rate and intracellular calcium concentration in model group increased significantly(P 0. 05),compared with the model group. Con-clusion There are obvious calcium overload and sarcoplasmic reticulum calcium regulating proteins adjustment disor-der in the model of H9c2 rat myocardial cell with hypoxia / reoxygenation damage,Danggui Buxue Decoction can in-crease the expression of the sarcoplasmic reticulumcalcium regulating protein SERCA2a and CASQ mRNA after reoxy-genation,alleviate calcium overload,and significantly reduce the early apoptosis rate of reoxygenation damage cells.%目的:建立缺氧/复氧大鼠 H9c2心肌细胞损伤模型,观察心肌细胞肌浆网钙调控相关蛋白表达及当归补血汤对 H9c2细胞缺氧/复氧损伤钙超载的影响。方法 JC-1染色流式细胞仪检测细胞线粒体膜电位, Fluo-3 AM 钙离子荧光探针检测细胞内钙离子浓度,RT-PCR 荧光相对定量检测大鼠心肌肌浆网 Ca 转运 ATP酶(SERCA2a)、L 型钙通道(CAV1.3)、兰尼碱受体(RyR1,RyR2)、受磷蛋白(PLB)、肌集钙蛋白( CASQ)的mRNA 表达水平。结果与正常对照组比较,模型组细胞早期凋亡显著增加(P <0.05),细胞内

  2. RyR2 modulates a Ca2+-activated K+ current in mouse cardiac myocytes.

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    Yong-Hui Mu

    Full Text Available In cardiomyocytes, Ca2+ entry through voltage-dependent Ca2+ channels (VDCCs binds to and activates RyR2 channels, resulting in subsequent Ca2+ release from the sarcoplasmic reticulum (SR and cardiac contraction. Previous research has documented the molecular coupling of small-conductance Ca2+-activated K+ channels (SK channels to VDCCs in mouse cardiac muscle. Little is known regarding the role of RyRs-sensitive Ca2+ release in the SK channels in cardiac muscle. In this study, using whole-cell patch clamp techniques, we observed that a Ca2+-activated K+ current (IK,Ca recorded from isolated adult C57B/L mouse atrial myocytes was significantly decreased by ryanodine, an inhibitor of ryanodine receptor type 2 (RyR2, or by the co-application of ryanodine and thapsigargin, an inhibitor of the sarcoplasmic reticulum calcium ATPase (SERCA (p<0.05, p<0.01, respectively. The activation of RyR2 by caffeine increased the IK,Ca in the cardiac cells (p<0.05, p<0.01, respectively. We further analyzed the effect of RyR2 knockdown on IK,Ca and Ca2+ in isolated adult mouse cardiomyocytes using a whole-cell patch clamp technique and confocal imaging. RyR2 knockdown in mouse atrial cells transduced with lentivirus-mediated small hairpin interference RNA (shRNA exhibited a significant decrease in IK,Ca (p<0.05 and [Ca2+]i fluorescence intensity (p<0.01. An immunoprecipitated complex of SK2 and RyR2 was identified in native cardiac tissue by co-immunoprecipitation assays. Our findings indicate that RyR2-mediated Ca2+ release is responsible for the activation and modulation of SK channels in cardiac myocytes.

  3. Ca2+-Clock-Dependent Pacemaking in the Sinus Node Is Impaired in Mice with a Cardiac Specific Reduction in SERCA2 Abundance (United States)

    Logantha, Sunil Jit R. J.; Stokke, Mathis K.; Atkinson, Andrew J.; Kharche, Sanjay R.; Parveen, Sajida; Saeed, Yawer; Sjaastad, Ivar; Sejersted, Ole M.; Dobrzynski, Halina


    Background: The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) pump is an important component of the Ca2+-clock pacemaker mechanism that provides robustness and flexibility to sinus node pacemaking. We have developed transgenic mice with reduced cardiac SERCA2 abundance (Serca2 KO) as a model for investigating SERCA2's role in sinus node pacemaking. Methods and Results: In Serca2 KO mice, ventricular SERCA2a protein content measured by Western blotting was 75% (P 70% reduction in SERCA2 activity. Conclusions: Serca2 KO mice show a disrupted Ca2+-clock-dependent pacemaker mechanism contributing to impaired sinus node and atrioventricular node function. PMID:27313537

  4. Restoring the impaired cardiac calcium homeostasis and cardiac function in iron overload rats by the combined deferiprone and N-acetyl cysteine (United States)

    Wongjaikam, Suwakon; Kumfu, Sirinart; Khamseekaew, Juthamas; Chattipakorn, Siriporn C.; Chattipakorn, Nipon


    Intracellular calcium [Ca2+]i dysregulation plays an important role in the pathophysiology of iron overload cardiomyopathy. Although either iron chelators or antioxidants provide cardioprotection, a comparison of the efficacy of deferoxamine (DFO), deferiprone (DFP), deferasirox (DFX), N-acetyl cysteine (NAC) or a combination of DFP plus NAC on cardiac [Ca2+]i homeostasis in chronic iron overload has never been investigated. Male Wistar rats were fed with either a normal diet or a high iron (HFe) diet for 4 months. At 2 months, HFe rats were divided into 6 groups and treated with either a vehicle, DFO (25 mg/kg/day), DFP (75 mg/kg/day), DFX (20 mg/kg/day), NAC (100 mg/kg/day), or combined DFP plus NAC. At 4 months, the number of cardiac T-type calcium channels was increased, whereas cardiac sarcoplasmic-endoplasmic reticulum Ca2+ ATPase (SERCA) was decreased, leading to cardiac iron overload and impaired cardiac [Ca2+]i homeostasis. All pharmacological interventions restored SERCA levels. Although DFO, DFP, DFX or NAC alone shared similar efficacy in improving cardiac [Ca2+]i homeostasis, only DFP + NAC restored cardiac [Ca2+]i homeostasis, leading to restoring left ventricular function in the HFe-fed rats. Thus, the combined DFP + NAC was more effective than any monotherapy in restoring cardiac [Ca2+]i homeostasis, leading to restored myocardial contractility in iron-overloaded rats. PMID:28287621

  5. Mechanisms of Beat-to-Beat Regulation of Cardiac Pacemaker Cell Function by Ca2+ Cycling Dynamics (United States)

    Yaniv, Yael; Stern, Michael D.; Lakatta, Edward G.; Maltsev, Victor A.


    Whether intracellular Ca2+ cycling dynamics regulate cardiac pacemaker cell function on a beat-to-beat basis remains unknown. Here we show that under physiological conditions, application of low concentrations of caffeine (2–4 mM) to isolated single rabbit sinoatrial node cells acutely reduces their spontaneous action potential cycle length (CL) and increases Ca2+ transient amplitude for several cycles. Numerical simulations, using a modified Maltsev-Lakatta coupled-clock model, faithfully reproduced these effects, and also the effects of CL prolongation and dysrhythmic spontaneous beating (produced by cytosolic Ca2+ buffering) and an acute CL reduction (produced by flash-induced Ca2+ release from a caged Ca2+ buffer), which we had reported previously. Three contemporary numerical models (including the original Maltsev-Lakatta model) failed to reproduce the experimental results. In our proposed new model, Ca2+ releases acutely change the CL via activation of the Na+/Ca2+ exchanger current. Time-dependent CL reductions after flash-induced Ca2+ releases (the memory effect) are linked to changes in Ca2+ available for pumping into sarcoplasmic reticulum which, in turn, changes the sarcoplasmic reticulum Ca2+ load, diastolic Ca2+ releases, and Na+/Ca2+ exchanger current. These results support the idea that Ca2+ regulates CL in cardiac pacemaker cells on a beat-to-beat basis, and suggest a more realistic numerical mechanism of this regulation. PMID:24094396

  6. Mechanisms of beat-to-beat regulation of cardiac pacemaker cell function by Ca²⁺ cycling dynamics. (United States)

    Yaniv, Yael; Stern, Michael D; Lakatta, Edward G; Maltsev, Victor A


    Whether intracellular Ca(2+) cycling dynamics regulate cardiac pacemaker cell function on a beat-to-beat basis remains unknown. Here we show that under physiological conditions, application of low concentrations of caffeine (2-4 mM) to isolated single rabbit sinoatrial node cells acutely reduces their spontaneous action potential cycle length (CL) and increases Ca(2+) transient amplitude for several cycles. Numerical simulations, using a modified Maltsev-Lakatta coupled-clock model, faithfully reproduced these effects, and also the effects of CL prolongation and dysrhythmic spontaneous beating (produced by cytosolic Ca(2+) buffering) and an acute CL reduction (produced by flash-induced Ca(2+) release from a caged Ca(2+) buffer), which we had reported previously. Three contemporary numerical models (including the original Maltsev-Lakatta model) failed to reproduce the experimental results. In our proposed new model, Ca(2+) releases acutely change the CL via activation of the Na(+)/Ca(2+) exchanger current. Time-dependent CL reductions after flash-induced Ca(2+) releases (the memory effect) are linked to changes in Ca(2+) available for pumping into sarcoplasmic reticulum which, in turn, changes the sarcoplasmic reticulum Ca(2+) load, diastolic Ca(2+) releases, and Na(+)/Ca(2+) exchanger current. These results support the idea that Ca(2+) regulates CL in cardiac pacemaker cells on a beat-to-beat basis, and suggest a more realistic numerical mechanism of this regulation.

  7. Cardiac contraction and calcium transport function aftersevere burn injury in rats

    Institute of Scientific and Technical Information of China (English)


    Objective: To examine the function change of myocardial calcium transports and determined what role the change plays in cardiac dysfunction after severe burn injury in rats. Methods: The contraction and relaxation properties of the left ventricle (LV) were studied in the isolated hearts preparations of Wistar rats at 3, 8, and 24 h after a 30%TBSA (total body surface area) full-thickness burn. The calcium transport function of the sarcoplasmic reticulum (SR) was measured by the millipore filtration technique. Results: The maximal rate of LV pressure (± dp/dtmax) of the burn group was significantly lower than that of the control group (P < 0.01). In addition, the calciumdependent ATPase activity and the coupling ratio of SR were also markedly depressed. Conclusions: It indicates that the decrease in the SR calcium transport function is one of the important mechanisms for the cardiac contractile dysfunction after severe burn injury.

  8. The timing statistics of spontaneous calcium release in cardiac myocytes.

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    Mesfin Asfaw

    Full Text Available A variety of cardiac arrhythmias are initiated by a focal excitation that disrupts the regular beating of the heart. In some cases it is known that these excitations are due to calcium (Ca release from the sarcoplasmic reticulum (SR via propagating subcellular Ca waves. However, it is not understood what are the physiological factors that determine the timing of these excitations at both the subcellular and tissue level. In this paper we apply analytic and numerical approaches to determine the timing statistics of spontaneous Ca release (SCR in a simplified model of a cardiac myocyte. In particular, we compute the mean first passage time (MFPT to SCR, in the case where SCR is initiated by spontaneous Ca sparks, and demonstrate that this quantity exhibits either an algebraic or exponential dependence on system parameters. Based on this analysis we identify the necessary requirements so that SCR occurs on a time scale comparable to the cardiac cycle. Finally, we study how SCR is synchronized across many cells in cardiac tissue, and identify a quantitative measure that determines the relative timing of SCR in an ensemble of cells. Using this approach we identify the physiological conditions so that cell-to-cell variations in the timing of SCR is small compared to the typical duration of an SCR event. We argue further that under these conditions inward currents due to SCR can summate and generate arrhythmogenic triggered excitations in cardiac tissue.

  9. Recording of calcium transient and analysis of calcium removal mechanisms in cardiac myocytes from rats and ground squirrels

    Institute of Scientific and Technical Information of China (English)

    王世强; 周曾铨; 钱洪


    With confocal microscopy, we recorded calcium transients and analyzed calcium removal rate at different temperatures in cardiac myocytes from the rat, a non-hibernator, and the ground squirrel, a hibernator. The results showed a remarkable increase of the diastolic level of calcium transients in the rat but no detectable change in the ground squirrel. Calcium transient of the ground squirrel, compared with that of the rat at the same temperature, had a shorter duration and showed a faster calcium removal. As indicated by the pharmacological effect of cyclopiazonic acid, calcium uptake by sarcoplasmic reticulum (SR) was the major mechanism of calcium removal, and was faster in the ground squirrel than in the rat. Our results confirmed the essential role of SR in hypothermia-tolerant adaptation, and negated the importance of Na-Ca exchange. We postulated the possibility to improve hypothermia-tolerance of the cardiac tissue of non-hibernating mammals.

  10. [Cardiac contractility modulation. A new form of therapy for patients with heart failure and narrow QRS complex?]. (United States)

    Kleemann, T


    Cardiac contractility modulation (CCM) is a stimulation therapy by an implantable impulse generator, which enhances ventricular contractile performance by delivering CCM impulses to the right ventricle during the absolute refractory period. The CCM signals mediate increased inotropy by prolonging the duration of the action potential, which leads to an enhanced influx of calcium into cardiomyocytes and a greater release of calcium by the sarcoplasmic reticulum. The increase of cardiac contractility is not associated with increased oxygen consumption. Several small studies have shown that CCM therapy can safely improve symptoms of heart failure and peak oxygen consumption in patients with moderate to severe heart failure who are not eligible for resynchronization therapy. Therefore, CCM is a novel potential therapy for patients with heart failure, an ejection fraction ≤ 35 % and a normal QRS duration failure or mortality.

  11. Deletion of Pr130 Interrupts Cardiac Development in Zebrafish

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    Jie Yang


    Full Text Available Protein phosphatase 2 regulatory subunit B, alpha (PPP2R3A, a regulatory subunit of protein phosphatase 2A (PP2A, is a major serine/threonine phosphatase that regulates crucial function in development and growth. Previous research has implied that PPP2R3A was involved in heart failure, and PR130, the largest transcription of PPP2R3A, functioning in the calcium release of sarcoplasmic reticulum (SR, plays an important role in the excitation-contraction (EC coupling. To obtain a better understanding of PR130 functions in myocardium and cardiac development, two pr130-deletion zebrafish lines were generated using clustered regularly interspaced short palindromic repeats (CRISPR/CRISPR-associated proteins (Cas system. Pr130-knockout zebrafish exhibited cardiac looping defects and decreased cardiac function (decreased fractional area and fractional shortening. Hematoxylin and eosin (H&E staining demonstrated reduced cardiomyocytes. Subsequent transmission electron microscopy revealed that the bright and dark bands were narrowed and blurred, the Z- and M-lines were fogged, and the gaps between longitudinal myocardial fibers were increased. Additionally, increased apoptosis was observed in cardiomyocyte in pr130-knockout zebrafish compared to wild-type (WT. Taken together, our results suggest that pr130 is required for normal myocardium formation and efficient cardiac contractile function.

  12. Deletion of Pr130 Interrupts Cardiac Development in Zebrafish (United States)

    Yang, Jie; Li, Zuhua; Gan, Xuedong; Zhai, Gang; Gao, Jiajia; Xiong, Chenling; Qiu, Xueping; Wang, Xuebin; Yin, Zhan; Zheng, Fang


    Protein phosphatase 2 regulatory subunit B, alpha (PPP2R3A), a regulatory subunit of protein phosphatase 2A (PP2A), is a major serine/threonine phosphatase that regulates crucial function in development and growth. Previous research has implied that PPP2R3A was involved in heart failure, and PR130, the largest transcription of PPP2R3A, functioning in the calcium release of sarcoplasmic reticulum (SR), plays an important role in the excitation-contraction (EC) coupling. To obtain a better understanding of PR130 functions in myocardium and cardiac development, two pr130-deletion zebrafish lines were generated using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) system. Pr130-knockout zebrafish exhibited cardiac looping defects and decreased cardiac function (decreased fractional area and fractional shortening). Hematoxylin and eosin (H&E) staining demonstrated reduced cardiomyocytes. Subsequent transmission electron microscopy revealed that the bright and dark bands were narrowed and blurred, the Z- and M-lines were fogged, and the gaps between longitudinal myocardial fibers were increased. Additionally, increased apoptosis was observed in cardiomyocyte in pr130-knockout zebrafish compared to wild-type (WT). Taken together, our results suggest that pr130 is required for normal myocardium formation and efficient cardiac contractile function. PMID:27845735

  13. Endurance training in the spontaneously hypertensive rat: conversion of pathological into physiological cardiac hypertrophy. (United States)

    Garciarena, Carolina D; Pinilla, Oscar A; Nolly, Mariela B; Laguens, Ruben P; Escudero, Eduardo M; Cingolani, Horacio E; Ennis, Irene L


    The effect of endurance training (swimming 90 min/d for 5 days a week for 60 days) on cardiac hypertrophy was investigated in the spontaneously hypertensive rat (SHR). Sedentary SHRs (SHR-Cs) and normotensive Wistar rats were used as controls. Exercise training enhanced myocardial hypertrophy assessed by left ventricular weight/tibial length (228+/-7 versus 251+/-5 mg/cm in SHR-Cs and exercised SHRs [SHR-Es], respectively). Myocyte cross-sectional area increased approximately 40%, collagen volume fraction decreased approximately 50%, and capillary density increased approximately 45% in SHR-Es compared with SHR-Cs. The mRNA abundance of atrial natriuretic factor and myosin light chain 2 was decreased by the swimming routine (100+/-19% versus 41+/-10% and 100+/-8% versus 61+/-9% for atrial natriuretic factor and myosin light chain 2 in SHR-Cs and SHR-Es, respectively). The expression of sarcoplasmic reticulum Ca(2+) pump was significantly augmented, whereas that of Na(+)/Ca(2+) exchanger was unchanged (93+/-7% versus 167+/-8% and 158+/-13% versus 157+/-7%, sarcoplasmic reticulum Ca(2+) pump and Na(+)/Ca(2+) exchanger in SHR-Cs and SHR-Es, respectively; Peccentric model of cardiac hypertrophy (0.59+/-0.02 versus 0.53+/-0.01 in SHR-Cs and SHR-Es, respectively; Phypertrophy improving cardiac performance. The reduction of myocardial fibrosis and calcineurin activity plus the increase in capillary density represent factors to be considered in determining this beneficial effect.

  14. Photoperiod-dependent modulation of cardiac excitation contraction coupling in the Siberian hamster. (United States)

    Dibb, K M; Hagarty, C L; Loudon, A S I; Trafford, A W


    In mammals, changes in photoperiod regulate a diverse array of physiological and behavioral processes, an example of which in the Siberian hamster (Phodopus sungorus) is the expression of bouts of daily torpor following prolonged exposure to a short photoperiod. During torpor, body temperature drops dramatically; however, unlike in nonhibernating or nontorpid species, the myocardium retains the ability to contract and is resistant to the development of arrhythmias. In the present study, we sought to determine whether exposure to a short photoperiod results in alterations to cardiac excitation-contraction coupling, thus potentially enabling the heart to survive periods of low temperature during torpor. Experiments were performed on single ventricular myocytes freshly isolated from the hearts of Siberian hamsters that had been exposed to either 12 wk of short-day lengths (SD) or 12 wk of long-day lengths (LD). In SD-acclimated animals, the amplitude of the systolic Ca(2+) transient was increased (e.g., from 142 +/- 17 nmol/l in LD to 229 +/- 31 nmol/l in SD at 4 Hz; P < 0.001). The increased Ca(2+) transient amplitude in the SD-acclimated animals was not associated with any change in the shape or duration of the action potential. However, sarcoplasmic reticulum Ca(2+) content measured after current-clamp stimulation was increased in the SD-acclimated animals (at 4 Hz, 110 +/- 5 vs. 141 +/- 15 mumol/l, P < 0.05). We propose that short photoperiods reprogram the function of the cardiac sarcoplasmic reticulum, resulting in an increased Ca(2+) content, and that this may be a necessary precursor for maintenance of cardiac function during winter torpor.

  15. Activation of cardiac ryanodine receptors by cardiac glycosides. (United States)

    Sagawa, Toshio; Sagawa, Kazuko; Kelly, James E; Tsushima, Robert G; Wasserstrom, J Andrew


    This study investigated the effects of cardiac glycosides on single-channel activity of the cardiac sarcoplasmic reticulum (SR) Ca2+ release channels or ryanodine receptor (RyR2) channels and how this action might contribute to their inotropic and/or toxic actions. Heavy SR vesicles isolated from canine left ventricle were fused with artificial planar lipid bilayers to measure single RyR2 channel activity. Digoxin and actodigin increased single-channel activity at low concentrations normally associated with therapeutic plasma levels, yielding a 50% of maximal effect of approximately 0.2 nM for each agent. Channel activation by glycosides did not require MgATP and occurred only when digoxin was applied to the cytoplasmic side of the channel. Similar results were obtained in human RyR2 channels; however, neither the crude skeletal nor the purified cardiac channel was activated by glycosides. Channel activation was dependent on [Ca2+] on the luminal side of the bilayer with maximal stimulation occurring between 0.3 and 10 mM. Rat RyR2 channels were activated by digoxin only at 1 microM, consistent with the lower sensitivity to glycosides in rat heart. These results suggest a model in which RyR2 channel activation by digoxin occurs only when luminal [Ca2+] was increased above 300 microM (in the physiological range). Consequently, increasing SR load (by Na+ pump inhibition) serves to amplify SR release by promoting direct RyR2 channel activation via a luminal Ca2+-sensitive mechanism. This high-affinity effect of glycosides could contribute to increased SR Ca2+ release and might play a role in the inotropic and/or toxic actions of glycosides in vivo.

  16. Regulation of cardiac myocyte contractility by phospholemman: Na+/Ca2+ exchange versus Na+ -K+ -ATPase. (United States)

    Song, Jianliang; Zhang, Xue-Qian; Wang, JuFang; Cheskis, Ellina; Chan, Tung O; Feldman, Arthur M; Tucker, Amy L; Cheung, Joseph Y


    Phospholemman (PLM) regulates cardiac Na(+)/Ca(2+) exchanger (NCX1) and Na(+)-K(+)-ATPase in cardiac myocytes. PLM, when phosphorylated at Ser(68), disinhibits Na(+)-K(+)-ATPase but inhibits NCX1. PLM regulates cardiac contractility by modulating Na(+)-K(+)-ATPase and/or NCX1. In this study, we first demonstrated that adult mouse cardiac myocytes cultured for 48 h had normal surface membrane areas, t-tubules, and NCX1 and sarco(endo)plasmic reticulum Ca(2+)-ATPase levels, and retained near normal contractility, but alpha(1)-subunit of Na(+)-K(+)-ATPase was slightly decreased. Differences in contractility between myocytes isolated from wild-type (WT) and PLM knockout (KO) hearts were preserved after 48 h of culture. Infection with adenovirus expressing green fluorescent protein (GFP) did not affect contractility at 48 h. When WT PLM was overexpressed in PLM KO myocytes, contractility and cytosolic Ca(2+) concentration ([Ca(2+)](i)) transients reverted back to those observed in cultured WT myocytes. Both Na(+)-K(+)-ATPase current (I(pump)) and Na(+)/Ca(2+) exchange current (I(NaCa)) in PLM KO myocytes rescued with WT PLM were depressed compared with PLM KO myocytes. Overexpressing the PLMS68E mutant (phosphomimetic) in PLM KO myocytes resulted in the suppression of I(NaCa) but had no effect on I(pump). Contractility, [Ca(2+)](i) transient amplitudes, and sarcoplasmic reticulum Ca(2+) contents in PLM KO myocytes overexpressing the PLMS68E mutant were depressed compared with PLM KO myocytes overexpressing GFP. Overexpressing the PLMS68A mutant (mimicking unphosphorylated PLM) in PLM KO myocytes had no effect on I(NaCa) but decreased I(pump). Contractility, [Ca(2+)](i) transient amplitudes, and sarcoplasmic reticulum Ca(2+) contents in PLM KO myocytes overexpressing the S68A mutant were similar to PLM KO myocytes overexpressing GFP. We conclude that at the single-myocyte level, PLM affects cardiac contractility and [Ca(2+)](i) homeostasis primarily by its direct

  17. Strategies to Study Desmin in Cardiac Muscle and Culture Systems. (United States)

    Diokmetzidou, Antigoni; Tsikitis, Mary; Nikouli, Sofia; Kloukina, Ismini; Tsoupri, Elsa; Papathanasiou, Stamatis; Psarras, Stelios; Mavroidis, Manolis; Capetanaki, Yassemi


    Intermediate filament (IF) cytoskeleton comprises the fine-tuning cellular machinery regulating critical homeostatic mechanisms. In skeletal and cardiac muscle, deficiency or disturbance of the IF network leads to severe pathology, particularly in the latter. The three-dimensional scaffold of the muscle-specific IF protein desmin interconnects key features of the cardiac muscle cells, including the Z-disks, intercalated disks, plasma membrane, nucleus, mitochondria, lysosomes, and potentially sarcoplasmic reticulum. This is crucial for the highly organized striated muscle, in which effective energy production and transmission as well as mechanochemical signaling are tightly coordinated among the organelles and the contractile apparatus. The role of desmin and desmin-associated proteins in the biogenesis, trafficking, and organelle function, as well as the development, differentiation, and survival of the cardiac muscle begins to be enlightened, but the precise mechanisms remain elusive. We propose a set of experimental tools that can be used, in vivo and in vitro, to unravel crucial new pathways by which the IF cytoskeleton facilitates proper organelle function, homeostasis, and cytoprotection and further understand how its disturbance and deficiency lead to disease.

  18. Hearts of dystonia musculorum mice display normal morphological and histological features but show signs of cardiac stress.

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    Justin G Boyer

    Full Text Available Dystonin is a giant cytoskeletal protein belonging to the plakin protein family and is believed to crosslink the major filament systems in contractile cells. Previous work has demonstrated skeletal muscle defects in dystonin-deficient dystonia musculorum (dt mice. In this study, we show that the dystonin muscle isoform is localized at the Z-disc, the H zone, the sarcolemma and intercalated discs in cardiac tissue. Based on this localization pattern, we tested whether dystonin-deficiency leads to structural defects in cardiac muscle. Desmin intermediate filament, microfilament, and microtubule subcellular organization appeared normal in dt hearts. Nevertheless, increased transcript levels of atrial natriuretic factor (ANF, 66% beta-myosin heavy chain (beta-MHC, 95% and decreased levels of sarcoplasmic reticulum calcium pump isoform 2A (SERCA2a, 26%, all signs of cardiac muscle stress, were noted in dt hearts. Hearts from two-week old dt mice were assessed for the presence of morphological and histological alterations. Heart to body weight ratios as well as left ventricular wall thickness and left chamber volume measurements were similar between dt and wild-type control mice. Hearts from dt mice also displayed no signs of fibrosis or calcification. Taken together, our data provide new insights into the intricate structure of the sarcomere by situating dystonin in cardiac muscle fibers and suggest that dystonin does not significantly influence the structural organization of cardiac muscle fibers during early postnatal development.

  19. Protein kinase C modulation of the regulation of sarcoplasmic reticular function by protein kinase A-mediated phospholamban phosphorylation in diabetic rats. (United States)

    Watanuki, Satoko; Matsuda, Naoyuki; Sakuraya, Fumika; Jesmin, Subrina; Hattori, Yuichi


    1. The goal of this study was to elucidate the possible mechanisms by which protein kinase A (PKA)-mediated regulation of the sarcoplasmic reticulum (SR) via phospholambin protein phosphorylation is functionally impaired in streptozotocin-induced diabetic rats. 2. Phospholamban (PLB) protein and mRNA levels were 1.3-fold higher in diabetic than in control hearts, while protein expression of cardiac SR Ca(2+)-ATPase (SERCA2a) was unchanged. 3. Basal and isoprenaline-stimulated phosphorylation of PLB at Ser(16) or Thr(17) was unchanged in diabetic hearts. However, stronger immunoreactivity was observed at the basal level in diabetic hearts when antiphosphoserine antibody was used. 4. Basal (32)P incorporation into PLB was significantly higher in diabetic than in control SR vesicles, but the extent of the PKA-mediated increase in PLB phosphorylation was the same in the two groups of vesicles. 5. Stimulation of Ca(2+) uptake by PKA-catalyzed PLB phosphorylation was weaker in diabetic than in control SR vesicles. The PKA-induced increase in Ca(2+) uptake was attenuated when control SR vesicles were preincubated with protein kinase C (PKC). 6. PKC activities were increased by more than two-fold in the membranous fractions from diabetic hearts in comparison with control values, regardless of whether Ca(2+) was present. This was associated with increases in the protein content of PKCdelta, PKCeta, PKCiota, and PKClambda in diabetic membranous fractions. 7. The changes observed in diabetic rats were reversed by insulin therapy. 8. These results suggest that PKA-dependent phosphorylation may incompletely counteract the function of PLB as an inhibitor of SERCA2a activity in diabetes in which PKC expression and activity are enhanced.

  20. Use-dependence of ryanodine effects on postrest contraction in ferret cardiac muscle. (United States)

    Malecot, C O; Katzung, B G


    During an investigation of the effect of ryanodine on contractions in cardiac muscle, it was found that long rest periods removed all or most of the drug's effect. Therefore, we studied the kinetics of block development and recovery from block produced by low concentrations of ryanodine (1-100 pM) on the postrest contractions of ferret papillary muscle. At 100 pM, ryanodine depressed steady-state contraction amplitude slightly (4.2 +/- 1.1% mean +/- SEM, n = 10) but strongly inhibited (40-80%) the first contraction (postrest contraction) elicited on restimulation of the preparation after rest periods of 1 second to 5 minutes. Under control conditions, the nearly maximal potentiation of the twitch occurring after a standard test rest period (30 seconds of rest) was not affected by a preceding conditioning rest of up to 20 minutes. In the presence of 100 pM ryanodine, a conditioning rest increased the amplitude of the twitch elicited after a test rest, and the test rest contraction recovered toward control (drug-free) amplitude monoexponentially (time constant, 582 +/- 105 seconds). Block of postrest contraction could be reinduced by stimulation and occurred faster when higher rates were used (time constants, 758 seconds at 1 Hz and 107 +/- 26 seconds at 3 Hz). Since rest potentiation of twitch tension is believed to be mostly dependent on extra calcium released from the sarcoplasmic reticulum, the results suggest that the ryanodine-induced blockade of calcium release from the sarcoplasmic reticulum is use-dependent and recovers during diastole.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Up-regulation of cardiac nitric oxide synthase 1-derived nitric oxide after myocardial infarction in senescent rats. (United States)

    Damy, Thibaud; Ratajczak, Philippe; Robidel, Estelle; Bendall, Jennifer K; Oliviéro, Patricia; Boczkowski, Jorge; Ebrahimian, Talin; Marotte, Françoise; Samuel, Jane-Lise; Heymes, Christophe


    Nitric oxide (NO) has been implicated in the development of heart failure, although the source, significance, and functional role of the different NO synthase (NOS) isoforms in this pathology are controversial. The presence of a neuronal-type NOS isoform (NOS1) in the cardiac sarcoplasmic reticulum has been recently discovered, leading to the hypothesis that NOS1-derived NO may notably alter myocardial inotropy. However, the regulation and role(s) of NOS1 in cardiac diseases remain to be determined. Using an experimental model of myocardial infarction (MI) in senescent rats, we demonstrated a significant increase in cardiac NOS1 expression and activity in MI, coupled with the translocation of this enzyme to the sarcolemma through interactions with caveolin-3. The enhanced NOS1 activity counteracts the decrease in cardiac NOS3 expression and activity observed in heart failure. We demonstrated an increased interaction between NOS1 and its regulatory protein HSP90 in post-MI hearts, a potential mechanism for the higher NOS1 activity in this setting. Finally, preferential in vivo inhibition of NOS1 activity enhanced basal post-MI left ventricular dysfunction in senescent rats. These results provide the first evidence that increased NOS1-derived NO production may play a significant role in the autocrine regulation of myocardial contractility after MI in aging rats.

  2. Bioactive electrospun fish sarcoplasmic proteins as a drug delivery system

    DEFF Research Database (Denmark)

    Stephansen, Karen; Chronakis, Ioannis S.; Jessen, Flemming


    Nano-microfibers were made from cod (Gadus morhua) sarcoplasmic proteins (FSP) (Mwelectrospinning technique. The FSP fibers were studied by scanning electron microscopy, and thefiber morphology was found to be strongly dependent on FSP concentration. Interestingly, the FSP...

  3. PGC-1{alpha} accelerates cytosolic Ca{sup 2+} clearance without disturbing Ca{sup 2+} homeostasis in cardiac myocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Min, E-mail: [Institute of Molecular Medicine, State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871 (China); Yunnan Centers for Diseases Prevention and Control, Kunming 650022 (China); Wang, Yanru [Institute of Molecular Medicine, State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871 (China); Qu, Aijuan [Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States)


    Energy metabolism and Ca{sup 2+} handling serve critical roles in cardiac physiology and pathophysiology. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1{alpha}) is a multi-functional coactivator that is involved in the regulation of cardiac mitochondrial functional capacity and cellular energy metabolism. However, the regulation of PGC-1{alpha} in cardiac Ca{sup 2+} signaling has not been fully elucidated. To address this issue, we combined confocal line-scan imaging with off-line imaging processing to characterize calcium signaling in cultured adult rat ventricular myocytes expressing PGC-1{alpha} via adenoviral transduction. Our data shows that overexpressing PGC-1{alpha} improved myocyte contractility without increasing the amplitude of Ca{sup 2+} transients, suggesting that myofilament sensitivity to Ca{sup 2+} increased. Interestingly, the decay kinetics of global Ca{sup 2+} transients and Ca{sup 2+} waves accelerated in PGC-1{alpha}-expressing cells, but the decay rate of caffeine-elicited Ca{sup 2+} transients showed no significant change. This suggests that sarcoplasmic reticulum (SR) Ca{sup 2+}-ATPase (SERCA2a), but not Na{sup +}/Ca{sup 2+} exchange (NCX) contribute to PGC-1{alpha}-induced cytosolic Ca{sup 2+} clearance. Furthermore, PGC-1{alpha} induced the expression of SERCA2a in cultured cardiac myocytes. Importantly, overexpressing PGC-1{alpha} did not disturb cardiac Ca{sup 2+} homeostasis, because SR Ca{sup 2+} load and the propensity for Ca{sup 2+} waves remained unchanged. These data suggest that PGC-1{alpha} can ameliorate cardiac Ca{sup 2+} cycling and improve cardiac work output in response to physiological stress. Unraveling the PGC-1{alpha}-calcium handing pathway sheds new light on the role of PGC-1{alpha} in the therapy of cardiac diseases.

  4. Effect of Yiqi Huoxue Recipe(益气活血方)on Cardiac Function and Ultrastructure in Regression of Pressure Overload-induced Myocardial Hypertrophy in Rats

    Institute of Scientific and Technical Information of China (English)


    Objective:To investigate the effect of Yiqi Huoxue Recipe(YHR,益气活血方)on the cardiac function and ultrastructure during the regression of myocardial hypertrophy induced by pressure overload in rats.Methods:The model of myocardial hypertrophy was established by abdominal aortic banding.Eighty male Wistar rats were divided into six groups,the normal control group Ⅰ(n=20),the normal control group Ⅱ(n=12),the hypertension model group [(n=12),the hypertension model group Ⅱ(n=12),the YHR group(n=12)and the Captopril group(n=12).The observation was carried out in the normal control group Ⅰ and the hypertension model group Ⅰ after 4weeks of modeling,and the other four groups were observed after 16 weeks of modeling(12 weeks of administration).The cardiac function was measured with a multichannel biological signal analysis system,and the myocardium ultrastructure was observed by a transmission electron microscope.Results:(1)Compared with the normal control group Ⅰ,the systolic blood pressure and cardiac coefficient(left ventricular weight/body weight)in the model Ⅰ group was higher(P<0.05,P<0.01).(2)In the YHR group,cardiac coefficient and -dp/dtmax were lower,left ventricular systolic pressure and +dp/dtmin were higher when compared with the model group Ⅱ and the Captopril group(P<0.05or P<0.01).In the Captopril group,only cardiac coefficient was lower when compared with the mode group Ⅱ(P<0.05).(3)Compared with the normal control group Ⅱ,+dp/dtrmax was higher(P<0.01),-dp/dtnmax and isovolumetric contraction time(ICT)was lower(P<0.05,P<0.01)in both the YHR group and the Captopril group.(4)Results of the myocardium ultrastructure showed edema under myocardium plasmalemma,enlarged sarcoplasmic reticulum and T tube,and significantly enlarged intercalated disc of the cardiac muscle in the model groups.In the Captopril group,the extension of sarcoplasmic reticulum and T tube as well as the pathological changes of intercalated disc

  5. Is the Ca2+-ATPase from sarcoplasmic reticulum also a heat pump? (United States)

    Kjelstrup, Signe; de Meis, Leopoldo; Bedeaux, Dick; Simon, Jean-Marc


    We calculate, using the first law of thermodynamics, the membrane heat fluxes during active transport of Ca(2+) in the Ca(2+)-ATPase in leaky and intact vesicles, during ATP hydrolysis or synthesis conditions. The results show that the vesicle interior may cool down during hydrolysis and Ca(2+)-uptake, and heat up during ATP synthesis and Ca(2+)-efflux. The heat flux varies with the SERCA isoform. Electroneutral processes and rapid equilibration of water were assumed. The results are consistent with the second law of thermodynamics for the overall processes. The expression for the heat flux and experimental data, show that important contributions come from the enthalpy of hydrolysis for the medium in question, and from proton transport between the vesicle interior and exterior. The analysis give quantitative support to earlier proposals that certain, but not all, Ca(2+)-ATPases, not only act as Ca(2+)-pumps, but also as heat pumps. It can thus help explain why SERCA 1 type enzymes dominate in tissues where thermal regulation is important, while SERCA 2 type enzymes, with their lower activity and better ability to use the energy from the reaction to pump ions, dominate in tissues where this is not an issue.

  6. Role of glycogen availability in sarcoplasmic reticulum Ca2+ kinetics in human skeletal muscle

    DEFF Research Database (Denmark)

    Ørtenblad, Niels; Nielsen, Joachim; Saltin, Bengt;


    Glucose is stored as glycogen in skeletal muscle. The importance of glycogen as a fuel during exercise has been recognized since the 1960s; however, little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. We show that low muscle glycogen is associated ...

  7. Ouabain facilitates cardiac differentiation of mouse embryonic stem cells through ERK1/2 pathway

    Institute of Scientific and Technical Information of China (English)

    Yee-ki LEE; Kwong-man NG; Wing-hon LAI; Cornelia MAN; Deborah K LIEU; Chu-pak LAU; Hung-fat TSE; Chung-wah SIU


    Aim:To investigate the effects of the cardiotonic steroid, ouabain, on cardiac differentiation of murine embyronic stem cells (mESCs).Methods:Cardiac differentiation of murine ESCs was enhanced by standard hanging drop method in the presence of ouabain (20 μmol/L) for 7 d. The dissociated ES derived cardiomyocytes were examined by flow cytometry, RT-PCR and confocal calcium imaging.Results:Compared with control, mESCs treated with ouabain (20 μmol/L) yielded a significantly higher percentage of cardiomyocytesand significantly increased expression of a panel of cardiac markers including Nkx 2.5, α-MHC, and β-MHC. The α1 and 2- isoforms Na+/K+ -ATPase, on which ouabain acted, were also increased in mESCs during differentiation. Among the three MAPKs involved in the cardiac hypertrophy pathway, ouabain enhanced ERK1/2 activation. Blockage of the Erk1/2 pathway by U0126 (10 μmol/L) inhibited cardiac differentiation while ouabain (20 μmol/L) rescued the effect. Interestingly, the expression of calcium handling proteins, includ ing ryanodine receptor (RyR2) and sacroplasmic recticulum Ca2+ ATPase (SERCA2a) was also upregulated in ouabain-treated mESCs.ESC-derived cardiomyocyes (CM) treated with ouabain appeared to have more mature calcium handling. As demonstrated by confocal Ca2+ imaging, cardiomyocytes isolated from ouabain-treated mESCs exhibited higher maximum upstroke velocity (P<0.01) and maximum decay velocity (P<0.05), as well as a higher amplitude of caffeine induced Ca2+ transient (P<0.05), suggesting more mature sarcoplasmic reticulum (SR).Conclusion:Ouabain induces cardiac differentiation and maturation of mESC-derived cardiomyocytes via activation of Erk1/2 and more mature SR for calcium handling.

  8. Ghrelin对急性心肌梗死大鼠心功能的影响及其机制研究%Mechanism of ghrelin in improving cardiac function by inhibiting endoplasmic reticulum stress in rats with acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    蔡敏; 刘地川; 童欣; 吴泓权; 黄晶


    目的 探讨Ghrelin对急性心肌梗死(AMI)模型大鼠心功能的影响及其可能机制.方法 成年雄性SD大鼠18只,结扎冠状动脉前降支建立AMI模型.于建模后第4天,将存活的14只大鼠随机分为模型组(AMI+NS组,n=7)和处理组(AMI+Ghrelin组,n=7),处理组按100μg/kg皮下注射Ghrelin,2次/d,间隔12h,共2周,模型组按100μg/kg皮下注射生理盐水(NS).另设假手术组(n=8).2周后,超声心动图(UCG)检测大鼠心功能,ELISA法检测血清LDH、CK-MB含量,HE染色观察心肌组织形态学变化,Western blotting检测内质网应激(ERS)标志物GRP-78、CHOP蛋白表达.结果 成功建立AMI大鼠模型.与假手术组比较,UCG提示模型组大鼠心功能明显下降(P<0.05),HE染色可见组织疏松、水肿较明显,血清LDH、CK-MB明显升高(P<0.05),Western blotting检测显示GRP-78、CHOP蛋白表达增加(P<0.05);与模型组比较,处理组心功能明显改善,组织疏松、水肿明显减轻,血清LDH、CK-MB降低(P<0.05),GRP-78、CHOP蛋白表达下降(P<0.05).结论 Ghrelin可能通过抑制ERS途径改善AMI引起的心肌损伤,从而改善心功能.%Objective To establish the rat model of acute myocardial infarction (AMI), and to explore the mechanism of ghrelin in improving cardiac function through inhibiting endoplasmic reticulum stress (ERS), Methods AMI model was reproduced in 18 adult male Sprague-Dawley rats (220 ± 20g) by ligation of the left anterior descending coronary artery. Four days after the reproduction of the model, 14 survived rats with AMI were randomly divided into two groups (7 each): model group, animals were subcutaneously (sc) injected with normal saline only; treatment group, animals were given ghrelin (l00μg/kg) twice a day (l2h interval) for two weeks. In addition, a sham-operated group was set up (Sham operation+saline, n=8). Two weeks later, the cardiac function was examined by echocardiography (UCG), the morphological changes in myocardial tissue

  9. Cardiac electrical defects in progeroid mice and Hutchinson–Gilford progeria syndrome patients with nuclear lamina alterations (United States)

    Rivera-Torres, José; Calvo, Conrado J.; Llach, Anna; Guzmán-Martínez, Gabriela; Caballero, Ricardo; González-Gómez, Cristina; Jiménez-Borreguero, Luis J.; Guadix, Juan A.; Osorio, Fernando G.; López-Otín, Carlos; Herraiz-Martínez, Adela; Cabello, Nuria; Vallmitjana, Alex; Benítez, Raul; Gordon, Leslie B.; Pérez-Pomares, José M.; Tamargo, Juan; Delpón, Eva; Hove-Madsen, Leif; Filgueiras-Rama, David; Andrés, Vicente


    Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic disease caused by defective prelamin A processing, leading to nuclear lamina alterations, severe cardiovascular pathology, and premature death. Prelamin A alterations also occur in physiological aging. It remains unknown how defective prelamin A processing affects the cardiac rhythm. We show age-dependent cardiac repolarization abnormalities in HGPS patients that are also present in the Zmpste24−/− mouse model of HGPS. Challenge of Zmpste24−/− mice with the β-adrenergic agonist isoproterenol did not trigger ventricular arrhythmia but caused bradycardia-related premature ventricular complexes and slow-rate polymorphic ventricular rhythms during recovery. Patch-clamping in Zmpste24−/− cardiomyocytes revealed prolonged calcium-transient duration and reduced sarcoplasmic reticulum calcium loading and release, consistent with the absence of isoproterenol-induced ventricular arrhythmia. Zmpste24−/− progeroid mice also developed severe fibrosis-unrelated bradycardia and PQ interval and QRS complex prolongation. These conduction defects were accompanied by overt mislocalization of the gap junction protein connexin43 (Cx43). Remarkably, Cx43 mislocalization was also evident in autopsied left ventricle tissue from HGPS patients, suggesting intercellular connectivity alterations at late stages of the disease. The similarities between HGPS patients and progeroid mice reported here strongly suggest that defective cardiac repolarization and cardiomyocyte connectivity are important abnormalities in the HGPS pathogenesis that increase the risk of arrhythmia and premature death. PMID:27799555

  10. Isoprenaline enhances local Ca2+ release in cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    Jian-xin SHEN


    Aim: Contraction of cardiac myocytes is controlled by the generation and amplification of intracellular Ca2+ signals. The key step of this process is the coupling between sarcolemma L-type Ca2+ channels (LCCs) and ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). β-Adrenergic stimulation is an important regulatory mechanism for this coupling process. But the details underlied the global level, which require local Ca2+ release study are still unclear. The present study is to explore the effects of β-adrenergic stimulation on local Ca2+ release. Methods: Using confocal microscopy combined with loose-seal patch-clamp approaches, effects of isoprenaline (1 μmol·L-1), a β-adrenergic agonist, on local SR Ca2+ release triggered by Ca2+ influx through LCCs in intact rat cardiac myocytes were investigated. Results: Isoprenaline increased the intensity of ensemble averaged local Ca2+ transients, the peak of which displayed a typical bell-shaped voltage-dependence over the membrane voltages ranging from ~-40mV to ~+35mV. Further analysis showed that this enhancement could be explained by the increased coupling fidelity (which refers the increased probability of RyRs activation upon depolarization), and the increased amplitude of evoked Ca2+ sparks (due to more Ca2+ releases through local RyRs). In addition, isoprenaline decreased the first latency, which displayed a typical "U"-shaped voltage-dependence, showing the available acceleration and synchronization of β-adrenergic stimulation on intracellular calcium release. Conclusions: Isoprenaline enhances local Ca2+ release in cardiac myocytes. These results underscore the importance of regulation of β-adrenergic stimulation on local intermolecular signals between LCCs and RyRs in heart cells.

  11. Functional Effects of Hyperthyroidism on Cardiac Papillary Muscle in Rats

    Directory of Open Access Journals (Sweden)

    Fabricio Furtado Vieira

    Full Text Available Abstract Background: Hyperthyroidism is currently recognized to affect the cardiovascular system, leading to a series of molecular and functional changes. However, little is known about the functional influence of hyperthyroidism in the regulation of cytoplasmic calcium and on the sodium/calcium exchanger (NCX in the cardiac muscle. Objectives: To evaluate the functional changes in papillary muscles isolated from animals with induced hyperthyroidism. Methods: We divided 36 Wistar rats into a group of controls and another of animals with hyperthyroidism induced by intraperitoneal T3 injection. We measured in the animals' papillary muscles the maximum contraction force, speed of contraction (+df/dt and relaxation (-df/dt, contraction and relaxation time, contraction force at different concentrations of extracellular sodium, post-rest potentiation (PRP, and contraction force induced by caffeine. Results: In hyperthyroid animals, we observed decreased PRP at all rest times (p < 0.05, increased +df/dt and -df/dt (p < 0.001, low positive inotropic response to decreased concentration of extracellular sodium (p < 0.001, reduction of the maximum force in caffeine-induced contraction (p < 0.003, and decreased total contraction time (p < 0.001. The maximal contraction force did not differ significantly between groups (p = 0.973. Conclusion: We hypothesize that the changes observed are likely due to a decrease in calcium content in the sarcoplasmic reticulum, caused by calcium leakage, decreased expression of NCX, and increased expression of a-MHC and SERCA2.

  12. Functional Effects of Hyperthyroidism on Cardiac Papillary Muscle in Rats (United States)

    Vieira, Fabricio Furtado; Olivoto, Robson Ruiz; da Silva, Priscyla Oliveira; Francisco, Julio Cesar; Fogaça, Rosalvo Tadeu Hochmuller


    Background Hyperthyroidism is currently recognized to affect the cardiovascular system, leading to a series of molecular and functional changes. However, little is known about the functional influence of hyperthyroidism in the regulation of cytoplasmic calcium and on the sodium/calcium exchanger (NCX) in the cardiac muscle. Objectives To evaluate the functional changes in papillary muscles isolated from animals with induced hyperthyroidism. Methods We divided 36 Wistar rats into a group of controls and another of animals with hyperthyroidism induced by intraperitoneal T3 injection. We measured in the animals' papillary muscles the maximum contraction force, speed of contraction (+df/dt) and relaxation (-df/dt), contraction and relaxation time, contraction force at different concentrations of extracellular sodium, post-rest potentiation (PRP), and contraction force induced by caffeine. Results In hyperthyroid animals, we observed decreased PRP at all rest times (p < 0.05), increased +df/dt and -df/dt (p < 0.001), low positive inotropic response to decreased concentration of extracellular sodium (p < 0.001), reduction of the maximum force in caffeine-induced contraction (p < 0.003), and decreased total contraction time (p < 0.001). The maximal contraction force did not differ significantly between groups (p = 0.973). Conclusion We hypothesize that the changes observed are likely due to a decrease in calcium content in the sarcoplasmic reticulum, caused by calcium leakage, decreased expression of NCX, and increased expression of a-MHC and SERCA2.

  13. Preserved cardiac function despite marked impairment of cAMP generation.

    Directory of Open Access Journals (Sweden)

    Mei Hua Gao

    Full Text Available OBJECTIVES: So many clinical trials of positive inotropes have failed, that it is now axiomatic that agents that increase cAMP are deleterious to the failing heart. An alternative strategy is to alter myocardial Ca(2+ handling or myofilament response to Ca(2+ using agents that do not affect cAMP. Although left ventricular (LV function is tightly linked to adenylyl cyclase (AC activity, the beneficial effects of AC may be independent of cAMP and instead stem from effects on Ca(2+ handling. Here we ask whether an AC mutant molecule that reduces LV cAMP production would have favorable effects on LV function through its effects on Ca(2+ handling alone. METHODS AND RESULTS: We generated transgenic mice with cardiac-directed expression of an AC6 mutant (AC6mut. Cardiac myocytes showed impaired cAMP production in response to isoproterenol (74% reduction; p<0.001, but LV size and function were normal. Isolated hearts showed preserved LV function in response to isoproterenol stimulation. AC6mut expression was associated with increased sarcoplasmic reticulum Ca(2+ uptake and the EC50 for SERCA2a activation was reduced. Cardiac myocytes isolated from AC6mut mice showed increased amplitude of Ca(2+ transients in response to isoproterenol (p = 0.0001. AC6mut expression also was associated with increased expression of LV S100A1 (p = 0.03 and reduced expression of phospholamban protein (p = 0.01. CONCLUSION: LV AC mutant expression is associated with normal cardiac function despite impaired cAMP generation. The mechanism appears to be through effects on Ca(2+ handling - effects that occur despite diminished cAMP.

  14. Steady-state solutions of cell volume in a cardiac myocyte model elaborated for membrane excitation, ion homeostasis and Ca2+ dynamics. (United States)

    Cha, Chae Young; Noma, Akinori


    The cell volume continuously changes in response to varying physiological conditions, and mechanisms underlying volume regulation have been investigated in both experimental and theoretical studies. Here, general formulations concerning cell volume change are presented in the context of developing a comprehensive cell model which takes Ca(2+) dynamics into account. Explicit formulas for charge conservation and steady-state volumes of the cytosol and endoplasmic reticulum (ER) are derived in terms of membrane potential, amount of ions, Ca(2+)-bound buffer molecules, and initial cellular conditions. The formulations were applied to a ventricular myocyte model which has plasma-membrane Ca(2+) currents with dynamic gating mechanisms, Ca(2+)-buffering reactions with diffusive and non-diffusive buffer proteins, and Ca(2+) uptake into or release from the sarcoplasmic reticulum (SR) accompanied by compensatory cationic or anionic currents through the SR membrane. Time-dependent volume changes in cardiac myocytes induced by varying extracellular osmolarity or by action potential generation were successfully simulated by the novel formulations. Through application of bifurcation analysis, the existence and uniqueness of steady-state solutions of the cell volume were validated, and contributions of individual ion channels and transporters to the steady-state volume were systematically analyzed. The new formulas are consistent with previous fundamental theory derived from simple models of minimum compositions. The new formulations may be useful for examination of the relationship between cell function and volume change in other cell types.

  15. Pitavastatin-attenuated cardiac dysfunction in mice with dilated cardiomyopathy via regulation of myocardial calcium handling proteins

    Directory of Open Access Journals (Sweden)

    Hu Wei


    Full Text Available C57BL/6 mice with dilated cardiomyopathy (DCM were randomly divided to receive placebo or pitavastatin at a dose of 1 or 3 mg kg-1d-1. After 8 weeks treatment, mice with dilated cardiomyopathy developed serious cardiac dysfunction characterized by significantly enhanced left ventricular end-diastolic diameter (LVIDd, decreased left ventricular ejection fraction (LVEF as well as left ventricular short axis fractional shortening (LVFS, accompanied with enlarged cardiomyocytes, and increased plasma levels of N-terminal pro-B type natriuretic peptide (NT-proBNP and plasma angiotensin II (AngII concentration. Moreover, myocardium sarcoplasmic reticulum Ca2+ pump (SERCA-2 activity was decreased. The ratio of phosphorylated phospholamban (PLB to total PLB decreased significantly with the down-regulation of SERCA- -2a and ryanodine receptor (RyR2 expression. Pitavastatin was found to ameliorate the cardiac dysfunction in mice with dilated cardiomyopathy by reversing the changes in the ratios of phosphorylated PLB to total PLB, SERCA-2a and RyR2 via reducing the plasma AngII concentration and the expressions of myocardium angiotensin II type 1 receptor (AT1R and protein kinase C (PKCb2. The possible underlying mechanism might be the regulation of myocardial AT1R-PKCb2-Ca2+ handling proteins.

  16. Role of Mitochondrial Enzymes and Sarcoplasmic ATPase in Cardioprotection Mediated by Aqueous Extract of Desmodium gangeticum (L) DC Root on Ischemic Reperfusion Injury. (United States)

    Kurian, G A; Paddikkala, J


    The present study investigate the protective effect of aqueous root extract of Desmodium gangeticum in preserving mitochondrial and sarcoplasmic ATPase during ischemia reperfusion injury. The isolated rat hearts in both drug and control group were subjected to warm ischemia (37°), followed by reperfusion with the Langendorff perfusion system. The aqueous root extract of Desmodium gangeticum (L) at a dose of 50 mg/kg body weight was found to be effective in the rat heart for the management of ischemic reperfusion injury. Physiological parameters were significantly (PDesmodium gangeticum treated rat heart. These results suggest that Desmodium gangeticum aqueous root extract can preserve the mitochondrial and sarcoplasmic ATPase in the myocardium, resulting in the improvement of cardiac function after ischemia reperfusion injury.

  17. Cooked sausage batter cohesiveness as affected by sarcoplasmic proteins. (United States)

    Farouk, M M; Wieliczko, K; Lim, R; Turnwald, S; Macdonald, G A


    In the first trial, m. semitendinosus and m. biceps femoris were held at 0, 10 and 35 °C until they entered rigor, and in the second trial, minced m. semitendinosus was washed in water for 15, 30, 45 or 60 min. The samples from both the trials were then used to make a finely comminuted sausage batter. Soluble sarcoplasmic protein (SSP) levels decreased with increasing rigor temperature (P batter shear stress was not affected by SSP level, but batter shear strain decreased with the decreasing SSP level associated with an increasing rigor temperature (P batter from the washed samples compared to that of controls. The results suggest that sarcoplasmic proteins are important in determining the strain values (cohesiveness) of cooked sausage batter.

  18. Transitions of protein traffic from cardiac ER to junctional SR


    Sleiman, Naama H.; McFarland, Timothy P.; Jones, Larry R.; Cala, Steven E.


    The junctional sarcoplasmic reticulum (jSR) is an important and unique ER subdomain in the adult myocyte that concentrates resident proteins to regulate Ca2+ release. To investigate cellular mechanisms for sorting and trafficking proteins to jSR, we overexpressed canine forms of junctin (JCT) or triadin (TRD) in adult rat cardiomyocytes. Protein accumulation over time was visualized by confocal fluorescence microscopy using species-specific antibodies. Newly synthesized JCTdog and TRDdog appe...

  19. Cardiac ryanodine receptor in metabolic syndrome: is JTV519 (K201 future therapy?

    Directory of Open Access Journals (Sweden)

    Dincer UD


    Full Text Available U Deniz DincerDepartment of Pharmacology, Ufuk University School of Medicine. Mevlana Bulvari, Balgat, Ankara, TurkeyAbstract: Metabolic syndrome is characterized by a combination of obesity, hypertension, insulin resistance, dyslipidemia, and impaired glucose tolerance. This multifaceted syndrome is often accompanied by a hyperdynamic circulatory state characterized by increased blood pressure, total blood volume, cardiac output, and metabolic tissue demand. Experimental, epidemiological, and clinical studies have demonstrated that patients with metabolic syndrome have significantly elevated cardiovascular morbidity and mortality rates. One of the main and frequent complications seen in metabolic syndrome is cardiovascular disease. The primary endpoints of cardiometabolic risk are coronary and peripheral arterial disease, myocardial infarction, congestive heart failure, arrhythmia, and stroke. Alterations in expression and/or functioning of several key proteins involved in regulating and maintaining ionic homeostasis can cause cardiac disturbances. One such group of proteins is known as ryanodine receptors (intracellular calcium release channels, which are the major channels through which Ca2+ ions leave the sarcoplasmic reticulum, leading to cardiac muscle contraction. The economic cost of metabolic syndrome and its associated complications has a significant effect on health care budgets. Improvements in body weight, blood lipid profile, and hyperglycemia can reduce cardiometabolic risk. However, constant hyperadrenergic stimulation still contributes to the burden of disease. Normalization of the hyperdynamic circulatory state with conventional therapies is the most reasonable therapeutic strategy to date. JTV519 (K201 is a newly developed 1,4-benzothiazepine drug with antiarrhythmic and cardioprotective properties. It appears to be very effective in not only preventing but also in reversing the characteristic myocardial changes and preventing

  20. Effect of cardiac glycosides on action potential characteristics and contractility in cat ventricular myocytes: role of calcium overload. (United States)

    Ruch, Stuart R; Nishio, Manabu; Wasserstrom, J Andrew


    There is increasing evidence that cardiac glycosides act through mechanisms distinct from inhibition of the sodium pump but which may contribute to their cardiac actions. To more fully define differences between agents indicative of multiple sites of action, we studied changes in contractility and action potential (AP) configuration in cat ventricular myocytes produced by six cardiac glycosides (ouabain, ouabagenin, dihydroouabain, actodigin, digoxin, and resibufogenin). AP shortening was observed only with ouabain and actodigin. There was extensive inotropic variability between agents, with some giving full inotropic effects before automaticity occurred whereas others produced minimal inotropy before toxicity. AP shortening was not a result of alterations in calcium current or the inward rectifier potassium current, but correlated with an increase in steady-state outward current (Iss), which was sensitive to KB-R7943, a Na+-Ca2+ exchange (NCX) inhibitor. Interestingly, Iss was observed following exposure to ouabain and dihydroouabain, suggesting that an additional mechanism is operative with dihydroouabain that prevents AP shortening. Further investigation into differences in inotropy between ouabagenin, dihydroouabain and ouabain revealed almost identical responses under AP voltage clamp. Thus all agents appear to act on the sodium pump and thereby secondarily increase the outward reverse mode NCX current, but the extent of AP duration shortening and positive inotropy elicited by each agent is limited by development of their toxic actions. The quantitative differences between cardiac glycosides suggest that mechanisms independent of sodium pump inhibition may result from an altered threshold for calcium overload possibly involving direct or indirect effects on calcium release from the sarcoplasmic reticulum.

  1. In Silico Investigation into Cellular Mechanisms of Cardiac Alternans in Myocardial Ischemia

    Directory of Open Access Journals (Sweden)

    Jiaqi Liu


    Full Text Available Myocardial ischemia is associated with pathophysiological conditions such as hyperkalemia, acidosis, and hypoxia. These physiological disorders may lead to changes on the functions of ionic channels, which in turn form the basis for cardiac alternans. In this paper, we investigated the roles of hyperkalemia and calcium handling components played in the genesis of alternans in ischemia at the cellular level by using computational simulations. The results show that hyperkalemic reduced cell excitability and delayed recovery from inactivation of depolarization currents. The inactivation time constant τf of L-type calcium current (ICaL increased obviously in hyperkalemia. One cycle length was not enough for ICaL to recover completely. Alternans developed as a result of ICaL responding to stimulation every other beat. Sarcoplasmic reticulum calcium-ATPase (SERCA2a function decreased in ischemia. This change resulted in intracellular Ca (Cai alternans of small magnitude. A strong Na+-Ca2+ exchange current (INCX increased the magnitude of Cai alternans, leading to APD alternans through excitation-contraction coupling. Some alternated repolarization currents contributed to this repolarization alternans.

  2. Parameter sensitivity analysis of stochastic models provides insights into cardiac calcium sparks. (United States)

    Lee, Young-Seon; Liu, Ona Z; Hwang, Hyun Seok; Knollmann, Bjorn C; Sobie, Eric A


    We present a parameter sensitivity analysis method that is appropriate for stochastic models, and we demonstrate how this analysis generates experimentally testable predictions about the factors that influence local Ca(2+) release in heart cells. The method involves randomly varying all parameters, running a single simulation with each set of parameters, running simulations with hundreds of model variants, then statistically relating the parameters to the simulation results using regression methods. We tested this method on a stochastic model, containing 18 parameters, of the cardiac Ca(2+) spark. Results show that multivariable linear regression can successfully relate parameters to continuous model outputs such as Ca(2+) spark amplitude and duration, and multivariable logistic regression can provide insight into how parameters affect Ca(2+) spark triggering (a probabilistic process that is all-or-none in a single simulation). Benchmark studies demonstrate that this method is less computationally intensive than standard methods by a factor of 16. Importantly, predictions were tested experimentally by measuring Ca(2+) sparks in mice with knockout of the sarcoplasmic reticulum protein triadin. These mice exhibit multiple changes in Ca(2+) release unit structures, and the regression model both accurately predicts changes in Ca(2+) spark amplitude (30% decrease in model, 29% decrease in experiments) and provides an intuitive and quantitative understanding of how much each alteration contributes to the result. This approach is therefore an effective, efficient, and predictive method for analyzing stochastic mathematical models to gain biological insight.

  3. In Silico Investigation into Cellular Mechanisms of Cardiac Alternans in Myocardial Ischemia (United States)

    Liu, Jiaqi; Zhao, Xiaopeng


    Myocardial ischemia is associated with pathophysiological conditions such as hyperkalemia, acidosis, and hypoxia. These physiological disorders may lead to changes on the functions of ionic channels, which in turn form the basis for cardiac alternans. In this paper, we investigated the roles of hyperkalemia and calcium handling components played in the genesis of alternans in ischemia at the cellular level by using computational simulations. The results show that hyperkalemic reduced cell excitability and delayed recovery from inactivation of depolarization currents. The inactivation time constant τf of L-type calcium current (ICaL) increased obviously in hyperkalemia. One cycle length was not enough for ICaL to recover completely. Alternans developed as a result of ICaL responding to stimulation every other beat. Sarcoplasmic reticulum calcium-ATPase (SERCA2a) function decreased in ischemia. This change resulted in intracellular Ca (Cai) alternans of small magnitude. A strong Na+-Ca2+ exchange current (INCX) increased the magnitude of Cai alternans, leading to APD alternans through excitation-contraction coupling. Some alternated repolarization currents contributed to this repolarization alternans. PMID:28070211

  4. Overexpression of ryanodine receptor type 1 enhances mitochondrial fragmentation and Ca2+-induced ATP production in cardiac H9c2 myoblasts. (United States)

    O-Uchi, Jin; Jhun, Bong Sook; Hurst, Stephen; Bisetto, Sara; Gross, Polina; Chen, Ming; Kettlewell, Sarah; Park, Jongsun; Oyamada, Hideto; Smith, Godfrey L; Murayama, Takashi; Sheu, Shey-Shing


    Ca(+) influx to mitochondria is an important trigger for both mitochondrial dynamics and ATP generation in various cell types, including cardiac cells. Mitochondrial Ca(2+) influx is mainly mediated by the mitochondrial Ca(2+) uniporter (MCU). Growing evidence also indicates that mitochondrial Ca(2+) influx mechanisms are regulated not solely by MCU but also by multiple channels/transporters. We have previously reported that skeletal muscle-type ryanodine receptor (RyR) type 1 (RyR1), which expressed at the mitochondrial inner membrane, serves as an additional Ca(2+) uptake pathway in cardiomyocytes. However, it is still unclear which mitochondrial Ca(2+) influx mechanism is the dominant regulator of mitochondrial morphology/dynamics and energetics in cardiomyocytes. To investigate the role of mitochondrial RyR1 in the regulation of mitochondrial morphology/function in cardiac cells, RyR1 was transiently or stably overexpressed in cardiac H9c2 myoblasts. We found that overexpressed RyR1 was partially localized in mitochondria as observed using both immunoblots of mitochondrial fractionation and confocal microscopy, whereas RyR2, the main RyR isoform in the cardiac sarcoplasmic reticulum, did not show any expression at mitochondria. Interestingly, overexpression of RyR1 but not MCU or RyR2 resulted in mitochondrial fragmentation. These fragmented mitochondria showed bigger and sustained mitochondrial Ca(2+) transients compared with basal tubular mitochondria. In addition, RyR1-overexpressing cells had a higher mitochondrial ATP concentration under basal conditions and showed more ATP production in response to cytosolic Ca(2+) elevation compared with nontransfected cells as observed by a matrix-targeted ATP biosensor. These results indicate that RyR1 possesses a mitochondrial targeting/retention signal and modulates mitochondrial morphology and Ca(2+)-induced ATP production in cardiac H9c2 myoblasts.

  5. Dynamic interactions of an intracellular Ca2+ clock and membrane ion channel clock underlie robust initiation and regulation of cardiac pacemaker function. (United States)

    Maltsev, Victor A; Lakatta, Edward G


    For almost half a century it has been thought that the initiation of each heartbeat is driven by surface membrane voltage-gated ion channels (M clocks) within sinoatrial nodal cells. It has also been assumed that pacemaker cell automaticity is initiated at the maximum diastolic potential (MDP). Recent experimental evidence based on confocal cell imaging and supported by numerical modelling, however, shows that initiation of cardiac impulse is a more complex phenomenon and involves yet another clock that resides under the sarcolemma. This clock is the sarcoplasmic reticulum (SR): it generates spontaneous, but precisely timed, rhythmic, submembrane, local Ca(2+) releases (LCR) that appear not at the MDP but during the late, diastolic depolarization (DD). The Ca(2+) clock and M clock dynamically interact, defining a novel paradigm of robust cardiac pacemaker function and regulation. Rhythmic LCRs during the late DD activate inward Na(+)/Ca(2+) exchanger currents and ignite action potentials, which in turn induceCa(2+) transients and SR depletions, resetting the Ca(2+) clock. Both basal and reserve protein kinaseA-dependent phosphorylation of Ca(2+) cycling proteins control the speed and amplitude of SR Ca(2+) cycling to regulate the beating rate by strongly coupled Ca(2+) and M clocks.

  6. Kinetic characterization of Channa striatus muscle sarcoplasmic and myofibrillar protein hydrolysates. (United States)

    Ghassem, Masomeh; Fern, See Siau; Said, Mamot; Ali, Zainon Mohd; Ibrahim, Saadiah; Babji, Abdul Salam


    This study was conducted to evaluate the kinetic characteristics of proteolytic activity of proteases on Channa striatus protein fractions. Degree of hydrolysis (DH), amino acid composition and kinetic parameters of sarcoplasmic and myofibrillar proteins were investigated when incubated with proteinase K and thermolysin, separately. After 30 min incubation with proteases, a decrease in DH of sarcoplasmic protein was observed whereas, hydrolysis of myofibrillar protein with proteases took 2 h with an increase in DH. The major amino acids were glutamic acid (16.6%) in thermolysin- myofibrillar hydrolysate followed by aspartic acid (11.1%) in sarcoplasmic protein fraction with no enzyme treatment and lysine (10%) in thermolysin-myofibrillar hydrolysate. The apparent Michaelis constant of proteinase K was lower than thermolysin for both sarcoplasmic and myofibrillar proteins. However, rate of turnover and enzyme efficiency suggested that sarcoplasmic and myofibrillar proteins are suitable substrates for proteinase K and thermolysin hydrolytic reaction, respectively.

  7. Life and death of a cardiac calcium spark. (United States)

    Stern, Michael D; Ríos, Eduardo; Maltsev, Victor A


    Calcium sparks in cardiac myocytes are brief, localized calcium releases from the sarcoplasmic reticulum (SR) believed to be caused by locally regenerative calcium-induced calcium release (CICR) via couplons, clusters of ryanodine receptors (RyRs). How such regeneration is terminated is uncertain. We performed numerical simulations of an idealized stochastic model of spark production, assuming a RyR gating scheme with only two states (open and closed). Local depletion of calcium in the SR was inevitable during a spark, and this could terminate sparks by interrupting CICR, with or without assumed modulation of RyR gating by SR lumenal calcium. Spark termination by local SR depletion was not robust: under some conditions, sparks could be greatly and variably prolonged, terminating by stochastic attrition-a phenomenon we dub "spark metastability." Spark fluorescence rise time was not a good surrogate for the duration of calcium release. Using a highly simplified, deterministic model of the dynamics of a couplon, we show that spark metastability depends on the kinetic relationship of RyR gating and junctional SR refilling rates. The conditions for spark metastability resemble those produced by known mutations of RyR2 and CASQ2 that cause life-threatening triggered arrhythmias, and spark metastability may be mitigated by altering the kinetics of the RyR in a manner similar to the effects of drugs known to prevent those arrhythmias. The model was unable to explain the distributions of spark amplitudes and rise times seen in chemically skinned cat atrial myocytes, suggesting that such sparks may be more complex events involving heterogeneity of couplons or local propagation among sub-clusters of RyRs.

  8. Myopathy in Marinesco-Sjögren syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology. (United States)

    Roos, Andreas; Buchkremer, Stephan; Kollipara, Laxmikanth; Labisch, Thomas; Gatz, Christian; Zitzelsberger, Manuela; Brauers, Eva; Nolte, Kay; Schröder, J Michael; Kirschner, Janbernd; Jesse, Christopher Marvin; Goebel, Hans Hilmar; Goswami, Anand; Zimmermann, Richard; Zahedi, René Peiman; Senderek, Jan; Weis, Joachim


    Marinesco-Sjögren syndrome (MSS) features cerebellar ataxia, mental retardation, cataracts, and progressive vacuolar myopathy with peculiar myonuclear alterations. Most MSS patients carry homozygous or compound heterozygous SIL1 mutations. SIL1 is a nucleotide exchange factor for the endoplasmic reticulum resident chaperone BiP which controls a plethora of essential processes in the endoplasmic reticulum. In this study we made use of the spontaneous Sil1 mouse mutant woozy to explore pathomechanisms leading to Sil1 deficiency-related skeletal muscle pathology. We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations. These abnormalities were remarkably similar to the myopathy in human patients with MSS. In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles. We found that these structures are derived from the nuclear envelope and nuclear lamina and associate with proliferations of the sarcoplasmic reticulum. In line with impaired function of BiP secondary to loss of its nucleotide exchange factor Sil1, we observed activation of the unfolded protein response and the endoplasmic-reticulum-associated protein degradation-pathway. Despite initiation of the autophagy-lysosomal system, autophagic clearance was found ineffective which is in agreement with the formation of autophagic vacuoles. This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy. Moreover, we provide a link between two well-established disease mechanisms in skeletal muscle, dysfunction of chaperones and nuclear envelope pathology.

  9. BIN1 localizes the L-type calcium channel to cardiac T-tubules.

    Directory of Open Access Journals (Sweden)

    Ting-Ting Hong


    Full Text Available The BAR domain protein superfamily is involved in membrane invagination and endocytosis, but its role in organizing membrane proteins has not been explored. In particular, the membrane scaffolding protein BIN1 functions to initiate T-tubule genesis in skeletal muscle cells. Constitutive knockdown of BIN1 in mice is perinatal lethal, which is associated with an induced dilated hypertrophic cardiomyopathy. However, the functional role of BIN1 in cardiomyocytes is not known. An important function of cardiac T-tubules is to allow L-type calcium channels (Cav1.2 to be in close proximity to sarcoplasmic reticulum-based ryanodine receptors to initiate the intracellular calcium transient. Efficient excitation-contraction (EC coupling and normal cardiac contractility depend upon Cav1.2 localization to T-tubules. We hypothesized that BIN1 not only exists at cardiac T-tubules, but it also localizes Cav1.2 to these membrane structures. We report that BIN1 localizes to cardiac T-tubules and clusters there with Cav1.2. Studies involve freshly acquired human and mouse adult cardiomyocytes using complementary immunocytochemistry, electron microscopy with dual immunogold labeling, and co-immunoprecipitation. Furthermore, we use surface biotinylation and live cell confocal and total internal fluorescence microscopy imaging in cardiomyocytes and cell lines to explore delivery of Cav1.2 to BIN1 structures. We find visually and quantitatively that dynamic microtubules are tethered to membrane scaffolded by BIN1, allowing targeted delivery of Cav1.2 from the microtubules to the associated membrane. Since Cav1.2 delivery to BIN1 occurs in reductionist non-myocyte cell lines, we find that other myocyte-specific structures are not essential and there is an intrinsic relationship between microtubule-based Cav1.2 delivery and its BIN1 scaffold. In differentiated mouse cardiomyocytes, knockdown of BIN1 reduces surface Cav1.2 and delays development of the calcium transient

  10. Endoplasmic reticulum stress and cardiovascular diseases

    Institute of Scientific and Technical Information of China (English)

    Xiaohui Duan; Yongfen Qi; Chaoshu Tang


    The endoplasmic reticulum (ER) serves several important functions, mainly post-translational modification, folding and assembly of newly synthesized secretary proteins, synthesizing lipids and cellular calcium storage. Various factors can disrupt ER homeostasis and disturb its functions, which leads to the accumulation of unfolded and misfolded proteins and to potential cellular dysfunction and pathological consequences, collectively termed ER stress. Recent progress suggests that ER stress plays a key role in the immune response, diabetes, tumor growth, and some neurodegenerative diseases. In particular, ER stress is involved in several processes of cardiovascular diseases, such as ischemia/reperfusion injury, cardiomyopathy, cardiac hypertrophy, heart failure, and atherosclerosis. Further research on the relation of ER stress to cardiovascular diseases will greatly enhance the understanding of these pathological processes and provide novel avenues to potential therapies.

  11. Adenosine A2A receptor agonist prevents cardiac remodeling and dysfunction in spontaneously hypertensive male rats after myocardial infarction (United States)

    da Silva, Jaqueline S; Gabriel-Costa, Daniele; Sudo, Roberto T; Wang, Hao; Groban, Leanne; Ferraz, Emanuele B; Nascimento, José Hamilton M; Fraga, Carlos Alberto M; Barreiro, Eliezer J; Zapata-Sudo, Gisele


    Background This work evaluated the hypothesis that 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294), an agonist of adenosine A2A receptor, could be beneficial for preventing cardiac dysfunction due to hypertension associated with myocardial infarction (MI). Methods Male spontaneously hypertensive rats (SHR) were randomly divided into four groups (six animals per group): sham-operation (SHR-Sham), and myocardial infarction rats (SHR-MI) were treated orally either with vehicle or LASSBio-294 (10 and 20−1.d−1) for 4 weeks. Echocardiography and in vivo hemodynamic parameters measured left ventricle (LV) structure and function. Exercise tolerance was evaluated using a treadmill test. Cardiac remodeling was accessed by LV collagen deposition and tumor necrosis factor α expression. Results Early mitral inflow velocity was significantly reduced in the SHR-MI group, and there was significant recovery in a dose-dependent manner after treatment with LASSBio-294. Exercise intolerance observed in the SHR-MI group was prevented by 10−1.d−1 of LASS-Bio-294, and exercise tolerance exceeded that of the SHR-Sham group at 20−1.d−1. LV end-diastolic pressure increased after MI, and this was prevented by 10 and 20−1.d−1 of LASSBio-294. Sarcoplasmic reticulum Ca2+ ATPase levels were restored in a dose-dependent manner after treatment with LASSBio-294. Fibrosis and inflammatory processes were also counteracted by LASSBio-294, with reductions in LV collagen deposition and tumor necrosis factor α expression. Conclusion In summary, oral administration of LASSBio-294 after MI in a dose-dependent manner prevented the development of cardiac dysfunction, demonstrating this compound’s potential as an alternative treatment for heart failure in the setting of ischemic heart disease with superimposed chronic hypertension.

  12. HCM-Linked Δ 160E Cardiac Troponin T Mutation Causes Unique Progressive Structural and Molecular Ventricular Remodeling in Transgenic Mice (United States)

    Moore, Rachel K.; Grinspan, Lauren Tal; Jimenez, Jesus; Guinto, Pia J.; Ertz-Berger, Briar; Tardiff, Jil C.


    Hypertrophic cardiomyopathy (HCM) is a primary disease of cardiac muscle, and one of the most common causes of sudden cardiac death (SCD) in young people. Many mutations in cardiac troponin T (cTnT) lead to a complex form of HCM with varying degrees of ventricular hypertrophy and ~65% of all cTnT mutations occur within or flanking the elongated N-terminal TNT1 domain. Biophysical studies have predicted that distal TNT1 mutations, including Δ160E, cause disease by a novel, yet unknown mechanism as compared to N-terminal mutations. To begin to address the specific effects of this commonly observed cTnT mutation we generated two independent transgenic mouse lines carrying variant doses of the mutant transgene. Hearts from the 30% and 70% cTnT Δ160E lines demonstrated a highly unique, dose-dependent disruption in cellular and sarcomeric architecture and a highly progressive pattern of ventricular remodeling. While adult ventricular myocytes isolated from Δ160E transgenic mice exhibited dosage-independent mechanical impairments, decreased sarcoplasmic reticulum calcium load and SERCA2a calcium uptake activity, the observed decreases in calcium transients were dosage-dependent. The latter findings were concordant with measures of calcium regulatory proteins abundance and phosphorylation state. Finally, studies of whole heart physiology in the isovolumic mode demonstrated dose-dependent differences in the degree of cardiac dysfuction. We conclude that the observed clinical severity of the cTnT Δ160E mutation is caused by a combination of direct sarcomeric disruption coupled to a profound disregulation of Ca2+ homeostasis at the cellular level that results in a unique and highly progressive pattern of ventricular remodeling. PMID:23434821

  13. Biophysical adaptation of the theory of photo-induced phase transition: model of cooperative gating of cardiac ryanodine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Moskvin, A S [Ural State University, Ekaterinburg, 620083 (Russian Federation); Philipiev, M P [Ural State University, Ekaterinburg, 620083 (Russian Federation); Solovyova, O E [Ural State University, Ekaterinburg, 620083 (Russian Federation); Markhasin, V S [Institute of Immunology and Physiology, Ekaterinburg, 620219 (Russian Federation)


    Theory of photo-induced phase transitions has been adapted to describe the cooperative dynamics of the lattice of ryanodine receptors/channels (RyR) in cardiac muscle which regulate the release of the intracellular activator calcium from calcium stores in the sarcoplasmic reticulum (SR) by a process of Ca{sup 2+}-induced Ca{sup 2+} release (CICR). We introduce two main degrees of freedom for RyR channel, fast electronic and slow conformational ones. The RyR lattice response to the L-type channel triggering evolves due to a nucleation process with a step-by-step domino-like opening of RyR channels. Typical mode of RyR lattice functioning in a CICR process implies the fractional release with a robust termination due to the depletion of SR with a respective change in effective conformational strain. The SR overload leads to an unconventional auto-oscillation regime with a spontaneous calcium release. The model is believed to consistently describe the main features of CICR, that is its gradedness, coupled gating, irreversibility, inactivation/adaptation, and spark termination.

  14. Exposure to a Low Lead Concentration Impairs Contractile Machinery in Rat Cardiac Muscle. (United States)

    Silva, Marito A S C; de Oliveira, Thiago F; Almenara, Camila C P; Broseghini-Filho, Gilson B; Vassallo, Dalton V; Padilha, Alessandra S; Silveira, Edna A


    Lead exposure has been considered to be a risk factor for hypertension and cardiovascular disease. Our purpose was to evaluate the effects of low plasma lead concentration on cardiac contractility in isolated papillary muscles. Wistar rats were divided in control group or group treated with 100 ppm of lead acetate in the drinking water for 15 days. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anesthetized and euthanized, and parameters related to isolated papillary muscle contractility were recorded. The lead concentrations in the blood reached 12.3 ± 2 μg/dL. The BP was increased in the group treated with 100 ppm of lead acetate. Lead treatment did not alter force and time derivatives of the force of left ventricular papillary muscles. In addition, the inotropic response induced by an increase in the extracellular Ca(2+) concentration was reduced in the Pb(2+) group. However, the uptake of Ca(2+) by the sarcoplasmic reticulum and the protein expression of SERCA and phospholamban remained unchanged. Postrest contraction was similar in the both groups, and tetanic peak and plateau tension were reduced in lead group. These results demonstrated that the reduction in the inotropic response to calcium does not appear to be caused by changes in the trans-sarcolemmal calcium flux but suggest that an impairment of the contractile machinery might be taking place. Our results demonstrate that even at a concentration below the limit considered to be safe, lead exerts deleterious effects on the cardiac contractile machinery.

  15. Calpains and proteasomes mediate degradation of ryanodine receptors in a model of cardiac ischemic reperfusion. (United States)

    Pedrozo, Zully; Sánchez, Gina; Torrealba, Natalia; Valenzuela, Rodrigo; Fernández, Carolina; Hidalgo, Cecilia; Lavandero, Sergio; Donoso, Paulina


    Type-2 ryanodine receptors (RyR2)--the calcium release channels of cardiac sarcoplasmic reticulum--have a central role in cardiac excitation-contraction coupling. In the heart, ischemia/reperfusion causes a rapid and significant decrease in RyR2 content but the mechanisms responsible for this effect are not fully understood. We have studied the involvement of three proteolytic systems--calpains, the proteasome and autophagy--on the degradation of RyR2 in rat neonatal cardiomyocyte cultures subjected to simulated ischemia/reperfusion (sI/R). We found that 8h of ischemia followed by 16h of reperfusion decreased RyR2 content by 50% without any changes in RyR2 mRNA. Specific inhibitors of calpains and the proteasome prevented the decrease of RyR2 caused by sI/R, implicating both pathways in its degradation. Proteasome inhibitors also prevented the degradation of calpastatin, the endogenous calpain inhibitor, hindering the activation of calpain induced by calpastatin degradation. Autophagy was activated during sI/R as evidenced by the increase in LC3-II and beclin-1, two proteins involved in autophagosome generation, and in the emergence of GFP-LC3 containing vacuoles in adenovirus GFP-LC3 transduced cardiomyocytes. Selective autophagy inhibition, however, induced even further RyR2 degradation, making unlikely the participation of autophagy in sI/R-induced RyR2 degradation. Our results suggest that calpain activation as a result of proteasome-induced degradation of calpastatin initiates RyR2 proteolysis, which is followed by proteasome-dependent degradation of the resulting RyR2 fragments. The decrease in RyR2 content during ischemia/reperfusion may be relevant to the decrease of heart contractility after ischemia.

  16. Serial block face scanning electron microscopy for the study of cardiac muscle ultrastructure at nanoscale resolutions. (United States)

    Pinali, Christian; Kitmitto, Ashraf


    Electron microscopy techniques have made a significant contribution towards understanding muscle physiology since the 1950s. Subsequent advances in hardware and software have led to major breakthroughs in terms of image resolution as well as the ability to generate three-dimensional (3D) data essential for linking structure to function and dysfunction. In this methodological review we consider the application of a relatively new technique, serial block face scanning electron microscopy (SBF-SEM), for the study of cardiac muscle morphology. Employing SBF-SEM we have generated 3D data for cardiac myocytes within the myocardium with a voxel size of ~15 nm in the X-Y plane and 50 nm in the Z-direction. We describe how SBF-SEM can be used in conjunction with selective staining techniques to reveal the 3D cellular organisation and the relationship between the t-tubule (t-t) and sarcoplasmic reticulum (SR) networks. These methods describe how SBF-SEM can be used to provide qualitative data to investigate the organisation of the dyad, a specialised calcium microdomain formed between the t-ts and the junctional portion of the SR (jSR). We further describe how image analysis methods may be applied to interrogate the 3D volumes to provide quantitative data such as the volume of the cell occupied by the t-t and SR membranes and the volumes and surface area of jSR patches. We consider the strengths and weaknesses of the SBF-SEM technique, pitfalls in sample preparation together with tips and methods for image analysis. By providing a 'big picture' view at high resolutions, in comparison to conventional confocal microscopy, SBF-SEM represents a paradigm shift for imaging cellular networks in their native environment.

  17. Voltage-dependent modulation of cardiac ryanodine receptors (RyR2 by protamine.

    Directory of Open Access Journals (Sweden)

    Paula L Diaz-Sylvester

    Full Text Available It has been reported that protamine (>10 microg/ml blocks single skeletal RyR1 channels and inhibits RyR1-mediated Ca2+ release from sarcoplasmic reticulum microsomes. We extended these studies to cardiac RyR2 reconstituted into planar lipid bilayers. We found that protamine (0.02-20 microg/ml added to the cytosolic surface of fully activated RyR2 affected channel activity in a voltage-dependent manner. At membrane voltage (V(m; SR lumen-cytosol = 0 mV, protamine induced conductance transitions to several intermediate states (substates as well as full block of RyR2. At V(m>10 mV, the substate with the highest level of conductance was predominant. Increasing V(m from 0 to +80 mV, decreased the number of transitions and residence of the channel in this substate. The drop in current amplitude (full opening to substate had the same magnitude at 0 and +80 mV despite the approximately 3-fold increase in amplitude of the full opening. This is more similar to rectification of channel conductance induced by other polycations than to the action of selective conductance modifiers (ryanoids, imperatoxin. A distinctive effect of protamine (which might be shared with polylysines and histones but not with non-peptidic polycations is the activation of RyR2 in the presence of nanomolar cytosolic Ca2+ and millimolar Mg2+ levels. Our results suggest that RyRs would be subject to dual modulation (activation and block by polycationic domains of neighboring proteins via electrostatic interactions. Understanding these interactions could be important as such anomalies may be associated with the increased RyR2-mediated Ca2+ leak observed in cardiac diseases.

  18. SUMO-1 gene transfer improves cardiac function in a large-animal model of heart failure. (United States)

    Tilemann, Lisa; Lee, Ahyoung; Ishikawa, Kiyotake; Aguero, Jaume; Rapti, Kleopatra; Santos-Gallego, Carlos; Kohlbrenner, Erik; Fish, Kenneth M; Kho, Changwon; Hajjar, Roger J


    Recently, the impact of small ubiquitin-related modifier 1 (SUMO-1) on the regulation and preservation of sarcoplasmic reticulum calcium adenosine triphosphatase (SERCA2a) function was discovered. The amount of myocardial SUMO-1 is decreased in failing hearts, and its knockdown results in severe heart failure (HF) in mice. In a previous study, we showed that SUMO-1 gene transfer substantially improved cardiac function in a murine model of pressure overload-induced HF. Toward clinical translation, we evaluated in this study the effects of SUMO-1 gene transfer in a swine model of ischemic HF. One month after balloon occlusion of the proximal left anterior descending artery followed by reperfusion, the animals were randomized to receive either SUMO-1 at two doses, SERCA2a, or both by adeno-associated vector type 1 (AAV1) gene transfer via antegrade coronary infusion. Control animals received saline infusions. After gene delivery, there was a significant increase in the maximum rate of pressure rise [dP/dt(max)] that was most pronounced in the group that received both SUMO-1 and SERCA2a. The left ventricular ejection fraction (LVEF) improved after high-dose SUMO-1 with or without SERCA2a gene delivery, whereas there was a decline in LVEF in the animals receiving saline. Furthermore, the dilatation of LV volumes was prevented in the treatment groups. SUMO-1 gene transfer therefore improved cardiac function and stabilized LV volumes in a large-animal model of HF. These results support the critical role of SUMO-1 in SERCA2a function and underline the therapeutic potential of SUMO-1 for HF patients.

  19. Temperature and Ca2+-dependence of the sarcoplasmic reticulum Ca2(+)-ATPase in haddock, salmon, rainbow trout and zebra cichlid

    DEFF Research Database (Denmark)

    Godiksen, Helene; Jessen, Flemming


    in the enzyme or its membrane lipid environment is still a matter of discussion. In this study we compared the temperature dependence and Ca2+-dependence of SR Ca2+-ATPase in haddock (Melanogrammus aeglefinus), salmon (Salmo, salar), rainbow trout (Oncorhynchus mykiss) and zebra cichlid (Cichlasoma...... nigrofasciatum). The Arrhenius plot of zebra cichlid showed a break point at 20 degreesC, and the haddock Arrhenius plot was non-linear with pronounced changes in slope in the. temperature area, 6-14 degreesC. In Arrhenius plot from both salmon and rainbow trout a plateau exists with an almost constant SR Ca2...

  20. Doublet discharge stimulation increases sarcoplasmic reticulum Ca2+ release and improves performance during fatiguing contractions in mouse muscle fibres. (United States)

    Cheng, Arthur J; Place, Nicolas; Bruton, Joseph D; Holmberg, Hans-Christer; Westerblad, Håkan


    Double discharges (doublets) of motor neurones at the onset of contractions increase both force and rate of force development during voluntary submaximal contractions. The purpose of this study was to examine the role of doublet discharges on force and myoplasmic free [Ca(2+)] ([Ca(2+)]i) during repeated fatiguing contractions, using a stimulation protocol mimicking the in vivo activation pattern during running. Individual intact fibres from the flexor digitorum brevis muscle of mice were stimulated at 33°C to undergo 150 constant-frequency (five pulses at 70 Hz) or doublet (an initial, extra pulse at 200 Hz) contractions at 300 ms intervals. In the unfatigued state, doublet stimulation resulted in a transient (∼10 ms) approximate doubling of [Ca(2+)]i, which was accompanied by a greater force-time integral (∼70%) and peak force (∼40%) compared to constant frequency contractions. Moreover, doublets markedly increased force-time integral and peak force during the first 25 contractions of the fatiguing stimulation. In later stages of fatigue, addition of doublets increased force production but the increase in force production corresponded to only a minor portion of the fatigue-induced reduction in force. In conclusion, double discharges at the onset of contractions effectively increase force production, especially in early stages of fatigue. This beneficial effect occurs without additional force loss in later stages of fatigue, indicating that the additional energy cost induced by doublet discharges to skeletal muscle is limited.

  1. Defective sarcoplasmic reticulum-mitochondria communication in aged heart and its effect on ischemia and reperfusion injury


    Fernández Sanz, Celia


    Las alteraciones mitocondriales están vinculadas a la mayor vulnerabilidad de padecer enfermedades durante el envejecimiento. La edad avanzada es un factor determinante de la incidencia y gravedad de la cardiopatía isquémica. Estudios preclínicos sugieren la existencia de un daño celular intrínseco, por mecanismos no del todo establecidos, que contribuye a un incremento de la susceptibilidad del miocardio senescente al daño isquémico. Esta tesis investiga el papel de la comunicación mitoco...

  2. Defective sarcoplasmic reticulum-mitochondria communication in aged heart and its effect on ischemia and reperfusion injury


    Fernández Sanz, Celia; Meseguer Navarro, Anna


    Las alteraciones mitocondriales están vinculadas a la mayor vulnerabilidad de padecer enfermedades durante el envejecimiento. La edad avanzada es un factor determinante de la incidencia y gravedad de la cardiopatía isquémica. Estudios preclínicos sugieren la existencia de un daño celular intrínseco, por mecanismos no del todo establecidos, que contribuye a un incremento de la susceptibilidad del miocardio senescente al daño isquémico. Esta tesis investiga el papel de la comunicación mitocondr...

  3. Effects of free oxygen radicals on Ca2+ release mechanisms in the sarcoplasmic reticulum of scallop (Pecten jacobaeus) adductor muscle. (United States)

    Burlando, B; Viarengo, A; Pertica, M; Ponzano, E; Orunesu, M


    In vitro oxyradical effects on SR Ca2+ regulation were studied by using a SR-containing cell-free preparation from scallop (Pecten jacobaeus) adductor muscle. Ca2+ variations were fluorimetrically detected after incubation with Fluo-3 in the presence of ATP. Exposure to Fe3+/ascorbate produced dose-dependent Ca2+ release from SR vesicles, eventually leading to massive Ca2+ loss. Exposure to hypoxanthine/xanthine oxidase also caused Ca2+ release but at a much slower rate. Pre-incubations with catalase or with the hydroxyl radical scavenger KMBA led to a significant decrease in the Fe3+/ascorbate-induced Ca2+ release rate and to a delay of massive Ca2+ loss. Pre-incubations with GSH or DTT strongly reduced the Ca2+ release caused by Fe3+/ascorbate and, moreover, they prevented massive Ca2+ loss from SR vesicles. Addition of GSH or DTT after Fe3+/ascorbate promptly reduced the Ca2+ release rate and delayed massive Ca2+ release. Pre-incubation with the SR Ca2+ channel blocker ruthenium red strongly reduced the Ca2+ release caused by Fe3+/ascorbate, and also prevented massive Ca2+ loss. In the presence of ruthenium red, Fe3+/ascorbate treatments followed by Ca2+ addition revealed that Ca2+ uptake inhibition was slower than Ca2+ release. Taken together, data showed that free radicals and, in particular, hydroxyl radicals, affected the scallop SR Ca2+ regulation. This mainly occurred through Ca2+ channel opening, most likely triggered by sulfhydryl oxidation, which eventually led to massive Ca2+ release from SR vesicles. The demonstration of a specific effect of oxyradicals on SR Ca2+ channels is in line with their possible involvement in cell signaling.

  4. Induction of Apoptosis by Hypertension Via Endoplasmic Reticulum Stress

    Directory of Open Access Journals (Sweden)

    Yingying Sun


    Full Text Available Background/Aims: Endoplasmic reticulum (ER stress is one of the intrinsic apoptosis pathways, and cardiac apoptosis can occur in cardiovascular diseases, such as hypertension. However, the mechanisms by which ER stress leads to apoptosis remain enigmatic, particularly in the progression from cardiac hypertrophy to diastolic heart failure due to hypertension. Methods: We used spontaneously hypertensive rats (SHRs to investigate possible signalling pathways for ER stress. Results: We found that cardiac protein and mRNA levels of glucose-regulated protein 78 were up-regulated. In addition, the CHOP- and caspase-12-dependent pathways, but not that of JNK, were activated in the SHR rats. Conclusions: These results suggest that ER stress can contribute to myocardial apoptosis during hypertensive disease.

  5. Kinetic characterization of Channa striatus muscle sarcoplasmic and myofibrillar protein hydrolysates


    Ghassem, Masomeh; Fern, See Siau; Said, Mamot; Ali, Zainon Mohd; Ibrahim, Saadiah; Babji, Abdul Salam


    This study was conducted to evaluate the kinetic characteristics of proteolytic activity of proteases on Channa striatus protein fractions. Degree of hydrolysis (DH), amino acid composition and kinetic parameters of sarcoplasmic and myofibrillar proteins were investigated when incubated with proteinase K and thermolysin, separately. After 30 min incubation with proteases, a decrease in DH of sarcoplasmic protein was observed whereas, hydrolysis of myofibrillar protein with proteases took 2 h ...

  6. Low-Level Vagus Nerve Stimulation Reverses Cardiac Dysfunction and Subcellular Calcium Handling in Rats With Post-Myocardial Infarction Heart Failure. (United States)

    Zhang, Yunhe; Chen, Ao; Song, Lei; Li, Min; Luo, Zhangyuan; Zhang, Wenzan; Chen, Yingmin; He, Ben


    Vagus nerve stimulation (VNS), targeting the imbalanced autonomic nervous system, is a promising therapeutic approach for chronic heart failure (HF). Moreover, calcium cycling is an important part of cardiac excitation-contraction coupling (ECC), which also participates in the antiarrhythmic effects of VNS. We hypothesized that low-level VNS (LL-VNS) could improve cardiac function by regulation of intracellular calcium handling properties. The experimental HF model was established by ligation of the left anterior descending coronary artery (LAD). Thirty-two male Sprague-Dawley rats were divided into 3 groups as follows; control group (sham operated without coronary ligation, n = 10), HF-VNS group (HF rats with VNS, n = 12), and HF-SS group (HF rats with sham nerve stimulation, n = 10). After 8 weeks of treatment, LL-VNS significantly improved left ventricular ejection fraction (LVEF) and attenuated myocardial interstitial fibrosis in the HF-VNS group compared with the HF-SS group. Elevated plasma norepinephrine and dopamine, but not epinephrine, were partially reduced by LL-VNS. Additionally, LL-VNS restored the protein and mRNA levels of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a), Na(+)-Ca(2+) exchanger 1 (NCX1), and phospholamban (PLB) whereas the expression of ryanodine receptor 2 (RyR2) as well as mRNA level was unaffected. Thus, our study results suggest that the improvement of cardiac performance by LL-VNS is accompanied by the reversal of dysfunctional calcium handling properties including SERCA2a, NCX1, and PLB which may be a potential molecular mechanism of VNS for HF.

  7. Effects of alpha-linolenic acid vs. docosahexaenoic acid supply on the distribution of fatty acids among the rat cardiac subcellular membranes after a short- or long-term dietary exposure

    Directory of Open Access Journals (Sweden)

    Rousseau-Ralliard Delphine


    Full Text Available Abstract Background Previous work showed that the functional cardiac effect of dietary alpha-linolenic acid (ALA in rats requires a long feeding period (6 months, although a docosahexaenoic (DHA acid-supply affects cardiac adrenergic response after 2 months. However, the total cardiac membrane n-3 polyunsaturated fatty acid (PUFA composition remained unchanged after 2 months. This delay could be due to a specific reorganization of the different subcellular membrane PUFA profiles. This study was designed to investigate the evolution between 2 and 6 months of diet duration of the fatty acid profile in sarcolemmal (SL, mitochondrial (MI, nuclear (NU and sarcoplasmic reticulum (SR membrane fractions. Methods Male Wistar rats were randomly assigned to 3 dietary groups (n = 10/diet/period, either n-3 PUFA-free diet (CTL, or ALA or DHA-rich diets. After 2 or 6 months, the subcellular cardiac membrane fractions were separated by differential centrifugations and sucrose gradients. Each membrane profile was analysed by gas chromatography (GC after lipid extraction. Results As expected the n-3 PUFA-rich diets incorporated n-3 PUFA instead of n-6 PUFA in all the subcellular fractions, which also exhibited individual specificities. The diet duration increased SFA and decreased PUFA in SL, whereas NU remained constant. The SR and MI enriched in n-3 PUFA exhibited a decreased DHA level with ageing in the DHA and CTL groups. Conversely, the n-3 PUFA level remained unchanged in the ALA group, due to a significant increase in docosapentaenoic acid (DPA. N-3 PUFA rich diets lead to a better PUFA profile in all the fractions and significantly prevent the profile modifications induced by ageing. Conclusion With the ALA diet the n-3 PUFA content, particularly in SR and SL kept increasing between 2 and 6 months, which may partly account for the delay to achieve the modification of adrenergic response.

  8. Contribution of spontaneous L-type Ca2+ channel activation to the genesis of Ca2+ sparks in resting cardiac myocytes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guangqin; FU Yu; YANG Dongmei; HAO Xuemei; BAI Shuhua; TANG Yiqun; Edward G LAKATTA; WU Caihong; CHENG Heping


    Ca2+ sparks are the elementary events of intracellular Ca2+ release from the sarcoplasmic reticulum in cardiac myocytes. In order to investigate whether spontaneous L-type Ca2+ channel activation contributes to the genesis of spontaneous Ca2+ sparks, we used confocal laser scanning microscopy and fluo-4 to visualize local Ca2+ sparks in intact rat ventricular myocytes. In the presence of 0.2 mmol/L CdCl2 which inhibits spontaneous L-type Ca2+ channel activation, the rate of occurrence of spontaneous Ca2+ sparks was halved from 4.20 to 2.04 events/(100 μm·s), with temporal and spatial properties of individual Ca2+ sparks unchanged. Analysis of the Cd2+-sensitive spark production revealed an open probability of ~10-5 for L-type channels at the rest membrane potentials (-80 mV). Thus, infrequent and stochastic openings of sarcolemmal L-type Ca2+ channels in resting heart cells contribute significantly to the production of spontaneous Ca2+ sparks.

  9. Membrane phospholipid fatty acid composition regulates cardiac SERCA activity in a hibernator, the Syrian hamster (Mesocricetus auratus.

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    Sylvain Giroud

    Full Text Available Polyunsaturated fatty acids (PUFA have strong effects on hibernation and daily torpor. Increased dietary uptake of PUFA of the n-6 class, particularly of Linoleic acid (LA, C18:2 n-6 lengthens torpor bout duration and enables animals to reach lower body temperatures (T(b and metabolic rates. As previously hypothesized, this well-known influence of PUFA may be mediated via effects of the membrane fatty acid composition on sarcoplasmic reticulum (SR Ca(2+-ATPase 2a (SERCA in the heart of hibernators. We tested the hypotheses that high proportions of n-6 PUFA in general, or specifically high proportions of LA (C18:2 n-6 in SR phospholipids (PL should be associated with increased cardiac SERCA activity, and should allow animals to reach lower minimum T(b in torpor. We measured activity of SERCA from hearts of hibernating and non-hibernating Syrian hamsters (Mesocricetus auratus in vitro at 35 °C. Further, we determined the PL fatty acid composition of the SR membrane of these hearts. We found that SERCA activity strongly increased as the proportion of LA in SR PL increased but was negatively affected by the content of Docosahexaenoic acid (DHA; C22:6 n-3. SR PL from hibernating hamsters were characterized by high proportions of LA and low proportions of DHA. As a result, SERCA activity was significantly higher during entrance into torpor and in torpor compared to inter-bout arousal. Also, animals with increased SERCA activity reached lower T(b during torpor. Interestingly, a subgroup of hamsters which never entered torpor but remained euthermic throughout winter displayed a phenotype similar to animals in summer. This was characterized by lower proportions of LA and increased proportions of DHA in SR membranes, which is apparently incompatible with torpor. We conclude that the PUFA composition of SR membranes affects cardiac function via modulating SERCA activity, and hence determines the minimum T(b tolerated by hibernators.

  10. Endoplasmic Reticulum Stress and Diabetic Cardiomyopathy

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    Jiancheng Xu


    Full Text Available The endoplasmic reticulum (ER is an organelle entrusted with lipid synthesis, calcium homeostasis, protein folding, and maturation. Perturbation of ER-associated functions results in an evolutionarily conserved cell stress response, the unfolded protein response (UPR that is also called ER stress. ER stress is aimed initially at compensating for damage but can eventually trigger cell death if ER stress is excessive or prolonged. Now the ER stress has been associated with numerous diseases. For instance, our recent studies have demonstrated the important role of ER stress in diabetes-induced cardiac cell death. It is known that apoptosis has been considered to play a critical role in diabetic cardiomyopathy. Therefore, this paper will summarize the information from the literature and our own studies to focus on the pathological role of ER stress in the development of diabetic cardiomyopathy. Improved understanding of the molecular mechanisms underlying UPR activation and ER-initiated apoptosis in diabetic cardiomyopathy will provide us with new targets for drug discovery and therapeutic intervention.

  11. CaMKII Regulation of Cardiac Ryanodine Receptors and Inositol Triphosphate Receptors

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    Emmanuel eCamors


    Full Text Available Ryanodine receptors (RyRs and inositol triphosphate receptors (InsP3Rs are structurally related intracellular calcium release channels that participate in multiple primary or secondary amplified Ca2+ signals, triggering muscle contraction and oscillatory Ca2+ waves, or activating transcription factors. In the heart, RyRs play an indisputable role in the process of excitation-contraction coupling as the main pathway for Ca2+ release from sarcoplasmic reticulum (SR, and a less prominent role in the process of excitation-transcription coupling. Conversely, InsP3Rs are believed to contribute in subtle ways, only, to contraction of the heart, and in more important ways to regulation of transcription factors. Because uncontrolled activity of either RyRs or InsP3Rs may elicit life-threatening arrhythmogenic and/or remodeling Ca2+ signals, regulation of their activity is of paramount importance for normal cardiac function. Due to their structural similarity, many regulatory factors, accessory proteins, and posttranslational processes are equivalent for RyRs and InsP3Rs. Here we discuss regulation of RyRs and InsP3Rs by CaMKII phosphorylation, but touch on other kinases whenever appropriate. CaMKII is emerging as a powerful modulator of RyR and InsP3R activity but interestingly, some of the complexities and controversies surrounding phosphorylation of RyRs also apply to InsP3Rs, and a clear-cut effect of CaMKII on either channel eludes investigators for now. Nevertheless, some effects of CaMKII on global cellular activity, such as SR Ca2+ leak or force-frequency potentiation, appear clear now, and this constrains the limits of the controversies and permits a more tractable approach to elucidate the effects of phosphorylation at the single channel level.

  12. Type 1 ryanodine receptor in cardiac mitochondria: transducer of excitation-metabolism coupling. (United States)

    Beutner, Gisela; Sharma, Virendra K; Lin, Lin; Ryu, Shin-Young; Dirksen, Robert T; Sheu, Shey-Shing


    Mitochondria in a variety of cell types respond to physiological Ca(2+) oscillations in the cytosol dynamically with Ca(2+) uptakes. In heart cells, mitochondrial Ca(2+) uptakes occur by a ruthenium red-sensitive Ca(2+) uniporter (CaUP), a rapid mode of Ca(2+) uptake (RaM) and a ryanodine receptor (RyR) localized in the inner mitochondrial membrane (IMM). Three subtypes of RyRs have been described and cloned, however, the subtype identity of the mitochondrial ryanodine receptor (mRyR) is unknown. Using subtype specific antibodies, we characterized the mRyR in the IMM from rat heart as RyR1. These results are substantiated by the absence of RyR protein in heart mitochondria from RyR1 knockout mice. The bell-shape Ca(2+)-dependent [(3)H]ryanodine binding curve and its modulation by caffeine and adenylylmethylenediphosphonate (AMPPCP) give further evidence that mRyR functions pharmacologically like RyR1. Ryanodine prevents mitochondrial Ca(2+) uptake induced by raising extramitochondrial Ca(2+) to 10 microM. Similarly, ryanodine inhibits oxidative phosphorylation stimulated by 10 microM extramitochondrial Ca(2+). In summary, our results show that the mRyR in cardiac muscle has similar biochemical and pharmacological properties to the RyR1 in the sarcoplasmic reticulum (SR) of skeletal muscle. These results could also suggest an efficient mechanism by which mitochondria sequesters Ca(2+) via mRyR during excitation-contraction coupling to stimulate oxidative phosphorylation for ATP production to meet metabolic demands. Thus, the mRyR functions as a transducer for excitation-metabolism coupling.

  13. Contractile systolic and diastolic dysfunction in renin-induced hypertensive cardiomyopathy

    NARCIS (Netherlands)

    Flesch, M; Schiffer, F; Zolk, O; Pinto, Y; Rosenkranz, S; HirthDietrich, C; Arnold, G; Paul, M; Bohm, M


    The present study investigated whether functional, molecular, and biochemical alterations occurring in chronic heart failure can already be detected in compensated hypertensive cardiac hypertrophy. Force of contraction (isolated papillary muscle strip preparations), sarcoplasmic reticulum (SR) prote

  14. Characterization of the functional and anatomical differences in the atrial and ventricular myocardium from three species of elasmobranch fishes

    DEFF Research Database (Denmark)

    Larsen, Julie; Bushnell, Peter; Steffensen, John Fleng


    We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine...

  15. Calcium response of KCl-excited populations of ventricular myocytes from the European sea bass (Dicentrarchus labrax): a promising approach to integrate cell-to-cell heterogeneity in studying the cellular basis of fish cardiac performance. (United States)

    Ollivier, Hélène; Marchant, James; Le Bayon, Nicolas; Servili, Arianna; Claireaux, Guy


    Climate change challenges the capacity of fishes to thrive in their habitat. However, through phenotypic diversity, they demonstrate remarkable resilience to deteriorating conditions. In fish populations, inter-individual variation in a number of fitness-determining physiological traits, including cardiac performance, is classically observed. Information about the cellular bases of inter-individual variability in cardiac performance is scarce including the possible contribution of excitation-contraction (EC) coupling. This study aimed at providing insight into EC coupling-related Ca(2+) response and thermal plasticity in the European sea bass (Dicentrarchus labrax). A cell population approach was used to lay the methodological basis for identifying the cellular determinants of cardiac performance. Fish were acclimated at 12 and 22 °C and changes in intracellular calcium concentration ([Ca(2+)]i) following KCl stimulation were measured using Fura-2, at 12 or 22 °C-test. The increase in [Ca(2+)]i resulted primarily from extracellular Ca(2+) entry but sarcoplasmic reticulum stores were also shown to be involved. As previously reported in sea bass, a modest effect of adrenaline was observed. Moreover, although the response appeared relatively insensitive to an acute temperature change, a difference in Ca(2+) response was observed between 12- and 22 °C-acclimated fish. In particular, a greater increase in [Ca(2+)]i at a high level of adrenaline was observed in 22 °C-acclimated fish that may be related to an improved efficiency of adrenaline under these conditions. In conclusion, this method allows a rapid screening of cellular characteristics. It represents a promising tool to identify the cellular determinants of inter-individual variability in fishes' capacity for environmental adaptation.

  16. Effect of intracellular Ca2+ and action potential duration on L-type Ca2+ channel inactivation and recovery from inactivation in rabbit cardiac myocytes. (United States)

    Altamirano, Julio; Bers, Donald M


    Ca(2+) current (I(Ca)) recovery from inactivation is necessary for normal cardiac excitation-contraction coupling. In normal hearts, increased stimulation frequency increases force, but in heart failure (HF) this force-frequency relationship (FFR) is often flattened or reversed. Although reduced sarcoplasmic reticulum Ca(2+)-ATPase function may be involved, decreased I(Ca) availability may also contribute. Longer action potential duration (APD), slower intracellular Ca(2+) concentration ([Ca(2+)](i)) decline, and higher diastolic [Ca(2+)](i) in HF could all slow I(Ca) recovery from inactivation, thereby decreasing I(Ca) availability. We measured the effect of different diastolic [Ca(2+)](i) on I(Ca) inactivation and recovery from inactivation in rabbit cardiac myocytes. Both I(Ca) and Ba(2+) current (I(Ba)) were measured. I(Ca) decay was accelerated only at high diastolic [Ca(2+)](i) (600 nM). I(Ba) inactivation was slower but insensitive to [Ca(2+)](i). Membrane potential dependence of I(Ca) or I(Ba) availability was not affected by [Ca(2+)](i) <600 nM. Recovery from inactivation was slowed by both depolarization and high [Ca(2+)](i). We also used perforated patch with action potential (AP)-clamp and normal Ca(2+) transients, using various APDs as conditioning pulses for different frequencies (and to simulate HF APD). Recovery of I(Ca) following longer APD was increasingly incomplete, decreasing I(Ca) availability. Trains of long APs caused a larger I(Ca) decrease than short APD at the same frequency. This effect on I(Ca) availability was exacerbated by slowing twitch [Ca(2+)](i) decline by approximately 50%. We conclude that long APD and slower [Ca(2+)](i) decline lead to cumulative inactivation limiting I(Ca) at high heart rates and might contribute to the negative FFR in HF, independent of altered Ca(2+) channel properties.

  17. Genetic Background Influences Adaptation To Cardiac Hypertrophy and Ca2+ Handling Gene Expression

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    Steve B Waters


    Full Text Available Genetic variability has a profound effect on the development of cardiac hypertrophy in response to stress. Consequently, using a variety of inbred mouse strains with known genetic profiles may be powerful models for studying the response to cardiovascular stress. To explore this approach we looked at male C57BL/6J and 129/SvJ mice. Hemodynamic analyses of left ventricular pressures indicated significant differences in 129/SvJ and C57BL/6J mice that implied altered Ca2+ handling. Specifically, 129/SvJ mice demonstrated reduced rates of relaxation and insensitivity to dobutamine(Db. We hypothesized that altered expression of genes controlling the influx and efflux of Ca2+ from the sarcoplasmic reticulum was responsible and investigated the expression of several genes involved in maintaining the intracellular and sarcoluminal Ca2+ concentration using quantitative real-time PCR analyses (qRT-PCR. We observed significant differences in baseline gene expression as well as different responses in expression to isoproterenol (ISO challenge. In untreated control animals, 129/SvJ mice expressed 1.68x more ryanodine recptor 2(Ryr2 mRNA than C57BL/6J mice but only 0.37x as much calsequestrin 2(Casq2. After treatment with ISO, sarco(endoplasmic reticulum Ca2+-ATPase(Serca2 expression was reduced nearly two-fold in 129/SvJ while expression in C57BL/6J was stable. Interestingly, β(1 adrenergic receptor(Adrb1 expression was lower in 129/SvJ compared to C57BL/6J at baseline and lower in both strains after treatment. Metabolically, the brain isoform of creatine kinase(Ckb was up-regulated in response to ISO in C57BL/6J but not in 129/SvJ. These data suggest that the two strains of mice regulate Ca2+ homeostasis via different mechanisms and may be useful in developing personalized therapies in human patients.

  18. Genetic background influences adaptation to cardiac hypertrophy and Ca(2+) handling gene expression. (United States)

    Waters, Steve B; Diak, Douglass M; Zuckermann, Matthew; Goldspink, Paul H; Leoni, Lara; Roman, Brian B


    Genetic variability has a profound effect on the development of cardiac hypertrophy in response to stress. Consequently, using a variety of inbred mouse strains with known genetic profiles may be powerful models for studying the response to cardiovascular stress. To explore this approach we looked at male C57BL/6J and 129/SvJ mice. Hemodynamic analyses of left ventricular pressures (LVPs) indicated significant differences in 129/SvJ and C57BL/6J mice that implied altered Ca(2+) handling. Specifically, 129/SvJ mice demonstrated reduced rates of relaxation and insensitivity to dobutamine (Db). We hypothesized that altered expression of genes controlling the influx and efflux of Ca(2+) from the sarcoplasmic reticulum (SR) was responsible and investigated the expression of several genes involved in maintaining the intracellular and sarcoluminal Ca(2+) concentration using quantitative real-time PCR analyses (qRT-PCR). We observed significant differences in baseline gene expression as well as different responses in expression to isoproterenol (ISO) challenge. In untreated control animals, 129/SvJ mice expressed 1.68× more ryanodine receptor 2(Ryr2) mRNA than C57BL/6J mice but only 0.37× as much calsequestrin 2 (Casq2). After treatment with ISO, sarco(endo)plasmic reticulum Ca(2+)-ATPase(Serca2) expression was reduced nearly two-fold in 129/SvJ while expression in C57BL/6J was stable. Interestingly, β (1) adrenergic receptor(Adrb1) expression was lower in 129/SvJ compared to C57BL/6J at baseline and lower in both strains after treatment. Metabolically, the brain isoform of creatine kinase (Ckb) was up-regulated in response to ISO in C57BL/6J but not in 129/SvJ. These data suggest that the two strains of mice regulate Ca(2+) homeostasis via different mechanisms and may be useful in developing personalized therapies in human patients.

  19. Four Dimensional (4-D BioChemInfoPhysics Models of Cardiac Cellular and Sub-Cellular Vibrations (Oscillations

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    Chang-Hua Zou


    Full Text Available Problem statement: Cardiovascular Diseases (CVD continued to be the leading cause of death. Failure or abnormal cardiac cellular or sub-cellular vibrations (oscillations could lead failure or abnormal heart beats that could cause CVD. Understanding the mechanisms of the vibrations (oscillations could help to prevent or to treat the diseases. Scientists have studied the mechanisms for more than 100 years. To our knowledge, the mechanisms are still unclear today. In this investigation, based on published data or results, conservation laws of the momentum as well as the energy, in views of biology, biochemistry, informatics and physics (BioChemInfoPhysics, we proposed our models of cardiac cellular and sub-cellular vibrations (oscillations of biological components, such as free ions in Biological Fluids (BF, Biological Membranes (BM, Ca++H+ (Ca++ and Na+K+ ATPases, Na+Ca++ exchangers (NCX, Ca++ carriers and myosin heads. Approach: Our models were described with 4-D (x, y, z, t or r, ?, z, t momentum transfer equations in mathematical physics. Results: The momentum transfer equations were solved with free and forced, damped, un-damped and over-damped, vibrations (oscillations. The biological components could be modeled as resonators or vibrators (oscillators, such as liquid plasmas, membranes, active springs, passive springs and active swings. Conclusion: We systematically provided new insights of automation (ignition and maintain, transportation, propagation and orientation of the cardiac cellular and sub-cellular vibrations (oscillations and resonances, with our BioChemInfoPhysics models of 4-D momentum transfer equations. Our modeling results implied: Auto-rhythmic cells (Sinoatrial Node Cells (SANC, Atrioventricular Node Cells (AVNC, Purkinje fibers, non-Auto-rhythmic ventricular myocytes and their Sarcoplasmic Reticulums (SR work as Biological Liquid Plasma Resonators (BLPR. The resonators were

  20. Cardiac arrest (United States)

    ... Article.jsp. Accessed June 16, 2014. Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening ... PA: Elsevier Saunders; 2011:chap 63. Myerburg RJ, Castellanos A. Cardiac arrest and audden aardiac death. In: ...

  1. A novel quantitative explanation for the autonomic modulation of cardiac pacemaker cell automaticity via a dynamic system of sarcolemmal and intracellular proteins. (United States)

    Maltsev, Victor A; Lakatta, Edward G


    Classical numerical models have attributed the regulation of normal cardiac automaticity in sinoatrial node cells (SANCs) largely to G protein-coupled receptor (GPCR) modulation of sarcolemmal ion currents. More recent experimental evidence, however, has indicated that GPCR modulation of SANCs automaticity involves spontaneous, rhythmic, local Ca(2+) releases (LCRs) from the sarcoplasmic reticulum (SR). We explored the GPCR rate modulation of SANCs using a unique and novel numerical model of SANCs in which Ca(2+)-release characteristics are graded by variations in the SR Ca(2+) pumping capability, mimicking the modulation by phospholamban regulated by cAMP-mediated, PKA-activated signaling. The model faithfully predicted the entire range of physiological chronotropic modulation of SANCs by the activation of beta-adrenergic receptors or cholinergic receptors only when experimentally documented changes of sarcolemmal ion channels are combined with a simultaneous increase/decrease in SR Ca(2+) pumping capability. The novel numerical mechanism of GPCR rate modulation is based on numerous complex synergistic interactions between sarcolemmal and intracellular processes via membrane voltage and Ca(2+). Major interactions include changes of diastolic Na(+)/Ca(2+) exchanger current that couple earlier/later diastolic Ca(2+) releases (predicting the experimentally defined LCR period shift) of increased/decreased amplitude (predicting changes in LCR signal mass, i.e., the product of LCR spatial size, amplitude, and number per cycle) to the diastolic depolarization and ultimately to the spontaneous action potential firing rate. Concomitantly, larger/smaller and more/less frequent activation of L-type Ca(2+) current shifts the cellular Ca(2+) balance to support the respective Ca(2+) cycling changes. In conclusion, our model simulations corroborate recent experimental results in rabbit SANCs pointing to a new paradigm for GPCR heart rate modulation by a complex system of

  2. Dialogue between endoplasmic reticulum and mitochondria as a key actor of vascular dysfunction associated to metabolic disorders. (United States)

    Safiedeen, Zainab; Andriantsitohaina, Ramaroson; Martinez, M Carmen


    Metabolic syndrome due to its association with increased risk of cardiovascular diseases and cardiac mortality, comprises a cluster of metabolic abnormalities such as central obesity, hyperglycemia, dyslipidemia, and hypertension. Recent studies have shown that metabolic syndrome patients exhibit impaired nitric oxide-mediated vasodilatation leading to endothelial dysfunction in addition to insulin resistance. Interestingly, development and maintenance of the unfolded protein response of the endoplasmic reticulum stress revealed a surprisingly direct link with metabolic syndrome and endothelial dysfunction. On the other hand, in metabolic disorders, interaction between endoplasmic reticulum and mitochondria is mandatory for the generation of mitochondrial oxidative stress and perturbation of mitochondrial function accounting, at least in part, for vascular dysfunction. Herein, we review the impact of the dialogue between endoplasmic reticulum and mitochondria in modulating the cellular signals governing vascular alterations associated to metabolic disorders.

  3. Targeting and retention of type 1 ryanodine receptors to the endoplasmic reticulum. (United States)

    Meur, Gargi; Parker, Andrew K T; Gergely, Fanni V; Taylor, Colin W


    Most ryanodine receptors and their relatives, inositol 1,4,5-trisphosphate receptors, are expressed in the sarcoplasmic or endoplasmic reticulum (ER), where they mediate Ca(2+) release. We expressed fragments of ryanodine receptor type 1 (RyR1) in COS cells alone or fused to intercellular adhesion molecule-1 (ICAM-1), each tagged with yellow fluorescent protein, and used confocal imaging and glycoprotein analysis to identify the determinants of ER targeting and retention. Single transmembrane domains (TMD) of RyR1 taken from the first (TMD1-TMD2) or last (TMD5-TMD6) pair were expressed in the ER membrane. TMD3-TMD4 was expressed in the outer mitochondrial membrane. The TMD outer pairs (TMD1-TMD2 and TMD5-TMD6) retained ICAM-1, a plasma membrane-targeted protein, within the ER membrane. TMD1 alone provided a strong ER retention signal and TMD6 a weaker signal, but the other single TMD were unable to retain ICAM-1 in the ER. We conclude that TMD1 provides the first and sufficient signal for ER targeting of RyR1. The TMD outer pairs include redundant ER retention signals, with TMD1 providing the strongest signal.

  4. Adenosine A2A  receptor agonist prevents cardiac remodeling and dysfunction in spontaneously hypertensive male rats after myocardial infarction

    Directory of Open Access Journals (Sweden)

    da Silva JS


    Full Text Available Jaqueline S da Silva,1 Daniele Gabriel-Costa,1 Roberto T Sudo,1 Hao Wang,2 Leanne Groban,2 Emanuele B Ferraz,3 José Hamilton M Nascimento,3 Carlos Alberto M Fraga,1 Eliezer J Barreiro,1 Gisele Zapata-Sudo1 1Research Program Development of Drugs, Institute of Biomedical Sciences, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; 2Department of Anesthesiology, Wake Forest School of Medicine, Winston-Salem, NC, USA; 3Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil Background: This work evaluated the hypothesis that 3,4-methylenedioxybenzoyl-2- thienylhydrazone (LASSBio-294, an agonist of adenosine A2A  receptor, could be beneficial for preventing cardiac dysfunction due to hypertension associated with myocardial infarction (MI. Methods: Male spontaneously hypertensive rats (SHR were randomly divided into four groups (six animals per group: sham-operation (SHR-Sham, and myocardial infarction rats (SHR-MI were treated orally either with vehicle or LASSBio-294 (10 and 20 for 4 weeks. Echocardiography and in vivo hemodynamic parameters measured left ventricle (LV structure and function. Exercise tolerance was evaluated using a treadmill test. Cardiac remodeling was accessed by LV collagen deposition and tumor necrosis factor α expression. Results: Early mitral inflow velocity was significantly reduced in the SHR-MI group, and there was significant recovery in a dose-dependent manner after treatment with LASSBio-294. Exercise intolerance observed in the SHR-MI group was prevented by 10 of LASSBio-294, and exercise tolerance exceeded that of the SHR-Sham group at 20 LV end-diastolic pressure increased after MI, and this was prevented by 10 and 20 of LASSBio-294. Sarcoplasmic reticulum Ca2+ ATPase levels were restored in a dose-dependent manner after treatment with LASSBio-294. Fibrosis and inflammatory processes were also

  5. Gαq protein carboxyl terminus imitation polypeptide GCIP-27 improves cardiac function in chronic heart failure rats.

    Directory of Open Access Journals (Sweden)

    Xiao Lan Lu

    Full Text Available Gαq protein carboxyl terminus imitation polypeptide (GCIP-27 has been shown to alleviate pathological cardiomyocyte hypertrophy induced by various factors. Pathological cardiac hypertrophy increases the morbidity and mortality of cardiovascular diseases while it compensates for poor heart function. This study was designed to investigate the effects of GCIP-27 on heart function in rats with heart failure induced by doxorubicin.Forty-eight rats were randomly divided into the following six groups receiving vehicle (control, doxorubicin (Dox, losartan (6 mg/kg, i.g. and three doses of GCIP-27 (10, 30, 90 μg/kg; i.p., bid, respectively. Heart failure was induced by Dox, which was administered at a 20 mg/kg cumulative dose. After 10 weeks of treatment, we observed that GCIP-27 (30, 90 μg/kg significantly increased ejection fraction, fraction shortening, stroke volume and sarcoplasmic reticulum Ca2+ ATPase activity of Dox-treated hearts. Additionally, GCIP-27 decreased myocardial injury, heart weight index and left ventricular weight index, fibrosis and serum cardiac troponin-I concentration in Dox-treated mice. Immunohistochemistry, western blotting and real-time PCR experiments indicated that GCIP-27 (10-90 μg/kg could markedly upregulate the protein expression of myocardial α-myosin heavy chain (MHC, Bcl-2, protein kinase C (PKC ε and phosphorylated extracellular signal-regulated kinase (p-ERK 1/2 as well as the mRNA expression of α-MHC, but downregulated the expression of β-MHC, Bax and PKC βII, and the mRNA expression levels of β-MHC in Dox-treated mice. It was also found that GCIP-27 (30, 90 μg/L decreased cell size and protein content of cardiomyocytes significantly in vitro by comparison of Dox group.GCIP-27 could effectively ameliorate heart failure development induced by Dox. PKC-ERK1/2 signaling might represent the underlying mechanism of the beneficial effects of GCIP-27.

  6. Cardiac Sarcoidosis. (United States)

    Birnie, David; Ha, Andrew C T; Gula, Lorne J; Chakrabarti, Santabhanu; Beanlands, Rob S B; Nery, Pablo


    Studies suggest clinically manifest cardiac involvement occurs in 5% of patients with pulmonary/systemic sarcoidosis. The principal manifestations of cardiac sarcoidosis (CS) are conduction abnormalities, ventricular arrhythmias, and heart failure. Data indicate that an 20% to 25% of patients with pulmonary/systemic sarcoidosis have asymptomatic (clinically silent) cardiac involvement. An international guideline for the diagnosis and management of CS recommends that patients be screened for cardiac involvement. Most studies suggest a benign prognosis for patients with clinically silent CS. Immunosuppression therapy is advocated for clinically manifest CS. Device therapy, with implantable cardioverter defibrillators, is recommended for some patients.

  7. Design and characterization of self-assembled fish sarcoplasmic protein-alginate nanocomplexes

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; Mattebjerg, Maria Ahlm; Wattjes, Jasper;


    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged...... fish sarcoplasmic proteins (FSP), prepared by bulk mixing. A concentration screening revealed that there was a range of alginate and FSP concentrations where stable NCXs with similar properties were formed, rather than two exact concentrations. The size of the NCXs was 293 +/- 3 nm, and the zeta...

  8. Decavanadate, decaniobate, tungstate and molybdate interactions with sarcoplasmic reticulum Ca2+-ATPase: quercetin prevents cysteine oxidation by vanadate but does not reverse ATPase inhibition


    Fraqueza, Gil; de Carvalho, Luís A. E. Batista; Marques, M. Paula M.; Maia, Luisa; Ohlin, C. André; Casey, William H.; Aureliano, M.


    Recently we demonstrated that the decavanadate (V10) ion is a stronger Ca2+-ATPase inhibitor than other oxometalates, such as the isoelectronic and isostructural decaniobate ion, and the tungstate and molybdate monomer ions, and that it binds to this protein with a 1 : 1 stoichiometry. The V10 interaction is not affected by any of the protein conformations that occur during the process of calcium translocation (i.e. E1, E1P, E2 and E2P) (Fraqueza et al., J. Inorg. Biochem., 2012). In the p...

  9. Uncoupling of sarcoplasmic reticulum Ca²⁺-ATPase by N-arachidonoyl dopamine. Members of the endocannabinoid family as thermogenic drugs

    DEFF Research Database (Denmark)

    Mahmmoud, Yasser Ahmed; Gaster, Michel


    agents. EXPERIMENTAL APPROACH: Using isolated SR vesicles from rabbits, we have screened for endogenous compounds that uncouple SERCA. We have also studied their ability to deplete cytoplasmic ATP from human skeletal muscle cells in culture. KEY RESULTS: Studies on SR vesicles showed that the endogenous...... post-mitochondrial strategy for reduction of cellular ATP levels. In addition, signalling networks leading to SERCA uncoupling can be explored to study the importance of this ion pump in pathophysiological conditions related to metabolism....

  10. Single-channel properties of the sarcoplasmic reticulum calcium-release channel in slow- and fast-twitch muscles of Rhesus monkeys. (United States)

    Bastide, B; Mounier, Y


    RyR1 is the main isoform of ryanodine receptor expressed in fast- and slow-twitch mammalian skeletal muscles although differences in Ca2+-release kinetics and properties have been reported. Single-channel measurements reveal that a large proportion (82%) of Ca2+-release channels measured in slow-twitch muscle preparations have properties similar to those of the Ca2+-release channels of fast-twitch preparations, i.e. the same conductance, an identical sensitivity to caffeine and a bell-shaped Ca2+ activation curve for pCa (-log10[Ca2+]) 7 to 3. A low proportion (18%) of Ca2+-release channels observed in preparations from slow-twitch muscles were characterized by a very high activity level. These channels were not inhibited at a millimolar concentration of Ca2+. Our data suggest that the different properties of Ca2+ release in slow- and fast-twitch muscles might not be related to intrinsic properties of the Ca2+-release channels of each type of muscle but rather to the co-expression of two isoforms of ryanodine receptor and the lower amount of Ca2+-release channels expressed in slow- than in fast-twitch muscles.

  11. Critical roles of hydrophobicity and orientation of side chains for inactivation of sarcoplasmic reticulum Ca2+-ATPase with thapsigargin and thapsigargin analogs

    DEFF Research Database (Denmark)

    Winther, Anne-Marie Lund; Liu, Huizhen; Sonntag, Yonathan;


    transmembrane segments to the putative N-terminal Ca(2+) entry pathway. The long chain analogs provide a rational basis for the localization of the linker, the presence of which is necessary for enabling prostate-specific antigen to cleave peptide-conjugated prodrugs targeting SERCA of cancer cells (Denmeade, S....... R., Jakobsen, C. M., Janssen, S., Khan, S. R., Garrett, E. S., Lilja, H., Christensen, S. B., and Isaacs, J. T. (2003) J. Natl. Cancer Inst. 95, 990-1000). Our study demonstrates the usefulness of a simple in vitro system to test and direct development toward the formulation of new Tg derivatives...

  12. Effects of type 1 diabetes, sprint training and sex on skeletal muscle sarcoplasmic reticulum Ca2+ uptake and Ca2+-ATPase activity. (United States)

    Harmer, A R; Ruell, P A; Hunter, S K; McKenna, M J; Thom, J M; Chisholm, D J; Flack, J R


    Calcium cycling is integral to muscle performance during the rapid muscle contraction and relaxation of high-intensity exercise. Ca(2+) handling is altered by diabetes mellitus, but has not previously been investigated in human skeletal muscle. We investigated effects of high-intensity exercise and sprint training on skeletal muscle Ca(2+) regulation among men and women with type 1 diabetes (T1D, n = 8, 3F, 5M) and matched non-diabetic controls (CON, n = 8, 3F, 5M). Secondarily, we examined sex differences in Ca(2+) regulation. Subjects undertook 7 weeks of three times-weekly cycle sprint training. Before and after training, performance was measured, and blood and muscle were sampled at rest and after high-intensity exercise. In T1D, higher Ca(2+)-ATPase activity (+28%) and Ca(2+) uptake (+21%) than in CON were evident across both times and days (P women across both times and days. Intense exercise did not alter Ca(2+)-ATPase activity in T1D or CON. However, sex differences were evident: Ca(2+)-ATPase was reduced with exercise among men but increased among women across both days (time × sex interaction, P Sprint training reduced Ca(2+)-ATPase (-8%, P Sprint training reduced Ca(2+)-ATPase in T1D and CON. Sex differences in Ca(2+)-ATPase activity were evident and may be linked with fibre type proportion differences.

  13. Mapping the interactions between ATP and the sarcoplasmic reticulum Ca 2 + -ATPase with ATP and ATP analogs studied by Fourier transform infrared spectroscopy


    Liu, Man


    Die Infrarotspektroskopie in Verbindung mit photoaktivierbaren Substraten wurde zur Untersuchung von Substrat-Protein-Wechselwirkungen eingesetzt. Dabei wurden Konformationsänderungen der Ca2+-ATPase des Sarkoplasmatischen Retikulums bei Bindung des Nukleotids, der Phosphorylierung der ATPase und der Hydrolyse des Phosphoenzyms beobachtet. Verwender wurden das native Substrat ATP und seine Analoga ADP, AMPPNP, 2'-deoxyATP, 3'-deoxyATP, ITP, AMP, Pyrophosphat, Ribosetriphosphat und TNP-AMP beo...

  14. Cardiac Malpositions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Shi Joon; Im, Chung Gie; Yeon, Kyung Mo; Hasn, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)


    Cardiac Malposition refers to any position of the heart other than a left-sided heart in a situs solitus individual. Associated cardiac malformations are so complex that even angiocardiographic and autopsy studies may not afford an accurate information. Although the terms and classifications used to describe the internal cardiac anatomy and their arterial connections in cardiac malpositions differ and tend to be confusing, common agreement exists on the need for a segmental approach to diagnosis. Authors present 18 cases of cardiac malpositions in which cardiac catheterization and angiocardiography were done at the Department of Radiology, Seoul National University Hospital between 1971 and 1979. Authors analyzed the clinical, radiographic, operative and autopsy findings with the emphasis on the angiocardiographic findings. The results are as follows: 1. Among 18 cases with cardiac malpositions, 6 cases had dextrocardia with situs inversus, 9 cases had dextrocardia with situs solitus and 3 cases had levocardia with situs inversus. 2. There was no genuine exception to visceroatrial concordance rule. 3. Associated cardiac malpositions were variable and complex with a tendency of high association of transposition and double outlet varieties with dextrocardia in situs solitus and levocardia in situs inversus. Only one in 6 cases of dextrocardia with situs inversus had pure transposition. 4. In two cases associated pulmonary atresia was found at surgery which was not predicted by angiocardiography. 5. Because many of the associated complex lesions can be corrected surgically provided the diagnosis is accurate, the selective biplane angiocardiography with or without cineradiography is essential.

  15. Glycoprotein folding in the endoplasmic reticulum

    NARCIS (Netherlands)

    Braakman, L.J.; Benham, A.M.


    Our understanding of eukaryotic protein folding in the endoplasmic reticulum has increased enormously over the last 5 years. In this review, we summarize some of the major research themes that have captivated researchers in this field during the last years of the 20th century. We follow the path of

  16. Protein transport into the human endoplasmic reticulum

    NARCIS (Netherlands)

    Dudek, Johanna; Pfeffer, Stefan; Lee, Po-Hsien; Jung, Martin; Cavalié, Adolfo; Helms, Volkhard; Förster, Friedrich; Zimmermann, Richard


    Protein transport into the endoplasmic reticulum (ER) is essential for all eukaryotic cells and evolutionary related to protein transport into and across the cytoplasmic membrane of eubacteria and archaea. It is based on amino-terminal signal peptides in the precursor polypeptides plus various trans

  17. Mutations in calmodulin cause ventricular tachycardia and sudden cardiac death

    DEFF Research Database (Denmark)

    Nyegaard, Mette; Overgaard, Michael Toft; Søndergaard, Mads


    a substantial part of sudden cardiac deaths in young individuals. Mutations in RYR2, encoding the cardiac sarcoplasmic calcium channel, have been identified as causative in approximately half of all dominantly inherited CPVT cases. Applying a genome-wide linkage analysis in a large Swedish family with a severe...... dominantly inherited form of CPVT-like arrhythmias, we mapped the disease locus to chromosome 14q31-32. Sequencing CALM1 encoding calmodulin revealed a heterozygous missense mutation (c.161A>T [p.Asn53Ile]) segregating with the disease. A second, de novo, missense mutation (c.293A>G [p.Asn97Ser......]) was subsequently identified in an individual of Iraqi origin; this individual was diagnosed with CPVT from a screening of 61 arrhythmia samples with no identified RYR2 mutations. Both CALM1 substitutions demonstrated compromised calcium binding, and p.Asn97Ser displayed an aberrant interaction with the RYR2...

  18. Cardiac cameras. (United States)

    Travin, Mark I


    Cardiac imaging with radiotracers plays an important role in patient evaluation, and the development of suitable imaging instruments has been crucial. While initially performed with the rectilinear scanner that slowly transmitted, in a row-by-row fashion, cardiac count distributions onto various printing media, the Anger scintillation camera allowed electronic determination of tracer energies and of the distribution of radioactive counts in 2D space. Increased sophistication of cardiac cameras and development of powerful computers to analyze, display, and quantify data has been essential to making radionuclide cardiac imaging a key component of the cardiac work-up. Newer processing algorithms and solid state cameras, fundamentally different from the Anger camera, show promise to provide higher counting efficiency and resolution, leading to better image quality, more patient comfort and potentially lower radiation exposure. While the focus has been on myocardial perfusion imaging with single-photon emission computed tomography, increased use of positron emission tomography is broadening the field to include molecular imaging of the myocardium and of the coronary vasculature. Further advances may require integrating cardiac nuclear cameras with other imaging devices, ie, hybrid imaging cameras. The goal is to image the heart and its physiological processes as accurately as possible, to prevent and cure disease processes.

  19. Endoplasmic Reticulum Stress and Associated ROS

    Directory of Open Access Journals (Sweden)

    Hafiz Maher Ali Zeeshan


    Full Text Available The endoplasmic reticulum (ER is a fascinating network of tubules through which secretory and transmembrane proteins enter unfolded and exit as either folded or misfolded proteins, after which they are directed either toward other organelles or to degradation, respectively. The ER redox environment dictates the fate of entering proteins, and the level of redox signaling mediators modulates the level of reactive oxygen species (ROS. Accumulating evidence suggests the interrelation of ER stress and ROS with redox signaling mediators such as protein disulfide isomerase (PDI-endoplasmic reticulum oxidoreductin (ERO-1, glutathione (GSH/glutathione disuphide (GSSG, NADPH oxidase 4 (Nox4, NADPH-P450 reductase (NPR, and calcium. Here, we reviewed persistent ER stress and protein misfolding-initiated ROS cascades and their significant roles in the pathogenesis of multiple human disorders, including neurodegenerative diseases, diabetes mellitus, atherosclerosis, inflammation, ischemia, and kidney and liver diseases.

  20. Chemical and Functional Characterization of Sarcoplasmic Proteins from Giant Squid (Dosidicus gigas Mantle

    Directory of Open Access Journals (Sweden)

    Rosa Linda Lopez-Enriquez


    Full Text Available Modification of pH and NaCl concentration changed the physicochemical properties of sarcoplasmic proteins (SP from jumbo squid mantle and consequently their functional properties. Better results of emulsifying activity index (EAI and foam capacity (FC were exhibited at pH 11 in NaCl absence due to higher solubility. But better emulsifying stability index (ESI was obtained at pH 11 in 0.5 M NaCl, while, foaming stability (FS was better at pH near to isoelectric point (pI. These results suggest that SP from jumbo squid may be a promising ingredient, whose functional properties can be manipulated by changing pH and NaCl concentration.

  1. Cardiac echinococcosis

    Directory of Open Access Journals (Sweden)

    Ivanović-Krstić Branislava A.


    Full Text Available Cardiac hydatid disease is rare. We report on an uncommon hydatid cyst localized in the right ventricular wall, right atrial wall tricuspid valve left atrium and pericard. A 33-year-old woman was treated for cough, fever and chest pain. Cardiac echocardiograpic examination revealed a round tumor (5.8 x 4 cm in the right ventricular free wall and two smaller cysts behind that tumor. There were cysts in right atrial wall and tricuspidal valve as well. Serologic tests for hydatidosis were positive. Computed tomography finding was consistent with diagnosis of hydatid cyst in lungs and right hylar part. Surgical treatment was rejected due to great risk of cardiac perforation. Medical treatment with albendazole was unsuccessful and the patient died due to systemic hydatid involvement of the lungs, liver and central nervous system.

  2. Voltage dependence of cardiac excitation-contraction coupling: unitary Ca2+ current amplitude and open channel probability. (United States)

    Altamirano, Julio; Bers, Donald M


    Excitation-contraction coupling in cardiac myocytes occurs by Ca2+-induced Ca2+ release, where L-type Ca2+ current evokes a larger sarcoplasmic reticulum (SR) Ca2+ release. The Ca2+-induced Ca2+ release amplification factor or gain (SR Ca2+ release/I(Ca)) is usually assessed by the V(m) dependence of current and Ca2+ transients. Gain rises at negative V(m), as does single channel I(Ca) (i(Ca)), which has led to the suggestion that the increases of i(Ca) amplitude enhances gain at more negative V(m). However, I(Ca) = NP(o) x i(Ca) (where NP(o) is the number of open channels), and NP(o) and i(Ca) both depend on V(m). To assess how i(Ca) and NP(o) separately influence Ca2+-induced Ca2+ release, we measured I(Ca) and junctional SR Ca2+ release in voltage-clamped rat ventricular myocytes using "Ca2+ spikes" (confocal microscopy). To vary i(Ca) alone, we changed [Ca2+](o) rapidly at constant test V(m) (0 mV) or abruptly repolarized from +120 mV to different V(m) (at constant [Ca2+](o)). To vary NP(o) alone, we altered Ca2+ channel availability by varying holding V(m) (at constant test V(m)). Reducing either i(Ca) or NP(o) alone increased excitation-contraction coupling gain. Thus, increasing i(Ca) does not increase gain at progressively negative test V(m). Such enhanced gain depends on lower NP(o) and reduced redundant Ca2+ channel openings (per junction) and a consequently smaller denominator in the gain equation. Furthermore, modest i(Ca) (at V(m) = 0 mV) may still effectively trigger SR Ca2+ release, whereas at positive V(m) (and smaller i(Ca)), high and well-synchronized channel openings are required for efficient excitation-contraction coupling. At very positive V(m), reduced i(Ca) must explain reduced SR Ca2+ release.

  3. Rhythmic beating of stem cell-derived cardiac cells requires dynamic coupling of electrophysiology and Ca cycling. (United States)

    Zahanich, Ihor; Sirenko, Syevda G; Maltseva, Larissa A; Tarasova, Yelena S; Spurgeon, Harold A; Boheler, Kenneth R; Stern, Michael D; Lakatta, Edward G; Maltsev, Victor A


    There is an intense interest in differentiating embryonic stem cells to engineer biological pacemakers as an alternative to electronic pacemakers for patients with cardiac pacemaker function deficiency. Embryonic stem cell-derived cardiocytes (ESCs), however, often exhibit dysrhythmic excitations. Using Ca(2+) imaging and patch-clamp techniques, we studied requirements for generation of spontaneous rhythmic action potentials (APs) in late-stage mouse ESCs. Sarcoplasmic reticulum (SR) of ESCs generates spontaneous, rhythmic, wavelet-like Local Ca(2+)Releases (LCRs) (inhibited by ryanodine, tetracaine, or thapsigargin). L-type Ca(2+)current (I(CaL)) induces a global Ca(2+) release (CICR), depleting the Ca(2+) content SR which resets the phases of LCR oscillators. Following a delay, SR then generates a highly synchronized spontaneous Ca(2+)release of multiple LCRs throughout the cell. The LCRs generate an inward Na(+)/Ca(2+)exchanger (NCX) current (absent in Na(+)-free solution) that ignites the next AP. Interfering with SR Ca(2+) cycling (ryanodine, caffeine, thapsigargin, cyclopiazonic acid, BAPTA-AM), NCX (Na(+)-free solution), or I(CaL) (nifedipine) results in dysrhythmic excitations or cessation of automaticity. Inhibition of cAMP/PKA signaling by a specific PKA inhibitor, PKI, decreases SR Ca(2+) loading, substantially reducing both spontaneous LCRs (number, size, and amplitude) and rhythmic AP firing. In contrast, enhancing PKA signaling by cAMP increases the LCRs (number, size, duration) and converts irregularly beating ESCs to rhythmic "pacemaker-like" cells. SR Ca(2+) loading and LCR activity could be also increased with a selective activation of SR Ca(2+) pumping by a phospholamban antibody. We conclude that SR Ca(2+) loading and spontaneous rhythmic LCRs are driven by inherent cAMP/PKA activity. I(CaL) synchronizes multiple LCR oscillators resulting in strong, partially synchronized diastolic Ca(2+) release and NCX current. Rhythmic ESC automaticity can be

  4. Cardiac protective role of a novel erythrocyte-derived depressing factor on rats and its Ca2+ mechanism

    Institute of Scientific and Technical Information of China (English)

    WANG Yutang; WEN Yunyi; MA Ning; SHI Lei


    The cardiac protective role of a novel erythrocyte-derived depressing factor (EDDF) on spontaneous hypertensive rats (SHR), calcium overload (CaO) rats and Wistar rats and its mechanism was evaluated. Mean artery pressure (MAP), heart rate (HR) and LVdp/dtmax were measured by physiological recorder. The effect of EDDF on the Ca2+-ATPase activity in myocardial sarcoplasmic reticulum (SR) of CaO rats was determined by inorganic phosphate assay. Calcium transport in myocytes was measured by 45Ca2+ radioactive isotope measurement. The phosphorylation levels of extracellular signal-regulated protein kinases (ERK1/2) in myocardial tissue of SHR and CaO rats were measured by Western blot method. And the ultrastructures of cardiac muscle cells were observed with the transmission electron microscope. The results indicated that EDDF could significantly decrease MAP, HR and LVdp/dtmax in a dose dependent manner (P < 0.05). It seems that the mechanism might relate with activating the Ca2+-APTase, enhancing the uptake and release of Ca2+ from SR (P < 0.05), decreasing the phosphorylation levels of ERK1/2 of myocytes (P < 0.01) and lightening the ultrastructural lesion of cardiac muscle cells. In CaO rats, the Ca2+-ATPase activity decreased clearly compared to control (64.99 ± 7.16 vs 94.48 ± 7.68 nmol·min-1·mg-1 protein, P < 0.01), while EDDF (100 μg/mL) could significantly increase the activity (87.93 ± 9.54 vs 64.99 ± 7.16, P < 0.05, n = 7). Both uptake and release rate of Ca2+ (μmol 45Ca2+/g protein/min) from myocardial SR of CaO rats remarkably decreased compared to control (32.40 ± 2.70 and 15.46 ± 1.49 vs 61.09 ± 10.89 and 25.47 ± 4.29, P < 0.05); EDDF (100 μg/mL) could significantly stimulate their activities (50.48 ± 6.76 and 21.76 ± 2.75 vs 32.40 ± 2.70 and 15.46 ± 1.49, P < 0.05). EDDF could evidently down-regulate the phosphorylation of ERK1/2 in myocardial tissue from SHR and CaO rats (P < 0.01), lighten the ultrastructural lesion of cardiac muscle

  5. Ca2+ and endoplasmic reticulum Ca2+-ATPase regulate the formation of silk fibers with favorable mechanical properties. (United States)

    Wang, Xin; Li, Yi; Xie, Kang; Yi, Qiying; Chen, Quanmei; Wang, Xiaohuan; Shen, Hong; Xia, Qingyou; Zhao, Ping


    Calcium ions (Ca(2+)) are crucial for the conformational transition of silk fibroin in vitro, and silk fibroin conformations correlate with the mechanical properties of silk fibers. To investigate the relationship between Ca(2+) and mechanical properties of silk fibers, CaCl2 was injected into silkworms (Bombyx mori). Fourier-transform infrared spectroscopy (FTIR) analysis and mechanical testing revealed that injection of CaCl2 solution (7.5mg/g body weight) significantly increased the levels of α-helix and random coil structures of silk proteins. In addition, extension of silk fibers increased after CaCl2 injection. In mammals, sarcoplasmic reticulum Ca(2+)-ATPase in muscle and endoplasmic reticulum Ca(2+)-ATPase in other tissues (together denoted by SERCA) are responsible for calcium balance. Therefore, we analyzed the expression pattern of silkworm SERCA (BmSERCA) in silk glands and found that BmSERCA was abundant in the anterior silk gland (ASG). After injection of thapsigargin (TG) to block SERCA activity, silkworms showed a silk-spinning deficiency and their cocoons had higher calcium content compared to that of controls. Moreover, FTIR analysis revealed that the levels of α-helix and β-sheet structures increased in silk fibers from TG-injected silkworms compared to controls. The results provide evidence that BmSERCA has a key function in calcium transportation in ASG that is related to maintaining a suitable ionic environment. This ionic environment with a proper Ca(2+) concentration is crucial for the formation of silk fibers with favorable mechanical performances.

  6. Cardiac Rehabilitation (United States)

    ... your risk of future heart problems, and to improve your health and quality of life. Cardiac rehabilitation programs increase ... exercise routine at home or at a local gym. You may also continue to ... health concerns. Education about nutrition, lifestyle and weight loss ...

  7. Association of immunoproteasomes with the endoplasmic reticulum

    DEFF Research Database (Denmark)

    Brooks, P.; Murray, R.Z.; Mason, G.G.F.;


    pathway. Two of the gamma-interferon inducible subunits, LMP2 and LMP7, are encoded within the MHC class II region adjacent to the two TAP (transporter associated with antigen presentation) genes. We have investigated the localization of immunoproteasomes using monoclonal antibodies to LMP2 and LMP7...... that immunoproteasomes are strongly enriched at the endoplasmic reticulum, where they may be located close to the TAP transporter to provide efficient transport of peptides into the lumen of the endoplasmic recticulum for association with MHC class I molecules....

  8. Endoplasmic reticulum stress and diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Toshiyuki Oshitari


    Full Text Available Toshiyuki Oshitari1,2, Natsuyo Hata1, Shuichi Yamamoto11Department of Ophthalmology and Visual Science, Chiba University Graduate School of Medicine, Chiba City, Chiba, Japan; 2Department of Ophthalmology, Kimitsu Central Hospital, Kisarazu City, Chiba, JapanAbstract: Endoplasmic reticulum (ER stress is involved in the pathogenesis of several diseases including Alzheimer disease and Parkinson disease. Many recent studies have shown that ER stress is related to the pathogenesis of diabetes mellitus, and with the death of pancreatic β-cells, insulin resistance, and the death of the vascular cells in the retina. Diabetic retinopathy is a major complication of diabetes and results in death of both neural and vascular cells. Because the death of the neurons directly affects visual function, the precise mechanism causing the death of neurons in early diabetic retinopathy must be determined. The ideal therapy for preventing the onset and the progression of diabetic retinopathy would be to treat the factors involved with both the vascular and neuronal abnormalities in diabetic retinopathy. In this review, we present evidence that ER stress is involved in the death of both retinal neurons and vascular cells in diabetic eyes, and thus reducing or blocking ER stress may be a potential therapy for preventing the onset and the progression of diabetic retinopathy.Keywords: endoplasmic reticulum stress, diabetic retinopathy, vascular cell death, neuronal cell death

  9. Identification and characterization of alpha-I-proteinase inhibitor from common carp sarcoplasmic proteins. (United States)

    Siriangkanakun, Siriphon; Li-Chan, Eunice C Y; Yongsawadigul, Jirawat


    Purification of proteinase inhibitor from common carp (Cyprinus carpio) sarcoplasmic proteins resulted in 2.8% yield with purification fold of 111. Two inhibitors, namely inhibitor I and II, exhibited molecular mass of 47 and 52 kDa, respectively, based on non-reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both inhibitors I and II were identified to be alpha-1-proteinase inhibitor (α1-PI) based on LC-MS/MS. They were glycoproteins and molecular mass after peptide-N-glycosidase F treatment was 38 and 45 kDa, respectively. The N-glycosylation sites of both inhibitors were determined to be at N214 and N226. The inhibitors specifically inhibited trypsin. The common carp α1-PI showed high thermal stability with denaturation temperatures of 65.43 and 73.31 °C, which were slightly less than those of ovomucoid. High stability toward NaCl was also evident up to 3M. The common carp α1-PI effectively reduced autolytic degradation of bigeye snapper surimi at the concentration as low as 0.025%.

  10. Cardiac Calcification

    Directory of Open Access Journals (Sweden)

    Morteza Joorabian


    Full Text Available There is a spectrum of different types of cardiac"ncalcifications with the importance and significance"nof each type of cardiac calcification, especially"ncoronary artery calcification. Radiologic detection of"ncalcifications within the heart is quite common. The"namount of coronary artery calcification correlates"nwith the severity of coronary artery disease (CAD."nCalcification of the aortic or mitral valve may indicate"nhemodynamically significant valvular stenosis."nMyocardial calcification is a sign of prior infarction,"nwhile pericardial calcification is strongly associated"nwith constrictive pericarditis. A spectrum of different"ntypes of cardiac calcifications (linear, annular,"ncurvilinear,... could be seen in chest radiography and"nother imaging modalities. So a carful inspection for"ndetection and reorganization of these calcifications"nshould be necessary. Numerous modalities exist for"nidentifying coronary calcification, including plain"nradiography, fluoroscopy, intravascular ultrasound,"nMRI, echocardiography, and conventional, helical and"nelectron-beam CT (EBCT. Coronary calcifications"ndetected on EBCT or helical CT can be quantifie,"nand a total calcification score (Cardiac Calcification"nScoring may be calculated. In an asymptomatic"npopulation and/or patients with concomitant risk"nfactors like diabetes mellitus, determination of the"npresence of coronary calcifications identifies the"npatients at risk for future myocardial infarction and"ncoronary artery disease. In patients without coronary"ncalcifications, future cardiovascular events could"nbe excluded. Therefore, detecting and recognizing"ncalcification related to the heart on chest radiography"nand other imaging modalities such as fluoroscopy, CT"nand echocardiography may have important clinical"nimplications.

  11. Spermine inhibits Endoplasmic Reticulum Stress - induced Apoptosis: a New Strategy to Prevent Cardiomyocyte Apoptosis

    Directory of Open Access Journals (Sweden)

    Can Wei


    Full Text Available Background/Aims: Endoplasmic reticulum stress (ERS plays an important role in the progression of acute myocardial infarction (AMI, in part by mediating apoptosis. Polyamines, including putrescine, spermidine, and spermine, are polycations with anti-oxidative, anti-aging, and cell growth-promoting activities. This study aimed to determine the mechanisms by which spermine protects against ERS-induced apoptosis in rats following AMI. Methods and Results: AMI was established by ligation of the left anterior descending coronary artery (LAD in rats, and exogenous spermine was administered by intraperitoneal injection (2.5 mg/ml daily for 7 days pre-AMI. Spermine treatment limited infarct size, attenuated cardiac troponin I and creatinine kinase-MB release, improved cardiac function, and decreased ERS and apoptosis related protein expression. Isolated cardiomyocytes subjected to hypoxia showed significant increase in reactive oxygen species (ROS and the expression of apoptosis and ERS related proteins; these effects occurred through PERK and eIF2α phosphorylation. The addition of spermine attenuated cardiomyocyte apoptosis, suppressed the production of ROS, and inhibited ERS related pathways. Conclusions: Spermine was an effective pre-treatment strategy to attenuate cardiac ERS injury in rats, and the cardioprotective mechanism occurring through inhibition of ROS production and down regulation of the PERK-eIF2α pathway. These findings provide a novel target for the prevention of apoptosis in the setting of AMI.

  12. Endoplasmic Reticulum (ER) Stress and Endocrine Disorders (United States)

    Ariyasu, Daisuke; Yoshida, Hiderou; Hasegawa, Yukihiro


    The endoplasmic reticulum (ER) is the organelle where secretory and membrane proteins are synthesized and folded. Unfolded proteins that are retained within the ER can cause ER stress. Eukaryotic cells have a defense system called the “unfolded protein response” (UPR), which protects cells from ER stress. Cells undergo apoptosis when ER stress exceeds the capacity of the UPR, which has been revealed to cause human diseases. Although neurodegenerative diseases are well-known ER stress-related diseases, it has been discovered that endocrine diseases are also related to ER stress. In this review, we focus on ER stress-related human endocrine disorders. In addition to diabetes mellitus, which is well characterized, several relatively rare genetic disorders such as familial neurohypophyseal diabetes insipidus (FNDI), Wolfram syndrome, and isolated growth hormone deficiency type II (IGHD2) are discussed in this article. PMID:28208663

  13. Endoplasmic Reticulum (ER Stress and Endocrine Disorders

    Directory of Open Access Journals (Sweden)

    Daisuke Ariyasu


    Full Text Available The endoplasmic reticulum (ER is the organelle where secretory and membrane proteins are synthesized and folded. Unfolded proteins that are retained within the ER can cause ER stress. Eukaryotic cells have a defense system called the “unfolded protein response” (UPR, which protects cells from ER stress. Cells undergo apoptosis when ER stress exceeds the capacity of the UPR, which has been revealed to cause human diseases. Although neurodegenerative diseases are well-known ER stress-related diseases, it has been discovered that endocrine diseases are also related to ER stress. In this review, we focus on ER stress-related human endocrine disorders. In addition to diabetes mellitus, which is well characterized, several relatively rare genetic disorders such as familial neurohypophyseal diabetes insipidus (FNDI, Wolfram syndrome, and isolated growth hormone deficiency type II (IGHD2 are discussed in this article.

  14. Targeting endoplasmic reticulum stress in insulin resistance. (United States)

    Salvadó, Laia; Palomer, Xavier; Barroso, Emma; Vázquez-Carrera, Manuel


    The endoplasmic reticulum (ER) is involved in the development of insulin resistance and progression to type 2 diabetes mellitus (T2DM). Disruption of ER homeostasis leads to ER stress, which activates the unfolded protein response (UPR). This response is linked to different processes involved in the development of insulin resistance (IR) and T2DM, including inflammation, lipid accumulation, insulin biosynthesis, and β-cell apoptosis. Understanding the mechanisms by which disruption of ER homeostasis leads to IR and its progression to T2DM may offer new pharmacological targets for the treatment and prevention of these diseases. Here, we examine ER stress, the UPR, and downstream pathways in insulin sensitive tissues, and in IR, and offer insights towards therapeutic strategies.

  15. Endoplasmic Reticulum Stress and Ethanol Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Fanmuyi Yang


    Full Text Available Ethanol abuse affects virtually all organ systems and the central nervous system (CNS is particularly vulnerable to excessive ethanol exposure. Ethanol exposure causes profound damages to both the adult and developing brain. Prenatal ethanol exposure induces fetal alcohol spectrum disorders (FASD which is associated with mental retardation and other behavioral deficits. A number of potential mechanisms have been proposed for ethanol-induced brain damage; these include the promotion of neuroinflammation, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, and thiamine deficiency. The endoplasmic reticulum (ER regulates posttranslational protein processing and transport. The accumulation of unfolded or misfolded proteins in the ER lumen triggers ER stress and induces unfolded protein response (UPR which are mediated by three transmembrane ER signaling proteins: pancreatic endoplasmic reticulum kinase (PERK, inositol-requiring enzyme 1 (IRE1, and activating transcription factor 6 (ATF6. UPR is initiated to protect cells from overwhelming ER protein loading. However, sustained ER stress may result in cell death. ER stress has been implied in various CNS injuries, including brain ischemia, traumatic brain injury, and aging-associated neurodegeneration, such as Alzheimer’s disease (AD, Huntington’s disease (HD, Amyotrophic lateral sclerosis (ALS, and Parkinson’s disease (PD. However, effects of ethanol on ER stress in the CNS receive less attention. In this review, we discuss recent progress in the study of ER stress in ethanol-induced neurotoxicity. We also examine the potential mechanisms underlying ethanol-mediated ER stress and the interaction among ER stress, oxidative stress and autophagy in the context of ethanol neurotoxicity.

  16. ANGPTL2 activity in cardiac pathologies accelerates heart failure by perturbing cardiac function and energy metabolism (United States)

    Tian, Zhe; Miyata, Keishi; Kadomatsu, Tsuyoshi; Horiguchi, Haruki; Fukushima, Hiroyuki; Tohyama, Shugo; Ujihara, Yoshihiro; Okumura, Takahiro; Yamaguchi, Satoshi; Zhao, Jiabin; Endo, Motoyoshi; Morinaga, Jun; Sato, Michio; Sugizaki, Taichi; Zhu, Shunshun; Terada, Kazutoyo; Sakaguchi, Hisashi; Komohara, Yoshihiro; Takeya, Motohiro; Takeda, Naoki; Araki, Kimi; Manabe, Ichiro; Fukuda, Keiichi; Otsu, Kinya; Wada, Jun; Murohara, Toyoaki; Mohri, Satoshi; Yamashita, Jun K.; Sano, Motoaki; Oike, Yuichi


    A cardioprotective response that alters ventricular contractility or promotes cardiomyocyte enlargement occurs with increased workload in conditions such as hypertension. When that response is excessive, pathological cardiac remodelling occurs, which can progress to heart failure, a leading cause of death worldwide. Mechanisms underlying this response are not fully understood. Here, we report that expression of angiopoietin-like protein 2 (ANGPTL2) increases in pathologically-remodeled hearts of mice and humans, while decreased cardiac ANGPTL2 expression occurs in physiological cardiac remodelling induced by endurance training in mice. Mice overexpressing ANGPTL2 in heart show cardiac dysfunction caused by both inactivation of AKT and sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a signalling and decreased myocardial energy metabolism. Conversely, Angptl2 knockout mice exhibit increased left ventricular contractility and upregulated AKT-SERCA2a signalling and energy metabolism. Finally, ANGPTL2-knockdown in mice subjected to pressure overload ameliorates cardiac dysfunction. Overall, these studies suggest that therapeutic ANGPTL2 suppression could antagonize development of heart failure. PMID:27677409

  17. Development of Endoplasmic Reticulum Stress during Experimental Oxalate Nephrolithiasis. (United States)

    Motin, Yu G; Lepilov, A V; Bgatova, N P; Zharikov, A Yu; Motina, N V; Lapii, G A; Lushnikova, E L; Nepomnyashchikh, L M


    Morphological and ultrastructural study of the kidney was performed in rats with oxalate nephrolithiasis. Specific features of endoplasmic reticulum stress were evaluated during nephrolithiasis and treatment with α-tocopherol. We observed the signs of endoplasmic reticulum stress with activation of proapoptotic pathways and injury to the cell lining in nephron tubules and collecting ducts. Ultrastructural changes were found in the organelles, nuclei, and cell membranes of epitheliocytes. A relationship was revealed between endoplasmic reticulum stress and oxidative damage, which developed at the early state of lithogenesis.

  18. Numerical models based on a minimal set of sarcolemmal electrogenic proteins and an intracellular Ca(2+) clock generate robust, flexible, and energy-efficient cardiac pacemaking. (United States)

    Maltsev, Victor A; Lakatta, Edward G


    Recent evidence supports the idea that robust and, importantly, FLEXIBLE automaticity of cardiac pacemaker cells is conferred by a coupled system of membrane ion currents (an "M-clock") and a sarcoplasmic reticulum (SR)-based Ca(2+) oscillator ("Ca(2+)clock") that generates spontaneous diastolic Ca(2+) releases. This study identified numerical models of a human biological pacemaker that features robust and flexible automaticity generated by a minimal set of electrogenic proteins and a Ca(2+)clock. Following the Occam's razor principle (principle of parsimony), M-clock components of unknown molecular origin were excluded from Maltsev-Lakatta pacemaker cell model and thirteen different model types of only 4 or 5 components were derived and explored by a parametric sensitivity analysis. The extended ranges of SR Ca(2+) pumping (i.e. Ca(2+)clock performance) and conductance of ion currents were sampled, yielding a large variety of parameter combination, i.e. specific model sets. We tested each set's ability to simulate autonomic modulation of human heart rate (minimum rate of 50 to 70bpm; maximum rate of 140 to 210bpm) in response to stimulation of cholinergic and β-adrenergic receptors. We found that only those models that include a Ca(2+)clock (including the minimal 4-parameter model "ICaL+IKr+INCX+Ca(2+)clock") were able to reproduce the full range of autonomic modulation. Inclusion of If or ICaT decreased the flexibility, but increased the robustness of the models (a relatively larger number of sets did not fail during testing). The new models comprised of components with clear molecular identity (i.e. lacking IbNa & Ist) portray a more realistic pacemaking: A smaller Na(+) influx is expected to demand less energy for Na(+) extrusion. The new large database of the reduced coupled-clock numerical models may serve as a useful tool for the design of biological pacemakers. It will also provide a conceptual basis for a general theory of robust, flexible, and energy

  19. Numerical models based on a minimal set of sarcolemmal electrogenic proteins and an intracellular Ca2+ clock generate robust, flexible, and energy-efficient cardiac pacemaking (United States)

    Maltsev, Victor A.; Lakatta, Edward G.


    Recent evidence supports the idea that robust and, importantly, FLEXIBLE automaticity of cardiac pacemaker cells is conferred by a coupled system of membrane ion currents (an “M-clock”) and a sarcoplasmic reticulum (SR)-based Ca2+ oscillator (“Ca2+clock”) that generates spontaneous diastolic Ca2+ releases. This study identified numerical models of a human biological pacemaker that features robust and flexible automaticity generated by a minimal set of electrogenic proteins and a Ca2+clock. Following the Occam’s razor principle (principle of parsimony), M-clock components of unknown molecular origin were excluded from Maltsev-Lakatta pacemaker cell model and thirteen different model types of only 4 or 5 components were derived and explored by a parametric sensitivity analysis. The extended ranges of SR Ca2+ pumping (i.e. Ca2+clock performance) and conductance of ion currents were sampled, yielding a large variety of parameter combination, i.e. specific model sets. We tested each set’s ability to simulate autonomic modulation of human heart rate (minimum rate of 50 to 70 bpm; maximum rate of 140 to 210 bpm) in response to stimulation of cholinergic and β-adrenergic receptors. We found that only those models that include a Ca2+clock (including the minimal 4-parameter model “ICaL+IKr+INCX+Ca2+clock”) were able to reproduce the full range of autonomic modulation. Inclusion of If or ICaT decreased the flexibility, but increased the robustness of the models (a relatively larger number of sets did not fail during testing). The new models comprised of components with clear molecular identity (i.e. lacking IbNa & Ist) portray a more realistic pacemaking: A smaller Na+ influx is expected to demand less energy for Na+ extrusion. The new large database of the reduced coupled-clock numerical models may serve as a useful tool for the design of biological pacemakers. It will also provide a conceptual basis for a general theory of robust, flexible, and energy

  20. Regulation of endoplasmic reticulum turnover by selective autophagy

    NARCIS (Netherlands)

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K.; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Huebner, Christian A.; Dikic, Ivan


    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication(1). Constant ER turnover and modulation is needed to meet different cellular requirements

  1. Cardiac MRI in Athletes

    NARCIS (Netherlands)

    Luijkx, T.


    Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with C

  2. Teaching Calcium-Induced Calcium Release in Cardiomyocytes Using a Classic Paper by Fabiato (United States)

    Liang, Willmann


    This teaching paper utilizes the materials presented by Dr. Fabiato in his review article entitled "Calcium-induced release of calcium from the cardiac sarcoplasmic reticulum." In the review, supporting evidence of calcium-induced calcium release (CICR) is presented. Data concerning potential objections to the CICR theory are discussed as well. In…

  3. The use of label-free mass spectrometry for relative quantification of sarcoplasmic proteins during the processing of dry-cured ham. (United States)

    Gallego, Marta; Mora, Leticia; Concepción Aristoy, M; Toldrá, Fidel


    The aim of this work was to quantify changes in the abundance of the major sarcoplasmic proteins throughout the ham dry-curing process by using a label-free mass spectrometry methodology based on the measurement of mass spectral peak intensities obtained from the extracted ion chromatogram. For this purpose, extraction of sarcoplasmic proteins was followed by trypsin digestion and analysis by nanoliquid chromatography coupled to tandem mass spectrometry (Q/TOF) for the identification and relative quantification of sarcoplasmic proteins through individual quantification of trypsinised peptides. In total, 20 proteins, including 12 glycolytic enzymes, were identified and quantified. The accuracy of the protocol was based on MS/MS replicates, and beta-lactoglobulin protein was used to normalise data and correct possible variations during sample preparation or LC-MS/MS analysis. Mass spectrometry-based proteomics provides precise identification and quantification of proteins in comparison with traditional methodologies based on gel electrophoresis, especially in the case of overlapping proteins. Moreover, the label-free approach used in this study proved to be a simple, fast, reliable method for evaluating proteolytic degradation of sarcoplasmic proteins during the processing of dry-cured ham.

  4. Cardiac tamponade (image) (United States)

    Cardiac tamponade is a condition involving compression of the heart caused by blood or fluid accumulation in the space ... they cannot adequately fill or pump blood. Cardiac tamponade is an emergency condition that requires hospitalization.

  5. What Is Cardiac Rehabilitation? (United States)

    ANSWERS by heart Treatments + Tests What Is Cardiac Rehabilitation? A cardiac rehabilitation (rehab) program takes place in a hospital or ... special help in making lifestyle changes. During your rehabilitation program you’ll… • Have a medical evaluation to ...

  6. Structural plasticity of the nuclear envelope and the endoplasmic reticulum

    Directory of Open Access Journals (Sweden)

    Sheval E. V.


    Full Text Available The nuclear envelope is a double membrane structure, continuous with endoplasmic reticulum, and the morphological organization of both these structures is quite conservative. However, nuclear envelope and endoplasmic reticulum demonstrate distinct structural plasticity, i. e., based on common organization, cells may form various non-canonical membrane structures that are observed only in specialized types of cells or appear in different pathologies. In this review, we will discuss the mechanisms of the biogenesis of such non-canonical structures, and the possible role of this plasticity in the development of pathological processes.

  7. Cardiac sodium channelopathies

    NARCIS (Netherlands)

    Amin, A.S.; Asghari-Roodsari, A.; Tan, H.L.


    Cardiac sodium channel are protein complexes that are expressed in the sarcolemma of cardiomyocytes to carry a large inward depolarizing current (I-Na) during phase 0 of the cardiac action potential. The importance of I-Na for normal cardiac electrical activity is reflected by the high incidence of

  8. Cardiac sympathetic nerve terminal function in congestive heart failure

    Institute of Scientific and Technical Information of China (English)

    Chang-seng LIANG


    Increased cardiac release of norepinephrine (NE) and depleted cardiac stores of NE are two salient features of the human failing heart. Researches from my labo-ratory have shown that these changes are accompanied by a functional defect of NE uptake in the cardiac sympathetic nerve terminals. Our studies have shown that the decrease of NE uptake is caused by reduction of NE transporter density in the sympathetic nerve endings, and this change is responsible, at least in part, for the increased myocardial interstitial NE, decreased myocardial adrenoceptor density, and increased myocyte apoptosis in experimental cardiomyopathies. We have also provided evidence in both intact animals and cultured PC12 cells that the decrease of NE transporter is induced by the actions of oxidative metabolites of exogenous NE, involving endoplasmic reticulum stress and impaired N-glycosylation of the NE transporter. This change in the cardiac sympathetic NE uptake function, as demonstrated by [123I] metaiodobenzylguanidine in human studies, may not only serve as an important prognostic variable in patients with congestive heart failure, but also be used as a surrogate for the efficacies of various therapeutic interventions for heart failure. Finally, increasing evidence suggests and further studies are needed to show that the cardiac sympathetic nerve terminal function may be a direct target for pharmacologic treatment of congestive heart failure.

  9. Mechanisms of cardiac pain. (United States)

    Foreman, Robert D; Garrett, Kennon M; Blair, Robert W


    Angina pectoris is cardiac pain that typically is manifested as referred pain to the chest and upper left arm. Atypical pain to describe localization of the perception, generally experienced more by women, is referred to the back, neck, and/or jaw. This article summarizes the neurophysiological and pharmacological mechanisms for referred cardiac pain. Spinal cardiac afferent fibers mediate typical anginal pain via pathways from the spinal cord to the thalamus and ultimately cerebral cortex. Spinal neurotransmission involves substance P, glutamate, and transient receptor potential vanilloid-1 (TRPV1) receptors; release of neurokinins such as nuclear factor kappa b (NF-kb) in the spinal cord can modulate neurotransmission. Vagal cardiac afferent fibers likely mediate atypical anginal pain and contribute to cardiac ischemia without accompanying pain via relays through the nucleus of the solitary tract and the C1-C2 spinal segments. The psychological state of an individual can modulate cardiac nociception via pathways involving the amygdala. Descending pathways originating from nucleus raphe magnus and the pons also can modulate cardiac nociception. Sensory input from other visceral organs can mimic cardiac pain due to convergence of this input with cardiac input onto spinothalamic tract neurons. Reduction of converging nociceptive input from the gallbladder and gastrointestinal tract can diminish cardiac pain. Much work remains to be performed to discern the interactions among complex neural pathways that ultimately produce or do not produce the sensations associated with cardiac pain.

  10. A luminal flavoprotein in endoplasmic reticulum-associated degradation

    DEFF Research Database (Denmark)

    Riemer, Jan; Appenzeller-Herzog, Christian; Johansson, Linda


    The quality control system of the endoplasmic reticulum (ER) discriminates between native and nonnative proteins. The latter are degraded by the ER-associated degradation (ERAD) pathway. Whereas many cytosolic and membrane components of this system are known, only few luminal players have been id...

  11. Folding of viral envelope glycoproteins in the endoplasmic reticulum

    NARCIS (Netherlands)

    Braakman, L.J.; Anken, E. van


    Viral glycoproteins fold and oligomerize in the endoplasmic reticulum of the host cell. They employ the cellular machinery and receive assistance from cellular folding factors. During the folding process, they are retained in the compartment and their structural quality is checked by the quality con

  12. Sel1L is indispensable for mammalian endoplasmic reticulum-associated degradation, endoplasmic reticulum homeostasis, and survival

    NARCIS (Netherlands)

    Sun, S.; Shi, Guojun; Han, X.; Francisco, A.; Ji, Y.; Kersten, A.H.


    Suppressor/Enhancer of Lin-12-like (Sel1L) is an adaptor protein for the E3 ligase hydroxymethylglutaryl reductase degradation protein 1 (Hrd1) involved in endoplasmic reticulum-associated degradation (ERAD). Sel1L’s physiological importance in mammalian ERAD, however, remains to be established. Her

  13. Deficiency of cardiac Acyl-CoA synthetase-1 induces diastolic dysfunction, but pathologic hypertrophy is reversed by rapamycin

    DEFF Research Database (Denmark)

    Paul, David S; Grevengoed, Trisha J; Pascual, Florencia


    In mice with temporally-induced cardiac-specific deficiency of acyl-CoA synthetase-1 (Acsl1(H-/-)), the heart is unable to oxidize long-chain fatty acids and relies primarily on glucose for energy. These metabolic changes result in the development of both a spontaneous cardiac hypertrophy...... of sarco/endoplasmic reticulum calcium ATPase and phospholamban showed no difference between genotypes. To determine the role of mTOR in the development of cardiac hypertrophy, we treated Acsl1(H-/-) mice with rapamycin. Six to eight week old Acsl1(H-/-) mice and their littermate controls were given i.......p. tamoxifen to eliminate cardiac Acsl1, then concomitantly treated for 10weeks with i.p. rapamycin or vehicle alone. Rapamycin completely blocked the enhanced ventricular S6K phosphorylation and cardiac hypertrophy and attenuated the expression of hypertrophy-associated fetal genes, including α-skeletal actin...

  14. Stimulating endogenous cardiac regeneration

    Directory of Open Access Journals (Sweden)

    Amanda eFinan


    Full Text Available The healthy adult heart has a low turnover of cardiac myocytes. The renewal capacity, however, is augmented after cardiac injury. Participants in cardiac regeneration include cardiac myocytes themselves, cardiac progenitor cells, and peripheral stem cells, particularly from the bone marrow compartment. Cardiac progenitor cells and bone marrow stem cells are augmented after cardiac injury, migrate to the myocardium, and support regeneration. Depletion studies of these populations have demonstrated their necessary role in cardiac repair. However, the potential of these cells to completely regenerate the heart is limited. Efforts are now being focused on ways to augment these natural pathways to improve cardiac healing, primarily after ischemic injury but in other cardiac pathologies as well. Cell and gene therapy or pharmacological interventions are proposed mechanisms. Cell therapy has demonstrated modest results and has passed into clinical trials. However, the beneficial effects of cell therapy have primarily been their ability to produce paracrine effects on the cardiac tissue and recruit endogenous stem cell populations as opposed to direct cardiac regeneration. Gene therapy efforts have focused on prolonging or reactivating natural signaling pathways. Positive results have been demonstrated to activate the endogenous stem cell populations and are currently being tested in clinical trials. A potential new avenue may be to refine pharmacological treatments that are currently in place in the clinic. Evidence is mounting that drugs such as statins or beta blockers may alter endogenous stem cell activity. Understanding the effects of these drugs on stem cell repair while keeping in mind their primary function may strike a balance in myocardial healing. To maximize endogenous cardiac regeneration,a combination of these approaches couldameliorate the overall repair process to incorporate the participation ofmultiple cell players.

  15. Polyamine Depletion Attenuates Isoproterenol-Induced Hypertrophy and Endoplasmic Reticulum Stress in Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Yan Lin


    Full Text Available Background/Aim: Polyamines (putrescine, spermidine and spermine play an essential role in cell growth, differentiation and apoptosis. Hypertrophy is accompanied by an increase in polyamine synthesis and endoplasmic reticulum stress (ERS in cardiomyocytes. The present study was undertaken to elucidate the molecular interactions between polyamines, ERS and cardiac hypertrophy. Methods: Myocardial hypertrophy was simulated by incubating cultured neonatal rat cardiomyocytes in 100 nM isoproterenol (ISO. Polyamine deletion was achieved using 0.5 mM difluoromethylornithine (DFMO. Hypertrophy was estimated using cell surface area measurements, total protein concentrations and atrial natriuretic peptide (ANP gene expression. Apoptosis was measured using flow cytometry and transmission electron microscopy. Expression of ornithine decarboxylase (ODC and spermidine/spermine N1-acetyltransferase (SSAT were analyzed via real-time PCR and Western blotting. Protein expression of ERS and apoptosis factors were analyzed using Western blotting. Results: DFMO (0.5 mM and 2 mM treatments significantly attenuated hypertrophy and apoptosis induced by ISO in cardiomyocytes. DFMO also decreased lactate dehydrogenase (LDH and malondialdehyde (MDA level in the culture medium. In addition, DFMO (0.5 mM down regulated the expression of ODC, glucose-regulated protein 78 (GRP78, C/EBP homologous protein (CHOP, cleaved caspase-12, and Bax and up regulated the expression of SSAT and Bcl-2. Finally, these changes were partly reversed by the addition of exogenous putrescine (0.5 mM. Conclusion: The data presented here suggest that polyamine depletion could inhibit cardiac hypertrophy and apoptosis, which is closely related to the ERS pathway.

  16. Proteomic study of muscle sarcoplasmic proteins using AUT-PAGE/SDS-PAGE as two-dimensional gel electrophoresis. (United States)

    Picariello, Gianluca; De Martino, Alessandra; Mamone, Gianfranco; Ferranti, Pasquale; Addeo, Francesco; Faccia, Michele; Spagnamusso, Salvatore; Di Luccia, Aldo


    In the present study, an alternative procedure for two-dimensional (2D) electrophoretic analysis in proteomic investigation of the most represented basic muscle water-soluble proteins is suggested. Our method consists of Acetic acid-Urea-Triton polyacrylamide gel (AUT-PAGE) analysis in the first dimension and standard sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE) in the second dimension. Although standard two-dimensional Immobilized pH Gradient-Sodium Dodecyl-Sulphate (2D IPG-SDS) gel electrophoresis has been successfully used to study these proteins, most of the water-soluble proteins are spread on the alkaline part of the 2D map and are poorly focused. Furthermore, the similarity in their molecular weights impairs resolution of the classical approach. The addition of Triton X-100, a non-ionic detergent, into the gel induces a differential electrophoretic mobility of proteins as a result of the formation of mixed micelles between the detergent and the hydrophobic moieties of polypeptides, separating basic proteins with a criterion similar to reversed phase chromatography based on their hydrophobicity. The acid pH induces positive net charges, increasing with the isoelectric point of proteins, thus allowing enhanced resolution in the separation. By using 2D AUT-PAGE/SDS electrophoresis approach to separate water-soluble proteins from fresh pork and from dry-cured products, we could spread proteins over a greater area, achieving a greater resolution than that obtained by IPG in the pH range 3-10 and 6-11. Sarcoplasmic proteins undergoing proteolysis during the ripening of products were identified by Matrix Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry peptide mass fingerprinting in a easier and more effective way. Two-dimensional AUT-PAGE/SDS electrophoresis has allowed to simplify separation of sarcoplasmic protein mixtures making this technique suitable in the defining of quality of dry-cured pork products by immediate

  17. Marketing cardiac CT programs. (United States)

    Scott, Jason


    There are two components of cardiac CT discussed in this article: coronary artery calcium scoring (CACS) and coronary computed tomography angiography (CCTA).The distinctive advantages of each CT examination are outlined. In order to ensure a successful cardiac CT program, it is imperative that imaging facilities market their cardiac CT practices effectively in order to gain a competitive advantage in this valuable market share. If patients receive quality care by competent individuals, they are more likely to recommend the facility's cardiac CT program. Satisfied patients will also be more willing to come back for any further testing.

  18. A novel protein involved in heart development in Ambystoma mexicanum is localized in endoplasmic reticulum. (United States)

    Jia, P; Zhang, C; Huang, X P; Poda, M; Akbas, F; Lemanski, S L; Erginel-Unaltuna, N; Lemanski, L F


    The discovery of the naturally occurring cardiac non-function (c) animal strain in Ambystoma mexicanum (axolotl) provides a valuable animal model to study cardiomyocyte differentiation. In homozygous mutant animals (c/c), rhythmic contractions of the embryonic heart are absent due to a lack of organized myofibrils. We have previously cloned a partial sequence of a peptide cDNA (N1) from an anterior-endoderm-conditioned-medium RNA library that had been shown to be able to rescue the mutant phenotype. In the current studies we have fully cloned the N1 full length cDNA sequence from the library. N1 protein has been detected in both adult heart and skeletal muscle but not in any other adult tissues. GFP-tagged expression of the N1 protein has revealed localization of the N1 protein in the endoplasmic reticulum (ER). Results from in situ hybridization experiments have confirmed the dramatic decrease of expression of N1 mRNA in mutant (c/c) embryos indicating that the N1 gene is involved in heart development.

  19. Formalin evokes calcium transients from the endoplasmatic reticulum.

    Directory of Open Access Journals (Sweden)

    Michael J M Fischer

    Full Text Available The formalin test is the most widely used behavioral screening test for analgesic compounds. The cellular mechanism of action of formaldehyde, inducing a typically biphasic pain-related behavior in rodents is addressed in this study. The chemoreceptor channel TRPA1 was suggested as primary transducer, but the high concentrations used in the formalin test elicit a similar response in TRPA1 wildtype and knockout animals. Here we show that formaldehyde evokes a dose-dependent calcium release from intracellular stores in mouse sensory neurons and primary keratinocytes as well as in non-neuronal cell lines, and independent of TRPA1. The source of calcium is the endoplasmatic reticulum and inhibition of the sarco/endoplasmic reticulum calcium-ATPase has a major contribution. This TRPA1-independent mechanism may underlie formaldehyde-induced pan-neuronal excitation and subsequent inflammation.

  20. Influence of inorganic phosphate and pH on sarcoplasmic reticular ATPase in skinned muscle fibres of Xenopus laevis. (United States)

    Stienen, G J; Papp, Z; Zaremba, R


    1. The influence of 30 mM inorganic phosphate (Pi) and pH (6.2-7.4) on the rate of ATP utilization was determined in mechanically skinned bundles of myofibrils from the iliofibularis muscle of Xenopus laevis at approximately 5 C. 2. BDM (2,3-butanedione monoxime; 10 mM) depressed isometric force production and actomyosin (AM) ATPase activity equally. Therefore sarcoplasmic reticular (SR) ATPase activity could be determined by extrapolation of the total ATPase activity to zero force. 3. The SR ATPase activity without added Pi at pH 7.1 was 42 +/- 2 % of the total ATPase activity. Addition of 30 mM Pi reduced SR ATPase activity slightly, by 9 +/- 5 %, and depressed force by 62 +/- 2 % and AM ATPase activity by 21 +/- 6 %. 4. At pH 6.2, force, SR ATPase activity and AM ATPase activity were reduced by 21 +/- 5, 61 +/- 5 and 10 +/- 4 % of their respective values at pH 7.1. 5. The SR ATPase activity at 30 mM Pi and pH 6.2 was reduced markedly to 20 +/- 6 % of the value under control conditions, suggesting that the maximum rate of Ca2+ uptake during muscle fatigue was strongly depressed. This reduction was larger than expected on the basis of the effects of Pi and pH alone.

  1. Endoplasmic Reticulum Stress and Insulin Biosynthesis: A Review



    Insulin resistance and pancreatic beta cell dysfunction are major contributors to the pathogenesis of diabetes. Various conditions play a role in the pathogenesis of pancreatic beta cell dysfunction and are correlated with endoplasmic reticulum (ER) stress. Pancreatic beta cells are susceptible to ER stress. Many studies have shown that increased ER stress induces pancreatic beta cell dysfunction and diabetes mellitus using genetic models of ER stress and by various stimuli. There are many re...

  2. 收缩潜伏期骨骼肌肌浆网的超微结构变化%Ultrastructural Change of Sarcoplasmic Reticulum in Skeletal Muscle during Contraction-Latency

    Institute of Scientific and Technical Information of China (English)

    邰艳红; 杨勇骥; 宋田斌; 汤莹; 吴越


    采用双向红外线探测--计算机控制的电刺激与超低温快速冷冻固定同步技术对收缩潜伏期的骨骼肌作实时固定,采用透射电镜对电刺激后0.8 ms,5.6 ms,8.4 ms及静息期的骨骼肌超微结构变化进行了对比研究,发现在骨骼肌收缩潜伏期(小于10 ms)内,肌浆网内的Ca2+从面向T-管的肌浆网前端流出.同时发现肌膜与肌纤维间的间隙大大变窄,肌浆网前端的膜产生两个圆孔,而静息时的骨骼肌却无上述改变.这些发现对揭示骨骼肌兴奋-收缩偶联的发生机制有重大意义.

  3. Cardiac Procedures and Surgeries (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Cardiac Procedures and Surgeries Updated:Sep 16,2016 If you've had ... degree of coronary artery disease (CAD) you have. Cardiac Procedures and Surgeries Angioplasty Also known as Percutaneous Coronary Interventions [PCI], ...

  4. [Advances in cardiac pacing]. (United States)

    de Carranza, María-José Sancho-Tello; Fidalgo-Andrés, María Luisa; Ferrer, José Martínez; Mateas, Francisco Ruiz


    This article contains a review of the current status of remote monitoring and follow-up involving cardiac pacing devices and of the latest developments in cardiac resynchronization therapy. In addition, the most important articles published in the last year are discussed.

  5. Endoplasmic reticulum stress in spinal and bulbar muscular atrophy: a potential target for therapy. (United States)

    Montague, Karli; Malik, Bilal; Gray, Anna L; La Spada, Albert R; Hanna, Michael G; Szabadkai, Gyorgy; Greensmith, Linda


    Spinal and bulbar muscular atrophy is an X-linked degenerative motor neuron disease caused by an abnormal expansion in the polyglutamine encoding CAG repeat of the androgen receptor gene. There is evidence implicating endoplasmic reticulum stress in the development and progression of neurodegenerative disease, including polyglutamine disorders such as Huntington's disease and in motor neuron disease, where cellular stress disrupts functioning of the endoplasmic reticulum, leading to induction of the unfolded protein response. We examined whether endoplasmic reticulum stress is also involved in the pathogenesis of spinal and bulbar muscular atrophy. Spinal and bulbar muscular atrophy mice that carry 100 pathogenic polyglutamine repeats in the androgen receptor, and develop a late-onset neuromuscular phenotype with motor neuron degeneration, were studied. We observed a disturbance in endoplasmic reticulum-associated calcium homeostasis in cultured embryonic motor neurons from spinal and bulbar muscular atrophy mice, which was accompanied by increased endoplasmic reticulum stress. Furthermore, pharmacological inhibition of endoplasmic reticulum stress reduced the endoplasmic reticulum-associated cell death pathway. Examination of spinal cord motor neurons of pathogenic mice at different disease stages revealed elevated expression of markers for endoplasmic reticulum stress, confirming an increase in this stress response in vivo. Importantly, the most significant increase was detected presymptomatically, suggesting that endoplasmic reticulum stress may play an early and possibly causal role in disease pathogenesis. Our results therefore indicate that the endoplasmic reticulum stress pathway could potentially be a therapeutic target for spinal and bulbar muscular atrophy and related polyglutamine diseases.

  6. Biomaterials for cardiac regeneration

    CERN Document Server

    Ruel, Marc


    This book offers readers a comprehensive biomaterials-based approach to achieving clinically successful, functionally integrated vasculogenesis and myogenesis in the heart. Coverage is multidisciplinary, including the role of extracellular matrices in cardiac development, whole-heart tissue engineering, imaging the mechanisms and effects of biomaterial-based cardiac regeneration, and autologous bioengineered heart valves. Bringing current knowledge together into a single volume, this book provides a compendium to students and new researchers in the field and constitutes a platform to allow for future developments and collaborative approaches in biomaterials-based regenerative medicine, even beyond cardiac applications. This book also: Provides a valuable overview of the engineering of biomaterials for cardiac regeneration, including coverage of combined biomaterials and stem cells, as well as extracellular matrices Presents readers with multidisciplinary coverage of biomaterials for cardiac repair, including ...

  7. Mathematical cardiac electrophysiology

    CERN Document Server

    Colli Franzone, Piero; Scacchi, Simone


    This book covers the main mathematical and numerical models in computational electrocardiology, ranging from microscopic membrane models of cardiac ionic channels to macroscopic bidomain, monodomain, eikonal models and cardiac source representations. These advanced multiscale and nonlinear models describe the cardiac bioelectrical activity from the cell level to the body surface and are employed in both the direct and inverse problems of electrocardiology. The book also covers advanced numerical techniques needed to efficiently carry out large-scale cardiac simulations, including time and space discretizations, decoupling and operator splitting techniques, parallel finite element solvers. These techniques are employed in 3D cardiac simulations illustrating the excitation mechanisms, the anisotropic effects on excitation and repolarization wavefronts, the morphology of electrograms in normal and pathological tissue and some reentry phenomena. The overall aim of the book is to present rigorously the mathematica...

  8. Exendin-4 improves cardiac function in mice overexpressing monocyte chemoattractant protein-1 in cardiomyocytes. (United States)

    Younce, Craig W; Niu, Jianli; Ayala, Jennifer; Burmeister, Melissa A; Smith, Layton H; Kolattukudy, Pappachan; Ayala, Julio E


    The incretin hormone glucagon-like peptide-1 (Glp1) is cardioprotective in models of ischemia-reperfusion injury, myocardial infarction and gluco/lipotoxicity. Inflammation is a factor in these models, yet it is unknown whether Glp1 receptor (Glp1r) agonists are protective against cardiac inflammation. We tested the hypothesis that the Glp1r agonist Exendin-4 (Ex4) is cardioprotective in mice with cardiac-specific monocyte chemoattractant protein-1 overexpression. These MHC-MCP1 mice exhibit increased cardiac monocyte infiltration, endoplasmic reticulum (ER) stress, apoptosis, fibrosis and left ventricular dysfunction. Ex4 treatment for 8 weeks improved cardiac function and reduced monocyte infiltration, fibrosis and apoptosis in MHC-MCP1 mice. Ex4 enhanced expression of the ER chaperone glucose-regulated protein-78 (GRP78), decreased expression of the pro-apoptotic ER stress marker CCAAT/-enhancer-binding protein homologous protein (CHOP) and increased expression of the ER calcium regulator Sarco/Endoplasmic Reticulum Calcium ATPase-2a (SERCA2a). These findings suggest that the Glp1r is a viable target for treating cardiomyopathies associated with stimulation of pro-inflammatory factors.

  9. Cardiac tumors: echo assessment. (United States)

    Mankad, Rekha; Herrmann, Joerg


    Cardiac tumors are exceedingly rare (0.001-0.03% in most autopsy series). They can be present anywhere within the heart and can be attached to any surface or be embedded in the myocardium or pericardial space. Signs and symptoms are nonspecific and highly variable related to the localization, size and composition of the cardiac mass. Echocardiography, typically performed for another indication, may be the first imaging modality alerting the clinician to the presence of a cardiac mass. Although echocardiography cannot give the histopathology, certain imaging features and adjunctive tools such as contrast imaging may aid in the differential diagnosis as do the adjunctive clinical data and the following principles: (1) thrombus or vegetations are the most likely etiology, (2) cardiac tumors are mostly secondary and (3) primary cardiac tumors are mostly benign. Although the finding of a cardiac mass on echocardiography may generate confusion, a stepwise approach may serve well practically. Herein, we will review such an approach and the role of echocardiography in the assessment of cardiac masses.

  10. Molecular Basis of Cardiac Myxomas

    Directory of Open Access Journals (Sweden)

    Pooja Singhal


    Full Text Available Cardiac tumors are rare, and of these, primary cardiac tumors are even rarer. Metastatic cardiac tumors are about 100 times more common than the primary tumors. About 90% of primary cardiac tumors are benign, and of these the most common are cardiac myxomas. Approximately 12% of primary cardiac tumors are completely asymptomatic while others present with one or more signs and symptoms of the classical triad of hemodynamic changes due to intracardiac obstruction, embolism and nonspecific constitutional symptoms. Echocardiography is highly sensitive and specific in detecting cardiac tumors. Other helpful investigations are chest X-rays, magnetic resonance imaging and computerized tomography scan. Surgical excision is the treatment of choice for primary cardiac tumors and is usually associated with a good prognosis. This review article will focus on the general features of benign cardiac tumors with an emphasis on cardiac myxomas and their molecular basis.

  11. Emergence of the mitochondrial reticulum from fission and fusion dynamics.

    Directory of Open Access Journals (Sweden)

    Valerii M Sukhorukov

    Full Text Available Mitochondria form a dynamic tubular reticulum within eukaryotic cells. Currently, quantitative understanding of its morphological characteristics is largely absent, despite major progress in deciphering the molecular fission and fusion machineries shaping its structure. Here we address the principles of formation and the large-scale organization of the cell-wide network of mitochondria. On the basis of experimentally determined structural features we establish the tip-to-tip and tip-to-side fission and fusion events as dominant reactions in the motility of this organelle. Subsequently, we introduce a graph-based model of the chondriome able to encompass its inherent variability in a single framework. Using both mean-field deterministic and explicit stochastic mathematical methods we establish a relationship between the chondriome structural network characteristics and underlying kinetic rate parameters. The computational analysis indicates that mitochondrial networks exhibit a percolation threshold. Intrinsic morphological instability of the mitochondrial reticulum resulting from its vicinity to the percolation transition is proposed as a novel mechanism that can be utilized by cells for optimizing their functional competence via dynamic remodeling of the chondriome. The detailed size distribution of the network components predicted by the dynamic graph representation introduces a relationship between chondriome characteristics and cell function. It forms a basis for understanding the architecture of mitochondria as a cell-wide but inhomogeneous organelle. Analysis of the reticulum adaptive configuration offers a direct clarification for its impact on numerous physiological processes strongly dependent on mitochondrial dynamics and organization, such as efficiency of cellular metabolism, tissue differentiation and aging.

  12. Cardiac Tumors; Tumeurs cardiaques

    Energy Technology Data Exchange (ETDEWEB)

    Laissy, J.P.; Fernandez, P. [Centre Hospitalier Universitaire Bichat Claude Bernard, Service d' Imagerie, 76 - Rouen (France); Mousseaux, E. [Hopital Europeen Georges Pompidou (HEGP), Service de Radiologie Cardio Vasculaire et Interventionnelle, 75 - Paris (France); Dacher, J.N. [Centre Hospitalier Universitaire Charles Nicolle, 75 - Rouen (France); Crochet, D. [Centre Hospitalier Universitaire, Hopital Laennec, Centre Hemodynamique, Radiologie Thoracique et Vasculaire, 44 - Nantes (France)


    Metastases are the most frequent tumors of the heart even though they seldom are recognized. Most primary cardiac tumors are benign. The main role of imaging is to differentiate a cardiac tumor from thrombus and rare pseudo-tumors: tuberculoma, hydatid cyst. Echocardiography is the fist line imaging technique to detect cardiac tumors, but CT and MRl arc useful for further characterization and differential diagnosis. Myxoma of the left atrium is the most frequent benign cardiac tumor. It usually is pedunculated and sometimes calcified. Sarcoma is the most frequent primary malignant tumor and usually presents as a sessile infiltrative tumor. Lymphoma and metastases are usually recognized by the presence of known tumor elsewhere of by characteristic direct contiguous involvement. Diagnosing primary and secondary pericardial tumors often is difficult. Imaging is valuable for diagnosis, characterization, pre-surgical evaluation and follow-up. (author)

  13. Socially differentiated cardiac rehabilitation

    DEFF Research Database (Denmark)

    Meillier, Lucette Kirsten; Nielsen, Kirsten Melgaard; Larsen, Finn Breinholt;


    to a standard rehabilitation programme (SRP). If patients were identified as socially vulnerable, they were offered an extended version of the rehabilitation programme (ERP). Excluded patients were offered home visits by a cardiac nurse. Concordance principles were used in the individualised programme elements......%. Patients were equally distributed to the SRP and the ERP. No inequality was found in attendance and adherence among referred patients. Conclusions: It seems possible to overcome unequal referral, attendance, and adherence in cardiac rehabilitation by organisation of systematic screening and social......Aim: The comprehensive cardiac rehabilitation (CR) programme after myocardial infarction (MI) improves quality of life and results in reduced cardiac mortality and recurrence of MI. Hospitals worldwide face problems with low participation rates in rehabilitation programmes. Inequality...

  14. Mitochondria-endoplasmic reticulum choreography: structure and signaling dynamics. (United States)

    Pizzo, Paola; Pozzan, Tullio


    Mitochondria and endoplasmic reticulum (ER) have different roles in living cells but they interact both physically and functionally. A key aspect of the mitochondria-ER relationship is the modulation of Ca(2+) signaling during cell activation, which thus affects a variety of physiological processes. We focus here on the molecular aspects that control the dynamics of the organelle-organelle interaction and their relationship with Ca(2+) signals, also discussing the consequences that these phenomena have, not only for cell physiology but also in the control of cell death.

  15. Connections between microtubules and endoplasmic reticulum in mitotic spindle

    Directory of Open Access Journals (Sweden)

    J. A. Tarkowska


    Full Text Available Dividing endosperm cells of Haemanthus katherinae Bak. were treated with an 0.025 per cent aqueous solution of an oleander glycosides mixture which produces severe disturtaances in the mitotic spindle and high hypertrophy of the endoplasmic reticulum (ER in the whole cells. There appear between the kinetochore microtubules (MTs numerous elongated and narrow ER cisterns, particularly well visible when the number of kinetochore MTs is reduced. Both these structures (MTs and ER are frequently connected by cross-bridges. The presumable role of these connections is discused.

  16. Cardiac arrest - cardiopulmonary resuscitation

    Institute of Scientific and Technical Information of China (English)

    Basri Lenjani; Besnik Elshani; Nehat Baftiu; Kelmend Pallaska; Kadir Hyseni; Njazi Gashi; Nexhbedin Karemani; Ilaz Bunjaku; Taxhidin Zaimi; Arianit Jakupi


    Objective:To investigate application of cardiopulmonary resuscitation(CPR) measures within the golden minutes inEurope.Methods:The material was taken from theUniversityClinical Center ofKosovo -EmergencyCentre inPristina, during the two(2) year period(2010-2011).The collected date belong to the patients with cardiac arrest have been recorded in the patients' log book protocol at the emergency clinic.Results:During the2010 to2011 in the emergency center of theCUCK inPristina have been treated a total of269 patients with cardiac arrest, of whom159 or59.1% have been treated in2010, and110 patients or40.9% in2011.Of the269 patients treated in the emergency centre,93 or34.6% have exited lethally in the emergency centre, and176 or 65.4% have been transferred to other clinics.In the total number of patients with cardiac arrest, males have dominated with186 cases, or69.1%.The average age of patients included in the survey was56.7 year oldSD±16.0 years.Of the269 patients with cardiac arrest, defibrillation has been applied for93 or34.6% of patients.In the outpatient settings defibrillation has been applied for3 or3.2% of patients.Patients were defibrillated with application of one to four shocks. Of27 cases with who have survived cardiac arrest, none of them have suffered cardiac arrest at home,3 or11.1% of them have suffered cardiac arrest on the street, and24 or88.9% of them have suffered cardiac arrest in the hospital.5 out of27 patients survived have ended with neurological impairment.Cardiac arrest cases were present during all days of the week, but frequently most reported cases have been onMonday with32.0% of cases, and onFriday with24.5% of cases. Conclusions:All survivors from cardiac arrest have received appropriate medical assistance within10 min from attack, which implies that if cardiac arrest occurs near an institution health care(with an opportunity to provide the emergent health care) the rate of survival is higher.

  17. Cardiac imaging in adults

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, C.C.


    This book approaches adult cardiac disease from the correlative imaging perspective. It includes chest X-rays and angiographs, 2-dimensional echocardiograms with explanatory diagrams for clarity, plus details on digital radiology, nuclear medicine techniques, CT and MRI. It also covers the normal heart, valvular heart disease, myocardial disease, pericardial disease, bacterial endocarditis, aortic aneurysm, cardiac tumors, and congenital heart disease of the adult. It points out those aspects where one imaging technique has significant superiority.

  18. Port Access Cardiac Surgery. (United States)

    Viganó, Mario; Minzioni, Gaetano; Spreafico, Patrizio; Rinaldi, Mauro; Pasquino, Stefano; Ceriana, Piero; Locatelli, Alessandro


    The port-access technique for cardiac surgery was recently developed at Stanford University in California as a less invasive method to perform some cardiac operations. The port-access system has been described in detail elsewhere. It is based on femoral arterial and venous access for cardiopulmonary bypass (CPB) and on the adoption of a specially designed triple-lumen catheter described originally by Peters, and subsequently modified and developed in the definitive configuration called the endoaortic clamp.

  19. Awareness in cardiac anesthesia.

    LENUS (Irish Health Repository)

    Serfontein, Leon


    Cardiac surgery represents a sub-group of patients at significantly increased risk of intraoperative awareness. Relatively few recent publications have targeted the topic of awareness in this group. The aim of this review is to identify areas of awareness research that may equally be extrapolated to cardiac anesthesia in the attempt to increase understanding of the nature and significance of this scenario and how to reduce it.

  20. Post cardiac injury syndrome

    DEFF Research Database (Denmark)

    Nielsen, S L; Nielsen, F E


    The post-pericardiotomy syndrome is a symptom complex which is similar in many respects to the post-myocardial infarction syndrome and these are summarized under the diagnosis of the Post Cardiac Injury Syndrome (PCIS). This condition, which is observed most frequently after open heart surgery, i...... on the coronary vessels, with cardiac tamponade and chronic pericardial exudate. In the lighter cases, PCIS may be treated with NSAID and, in the more severe cases, with systemic glucocorticoid which has a prompt effect....

  1. Autonomic cardiac innervation


    Hasan, Wohaib


    Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targe...

  2. Infected cardiac hydatid cyst


    Ceviz, M; Becit, N; Kocak, H.


    A 24 year old woman presented with chest pain and palpitation. The presence of a semisolid mass—an echinococcal cyst or tumour—in the left ventricular apex was diagnosed by echocardiography, computed tomography, and magnetic resonance imaging. The infected cyst was seen at surgery. The cyst was removed successfully by using cardiopulmonary bypass with cross clamp.

Keywords: cardiac hydatid cyst; infected cardiac hydatid cyst

  3. Cardiac applications of optogenetics. (United States)

    Ambrosi, Christina M; Klimas, Aleksandra; Yu, Jinzhu; Entcheva, Emilia


    In complex multicellular systems, such as the brain or the heart, the ability to selectively perturb and observe the response of individual components at the cellular level and with millisecond resolution in time, is essential for mechanistic understanding of function. Optogenetics uses genetic encoding of light sensitivity (by the expression of microbial opsins) to provide such capabilities for manipulation, recording, and control by light with cell specificity and high spatiotemporal resolution. As an optical approach, it is inherently scalable for remote and parallel interrogation of biological function at the tissue level; with implantable miniaturized devices, the technique is uniquely suitable for in vivo tracking of function, as illustrated by numerous applications in the brain. Its expansion into the cardiac area has been slow. Here, using examples from published research and original data, we focus on optogenetics applications to cardiac electrophysiology, specifically dealing with the ability to manipulate membrane voltage by light with implications for cardiac pacing, cardioversion, cell communication, and arrhythmia research, in general. We discuss gene and cell delivery methods of inscribing light sensitivity in cardiac tissue, functionality of the light-sensitive ion channels within different types of cardiac cells, utility in probing electrical coupling between different cell types, approaches and design solutions to all-optical electrophysiology by the combination of optogenetic sensors and actuators, and specific challenges in moving towards in vivo cardiac optogenetics.

  4. CDIP1-BAP31 Complex Transduces Apoptotic Signals from Endoplasmic Reticulum to Mitochondria under Endoplasmic Reticulum Stress


    Takushi Namba; Fang Tian; Kiki Chu; So-Young Hwang; Kyoung Wan Yoon; Sanguine Byun; Masatsugu Hiraki; Anna Mandinova; Sam W. Lee


    Resolved endoplasmic reticulum (ER) stress response is essential for intracellular homeostatic balance, but unsettled ER stress can lead to apoptosis. Here, we show that a proapoptotic p53 target, CDIP1, acts as a key signal transducer of ER-stress-mediated apoptosis. We identify B-cell-receptor-associated protein 31 (BAP31) as an interacting partner of CDIP1. Upon ER stress, CDIP1 is induced and enhances an association with BAP31 at the ER membrane. We also show that CDIP1 binding to BAP31 i...

  5. Endoplasmic Reticulum Protein Quality Control Failure in Myelin Disorders (United States)

    Volpi, Vera G.; Touvier, Thierry; D'Antonio, Maurizio


    Reaching the correct three-dimensional structure is crucial for the proper function of a protein. The endoplasmic reticulum (ER) is the organelle where secreted and transmembrane proteins are synthesized and folded. To guarantee high fidelity of protein synthesis and maturation in the ER, cells have evolved ER-protein quality control (ERQC) systems, which assist protein folding and promptly degrade aberrant gene products. Only correctly folded proteins that pass ERQC checkpoints are allowed to exit the ER and reach their final destination. Misfolded glycoproteins are detected and targeted for degradation by the proteasome in a process known as endoplasmic reticulum-associated degradation (ERAD). The excess of unstructured proteins in the ER triggers an adaptive signal transduction pathway, called unfolded protein response (UPR), which in turn potentiates ERQC activities in order to reduce the levels of aberrant molecules. When the situation cannot be restored, the UPR drives cells to apoptosis. Myelin-forming cells of the central and peripheral nervous system (oligodendrocytes and Schwann cells) synthesize a large amount of myelin proteins and lipids and therefore are particularly susceptible to ERQC failure. Indeed, deficits in ERQC and activation of ER stress/UPR have been implicated in several myelin disorders, such as Pelizaeus-Merzbacher and Krabbe leucodystrophies, vanishing white matter disease and Charcot-Marie-Tooth neuropathies. Here we discuss recent evidence underlying the importance of proper ERQC functions in genetic disorders of myelinating glia. PMID:28101003

  6. Where is the origin of the activator calcium in cardiac ventricular contraction? (United States)

    Reiter, M; Vierling, W; Seibel, K


    Under normal experimental conditions, the force of rested-state contractions (i.e., contractions after a rest period of 15 min or longer) of mammalian ventricular myocardium is insignificant. In Mg2+-free solution, in low sodium solution or in the presence of a cardioactive steroid, a strong "early" rested-state contraction develops without delay after stimulation, indicating the accumulation during rest of intracellularly stored activator calcium. By contrast, catecholamines cause a "late" rested-state contraction with a characteristic latent period of about 100 ms between stimulation and onset of contraction. Inhibition of the slow inward current by nifedipine has no influence on the contraction velocity of the "early" rested-state contraction, indicating that Ca2+ of the slow inward current is not involved in the calcium release mechanism of prefilled stores during excitation-contraction coupling. Nifedipine suppresses the "late" rested-state contraction in the presence of noradrenaline. In view of the constancy of the latent period, it is proposed that the activator calcium for the "late" rested-state contraction enters the cell with the slow inward current, is sequestered at first by uptake sites of the sarcoplasmic reticulum and subsequently released from its release sites as long as the cell is depolarized. The model of the different origin of activator calcium is discussed in its implication for high-frequency contractions.

  7. [Psychosomatic aspects of cardiac arrhythmias]. (United States)

    Siepmann, Martin; Kirch, Wilhelm


    Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

  8. Cytokeratin-positive interstitial reticulum cell tumors of lymph nodes: a case report and review of literature

    Institute of Scientific and Technical Information of China (English)

    DONG Ying-chun; WU Bo; SHENG Zhen; WANG Jian-dong; ZHOU Hang-bo; ZHOU Xiao-jun


    @@ Cytokeratin-positive interstitial reticulum cells(CIRCs)are considered to represent a subset of fibroblastic reticulum cells(FBRCs)belonging to accessory dendritic cells in lymph nodes,the spleen and tonsils.1-3

  9. From endoplasmic reticulum to mitochondria: absence of the Arabidopsis ATP antiporter endoplasmic Reticulum Adenylate Transporter1 perturbs photorespiration. (United States)

    Hoffmann, Christiane; Plocharski, Bartolome; Haferkamp, Ilka; Leroch, Michaela; Ewald, Ralph; Bauwe, Hermann; Riemer, Jan; Herrmann, Johannes M; Neuhaus, H Ekkehard


    The carrier Endoplasmic Reticulum Adenylate Transporter1 (ER-ANT1) resides in the endoplasmic reticulum (ER) membrane and acts as an ATP/ADP antiporter. Mutant plants lacking ER-ANT1 exhibit a dwarf phenotype and their seeds contain reduced protein and lipid contents. In this study, we describe a further surprising metabolic peculiarity of the er-ant1 mutants. Interestingly, Gly levels in leaves are immensely enhanced (26×) when compared with that of wild-type plants. Gly accumulation is caused by significantly decreased mitochondrial glycine decarboxylase (GDC) activity. Reduced GDC activity in mutant plants was attributed to oxidative posttranslational protein modification induced by elevated levels of reactive oxygen species (ROS). GDC activity is crucial for photorespiration; accordingly, morphological and physiological defects in er-ant1 plants were nearly completely abolished by application of high environmental CO(2) concentrations. The latter observation demonstrates that the absence of ER-ANT1 activity mainly affects photorespiration (maybe solely GDC), whereas basic cellular metabolism remains largely unchanged. Since ER-ANT1 homologs are restricted to higher plants, it is tempting to speculate that this carrier fulfils a plant-specific function directly or indirectly controlling cellular ROS production. The observation that ER-ANT1 activity is associated with cellular ROS levels reveals an unexpected and critical physiological connection between the ER and other organelles in plants.

  10. Advances in the mechanisms of atherosclerosis vulnerable plague and endoplasmic reticulum stress

    Institute of Scientific and Technical Information of China (English)

    Zhong Zhang; Ruo-Lan Huang; Ru Mo; Ling Wang; Xiao Chang; Mu-Juan Xu


    Objective:Ischemic stroke and coronary heart disease occupy the first two place of world health economic burden, atherosclerotic vulnerable plaque rupture as the common factor of these diseases, is thought to be a key target of ischemic cardiovascular and cerebrovascular disease control. Endoplasmic reticulum stress is one of the classical pathway of cell apoptosis. More and more studies have indicated that the endoplasmic reticulum stress pathway was involved in the development of atherosclerotic plaque rupture. In this paper, the three main signal pathways of endoplasmic reticulum stress, including Protein kinase RNA-like ER kinase (PERK), Activating transcription factor 6 (ATF6) and Inositol-requiring protein 1αα(IRE1α) were reviewed. The relationship between the risk factors of atherosclerosis (including hyperlipidemia, hypertension and hyperglycemia) and endoplasmic reticulum stress, and the relationship between major cellular components (macrophages, vascular endothelial cells, vascular smooth muscle cells and vascular smooth muscle cells) of vulnerable plaque and endoplasmic reticulum stress were reviewed.

  11. Cell Death and Survival Through the Endoplasmic Reticulum-Mitochondrial Axis (United States)

    Bravo-Sagua, R.; Rodriguez, A.E.; Kuzmicic, J.; Gutierrez, T.; Lopez-Crisosto, C.; Quiroga, C.; Díaz-Elizondo, J.; Chiong, M.; Gillette, T.G.; Rothermel, B.A.; Lavandero, S.


    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial–associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate. PMID:23228132

  12. Cardiac radiology: centenary review. (United States)

    de Roos, Albert; Higgins, Charles B


    During the past century, cardiac imaging technologies have revolutionized the diagnosis and treatment of acquired and congenital heart disease. Many important contributions to the field of cardiac imaging were initially reported in Radiology. The field developed from the early stages of cardiac imaging, including the use of coronary x-ray angiography and roentgen kymography, to nowadays the widely used echocardiographic, nuclear medicine, cardiac computed tomographic (CT), and magnetic resonance (MR) applications. It is surprising how many of these techniques were not recognized for their potential during their early inception. Some techniques were described in the literature but required many years to enter the clinical arena and presently continue to expand in terms of clinical application. The application of various CT and MR contrast agents for the diagnosis of myocardial ischemia is a case in point, as the utility of contrast agents continues to expand the noninvasive characterization of myocardium. The history of cardiac imaging has included a continuous process of advances in our understanding of the anatomy and physiology of the cardiovascular system, along with advances in imaging technology that continue to the present day.

  13. Exogenous H2S regulates endoplasmic reticulum-mitochondria cross-talk to inhibit apoptotic pathways in STZ-induced type I diabetes. (United States)

    Yang, Fan; Yu, Xiangjing; Li, Ting; Wu, Jianjun; Zhao, Yajun; Liu, Jiaqi; Sun, Aili; Dong, Shiyun; Wu, Jichao; Zhong, Xin; Xu, Changqing; Lu, Fanghao; Zhang, Weihua


    The upregulation of reactive oxygen species (ROS) is a primary cause of cardiomyocyte apoptosis in diabetes cardiomyopathy (DCM). Mitofusin-2 (Mfn-2) is a key protein that bridges the mitochondria and endoplasmic reticulum (ER). Hydrogen sulfide (H2S)-mediated cardioprotection is related to antioxidant effects. The present study demonstrated that H2S inhibited the interaction between the ER and mitochondrial apoptotic pathway. This study investigated cardiac function, ultrastructural changes in the ER and mitochondria, apoptotic rate using TUNEL, and the expression of ER stress-associated proteins and mitochondrial apoptotic proteins in cardiac tissues in STZ-induced type I diabetic rats treated with or without NaHS (donor of H2S). Mitochondria of cardiac tissues were isolated, and MPTP opening and cytochrome c (cyt C) and Mfn-2 expression were also detected. Our data showed that hyperglycemia decreased the cardiac function by ultrasound cardiogram, and the administration of exogenous H2S ameliorated these changes. We demonstrated that the expression of ER stress sensors and apoptotic rates were elevated in cardiac tissue of DCM and cultured H9C2 cells, but the expression of these proteins was reduced following exogenous H2S treatment. The expression of mitochondrial apoptotic proteins, cyt C, and mPTP opening was decreased following treatment with exogenous H2S. In our experiment, the expression and immunofluorescence of Mfn-2 were both decreased after transfection with Mfn-2-siRNA. Hyperglycemia stimulated ER interactions and mitochondrial apoptotic pathways, which were inhibited by exogenous H2S treatment through the regulation of Mfn-2 expression.

  14. Effects of diltiazem on skinned skeletal muscle fibers of the African clawed toad. (United States)

    Ishizuka, T; Endo, M


    To examine the effects of diltiazem and its l-cis isomer (which possesses only a weak Ca++-antagonistic action) on the contractile system and the sarcoplasmic reticulum of skeletal muscle, we used skinned fibers isolated from iliofibularis muscle of the African clawed toad, Xenopus laevis. Diltiazem showed the following effects: an increase in the Ca++ sensitivity of the contractile system, a decrease in the maximal tension developed in a saturating concentration of Ca++, an inhibition of Ca++ uptake by the sarcoplasmic reticulum, an inhibition of Ca++ release from the sarcoplasmic reticulum by caffeine, and an increase in the Ca++ permeability of the sarcoplasmic reticulum membrane. The effects of the l-cis isomer were similar to those of diltiazem, and the potencies of the two substances were nearly equal, except with respect to the effect on the Ca++ release induced by caffeine: the l-cis isomer potentiated this type of Ca++ release. Diltiazem's effects on amphibian skinned skeletal muscle fibers may not be related qualitatively or quantitatively to the Ca++-antagonistic actions of the drug on mammalian cardiac and smooth muscles. The pharmacological spectrum of diltiazem on skinned skeletal muscle fibers is similar to that of some local anesthetics.

  15. Pediatric cardiac postoperative care

    Directory of Open Access Journals (Sweden)

    Auler Jr. José Otávio Costa


    Full Text Available The Heart Institute of the University of São Paulo, Medical School is a referral center for the treatment of congenital heart diseases of neonates and infants. In the recent years, the excellent surgical results obtained in our institution may be in part due to modern anesthetic care and to postoperative care based on well-structured protocols. The purpose of this article is to review unique aspects of neonate cardiovascular physiology, the impact of extracorporeal circulation on postoperative evolution, and the prescription for pharmacological support of acute cardiac dysfunction based on our cardiac unit protocols. The main causes of low cardiac output after surgical correction of heart congenital disease are reviewed, and methods of treatment and support are proposed as derived from the relevant literature and our protocols.

  16. Comprehensive cardiac rehabilitation

    DEFF Research Database (Denmark)

    Kruse, Marie; Hochstrasser, Stefan; Zwisler, Ann-Dorthe O;


    OBJECTIVES: The costs of comprehensive cardiac rehabilitation are established and compared to the corresponding costs of usual care. The effect on health-related quality of life is analyzed. METHODS: An unprecedented and very detailed cost assessment was carried out, as no guidelines existed...... for the situation at hand. Due to challenging circumstances, the cost assessment turned out to be ex-post and top-down. RESULTS: Cost per treatment sequence is estimated to be approximately euro 976, whereas the incremental cost (compared with usual care) is approximately euro 682. The cost estimate is uncertain...... and may be as high as euro 1.877. CONCLUSIONS: Comprehensive cardiac rehabilitation is more costly than usual care, and the higher costs are not outweighed by a quality of life gain. Comprehensive cardiac rehabilitation is, therefore, not cost-effective....

  17. Toothache of cardiac origin. (United States)

    Kreiner, M; Okeson, J P


    Pain referred to the orofacial structures can sometimes be a diagnostic challenge for the clinician. In some instances, a patient may complain of tooth pain that is completely unrelated to any dental source. This poses a diagnostic and therapeutic problem for the dentist. Cardiac pain most commonly radiates to the left arm, shoulder, neck, and face. In rare instances, angina pectoris may present as dental pain. When this occurs, an improper diagnosis frequently leads to unnecessary dental treatment or, more significantly, a delay of proper treatment. This delay may result in the patient experiencing an acute myocardial infarction. It is the dentist's responsibility to establish a proper diagnosis so that the treatment will be directed toward the source of pain and not to the site of pain. This article reviews the literature concerning referred pain of cardiac origin and presents a case report of toothache of cardiac origin.

  18. The cardiac anxiety questionnaire: cross-validation among cardiac inpatients

    NARCIS (Netherlands)

    Beek, M.H. van; Oude Voshaar, R.C.; Deelen, F.M. van; Balkom, A.J. van; Pop, G.A.; Speckens, A.E.


    OBJECTIVE: General anxiety symptoms are common in patients with cardiac disease and considered to have an adverse effect on cardiac prognosis. The role of specific cardiac anxiety, however, is still unknown. The aim of this study is to examine the factor structure, reliability, and validity of the D


    NARCIS (Netherlands)

    van Beek, M. H. C. T.; Voshaar, R. C. Oude; van Deelen, F. M.; van Balkom, A. J. L. M.; Pop, G.; Speckens, A. E. M.


    Objective: General anxiety symptoms are common in patients with cardiac disease and considered to have an adverse effect on cardiac prognosis. The role of specific cardiac anxiety, however, is still unknown. The aim of this study is to examine the factor structure, reliability, and validity of the D

  20. Plant transducers of the endoplasmic reticulum unfolded protein response

    KAUST Repository

    Iwata, Yuji


    The unfolded protein response (UPR) activates a set of genes to overcome accumulation of unfolded proteins in the endoplasmic reticulum (ER), a condition termed ER stress, and constitutes an essential part of ER protein quality control that ensures efficient maturation of secretory and membrane proteins in eukaryotes. Recent studies on Arabidopsis and rice identified the signaling pathway in which the ER membrane-localized ribonuclease IRE1 (inositol-requiring enzyme 1) catalyzes unconventional cytoplasmic splicing of mRNA, thereby producing the active transcription factor Arabidopsis bZIP60 (basic leucine zipper 60) and its ortholog in rice. Here we review recent findings identifying the molecular components of the plant UPR, including IRE1/bZIP60 and the membrane-bound transcription factors bZIP17 and bZIP28, and implicating its importance in several physiological phenomena such as pathogen response. © 2012 Elsevier Ltd.

  1. WLS retrograde transport to the endoplasmic reticulum during Wnt secretion. (United States)

    Yu, Jia; Chia, Joanne; Canning, Claire Ann; Jones, C Michael; Bard, Frédéric A; Virshup, David M


    Wnts are transported to the cell surface by the integral membrane protein WLS (also known as Wntless, Evi, and GPR177). Previous studies of WLS trafficking have emphasized WLS movement from the Golgi to the plasma membrane (PM) and then back to the Golgi via retromer-mediated endocytic recycling. We find that endogenous WLS binds Wnts in the endoplasmic reticulum (ER), cycles to the PM, and then returns to the ER through the Golgi. We identify an ER-targeting sequence at the carboxyl terminus of native WLS that is critical for ER retrograde recycling and contributes to Wnt secretory function. Golgi-to-ER recycling of WLS requires the COPI regulator ARF as well as ERGIC2, an ER-Golgi intermediate compartment protein that is also required for the retrograde trafficking of the KDEL receptor and certain toxins. ERGIC2 is required for efficient Wnt secretion. ER retrieval is an integral part of the WLS transport cycle.

  2. Homotypic fusion of endoplasmic reticulum membranes in plant cells

    Directory of Open Access Journals (Sweden)

    Junjie eHu


    Full Text Available The endoplasmic reticulum (ER is a membrane-bounded organelle whose membrane comprises a network of tubules and sheets. The formation of these characteristic shapes and maintenance of their continuity through homotypic membrane fusion appears to be critical for the proper functioning of the ER. The atlastins (ATLs, a family of ER-localized dynamin-like GTPases, have been identified as fusogens of the ER membranes in metazoans. Mutations of the ATL proteins in mammalian cells cause morphological defects in the ER, and purified Drosophila ATL mediates membrane fusion in vitro. Plant cells do not possess ATL, but a family of similar GTPases, named root hair defective 3 (RHD3, are likely the functional orthologs of ATLs. In this review, we summarize recent advances in our understanding of how RHD3 proteins play a role in homotypic ER fusion. We also discuss the possible physiological significance of forming a tubular ER network in plant cells.

  3. Quality Control System of the Endoplasmic Reticulum and Related Diseases

    Institute of Scientific and Technical Information of China (English)

    Jun-Chao WU; Zhong-Qin LIANG; Zheng-Hong QIN


    The quality control (QC) system of the endoplasmic reticulum (ER) is an important monitoring mechanism in the protein maturation process, which ensures export of properly folded proteins from the ER.Incorrectly or incompletely folded proteins are retained in the ER for refolding or degradation by the ER-residing proteasome. The calnexin/calreticulin cycle and ER-associated degradation are the key elements in QC. These two mechanisms work together to allow incorrectly folded proteins have additional opportunities to achieve their native conformations. The QC dysfunction is involved in many diseases caused by mutant proteins, many of which are causes of neurodegenerative disorders. A better understanding of molecular regulation in the QC system will uncover the molecular pathogenic mechanisms of many diseases caused by protein misfolding and help discover novel strategies for preventing or treating these diseases.

  4. Assembly of MHC class I molecules within the endoplasmic reticulum. (United States)

    Zhang, Yinan; Williams, David B


    MHC class I molecules bind cytosolically derived peptides within the endoplasmic reticulum (ER) and present them at the cell surface to cytotoxic T cells. A major focus of our laboratory has been to understand the functions of the diverse proteins involved in the intracellular assembly of MHC class I molecules. These include the molecular chaperones calnexin and calreticulin, which enhance the proper folding and subunit assembly of class I molecules and also retain assembly intermediates within the ER; ERp57, a thiol oxidoreductase that promotes heavy chain disulfide formation and proper assembly of the peptide loading complex; tapasin, which recruits class I molecules to the TAP peptide transporter and enhances the loading of high affinity peptide ligands; and Bap31, which is involved in clustering assembled class I molecules at ER exit sites for export along the secretory pathway. This review describes our contributions to elucidating the functions of these proteins; the combined effort of many dedicated students and postdoctoral fellows.

  5. Endoplasmic Reticulum Stress and Insulin Biosynthesis: A Review

    Directory of Open Access Journals (Sweden)

    Mi-Kyung Kim


    Full Text Available Insulin resistance and pancreatic beta cell dysfunction are major contributors to the pathogenesis of diabetes. Various conditions play a role in the pathogenesis of pancreatic beta cell dysfunction and are correlated with endoplasmic reticulum (ER stress. Pancreatic beta cells are susceptible to ER stress. Many studies have shown that increased ER stress induces pancreatic beta cell dysfunction and diabetes mellitus using genetic models of ER stress and by various stimuli. There are many reports indicating that ER stress plays an important role in the impairment of insulin biosynthesis, suggesting that reduction of ER stress could be a therapeutic target for diabetes. In this paper, we reviewed the relationship between ER stress and diabetes and how ER stress controls insulin biosynthesis.

  6. Endoplasmic reticulum stress and insulin biosynthesis: a review. (United States)

    Kim, Mi-Kyung; Kim, Hye-Soon; Lee, In-Kyu; Park, Keun-Gyu


    Insulin resistance and pancreatic beta cell dysfunction are major contributors to the pathogenesis of diabetes. Various conditions play a role in the pathogenesis of pancreatic beta cell dysfunction and are correlated with endoplasmic reticulum (ER) stress. Pancreatic beta cells are susceptible to ER stress. Many studies have shown that increased ER stress induces pancreatic beta cell dysfunction and diabetes mellitus using genetic models of ER stress and by various stimuli. There are many reports indicating that ER stress plays an important role in the impairment of insulin biosynthesis, suggesting that reduction of ER stress could be a therapeutic target for diabetes. In this paper, we reviewed the relationship between ER stress and diabetes and how ER stress controls insulin biosynthesis.


    Directory of Open Access Journals (Sweden)

    Barbora Radochová


    Full Text Available Image analysis techniques for preprocessing, segmentation and estimation of geometrical characteristics of fiber-like structures from 2-D or 3-D images captured by a confocal microscope are presented. Methods are demonstrated on fiber-like biological structure: endoplasmic reticulum (ER of tobacco cells. In the presented analysis of 2-D images of ER before and after the treatment of latrunculin B, ER and ER tubules were segmented and the area density of ER as well as the length density of ER tubules in the cell cortical layer were estimated by automatic image analysis algorithms. Images of 3-D arrangement of ER were reconstructed and rendered by various visualization techniques.

  8. Perioperative management of cardiac disease. (United States)

    Aresti, N A; Malik, A A; Ihsan, K M; Aftab, S M E; Khan, W S


    Pre-existing cardiac disease contributes significantly to morbidity and mortality amongst patients undergoing non cardiac surgery. Patients with pre-existing cardiac disease or with risk factors for it, have as much as a 3.9% risk of suffering a major perioperative cardiac event (Lee et al 1999, Devereaux 2005). Furthermore, the incidence of perioperative myocardial infarction (MI) is increased 10 to 50 fold in patients with previous coronary events (Jassal 2008).

  9. Maternal obesity alters endoplasmic reticulum homeostasis in offspring pancreas. (United States)

    Soeda, Jumpei; Mouralidarane, Angelina; Cordero, Paul; Li, Jiawei; Nguyen, Vi; Carter, Rebeca; Kapur, Sabrina R; Pombo, Joaquim; Poston, Lucilla; Taylor, Paul D; Vinciguerra, Manlio; Oben, Jude A


    The prevalence of non-alcoholic fatty pancreas disease (NAFPD) is increasing in parallel with obesity rates. Stress-related alterations in endoplasmic reticulum (ER), such as the unfolded protein response (UPR), are associated with obesity. The aim of this study was to investigate ER imbalance in the pancreas of a mice model of adult and perinatal diet-induced obesity. Twenty female C57BL/6J mice were assigned to control (Con) or obesogenic (Ob) diets prior to and during pregnancy and lactation. Their offspring were weaned onto Con or Ob diets up to 6 months post-partum. Then, after sacrifice, plasma biochemical analyses, gene expression, and protein concentrations were measured in pancreata. Offspring of Ob-fed mice had significantly increased body weight (p < 0.001) and plasma leptin (p < 0.001) and decreased insulin (p < 0.01) levels. Maternal obesogenic diet decreased the total and phosphorylated Eif2α and increased spliced X-box binding protein 1 (XBP1). Pancreatic gene expression of downstream regulators of UPR (EDEM, homocysteine-responsive endoplasmic reticulum-resident (HERP), activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP)) and autophagy-related proteins (LC3BI/LC3BII) were differently disrupted by obesogenic feeding in both mothers and offspring (from p < 0.1 to p < 0.001). Maternal obesity and Ob feeding in their offspring alter UPR in NAFPD, with involvement of proapoptotic and autophagy-related markers. Upstream and downstream regulators of PERK, IRE1α, and ATF6 pathways were affected differently following the obesogenic insults.

  10. Data analysis in cardiac arrhythmias. (United States)

    Rodrigo, Miguel; Pedrón-Torecilla, Jorge; Hernández, Ismael; Liberos, Alejandro; Climent, Andreu M; Guillem, María S


    Cardiac arrhythmias are an increasingly present in developed countries and represent a major health and economic burden. The occurrence of cardiac arrhythmias is closely linked to the electrical function of the heart. Consequently, the analysis of the electrical signal generated by the heart tissue, either recorded invasively or noninvasively, provides valuable information for the study of cardiac arrhythmias. In this chapter, novel cardiac signal analysis techniques that allow the study and diagnosis of cardiac arrhythmias are described, with emphasis on cardiac mapping which allows for spatiotemporal analysis of cardiac signals.Cardiac mapping can serve as a diagnostic tool by recording cardiac signals either in close contact to the heart tissue or noninvasively from the body surface, and allows the identification of cardiac sites responsible of the development or maintenance of arrhythmias. Cardiac mapping can also be used for research in cardiac arrhythmias in order to understand their mechanisms. For this purpose, both synthetic signals generated by computer simulations and animal experimental models allow for more controlled physiological conditions and complete access to the organ.

  11. Biosynthesis of cardiac natriuretic peptides

    DEFF Research Database (Denmark)

    Goetze, Jens Peter


    Cardiac-derived peptide hormones were identified more than 25 years ago. An astonishing amount of clinical studies have established cardiac natriuretic peptides and their molecular precursors as useful markers of heart disease. In contrast to the clinical applications, the biogenesis of cardiac...

  12. Cardiac troponins and high-sensitivity cardiac troponin assays. (United States)

    Conrad, Michael J; Jarolim, Petr


    Measurement of circulating cardiac troponins I and T has become integral to the diagnosis of myocardial infarction. This article discusses the structure and function of the troponin complex and the release of cardiac troponin molecules from the injured cardiomyocyte into the circulation. An overview of current cardiac troponin assays and their classification according to sensitivity is presented. The diagnostic criteria, role, and usefulness of cardiac troponin for myocardial infarction are discussed. In addition, several examples are given of the usefulness of high-sensitivity cardiac troponin assays for short-term and long-term prediction of adverse events.

  13. The overexpression of nuclear envelope protein Lap2β induces endoplasmic reticulum reorganisation via membrane stacking

    Directory of Open Access Journals (Sweden)

    Ekaterina G. Volkova


    Some nuclear envelope proteins are localised to both the nuclear envelope and the endoplasmic reticulum; therefore, it seems plausible that even small amounts of these proteins can influence the organisation of the endoplasmic reticulum. A simple method to study the possible effects of nuclear envelope proteins on endoplasmic reticulum organisation is to analyze nuclear envelope protein overexpression. Here, we demonstrate that Lap2β overexpression can induce the formation of cytoplasmic vesicular structures derived from endoplasmic reticulum membranes. Correlative light and electron microscopy demonstrated that these vesicular structures were composed of a series of closely apposed membranes that were frequently arranged in a circular fashion. Although stacked endoplasmic reticulum cisternae were highly ordered, Lap2β could readily diffuse into and out of these structures into the surrounding reticulum. It appears that low-affinity interactions between cytoplasmic domains of Lap2β can reorganise reticular endoplasmic reticulum into stacked cisternae. Although the effect of one protein may be insignificant at low concentrations, the cumulative effect of many non-specialised proteins may be significant.

  14. C1q/TNF-Related Protein 9 Protects Diabetic Rat Heart against Ischemia Reperfusion Injury: Role of Endoplasmic Reticulum Stress (United States)

    Bai, Sanxing; Cheng, Liang; Yang, Yang; Fan, Chongxi; Zhao, Dajun; Qin, Zhigang; Feng, Xiao; Zhao, Lin; Ma, Jipeng; Wang, Xiaowu; Yang, Jian; Xu, Xuezeng


    As a newly identified adiponectin paralog, C1q/TNF-related protein 9 (CTRP9) reduces myocardial ischemia reperfusion (IR) injury through partially understood mechanisms. In the present study, we sought to identify the role of endoplasmic reticulum stress (ERS) in CTRP9 induced cardioprotection in diabetic heart. Isolated hearts from high-fat-diet (HFD) induced type 2 diabetic Sprague-Dawley rats were subjected to ex vivo IR protocol via a Langendorff apparatus at the presence of globular CTRP9. CTRP9 significantly improved post-IR heart function and reduced cardiac infarction, cardiomyocytes apoptosis, Caspase-3, Caspase-9, Caspase-12, TNF-α expression, and lactate dehydrogenase activity. The cardioprotective effect of CTRP9 was associated with reduced ERS and increased expression of disulfide-bond A oxidoreductase-like protein (DsbA-L) in diabetic heart. CTRP9 reduced ERS in thapsigargin (TG) treated cardiomyocytes and protected endoplasmic reticulum (ER) stressed H9c2 cells against simulated ischemia reperfusion (SIR) injury, concurrent with increased expression of DsbA-L. Knockdown of DsbA-L increased ERS and attenuated CTRP9 induced protection against SIR injury in H9c2 cells. Our findings demonstrated for the first time that CTRP9 exerts cardioprotection by reducing ERS in diabetic heart through increasing DsbA-L.

  15. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter


    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...

  16. Cardiac Risk Assessment (United States)

    ... Risk Assessment Related tests: Lipid Profile , VLDL Cholesterol , hs-CRP , Lp(a) Overview | Common Questions | Related Pages What ... cardiac risk include: High-sensitivity C-reactive protein (hs-CRP) : Studies have shown that measuring CRP with a ...

  17. The cardiac malpositions. (United States)

    Perloff, Joseph K


    Dextrocardia was known in the 17th century and was 1 of the first congenital malformations of the heart to be recognized. Fifty years elapsed before Matthew Baillie published his account of complete transposition in a human of the thoracic and abdominal viscera to the opposite side from what is natural. In 1858, Thomas Peacock stated that "the heart may be congenitally misplaced in various ways, occupying either an unusual position within the thorax, or being situated external to that cavity." In 1915, Maude Abbott described ectopia cordis, and Richard Paltauf's remarkable illustrations distinguished the various types of dextrocardia. In 1928, the first useful classification of the cardiac malpositions was proposed, and in 1966, Elliott et al's radiologic classification set the stage for clinical recognition. The first section of this review deals with the 3 basic cardiac malpositions in the presence of bilateral asymmetry. The second section deals with cardiac malpositions in the presence of bilateral left-sidedness or right-sidedness. Previous publications on cardiac malpositions are replete with an arcane vocabulary that confounds rather than clarifies. Even if the terms themselves are understood, inherent complexity weighs against clarity. This review was designed as a guided tour of an unfamiliar subject.

  18. Hepato-cardiac disorders

    Institute of Scientific and Technical Information of China (English)

    Yasser; Mahrous; Fouad; Reem; Yehia


    Understanding the mutual relationship between the liver and the heart is important for both hepatologists and cardiologists. Hepato-cardiac diseases can be classified into heart diseases affecting the liver, liver diseases affecting the heart, and conditions affecting the heart and the liver at the same time. Differential diagnoses of liver injury are extremely important in a cardiologist’s clinical practice calling for collaboration between cardiologists and hepatologists due to the many other diseases that can affect the liver and mimic haemodynamic injury. Acute and chronic heart failure may lead to acute ischemic hepatitis or chronic congestive hepatopathy. Treatment in these cases should be directed to the primary heart disease. In patients with advanced liver disease, cirrhotic cardiomyopathy may develop including hemodynamic changes, diastolic and systolic dysfunctions, reduced cardiac performance and electrophysiological abnormalities. Cardiac evaluation is important for patients with liver diseases especially before and after liver transplantation. Liver transplantation may lead to the improvement of all cardiac changes and the reversal of cirrhotic cardiomyopathy. There are systemic diseases that may affect both the liver and the heart concomitantly including congenital, metabolic and inflammatory diseases as well as alcoholism. This review highlights these hepatocardiac diseases

  19. Cardiac fusion and complex congenital cardiac defects in thoracopagus twins: diagnostic value of cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Park, Jeong-Jun [University of Ulsan College of Medicine, Asan Medical Center, Department of Pediatric Cardiac Surgery, Seoul (Korea, Republic of); Kim, Ellen Ai-Rhan [University of Ulsan College of Medicine, Asan Medical Center, Division of Neonatology, Department of Pediatrics, Seoul (Korea, Republic of); Won, Hye-Sung [University of Ulsan College of Medicine, Asan Medical Center, Department of Obstetrics and Gynecology, Seoul (Korea, Republic of)


    Most thoracopagus twins present with cardiac fusion and associated congenital cardiac defects, and assessment of this anatomy is of critical importance in determining patient care and outcome. Cardiac CT with electrocardiographic triggering provides an accurate and quick morphological assessment of both intracardiac and extracardiac structures in newborns, making it the best imaging modality to assess thoracopagus twins during the neonatal period. In this case report, we highlight the diagnostic value of cardiac CT in thoracopagus twins with an interatrial channel and complex congenital cardiac defects. (orig.)

  20. Alcohol Dehydrogenase Protects against Endoplasmic Reticulum Stress-Induced Myocardial Contractile Dysfunction via Attenuation of Oxidative Stress and Autophagy: Role of PTEN-Akt-mTOR Signaling.

    Directory of Open Access Journals (Sweden)

    Jiaojiao Pang

    Full Text Available The endoplasmic reticulum (ER plays an essential role in ensuring proper folding of the newly synthesized proteins. Aberrant ER homeostasis triggers ER stress and development of cardiovascular diseases. ADH is involved in catalyzing ethanol to acetaldehyde although its role in cardiovascular diseases other than ethanol metabolism still remains elusive. This study was designed to examine the impact of ADH on ER stress-induced cardiac anomalies and underlying mechanisms involved using cardiac-specific overexpression of alcohol dehydrogenase (ADH.ADH and wild-type FVB mice were subjected to the ER stress inducer tunicamycin (1 mg/kg, i.p., for 48 hrs. Myocardial mechanical and intracellular Ca(2+ properties, ER stress, autophagy and associated cell signaling molecules were evaluated.ER stress compromised cardiac contractile function (evidenced as reduced fractional shortening, peak shortening, maximal velocity of shortening/relengthening, prolonged relengthening duration and impaired intracellular Ca(2+ homeostasis, oxidative stress and upregulated autophagy (increased LC3B, Atg5, Atg7 and p62, along with dephosphorylation of PTEN, Akt and mTOR, all of which were attenuated by ADH. In vitro study revealed that ER stress-induced cardiomyocyte anomaly was abrogated by ADH overexpression or autophagy inhibition using 3-MA. Interestingly, the beneficial effect of ADH was obliterated by autophagy induction, inhibition of Akt and mTOR. ER stress also promoted phosphorylation of the stress signaling ERK and JNK, the effect of which was unaffected by ADH transgene.Taken together, these findings suggested that ADH protects against ER stress-induced cardiac anomalies possibly via attenuation of oxidative stress and PTEN/Akt/mTOR pathway-regulated autophagy.

  1. Cardiac nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Gerson, M.C.


    The book begins with a review of the radionuclide methods available for evaluating cardiac perfusion and function. The authors discuss planar and tomographic thallium myocardial imaging, first-pass and equilibrium radionuclide angiography, and imaging with infarct-avid tracers. Several common but more specialized procedures are then reviewed: nonogemetric measurement of left ventricular volume, phase (Fourier) analysis, stroke volume ratio, right ventricular function, and diastolic function. A separate chapter is devoted to drug interventions and in particular the use of radionuclide ventriculography to monitor doxorubicin toxicity and therapy of congestive heart failure. The subsequent chapters provide a comprehensive guide to test selection, accuracy, and results in acute myocardial infarction, in postmyocardial infarction, in chronic coronary artery disease, before and after medical or surgical revascularization, in valvular heart disease, in cardiomyopathies, and in cardiac trauma.

  2. Sudden Cardiac Death

    Directory of Open Access Journals (Sweden)

    Yipsy María Gutiérrez Báez


    Full Text Available Since the second half of the twentieth century, dying suddenly due to heart-related problems has become the main health issue in all countries where infectious diseases are not prevalent. Sudden death from cardiac causes is an important global health problem. Major databases were searched for the leading causes of sudden cardiac death. It has been demonstrated that there is a group of hereditary diseases with structural alterations or without apparent organic cause that explains many cases of sudden death in young people, whether related or not to physical exertion. Certain population groups are at higher risk for this disease. They are relatively easy to identify and can be the target of primary prevention measures.

  3. Cardiac arrhythmias in pregnancy. (United States)

    Knotts, Robert J; Garan, Hasan


    As more women with repaired congenital heart disease survive to their reproductive years and many other women are delaying pregnancy until later in life, a rising concern is the risk of cardiac arrhythmias during pregnancy. Naturally occurring cardiovascular changes during pregnancy increase the likelihood that a recurrence of a previously experienced cardiac arrhythmia or a de novo arrhythmia will occur. Arrhythmias should be thoroughly investigated to determine if there is a reversible etiology, and risks/benefits of treatment options should be fully explored. We discuss the approach to working up and treating various arrhythmias during pregnancy with attention to fetal and maternal risks as well as treatment of fetal arrhythmias. Acute management in stable patients includes close monitoring and intravenous pharmacologic therapy, while DC cardioversion should be used to terminate arrhythmias in hemodynamically unstable patients. Long-term management may require continued oral antiarrhythmic therapy, with particular attention to fetal safety, to prevent complications associated with arrhythmias.

  4. Transitions of protein traffic from cardiac ER to junctional SR. (United States)

    Sleiman, Naama H; McFarland, Timothy P; Jones, Larry R; Cala, Steven E


    The junctional sarcoplasmic reticulum (jSR) is an important and unique ER subdomain in the adult myocyte that concentrates resident proteins to regulate Ca(2+) release. To investigate cellular mechanisms for sorting and trafficking proteins to jSR, we overexpressed canine forms of junctin (JCT) or triadin (TRD) in adult rat cardiomyocytes. Protein accumulation over time was visualized by confocal fluorescence microscopy using species-specific antibodies. Newly synthesized JCTdog and TRDdog appeared by 12-24h as bright fluorescent puncta close to the nuclear surface, decreasing in intensity with increasing radial distance. With increasing time (24-48h), fluorescent puncta appeared at further radial distances from the nuclear surface, eventually populating jSR similar to steady-state patterns. CSQ2-DsRed, a form of CSQ that polymerizes ectopically in rough ER, prevented anterograde traffic of newly made TRDdog and JCTdog, demonstrating common pathways of intracellular trafficking as well as in situ binding to CSQ2 in juxtanuclear rough ER. Reversal of CSQ-DsRed interactions occurred when a form of TRDdog was used in which CSQ2-binding sites are removed ((del)TRD). With increasing levels of expression, CSQ2-DsRed revealed a novel smooth ER network that surrounds nuclei and connects the nuclear axis. TRDdog was retained in smooth ER by binding to CSQ2-DsRed, but escaped to populate jSR puncta. TRDdog and (del)TRD were therefore able to elucidate areas of ER-SR transition. High levels of CSQ2-DsRed in the ER led to loss of jSR puncta labeling, suggesting a plasticity of ER-SR transition sites. We propose a model of ER and SR protein traffic along microtubules, with prominent transverse/radial ER trafficking of JCT and TRD along Z-lines to populate jSR, and an abundant longitudinal/axial smooth ER between and encircling myonuclei, from which jSR proteins traffic.

  5. Transitions of protein traffic from cardiac ER to junctional SR (United States)

    Sleiman, Naama H.; McFarland, Timothy P.; Jones, Larry R.; Cala, Steven E.


    The junctional sarcoplasmic reticulum (jSR) is an important and unique ER subdomain in the adult myocyte that concentrates resident proteins to regulate Ca2+ release. To investigate cellular mechanisms for sorting and trafficking proteins to jSR, we overexpressed canine forms of junctin (JCT) or triadin (TRD) in adult rat cardiomyocytes. Protein accumulation over time was visualized by confocal fluorescence microscopy using species-specific antibodies. Newly synthesized JCTdog and TRDdog appeared by 12-24 h as bright fluorescent puncta close to the nuclear surface, decreasing in intensity with increasing radial distance. With increasing time (24-48 h), fluorescent puncta appeared at further radial distances from the nuclear surface, eventually populating jSR similar to steady-state patterns. CSQ2-DsRed, a form of CSQ that polymerizes ectopically in rough ER, prevented anterograde traffic of newly made TRDdog and JCTdog, demonstrating common pathways of intracellular trafficking as well as in situ binding to CSQ2 in juxtanuclear rough ER. Reversal of CSQD-sRed interactions occurred when a form of TRDdog was used in which CSQ2-binding sites are removed (delTRD). With increasing levels of expression, CSQ2-DsRed revealed a novel smooth ER network that surrounds nuclei and connects the nuclear axis. TRDdog was retained in smooth ER by binding to CSQ2-DsRed, but escaped to populate jSR puncta. TRDdog and del TRD were therefore able to elucidate areas of ER-SR transition. High levels of CSQ2-DsRed in the ER led to loss of jSR puncta labeling, suggesting a plasticity of ER-SR transition sites. We propose a model of ER and SR protein traffic along microtubules, with prominent transverse/radial ER trafficking of JCT and TRD along Z-lines to populate jSR, and an abundant longitudinal/axial smooth ER between and encircling myonuclei, from which jSR proteins traffic. PMID:25640161

  6. Placental endoplasmic reticulum stress and acidosis: relevant aspects in gestational diabetes. (United States)

    Jawerbaum, Alicia


    In this issue, Yung and colleagues (doi: 10.1007/s00125-016-4040-2 ) report endoplasmic reticulum stress in the placenta of patients with gestational diabetes mellitus. With the use of a trophoblast-like cell line, these authors identify putative mechanisms involved in, and treatments to prevent the induction of endoplasmic reticulum stress. Here, the relevance and possible implications of these findings and areas for further research are discussed.

  7. Sodium Butyrate Induces Endoplasmic Reticulum Stress and Autophagy in Colorectal Cells: Implications for Apoptosis


    Jintao Zhang; Man Yi; Longying Zha; Siqiang Chen; Zhijia Li; Cheng Li; Mingxing Gong; Hong Deng; Xinwei Chu; Jiehua Chen; Zheqing Zhang; Limei Mao; Suxia Sun


    Purpose Butyrate, a short-chain fatty acid derived from dietary fiber, inhibits proliferation and induces cell death in colorectal cancer cells. However, clinical trials have shown mixed results regarding the anti-tumor activities of butyrate. We have previously shown that sodium butyrate increases endoplasmic reticulum stress by altering intracellular calcium levels, a well-known autophagy trigger. Here, we investigated whether sodium butyrate-induced endoplasmic reticulum stress mediated au...

  8. Cardiac surgery 2015 reviewed. (United States)

    Doenst, Torsten; Strüning, Constanze; Moschovas, Alexandros; Gonzalez-Lopez, David; Essa, Yasin; Kirov, Hristo; Diab, Mahmoud; Faerber, Gloria


    For the year 2015, almost 19,000 published references can be found in PubMed when entering the search term "cardiac surgery". The last year has been again characterized by lively discussions in the fields where classic cardiac surgery and modern interventional techniques overlap. Lacking evidence in the field of coronary revascularization with either percutaneous coronary intervention or bypass surgery has been added. As in the years before, CABG remains the gold standard for the revascularization of complex stable triple-vessel disease. Plenty of new information has been presented comparing the conventional to transcatheter aortic valve implantation (TAVI) demonstrating similar short- and mid-term outcomes at high and low risk, but even a survival advantage with transfemoral TAVI at intermediate risk. In addition, there were many relevant and interesting other contributions from the purely operative arena. This review article will summarize the most pertinent publications in the fields of coronary revascularization, surgical treatment of valve disease, heart failure (i.e., transplantation and ventricular assist devices), and aortic surgery. While the article does not have the expectation of being complete and cannot be free of individual interpretation, it provides a condensed summary that is intended to give the reader "solid ground" for up-to-date decision-making in cardiac surgery.

  9. Cardiac hybrid imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gaemperli, Oliver [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland)


    Hybrid cardiac single photon emission computed tomography (SPECT)/CT imaging allows combined assessment of anatomical and functional aspects of cardiac disease. In coronary artery disease (CAD), hybrid SPECT/CT imaging allows detection of coronary artery stenosis and myocardial perfusion abnormalities. The clinical value of hybrid imaging has been documented in several subsets of patients. In selected groups of patients, hybrid imaging improves the diagnostic accuracy to detect CAD compared to the single imaging techniques. Additionally, this approach facilitates functional interrogation of coronary stenoses and guidance with regard to revascularization procedures. Moreover, the anatomical information obtained from CT coronary angiography or coronary artery calcium scores (CACS) adds prognostic information over perfusion data from SPECT. The use of cardiac hybrid imaging has been favoured by the dissemination of dedicated hybrid systems and the release of dedicated image fusion software, which allow simple patient throughput for hybrid SPECT/CT studies. Further technological improvements such as more efficient detector technology to allow for low-radiation protocols, ultra-fast image acquisition and improved low-noise image reconstruction algorithms will be instrumental to further promote hybrid SPECT/CT in research and clinical practice. (orig.)

  10. Cardiac tissue engineering

    Directory of Open Access Journals (Sweden)



    Full Text Available We hypothesized that clinically sized (1-5 mm thick,compact cardiac constructs containing physiologically high density of viable cells (~108 cells/cm3 can be engineered in vitro by using biomimetic culture systems capable of providing oxygen transport and electrical stimulation, designed to mimic those in native heart. This hypothesis was tested by culturing rat heart cells on polymer scaffolds, either with perfusion of culture medium (physiologic interstitial velocity, supplementation of perfluorocarbons, or with electrical stimulation (continuous application of biphasic pulses, 2 ms, 5 V, 1 Hz. Tissue constructs cultured without perfusion or electrical stimulation served as controls. Medium perfusion and addition of perfluorocarbons resulted in compact, thick constructs containing physiologic density of viable, electromechanically coupled cells, in contrast to control constructs which had only a ~100 mm thick peripheral region with functionally connected cells. Electrical stimulation of cultured constructs resulted in markedly improved contractile properties, increased amounts of cardiac proteins, and remarkably well developed ultrastructure (similar to that of native heart as compared to non-stimulated controls. We discuss here the state of the art of cardiac tissue engineering, in light of the biomimetic approach that reproduces in vitro some of the conditions present during normal tissue development.

  11. Protein bodies in leaves exchange contents through the endoplasmic reticulum

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    Reza eSaberianfar


    Full Text Available Protein bodies (PBs are organelles found in seeds whose main function is the storage of proteins that are used during germination for sustaining growth. PBs can also be induced to form in leaves when foreign proteins are produced at high levels in the endoplasmic reticulum (ER and when fused to one of three tags: Zera®, elastin-like polypeptides (ELP, or hydrophobin-I (HFBI. In this study, we investigate the differences between ELP, HFBI and Zera PB formation, packing, and communication. Our results confirm the ER origin of all three fusion-tag-induced PBs. We show that secretory pathway proteins can be sequestered into all types of PBs but with different patterns, and that different fusion tags can target a specific protein to different PBs. Zera PBs are mobile and dependent on actomyosin motility similar to ELP and HFBI PBs. We show in vivo trafficking of proteins between PBs using GFP photoconversion. We also show that protein trafficking between ELP or HFBI PBs is faster and proteins travel further when compared to Zera PBs. Our results indicate that fusion-tag-induced PBs do not represent terminally stored cytosolic organelles, but that they form in, and remain part of the ER, and dynamically communicate with each other via the ER. We hypothesize that the previously documented PB mobility along the actin cytoskeleton is associated with ER movement rather than independent streaming of detached organelles.

  12. Heme oxygenase-1 comes back to endoplasmic reticulum

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Pyo [School of Biological Sciences, Ulsan University (Korea, Republic of); Pae, Hyun-Ock [Department of Immunology, Wonkwang University School of Medicine (Korea, Republic of); Back, Sung Hun; Chung, Su Wol [School of Biological Sciences, Ulsan University (Korea, Republic of); Woo, Je Moon [Department of Opthalmology, Ulasn University Hospital (Korea, Republic of); Son, Yong [Department of Anesthesiology and Pain Medicine, Wonkwang University School of Medicine (Korea, Republic of); Chung, Hun-Taeg, E-mail: [School of Biological Sciences, Ulsan University (Korea, Republic of)


    Research highlights: {yields} Although multiple compartmentalization of HO-1 has been documented, the functional implication of this enzyme at these subcellular organelles is only partially elucidated. {yields} HO-1 expression at ER is induced by a diverse set of conditions that cause ER stressors. {yields} CO may induce HO-1 expression in human ECs by activating Nrf2 through PERK phosphorylation in a positive-feedback manner. {yields} ER-residing HO-1 and its cytoprotective activity against ER stress is discussed. -- Abstract: Originally identified as a rate-limiting enzyme for heme catabolism, heme oxygenase-1 (HO-1) has expanded its roles in anti-inflammation, anti-apoptosis and anti-proliferation for the last decade. Regulation of protein activity by location is well appreciated. Even though multiple compartmentalization of HO-1 has been documented, the functional implication of this enzyme at these subcellular organelles is only partially elucidated. In this review we discuss the endoplasmic reticulum (ER)-residing HO-1 and its cytoprotective activity against ER stress.

  13. A Molecular Web: Endoplasmic Reticulum Stress, Inflammation and Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Namrata eChaudhari


    Full Text Available Execution of fundamental cellular functions demands regulated protein folding homeostasis. Endoplasmic reticulum (ER is an active organelle existing to implement this function by folding and modifying secretory and membrane proteins. Loss of protein folding homeostasis is central to various diseases and budding evidences suggest ER stress as being a major contributor in the development or pathology of a diseased state besides other cellular stresses. The trigger for diseases may be diverse but, inflammation and/or ER stress may be basic mechanisms increasing the severity or complicating the condition of the disease. Chronic ER stress and activation of the unfolded protein response (UPR through endogenous or exogenous insults may result in impaired calcium and redox homeostasis, oxidative stress via protein overload thereby also influencing vital mitochondrial functions. Calcium released from the ER augments the production of mitochondrial Reactive Oxygen Species (ROS. Toxic accumulation of ROS within ER and mitochondria disturb fundamental organelle functions. Sustained ER stress is known to potentially elicit inflammatory responses via UPR pathways. Additionally, ROS generated through inflammation or mitochondrial dysfunction could accelerate ER malfunction. Dysfunctional UPR pathways has been associated with a wide range of diseases including several neurodegenerative diseases, stroke, metabolic disorders, cancer, inflammatory disease, diabetes mellitus, cardiovascular disease and others. In this review we have discussed the UPR signaling pathways, and networking between ER stress induced inflammatory pathways, oxidative stress and mitochondrial signaling events which further induce or exacerbate ER stress.

  14. Endoplasmic reticulum stress, diabetes mellitus, and tissue injury. (United States)

    Huang, Liu; Xie, Hong; Liu, Hao


    Endoplasmic reticulum (ER) stress is characterized by the accumulation of unfolded and misfolded proteins in the ER lumen. Unfolded and misfolded protein accumulation interferes with the ER function and triggers ER stress response. Thus, ER stress response, also called unfolded protein response (UPR), is an adaptive process that controls the protein amount in the ER lumen and the downstream protein demand. In normal conditions, the role of ER stress is to maintain ER homeostasis, restore ER function, and protect stressed cells from apoptosis, by coordinating gene expression, protein synthesis, and accelerating protein degradation through several molecular pathways. However, prolonged ER stress response plays a paradoxical role, which leads to cell damage, apoptosis, and concomitant tissue injuries. A number of tissue alterations are involved with diabetes mellitus progress and its comorbidities via ER stress. However, certain pharmacological agents affecting ER stress have been identified. In this review, we summarized the relationship between ER stress and insulin resistance development. Moreover, we aim to explain how ER stress influences type 2 diabetes mellitus (T2DM) development. In addition, we reviewed the literature on ER stress and UPR in three kinds of tissue injuries induced by T2DM. Finally, a retrospective analysis of the effects of anti-diabetes medications on ER stress is presented.

  15. Hyperhomocysteinemia,endoplasmic reticulum stress,and alcoholic liver injury

    Institute of Scientific and Technical Information of China (English)

    Cheng Ji; Neil Kaplowitz


    Deficiencies in vitamins or other factors (B6, B12, folic acid,betaine) and genetic disorders for the metabolism of the non-protein amino acid-homocysteine (Hcy) lead to hyperhomocysteinemia (Hhcy). Hhcy is an integral component of several disorders including cardiovascular disease, neurodegeneration, diabetes and alcoholic liver disease. Hhcy unleashes mediators of inflammation such as NFκB, IL-1β, IL-6, and IL-8, increases production of intracellular superoxide anion causing oxidative stress and reducing intracellular level of nitric oxide (NO), and induces endoplasmic reticulum (ER) stress which can explain many processes of Hcy-promoted cell injury such as apoptosis,fat accumulation, and inflammation. Animal models have played an important role in determining the biological effects of Hhcy. ER stress may also be involved in other liver diseases such as α1-antitrypsin (α1-AT) deficiency and hepatitis C and/or B virus infection. Future research should evaluate the possible potentiative effects of alcohol and hepatic virus infection on ER stress-induced liver injury, study potentially beneficial effects of lowering Hcy and preventing ER stress in alcoholic humans,and examine polymorphism of Hcy metabolizing enzymes as potential risk-factors for the development of Hhcy and liver disease.

  16. Arachidonoyl-specific diacylglycerol kinase ε and the endoplasmic reticulum

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    Tomoyuki Nakano


    Full Text Available The endoplasmic reticulum (ER comprises an interconnected membrane network, which is made up of lipid bilayer and associated proteins. This organelle plays a central role in the protein synthesis and sorting. In addition, it represents the synthetic machinery of phospholipids, the major constituents of the biological membrane. In this process, phosphatidic acid (PA serves as a precursor of all phospholipids, suggesting that PA synthetic activity is closely associated with the ER function. One enzyme responsible for PA synthesis is diacylglycerol kinase (DGK that phosphorylates diacylglycerol (DG to PA. DGK is composed of a family of enzymes with distinct features assigned to each isozyme in terms of structure, enzymology and subcellular localization. Of DGKs, DGKε uniquely exhibits substrate specificity toward arachidonate-containing DG and is shown to reside in the ER. Arachidonic acid, a precursor of bioactive eicosanoids, is usually acylated at the sn-2 position of phospholipids, being especially enriched in phosphoinositide. In this review, we focus on arachidonoyl-specific DGKε with respect to the historical context, molecular basis of the substrate specificity and ER-targeting, and functional implications in the ER.

  17. Small GTPases and Brucella entry into the endoplasmic reticulum. (United States)

    de Bolle, Xavier; Letesson, Jean-Jacques; Gorvel, Jean-Pierre


    A key determinant for intracellular pathogenic bacteria to ensure their virulence within host cells is their ability to bypass the endocytic pathway and to reach a safe niche of replication. In the case of Brucella, the bacterium targets the ER (endoplasmic reticulum) to create a replicating niche called the BCV (Brucella-containing vacuole). The ER is a suitable strategic place for pathogenic Brucella. Indeed, bacteria can be hidden from host cell defences to persist within the host, and they can take advantage of the membrane reservoir delivered by the ER to replicate. Interaction with the ER leads to the presence on the BCV of the GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and the small GTPase Rab2 known to be located on secretory vesicles that traffic between the ER and the Golgi apparatus. GAPDH and the small GTPase Rab2 controls Brucella replication at late times post-infection. A specific interaction between the human small GTPase Rab2 and a Brucella spp. protein named RicA was identified. Altered kinetics of intracellular trafficking and faster proliferation of the Brucella abortus ΔricA mutant was observed compared with the wild-type strain. RicA is the first reported effector with a proposed function for B. abortus.

  18. Endoplasmic Reticulum-Mediated Protein Quality Control in Arabidopsis

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    Jianming eLi


    Full Text Available A correct three-dimensional structure is crucial for the physiological functions of a protein, yet the folding of proteins to acquire native conformation is a fundamentally error-prone process. Eukaryotic organisms have evolved a highly conserved endoplasmic reticulum-mediated protein quality control (ERQC mechanism to monitor folding processes of secretory and membrane proteins, allowing export of only correctly folded proteins to their physiological destinations, retaining incompletely/mis-folded ones in the ER for additional folding attempts, marking and removing terminally-misfolded ones via a unique multiple-step degradation process known as ER-associate degradation (ERAD. Most of our current knowledge on ERQC and ERAD came from genetic and biochemical investigations in yeast and mammalian cells. Recent studies in the reference plant Arabidopsis thaliana uncovered homologous components and similar mechanisms in plants for monitoring protein folding and for retaining, repairing, and removing misfolded proteins. These studies also revealed critical roles of the plant ERQC/ERAD systems in regulating important biochemical/physiological processes, such as abiotic stress tolerance and plant defense. In this review, we discuss our current understanding about the molecular components and biochemical mechanisms of the plant ERQC/ERAD system in comparison to yeast and mammalian systems.

  19. The Endoplasmic Reticulum: A Social Network in Plant Cells

    Institute of Scientific and Technical Information of China (English)

    Jun Chen; Caitlin Doyle; Xingyun Qi; Huanquan Zheng


    The endoplasmic reticulum (ER) is an interconnected network comprised of ribosome-studded sheets and smooth tubules.The ER plays crucial roles in the biosynthesis and transport of proteins and lipids,and in calcium (Ca2+) regulation in compartmentalized eukaryotic cells including plant cells.To support its well-segregated functions,the shape of the ER undergoes notable changes in response to both developmental cues and outside influences.In this review,we will discuss recent findings on molecular mechanisms underlying the unique morphology and dynamics of the ER,and the importance of the interconnected ER network in cell polarity.In animal and yeast cells,two family proteins,the reticulons and DP1/Yop1,are required for shaping high-curvature ER tubules,while members of the atlastin family of dynamin-like GTPases are involved in the fusion of ER tubules to make an interconnected ER network.In plant cells,recent data also indicate that the reticulons are involved in shaping ER tubules,while RHD3,a plant member of the atlastin GTPases,is required for the generation of an interconnected ER network.We will also summarize the current knowledge on how the ER interacts with other membrane-bound organelles,with a focus on how the ER and Golgi interplay in plant cells.

  20. Coordination of Endoplasmic Reticulum (ER) Signaling During Maize Seed Development

    Energy Technology Data Exchange (ETDEWEB)

    Boston, Rebecca S.


    Seed storage reserves represent one of the most important sources of renewable fixed carbon and nitrogen found in nature. Seeds are well-adapted for diverting metabolic resources to synthesize storage proteins as well as enzymes and structural proteins needed for their transport and packaging into membrane bound storage protein bodies. Our underlying hypothesis is that the endoplasmic reticulum (ER) stress response provides the critical cellular control of metabolic flux required for optimal accumulation of storage reserves in seeds. This highly conserved response is a cellular mechanism to monitor the protein folding environment of the ER and restore homeostasis in the presence of unfolded or misfolded proteins. In seeds, deposition of storage proteins in protein bodies is a highly specialized process that takes place even in the presence of mutant proteins that no longer fold and package properly. The capacity of the ER to deposit these aberrant proteins in protein bodies during a period that extends several weeks provides an excellent model for deconvoluting the ER stress response of plants. We have focused in this project on the means by which the ER senses and responds to functional perturbations and the underlying intracellular communication that occurs among biosynthetic, trafficking and degradative pathways for proteins during seed development.

  1. Regulation of endoplasmic reticulum turnover by selective autophagy. (United States)

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Hübner, Christian A; Dikic, Ivan


    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication. Constant ER turnover and modulation is needed to meet different cellular requirements and autophagy has an important role in this process. However, its underlying regulatory mechanisms remain unexplained. Here we show that members of the FAM134 reticulon protein family are ER-resident receptors that bind to autophagy modifiers LC3 and GABARAP, and facilitate ER degradation by autophagy ('ER-phagy'). Downregulation of FAM134B protein in human cells causes an expansion of the ER, while FAM134B overexpression results in ER fragmentation and lysosomal degradation. Mutant FAM134B proteins that cause sensory neuropathy in humans are unable to act as ER-phagy receptors. Consistently, disruption of Fam134b in mice causes expansion of the ER, inhibits ER turnover, sensitizes cells to stress-induced apoptotic cell death and leads to degeneration of sensory neurons. Therefore, selective ER-phagy via FAM134 proteins is indispensable for mammalian cell homeostasis and controls ER morphology and turnover in mice and humans.

  2. Mechanisms of CFTR folding at the endoplasmic reticulum

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    Soo Jung Kim


    Full Text Available In the past decade much has been learned about how CFTR folds and misfolds as the etiologic cause of cystic fibrosis (CF. CFTR folding is complex and hierarchical, takes place in multiple cellular compartments and physical environments, and involves several large networks of folding machineries. Insertion of transmembrane (TM segments into the endoplasmic reticulum (ER membrane and tertiary folding of cytosolic domains begin cotranslationally as the nascent polypeptide emerges from the ribosome, whereas posttranslational folding establishes critical domain-domain contacts needed to form a physiologically stable structure. Within the membrane, N- and C-terminal TM helices are sorted into bundles that project from the cytosol to form docking sites for nucleotide binding domains, NBD1 and NBD2, which in turn form a sandwich dimer for ATP binding. While tertiary folding is required for domain assembly, proper domain assembly also reciprocally affects folding of individual domains analogous to a jigsaw puzzle wherein the structure of each interlocking piece influences its neighbors. Superimposed on this process is an elaborate proteostatic network of cellular chaperones and folding machineries that facilitate the timing and coordination of specific folding steps in and across the ER membrane. While the details of this process require further refinement, we finally have a useful framework to understand key folding defect(s caused by ∆F508 that provides a molecular target(s for the next generation of CFTR small molecule correctors aimed at the specific defect present in the majority of CF patients.

  3. Endoplasmic reticulum stress in adipose tissue augments lipolysis. (United States)

    Bogdanovic, Elena; Kraus, Nicole; Patsouris, David; Diao, Li; Wang, Vivian; Abdullahi, Abdikarim; Jeschke, Marc G


    The endoplasmic reticulum (ER) is an organelle important for protein synthesis and folding, lipid synthesis and Ca(2+) homoeostasis. Consequently, ER stress or dysfunction affects numerous cellular processes and has been implicated as a contributing factor in several pathophysiological conditions. Tunicamycin induces ER stress in various cell types in vitro as well as in vivo. In mice, a hallmark of tunicamycin administration is the development of fatty livers within 24-48 hrs accompanied by hepatic ER stress. We hypothesized that tunicamycin would induce ER stress in adipose tissue that would lead to increased lipolysis and subsequently to fatty infiltration of the liver and hepatomegaly. Our results show that intraperitoneal administration of tunicamycin rapidly induced an ER stress response in adipose tissue that correlated with increased circulating free fatty acids (FFAs) and glycerol along with decreased adipose tissue mass and lipid droplet size. Furthermore, we found that in addition to fatty infiltration of the liver as well as hepatomegaly, lipid accumulation was also present in the heart, skeletal muscle and kidney. To corroborate our findings to a clinical setting, we examined adipose tissue from burned patients where increases in lipolysis and the development of fatty livers have been well documented. We found that burned patients displayed significant ER stress within adipose tissue and that ER stress augments lipolysis in cultured human adipocytes. Our results indicate a possible role for ER stress induced lipolysis in adipose tissue as an underlying mechanism contributing to increases in circulating FFAs and fatty infiltration into other organs.

  4. Endoplasmic reticulum localization and activity of maize auxin biosynthetic enzymes. (United States)

    Kriechbaumer, Verena; Seo, Hyesu; Park, Woong June; Hawes, Chris


    Auxin is a major growth hormone in plants and the first plant hormone to be discovered and studied. Active research over >60 years has shed light on many of the molecular mechanisms of its action including transport, perception, signal transduction, and a variety of biosynthetic pathways in various species, tissues, and developmental stages. The complexity and redundancy of the auxin biosynthetic network and enzymes involved raises the question of how such a system, producing such a potent agent as auxin, can be appropriately controlled at all. Here it is shown that maize auxin biosynthesis takes place in microsomal as well as cytosolic cellular fractions from maize seedlings. Most interestingly, a set of enzymes shown to be involved in auxin biosynthesis via their activity and/or mutant phenotypes and catalysing adjacent steps in YUCCA-dependent biosynthesis are localized to the endoplasmic reticulum (ER). Positioning of auxin biosynthetic enzymes at the ER could be necessary to bring auxin biosynthesis in closer proximity to ER-localized factors for transport, conjugation, and signalling, and allow for an additional level of regulation by subcellular compartmentation of auxin action. Furthermore, it might provide a link to ethylene action and be a factor in hormonal cross-talk as all five ethylene receptors are ER localized.

  5. Chemical chaperones mitigate experimental asthma by attenuating endoplasmic reticulum stress. (United States)

    Makhija, Lokesh; Krishnan, Veda; Rehman, Rakhshinda; Chakraborty, Samarpana; Maity, Shuvadeep; Mabalirajan, Ulaganathan; Chakraborty, Kausik; Ghosh, Balaram; Agrawal, Anurag


    Endoplasmic reticulum (ER) stress and consequent unfolded protein response (UPR) are important in inflammation but have been poorly explored in asthma. We used a mouse model of allergic airway inflammation (AAI) with features of asthma to understand the role of ER stress and to explore potential therapeutic effects of inhaled chemical chaperones, which are small molecules that can promote protein folding and diminish UPR. UPR markers were initially measured on alternate days during a 7-day daily allergen challenge model. UPR markers increased within 24 hours after the first allergen challenge and peaked by the third challenge, before AAI was fully established (from the fifth challenge onward). Three chemical chaperones-glycerol, trehalose, and trimethylamine-N-oxide (TMAO)-were initially administered during allergen challenge (preventive regimen). TMAO, the most effective of these chemical chaperones and 4-phenylbutyric acid, a chemical chaperone currently in clinical trials, were further tested for potential therapeutic activities after AAI was established (therapeutic regimen). Chemical chaperones showed a dose-dependent reduction in UPR markers, airway inflammation, and remodeling in both regimens. Our results indicate an early and important role of the ER stress pathway in asthma pathogenesis and show therapeutic potential for chemical chaperones.

  6. Stress responses from the endoplasmic reticulum in cancer

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    Hironori eKato


    Full Text Available The endoplasmic reticulum (ER is a dynamic organelle that is essential for multiple cellular functions. During cellular stress conditions, including nutrient deprivation and dysregulation of protein synthesis, unfolded/misfolded proteins accumulate in the ER lumen, resulting in activation of the unfolded protein response (UPR. The UPR also contributes to the regulation of various intracellular signalling pathways such as calcium signalling and lipid signalling. More recently, the mitochondria-associated ER membrane (MAM, which is a site of close contact between the ER and mitochondria, has been shown to function as a platform for various intracellular stress responses including apoptotic signalling, inflammatory signalling, the autophagic response, and the UPR. Interestingly, in cancer, these signalling pathways from the ER are often dysregulated, contributing to cancer cell metabolism. Thus, the signalling pathway from the ER may be a novel therapeutic target for various cancers. In this review, we discuss recent research on the roles of stress responses from the ER, including the MAM.

  7. Reduction of endoplasmic reticulum Ca2+ levels favors plasma membrane surface exposure of calreticulin. (United States)

    Tufi, R; Panaretakis, T; Bianchi, K; Criollo, A; Fazi, B; Di Sano, F; Tesniere, A; Kepp, O; Paterlini-Brechot, P; Zitvogel, L; Piacentini, M; Szabadkai, G; Kroemer, G


    Some chemotherapeutic agents can elicit apoptotic cancer cell death, thereby activating an anticancer immune response that influences therapeutic outcome. We previously reported that anthracyclins are particularly efficient in inducing immunogenic cell death, correlating with the pre-apoptotic exposure of calreticulin (CRT) on the plasma membrane surface of anthracyclin-treated tumor cells. Here, we investigated the role of cellular Ca(2+) homeostasis on CRT exposure. A neuroblastoma cell line (SH-SY5Y) failed to expose CRT in response to anthracyclin treatment. This defect in CRT exposure could be overcome by the overexpression of Reticulon-1C, a manipulation that led to a decrease in the Ca(2+) concentration within the endoplasmic reticulum lumen. The combination of Reticulon-1C expression and anthracyclin treatment yielded more pronounced endoplasmic reticulum Ca(2+) depletion than either of the two manipulations alone. Chelation of intracellular (and endoplasmic reticulum) Ca(2+), targeted expression of the ligand-binding domain of the IP(3) receptor and inhibition of the sarco-endoplasmic reticulum Ca(2+)-ATPase pump reduced endoplasmic reticulum Ca(2+) load and promoted pre-apoptotic CRT exposure on the cell surface, in SH-SY5Y and HeLa cells. These results provide evidence that endoplasmic reticulum Ca(2+) levels control the exposure of CRT.

  8. Adiponectin protects rat myocardium against chronic intermittent hypoxia-induced injury via inhibition of endoplasmic reticulum stress.

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    Wenxiao Ding

    Full Text Available Obstructive sleep apnea syndrome (OSAS is associated with many cardiovascular disorders such as heart failure, hypertension, atherosclerosis, and arrhythmia and so on. Of the many associated factors, chronic intermittent hypoxia (CIH in particular is the primary player in OSAS. To assess the effects of CIH on cardiac function secondary to OSAS, we established a model to study the effects of CIH on Wistar rats. Specifically, we examined the possible underlying cellular mechanisms of hypoxic tissue damage and the possible protective role of adiponectin against hypoxic insults. In the first treatment group, rats were exposed to CIH conditions (nadir O2, 5-6% for 8 hours/day, for 5 weeks. Subsequent CIH-induced cardiac dysfunction was measured by echocardiograph. Compared with the normal control (NC group, rats in the CIH-exposed group experienced elevated levels of left ventricular end-systolic dimension and left ventricular end-systolic volume and depressed levels of left ventricular ejection fraction and left ventricular fractional shortening (p<0.05. However, when adiponectin (Ad was added in CIH + Ad group, we saw a rescue in the elevations of the aforementioned left ventricular function (p<0.05. To assess critical cardiac injury, we detected myocardial apoptosis by Terminal deoxynucleotidyl transfer-mediated dUTP nick end-labeling (TUNEL analysis. It was showed that the apoptosis percentage in CIH group (2.948% was significantly higher than that in NC group (0.4167% and CIH + Ad group (1.219% (p<0.05. Protein expressions of cleaved caspase-3, cleaved caspase-9, and cleaved-caspase-12 validated our TUNEL results (p<0.05. Mechanistically, our results demonstrated that the proteins expressed with endoplasmic reticulum stress and the expression of reactive oxygen species (ROS were significantly elevated under CIH conditions, whereas Ad supplementation partially decreased them. Overall, our results suggested that Ad augmentation could improve CIH

  9. Synchronization of stochastic Ca²(+) release units creates a rhythmic Ca²(+) clock in cardiac pacemaker cells. (United States)

    Maltsev, Anna V; Maltsev, Victor A; Mikheev, Maxim; Maltseva, Larissa A; Sirenko, Syevda G; Lakatta, Edward G; Stern, Michael D


    In sinoatrial node cells of the heart, beating rate is controlled, in part, by local Ca²(+) releases (LCRs) from the sarcoplasmic reticulum, which couple to the action potential via electrogenic Na(+)/Ca²(+) exchange. We observed persisting, roughly periodic LCRs in depolarized rabbit sinoatrial node cells (SANCs). The features of these LCRs were reproduced by a numerical model consisting of a two-dimensional array of stochastic, diffusively coupled Ca²(+) release units (CRUs) with fixed refractory period. Because previous experimental studies showed that β-adrenergic receptor stimulation increases the rate of Ca²(+) release through each CRU (dubbed I(spark)), we explored the link between LCRs and I(spark) in our model. Increasing the CRU release current I(spark) facilitated Ca²(+)-induced-Ca²(+) release and local recruitment of neighboring CRUs to fire more synchronously. This resulted in a progression in simulated LCR size (from sparks to wavelets to global waves), LCR rhythmicity, and decrease of LCR period that parallels the changes observed experimentally with β-adrenergic receptor stimulation. The transition in LCR characteristics was steeply nonlinear over a narrow range of I(spark), resembling a phase transition. We conclude that the (partial) periodicity and rate regulation of the "Calcium clock" in SANCs are emergent properties of the diffusive coupling of an ensemble of interacting stochastic CRUs. The variation in LCR period and size with I(spark) is sufficient to account for β-adrenergic regulation of SANC beating rate.

  10. Indeterminacy of Spatiotemporal Cardiac Alternans

    CERN Document Server

    Zhao, Xiaopeng


    Cardiac alternans, a beat-to-beat alternation in action potential duration (at the cellular level) or in ECG morphology (at the whole heart level), is a marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of thousands of people in the US each year. Investigating cardiac alternans may lead to a better understanding of the mechanisms of cardiac arrhythmias and eventually better algorithms for the prediction and prevention of such dreadful diseases. In paced cardiac tissue, alternans develops under increasingly shorter pacing period. Existing experimental and theoretical studies adopt the assumption that alternans in homogeneous cardiac tissue is exclusively determined by the pacing period. In contrast, we find that, when calcium-driven alternans develops in cardiac fibers, it may take different spatiotemporal patterns depending on the pacing history. Because there coexist multiple alternans solutions for a given pacing period, the alternans pattern on a fiber becomes unpredictable. Usin...

  11. CDIP1-BAP31 Complex Transduces Apoptotic Signals from Endoplasmic Reticulum to Mitochondria under Endoplasmic Reticulum Stress

    Directory of Open Access Journals (Sweden)

    Takushi Namba


    Full Text Available Resolved endoplasmic reticulum (ER stress response is essential for intracellular homeostatic balance, but unsettled ER stress can lead to apoptosis. Here, we show that a proapoptotic p53 target, CDIP1, acts as a key signal transducer of ER-stress-mediated apoptosis. We identify B-cell-receptor-associated protein 31 (BAP31 as an interacting partner of CDIP1. Upon ER stress, CDIP1 is induced and enhances an association with BAP31 at the ER membrane. We also show that CDIP1 binding to BAP31 is required for BAP31 cleavage upon ER stress and for BAP31-Bcl-2 association. The recruitment of Bcl-2 to the BAP31-CDIP1 complex, as well as CDIP1-dependent truncated Bid (tBid and caspase-8 activation, contributes to BAX oligomerization. Genetic knockout of CDIP1 in mice leads to impaired response to ER-stress-mediated apoptosis. Altogether, our data demonstrate that the CDIP1/BAP31-mediated regulation of mitochondrial apoptosis pathway represents a mechanism for establishing an ER-mitochondrial crosstalk for ER-stress-mediated apoptosis signaling.

  12. CDIP1-BAP31 complex transduces apoptotic signals from endoplasmic reticulum to mitochondria under endoplasmic reticulum stress. (United States)

    Namba, Takushi; Tian, Fang; Chu, Kiki; Hwang, So-Young; Yoon, Kyoung Wan; Byun, Sanguine; Hiraki, Masatsugu; Mandinova, Anna; Lee, Sam W


    Resolved endoplasmic reticulum (ER) stress response is essential for intracellular homeostatic balance, but unsettled ER stress can lead to apoptosis. Here, we show that a proapoptotic p53 target, CDIP1, acts as a key signal transducer of ER-stress-mediated apoptosis. We identify B-cell-receptor-associated protein 31 (BAP31) as an interacting partner of CDIP1. Upon ER stress, CDIP1 is induced and enhances an association with BAP31 at the ER membrane. We also show that CDIP1 binding to BAP31 is required for BAP31 cleavage upon ER stress and for BAP31-Bcl-2 association. The recruitment of Bcl-2 to the BAP31-CDIP1 complex, as well as CDIP1-dependent truncated Bid (tBid) and caspase-8 activation, contributes to BAX oligomerization. Genetic knockout of CDIP1 in mice leads to impaired response to ER-stress-mediated apoptosis. Altogether, our data demonstrate that the CDIP1/BAP31-mediated regulation of mitochondrial apoptosis pathway represents a mechanism for establishing an ER-mitochondrial crosstalk for ER-stress-mediated apoptosis signaling.

  13. Case Report: Penetrating Cardiac Injury

    Directory of Open Access Journals (Sweden)

    Adem Grbolar


    Full Text Available Summary: Penetrating cardiac injurys caused by gunshots and penetrating tools have high mortality rates. The way of injury, how the cardiac area is effected and the presence of cardiac tamponadecauses mortality in different rates. However the better treatment quality of hospitals, increasingoperative techniques, and internel care unit quality has not been change during the years. Searching the literature, we want to present a 42 years old male patient whowas injured by knife and had a 1 cm skin wound on chest with cardiac tamponade. After sternotomy a 7 cm laseration was observed in heart. Cardioraphy was performed.

  14. Cardiac surgery for Kartagener syndrome. (United States)

    Tkebuchava, T; von Segesser, L K; Niederhäuser, U; Bauersfeld, U; Turina, M


    Two patients (one girl, one boy) with Kartagener syndrome (situs inversus, bronchiectasis, sinusitis), despite pulmonary problems and associated congenital cardiac anomalies, were operated on at the ages of 4 years and 7 years, respectively. They had had previous palliative treatment at the age of 3 months and 1.3 years, respectively. Both postoperative periods after total correction were without significant complications. Long-term follow-up was available for 9 and 19 years, respectively, with no manifestations of heart insufficiency. Both patients are physically active, and neither requires cardiac medication. Patients with Kartagener syndrome and associated congenital cardiac anomalies can successfully undergo multiple cardiac operations with good long-term outcome.

  15. Endoplasmic reticulum stress is chronically activated in chronic pancreatitis. (United States)

    Sah, Raghuwansh P; Garg, Sushil K; Dixit, Ajay K; Dudeja, Vikas; Dawra, Rajinder K; Saluja, Ashok K


    The pathogenesis of chronic pancreatitis (CP) is poorly understood. Endoplasmic reticulum (ER) stress has now been recognized as a pathogenic event in many chronic diseases. However, ER stress has not been studied in CP, although pancreatic acinar cells seem to be especially vulnerable to ER dysfunction because of their dependence on high ER volume and functionality. Here, we aim to investigate ER stress in CP, study its pathogenesis in relation to trypsinogen activation (widely regarded as the key event of pancreatitis), and explore its mechanism, time course, and downstream consequences during pancreatic injury. CP was induced in mice by repeated episodes of acute pancreatitis (AP) based on caerulein hyperstimulation. ER stress leads to activation of unfolded protein response components that were measured in CP and AP. We show sustained up-regulation of unfolded protein response components ATF4, CHOP, GRP78, and XBP1 in CP. Overexpression of GRP78 and ATF4 in human CP confirmed the experimental findings. We used novel trypsinogen-7 knock-out mice (T(-/-)), which lack intra-acinar trypsinogen activation, to clarify the relationship of ER stress to intra-acinar trypsinogen activation in pancreatic injury. Comparable activation of ER stress was seen in wild type and T(-/-) mice. Induction of ER stress occurred through pathologic calcium signaling very early in the course of pancreatic injury. Our results establish that ER stress is chronically activated in CP and is induced early in pancreatic injury through pathologic calcium signaling independent of trypsinogen activation. ER stress may be an important pathogenic mechanism in pancreatitis that needs to be explored in future studies.

  16. Sertraline induces endoplasmic reticulum stress in hepatic cells. (United States)

    Chen, Si; Xuan, Jiekun; Couch, Letha; Iyer, Advait; Wu, Yuanfeng; Li, Quan-Zhen; Guo, Lei


    Sertraline is used for the treatment of depression, and is also used for the treatment of panic, obsessive-compulsive, and post-traumatic stress disorders. Previously, we have demonstrated that sertraline caused hepatic cytotoxicity, with mitochondrial dysfunction and apoptosis being underlying mechanisms. In this study, we used microarray and other biochemical and molecular analyses to identify endoplasmic reticulum (ER) stress as a novel molecular mechanism. HepG2 cells were exposed to sertraline and subjected to whole genome gene expression microarray analysis. Pathway analysis revealed that ER stress is among the significantly affected biological changes. We confirmed the increased expression of ER stress makers by real-time PCR and Western blots. The expression of typical ER stress markers such as PERK, IRE1α, and CHOP was significantly increased. To study better ER stress-mediated drug-induced liver toxicity; we established in vitro systems for monitoring ER stress quantitatively and efficiently, using Gaussia luciferase (Gluc) and secreted alkaline phosphatase (SEAP) as ER stress reporters. These in vitro systems were validated using well-known ER stress inducers. In these two reporter assays, sertraline inhibited the secretion of Gluc and SEAP. Moreover, we demonstrated that sertraline-induced apoptosis was coupled to ER stress and that the apoptotic effect was attenuated by 4-phenylbutyrate, a potent ER stress inhibitor. In addition, we showed that the MAP4K4-JNK signaling pathway contributed to the process of sertraline-induced ER stress. In summary, we demonstrated that ER stress is a mechanism of sertraline-induced liver toxicity.

  17. Full-length Ebola glycoprotein accumulates in the endoplasmic reticulum

    Directory of Open Access Journals (Sweden)

    Bhattacharyya Suchita


    Full Text Available Abstract The Filoviridae family comprises of Ebola and Marburg viruses, which are known to cause lethal hemorrhagic fever. However, there is no effective anti-viral therapy or licensed vaccines currently available for these human pathogens. The envelope glycoprotein (GP of Ebola virus, which mediates entry into target cells, is cytotoxic and this effect maps to a highly glycosylated mucin-like region in the surface subunit of GP (GP1. However, the mechanism underlying this cytotoxic property of GP is unknown. To gain insight into the basis of this GP-induced cytotoxicity, HEK293T cells were transiently transfected with full-length and mucin-deleted (Δmucin Ebola GP plasmids and GP localization was examined relative to the nucleus, endoplasmic reticulum (ER, Golgi, early and late endosomes using deconvolution fluorescent microscopy. Full-length Ebola GP was observed to accumulate in the ER. In contrast, GPΔmucin was uniformly expressed throughout the cell and did not localize in the ER. The Ebola major matrix protein VP40 was also co-expressed with GP to investigate its influence on GP localization. GP and VP40 co-expression did not alter GP localization to the ER. Also, when VP40 was co-expressed with the nucleoprotein (NP, it localized to the plasma membrane while NP accumulated in distinct cytoplasmic structures lined with vimentin. These latter structures are consistent with aggresomes and may serve as assembly sites for filoviral nucleocapsids. Collectively, these data suggest that full-length GP, but not GPΔmucin, accumulates in the ER in close proximity to the nuclear membrane, which may underscore its cytotoxic property.

  18. Klotho Ameliorates Chemically Induced Endoplasmic Reticulum (ER Stress Signaling

    Directory of Open Access Journals (Sweden)

    Srijita Banerjee


    Full Text Available Background: Both endoplasmic reticulum (ER stress, a fundamental cell response associated with stress-initiated unfolded protein response (UPR, and loss of Klotho, an anti-aging hormone linked to NF-κB-induced inflammation, occur in chronic metabolic diseases such as obesity and type 2 diabetes. We investigated if the loss of Klotho is causally linked to increased ER stress. Methods: We treated human renal epithelial HK-2, alveolar epithelial A549, HEK293, and SH-SH-SY5Y neuroblastoma cells with ER stress-inducing agents, thapsigargin and/or tunicamycin. Effects of overexpression or siRNA-mediated knockdown of Klotho on UPR signaling was investigated by immunoblotting and Real-time PCR. Results: Elevated Klotho levels in HK-2 cells decreased expression of ER stress markers phospho-IRE1, XBP-1s, BiP, CHOP, pJNK, and phospho-p38, all of which were elevated in response to tunicamycin and/or thapsigargin. Similar results were observed using A549 cells for XBP-1s, BiP, and CHOP in response to thapsigargin. Conversely, knockdown of Klotho in HEK 293 cells using siRNA caused further thapsigargin-induced increases in pIRE-1, XBP-1s, and BiP. Klotho overexpression in A549 cells blocked thapsigargin-induced caspase and PARP cleavage and improved cell viability. Conclusion: Our data indicate that Klotho has an important role in regulating ER stress and that loss of Klotho is causally linked to ER stress-induced apoptosis.

  19. Disulfide Mispairing During Proinsulin Folding in the Endoplasmic Reticulum. (United States)

    Haataja, Leena; Manickam, Nandini; Soliman, Ann; Tsai, Billy; Liu, Ming; Arvan, Peter


    Proinsulin folding within the endoplasmic reticulum (ER) remains incompletely understood, but it is clear that in mutant INS gene-induced diabetes of youth (MIDY), progression of the (three) native disulfide bonds of proinsulin becomes derailed, causing insulin deficiency, β-cell ER stress, and onset of diabetes. Herein, we have undertaken a molecular dissection of proinsulin disulfide bond formation, using bioengineered proinsulins that can form only two (or even only one) of the native proinsulin disulfide bonds. In the absence of preexisting proinsulin disulfide pairing, Cys(B19)-Cys(A20) (a major determinant of ER stress response activation and proinsulin stability) preferentially initiates B-A chain disulfide bond formation, whereas Cys(B7)-Cys(A7) can initiate only under oxidizing conditions beyond that existing within the ER of β-cells. Interestingly, formation of these two "interchain" disulfide bonds demonstrates cooperativity, and together, they are sufficient to confer intracellular transport competence to proinsulin. The three most common proinsulin disulfide mispairings in the ER appear to involve Cys(A11)-Cys(A20), Cys(A7)-Cys(A20), and Cys(B19)-Cys(A11), each disrupting the critical Cys(B19)-Cys(A20) pairing. MIDY mutations inhibit Cys(B19)-Cys(A20) formation, but treatment to force oxidation of this disulfide bond improves folding and results in a small but detectable increase of proinsulin export. These data suggest possible therapeutic avenues to ameliorate ER stress and diabetes.

  20. Transcriptional analysis implicates endoplasmic reticulum stress in bovine spongiform encephalopathy.

    Directory of Open Access Journals (Sweden)

    Yue Tang

    Full Text Available Bovine spongiform encephalopathy (BSE is a fatal, transmissible, neurodegenerative disease of cattle. To date, the disease process is still poorly understood. In this study, brain tissue samples from animals naturally infected with BSE were analysed to identify differentially regulated genes using Affymetrix GeneChip Bovine Genome Arrays. A total of 230 genes were shown to be differentially regulated and many of these genes encode proteins involved in immune response, apoptosis, cell adhesion, stress response and transcription. Seventeen genes are associated with the endoplasmic reticulum (ER and 10 of these 17 genes are involved in stress related responses including ER chaperones, Grp94 and Grp170. Western blotting analysis showed that another ER chaperone, Grp78, was up-regulated in BSE. Up-regulation of these three chaperones strongly suggests the presence of ER stress and the activation of the unfolded protein response (UPR in BSE. The occurrence of ER stress was also supported by changes in gene expression for cytosolic proteins, such as the chaperone pair of Hsp70 and DnaJ. Many genes associated with the ubiquitin-proteasome pathway and the autophagy-lysosome system were differentially regulated, indicating that both pathways might be activated in response to ER stress. A model is presented to explain the mechanisms of prion neurotoxicity using these ER stress related responses. Clustering analysis showed that the differently regulated genes found from the naturally infected BSE cases could be used to predict the infectious status of the samples experimentally infected with BSE from the previous study and vice versa. Proof-of-principle gene expression biomarkers were found to represent BSE using 10 genes with 94% sensitivity and 87% specificity.

  1. Endoplasmic reticulum stress: key promoter of rosacea pathogenesis. (United States)

    Melnik, Bodo C


    Recent scientific interest in the pathogenesis of rosacea focuses on abnormally high facial skin levels of cathelicidin and the trypsin-like serine protease kallikrein 5 (KLK5) that cleaves the cathelicidin precursor protein into the bioactive fragment LL-37, which exerts crucial proinflammatory, angiogenic and antimicrobial activities. Furthermore, increased expression of toll-like receptor 2 (TLR2) has been identified in rosacea skin supporting the participation of the innate immune system. Notably, TLRs are expressed on sensory neurons and increase neuronal excitability linking TLR signalling to the transmission of neuroinflammatory responses. It is the intention of this viewpoint to present a unifying concept that links all known clinical trigger factors of rosacea such as UV irradiation, heat, skin irritants and special foods to one converging point: enhanced endoplasmic reticulum (ER) stress that activates the unfolded protein response (UPR). ER stress via upregulation of transcription factor ATF4 increases TLR2 expression, resulting in enhanced production of cathelicidin and KLK5 mediating downstream proinflammatory, angiogenic and antimicrobial signalling. The presented concept identifies rosacea trigger factors as environmental stressors that enhance the skin's ER stress response. Exaggerated cutaneous ER stress that stimulates the TLR2-driven inflammatory response may involve sebocytes, keratinocytes, monocyte-macrophages and sensory cutaneous neurons. Finally, all antirosacea drugs are proposed to attenuate the ER stress signalling cascade at some point. Overstimulated ER stress signalling may have evolutionarily evolved as a compensatory mechanism to balance impaired vitamin D-driven LL-37-mediated antimicrobial defenses due to lower exposure of UV-B irradiation of the northern Celtic population.

  2. Hypokalemia and sudden cardiac death

    DEFF Research Database (Denmark)

    Kjeldsen, Keld


    Worldwide, approximately three million people suffer sudden cardiac death annually. These deaths often emerge from a complex interplay of substrates and triggers. Disturbed potassium homeostasis among heart cells is an example of such a trigger. Thus, hypokalemia and, also, more transient...... of fatal arrhythmia and sudden cardiac death a patient is, the more attention should be given to the potassium homeostasis....

  3. The Danish Cardiac Rehabilitation Database

    DEFF Research Database (Denmark)

    Zwisler, Ann-Dorthe; Rossau, Henriette Knold; Nakano, Anne


    AIM OF DATABASE: The Danish Cardiac Rehabilitation Database (DHRD) aims to improve the quality of cardiac rehabilitation (CR) to the benefit of patients with coronary heart disease (CHD). STUDY POPULATION: Hospitalized patients with CHD with stenosis on coronary angiography treated with percutane...

  4. Biosynthesis of cardiac natriuretic peptides

    DEFF Research Database (Denmark)

    Goetze, Jens Peter


    . An inefficient post-translational prohormone maturation will also affect the biology of the cardiac natriuretic peptide system. This review aims at summarizing the myocardial synthesis of natriuretic peptides focusing on B-type natriuretic peptide, where new data has disclosed cardiac myocytes as highly...

  5. [Cardiac myxoma with cerebral metastases]. (United States)

    Bazin, A; Peruzzi, P; Baudrillard, J C; Pluot, M; Rousseaux, P


    A 56 year old woman developed multiple metastases in the cerebrum and cerebellum, four years after cardiac intervention on a left atrial myxoma. The absence of stroke is noteworthy. Multiple high density lesions with contrast enhancement were seen by CT scan, suggesting metastatic neoplasms. Histological examination confirmed the diagnosis of metastases of cardiac myxoma. Only four cases were recorded in the literature.

  6. Health Instruction Packages: Cardiac Anatomy. (United States)

    Phillips, Gwen; And Others

    Text, illustrations, and exercises are utilized in these five learning modules to instruct nurses, students, and other health care professionals in cardiac anatomy and functions and in fundamental electrocardiographic techniques. The first module, "Cardiac Anatomy and Physiology: A Review" by Gwen Phillips, teaches the learner to draw…

  7. Pneumothorax in cardiac pacing

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard;


    AIM: To identify risk factors for pneumothorax treated with a chest tube after cardiac pacing device implantation in a population-based cohort.METHODS AND RESULTS: A nationwide cohort study was performed based on data on 28 860 patients from the Danish Pacemaker Register, which included all Danish...... patients who received their first pacemaker (PM) or cardiac resynchronization device from 1997 to 2008. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals for the association between risk factors and pneumothorax treated with a chest tube. The median...... age was 77 years (25th and 75th percentile: 69-84) and 55% were male (n = 15 785). A total of 190 patients (0.66%) were treated for pneumothorax, which was more often in women [aOR 1.9 (1.4-2.6)], and in patients with age >80 years [aOR 1.4 (1.0-1.9)], a prior history of chronic obstructive pulmonary...

  8. Leadership in cardiac surgery. (United States)

    Rao, Christopher; Patel, Vanash; Ibrahim, Michael; Ahmed, Kamran; Wong, Kathie A; Darzi, Ara; von Segesser, Ludwig K; Athanasiou, Thanos


    Despite the efficacy of cardiac surgery, less invasive interventions with more uncertain long-term outcomes are increasingly challenging surgery as first-line treatment for several congenital, degenerative and ischemic cardiac diseases. The specialty must evolve if it is to ensure its future relevance. More importantly, it must evolve to ensure that future patients have access to treatments with proven long-term effectiveness. This cannot be achieved without dynamic leadership; however, our contention is that this is not enough. The demands of a modern surgical career and the importance of the task at hand are such that the serendipitous emergence of traditional charismatic leadership cannot be relied upon to deliver necessary change. We advocate systematic analysis and strategic leadership at a local, national and international level in four key areas: Clinical Care, Research, Education and Training, and Stakeholder Engagement. While we anticipate that exceptional individuals will continue to shape the future of our specialty, the creation of robust structures to deliver collective leadership in these key areas is of paramount importance.

  9. Cytokines downregulate the sarcoendoplasmic reticulum pump Ca2+ ATPase 2b and deplete endoplasmic reticulum Ca2+, leading to induction of endoplasmic reticulum stress in pancreatic beta-cells

    DEFF Research Database (Denmark)

    Cardozo, Alessandra K; Ortis, Fernanda; Storling, Joachim


    , beta-cells showed marked sensitivity to apoptosis induced by SERCA blockers, as compared with fibroblasts. Cytokine-induced ER Ca(2+) depletion was paralleled by an NO-dependent induction of CHOP protein and activation of diverse components of the ER stress response, including activation of inositol......Cytokines and free radicals are mediators of beta-cell death in type 1 diabetes. Under in vitro conditions, interleukin-1beta (IL-1beta) + gamma-interferon (IFN-gamma) induce nitric oxide (NO) production and apoptosis in rodent and human pancreatic beta-cells. We have previously shown......, by microarray analysis of primary beta-cells, that IL-1beta + IFN-gamma decrease expression of the mRNA encoding for the sarcoendoplasmic reticulum pump Ca(2+) ATPase 2b (SERCA2b) while inducing expression of the endoplasmic reticulum stress-related and proapoptotic gene CHOP (C/EBP [CCAAT/enhancer binding...

  10. Ablation of C/EBP homologous protein increases the acute phase mortality and doesn't attenuate cardiac remodeling in mice with myocardial infarction. (United States)

    Luo, Guangjin; Li, Qingman; Zhang, Xiajun; Shen, Liang; Xie, Jiahe; Zhang, Jingwen; Kitakaze, Masafumi; Huang, Xiaobo; Liao, Yulin


    Endoplasmic reticulum stress is a proapoptotic and profibrotic stimulus. Ablation of C/EBP homologous protein (CHOP) is reported to reverse cardiac dysfunction by attenuating cardiac endoplasmic reticulum stress in mice with pressure overload or ischemia/reperfusion, but it is unclear whether loss of CHOP also inhibits cardiac remodeling induced by permanent-infarction. In mice with permanent ligation of left coronary artery, we found that ablation of CHOP increased the acute phase mortality. For the mice survived to 4 weeks, left ventricular anterior (LV) wall thickness was larger in CHOP knockout mice than in the wildtype littermates, while no difference was noted on posterior wall thickness, LV dimensions, LV fractional shortening and ejection fraction. Similarly, invasive assessment of LV hemodynamics, morphological analysis of heart and lung weight indexes, myocardial fibrosis and TUNEL-assessed apoptosis showed no significant differences between CHOP knockout mice and their wildtype ones, while in mice with ischemia for 45 min and reperfusion for 1 week, myocardial fibrosis and apoptosis in the infarct area were significantly attenuated in CHOP knockout mice. These findings indicate that ablation of CHOP doesn't ameliorate cardiac remodeling induced by permanent-myocardial infarction, which implicates that early reperfusion is a prerequisite for ischemic myocardium to benefit from CHOP inhibition.

  11. Endoplasmic reticulum stress in pathogenesis of diabetic retinopathy and effect of calcium dobesilate

    Institute of Scientific and Technical Information of China (English)

    Yu-Min Gui; Ming Zhao; Jie Ding


    Objective:To study the mechanism of endoplasmic reticulum stress in the pathogenesis of diabetic retinopathy and effect of calcium dobesilate.Methods:A total of 120 diabetic retinopathy patients treated in our hospital from January 2010 to September 2015 were enrolled in this article. The serum endoplasmic reticulum stress protein and interleukin protein expression levels were analyzed before and after calcium dobesilate treatment. A total of 55 cases of healthy subjects receiving physical examination in our hospital during the same period were taken as control group.Results:Serum endoplasmic reticulum stress proteins PERK, CHOP and IRE as well as interleukin proteins IL1, IL2, IL6 and IL10 expression significantly increased, serum MDA level significantly increased while SOD, CAT and GSHpx levels significantly decreased in diabetic retinopathy patients, and compared with control group (P<0.01); after calcium dobesilate treatment, above factors were significantly restored (P<0.01).Conclusions: Diabetic retinopathy is closely related to endoplasmic reticulum stress and calcium dobesilate treatment may improve diabetic retinopathy by inhibiting endoplasmic reticulum stress.

  12. β-adrenergic effects on cardiac myofilaments and contraction in an integrated rabbit ventricular myocyte model. (United States)

    Negroni, Jorge A; Morotti, Stefano; Lascano, Elena C; Gomes, Aldrin V; Grandi, Eleonora; Puglisi, José L; Bers, Donald M


    A five-state model of myofilament contraction was integrated into a well-established rabbit ventricular myocyte model of ion channels, Ca(2+) transporters and kinase signaling to analyze the relative contribution of different phosphorylation targets to the overall mechanical response driven by β-adrenergic stimulation (β-AS). β-AS effect on sarcoplasmic reticulum Ca(2+) handling, Ca(2+), K(+) and Cl(-) currents, and Na(+)/K(+)-ATPase properties was included based on experimental data. The inotropic effect on the myofilaments was represented as reduced myofilament Ca(2+) sensitivity (XBCa) and titin stiffness, and increased cross-bridge (XB) cycling rate (XBcy). Assuming independent roles of XBCa and XBcy, the model reproduced experimental β-AS responses on action potentials and Ca(2+) transient amplitude and kinetics. It also replicated the behavior of force-Ca(2+), release-restretch, length-step, stiffness-frequency and force-velocity relationships, and increased force and shortening in isometric and isotonic twitch contractions. The β-AS effect was then switched off from individual targets to analyze their relative impact on contractility. Preventing β-AS effects on L-type Ca(2+) channels or phospholamban limited Ca(2+) transients and contractile responses in parallel, while blocking phospholemman and K(+) channel (IKs) effects enhanced Ca(2+) and inotropy. Removal of β-AS effects from XBCa enhanced contractile force while decreasing peak Ca(2+) (due to greater Ca(2+) buffering), but had less effect on shortening. Conversely, preventing β-AS effects on XBcy preserved Ca(2+) transient effects, but blunted inotropy (both isometric force and especially shortening). Removal of titin effects had little impact on contraction. Finally, exclusion of β-AS from XBCa and XBcy while preserving effects on other targets resulted in preserved peak isometric force response (with slower kinetics) but nearly abolished enhanced shortening. β-AS effects on XBCa and XBcy

  13. The cardiac L-type calcium channel distal carboxy terminus autoinhibition is regulated by calcium. (United States)

    Crump, Shawn M; Andres, Douglas A; Sievert, Gail; Satin, Jonathan


    The L-type calcium channel (LTCC) provides trigger Ca(2+) for sarcoplasmic reticulum Ca-release, and LTCC function is influenced by interacting proteins including the LTCC distal COOH terminus (DCT) and calmodulin. DCT is proteolytically cleaved and reassociates with the LTCC complex to regulate calcium channel function. DCT reduces LTCC barium current (I(Ba,L)) in reconstituted channel complexes, yet the contribution of DCT to LTCC Ca(2+) current (I(Ca,L)) in cardiomyocyte systems is unexplored. This study tests the hypothesis that DCT attenuates cardiomyocyte I(Ca,L). We measured LTCC current and Ca(2+) transients with DCT coexpressed in murine cardiomyocytes. We also heterologously coexpressed DCT and Ca(V)1.2 constructs with truncations corresponding to the predicted proteolytic cleavage site, Ca(V)1.2Δ1801, and a shorter deletion corresponding to well-studied construct, Ca(V)1.2Δ1733. DCT inhibited I(Ba,L) in cardiomyocytes, and in human embryonic kidney (HEK) 293 cells expressing Ca(V)1.2Δ1801 and Ca(V)1.2Δ1733. Ca(2+)-CaM relieved DCT block in cardiomyocytes and HEK cells. The selective block of I(Ba,L) combined with Ca(2+)-CaM effects suggested that DCT-mediated blockade may be relieved under conditions of elevated Ca(2+). We therefore tested the hypothesis that DCT block is dynamic, increasing under relatively low Ca(2+), and show that DCT reduced diastolic Ca(2+) at low stimulation frequencies but spared high frequency Ca(2+) entry. DCT reduction of diastolic Ca(2+) and relief of block at high pacing frequencies and under conditions of supraphysiological bath Ca(2+) suggests that a physiological function of DCT is to increase the dynamic range of Ca(2+) transients in response to elevated pacing frequencies. Our data motivate the new hypothesis that DCT is a native reverse use-dependent inhibitor of LTCC current.

  14. The missing link in the mystery of normal automaticity of cardiac pacemaker cells. (United States)

    Lakatta, Edward G; Vinogradova, Tatiana M; Maltsev, Victor A


    Earlier studies of the initiating event of normal automaticity of the heart's pacemaker cells, inspired by classical quantitative membrane theory, focused upon ion currents (IK, I f) that determine the maximum diastolic potential and the early phase of the spontaneous diastolic depolarization (DD). These early DD events are caused by the prior action potential (AP) and essentially reflect a membrane recovery process. Events following the recovery process that ignite APs have not been recognized and remained a mystery until recently. These critical events are linked to rhythmic intracellular signals initiated by Ca2+ clock (i.e., sarcoplasmic reticulum [SR] cycling Ca2+). Sinoatrial cells, regardless of size, exhibit intense ryanodine receptor (RyR), Na+/Ca2+ exchange (NCX)-1, and SR Ca2+ ATPase-2 immunolabeling and dense submembrane NCX/RyR colocalization; Ca2+ clocks generate spontaneous stochastic but roughly periodic local subsarcolemmal Ca2+ releases (LCR). LCRs generate inward currents via NCX that exponentially accelerate the late DD. The timing and amplitude of LCR/I NCX-coupled events control the timing and amplitude of the nonlinear terminal DD and therefore ultimately control the chronotropic state by determining the timing of the I CaL activation that initiates the next AP. LCR period is precisely controlled by the kinetics of SR Ca2+ cycling, which, in turn, are regulated by 1) the status of protein kinase A-dependent phosphorylation of SR Ca2+ cycling proteins; and 2) membrane ion channels ensuring the Ca2+ homeostasis and therefore the Ca2+ available to Ca2+ clock. Thus, the link between early DD and next AP, missed in earlier studies, is ensured by a precisely physiologically regulated Ca2+ clock within pacemaker cells that integrates multiple Ca2+-dependent functions and rhythmically ignites APs during late DD via LCRs-I NCX coupling.

  15. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish

    Energy Technology Data Exchange (ETDEWEB)

    Christen, Verena [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Capelle, Martinus [Crucell, P.O. Box 2048, NL-2301 Leiden (Netherlands); Fent, Karl, E-mail: [University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz (Switzerland); Swiss Federal Institute of Technology Zürich, Department of Environmental Systems Science, CH-8092 Zürich (Switzerland)


    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL and Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6 h and 24 h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5 mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24 h at 0.1 and 5 mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. - Highlights: • Effects of silver nanoparticles (120 nm AgNPs) are investigated in zebrafish. • AgNPs induce all ER stress reponses in vitro in zebrafish liver cells. • AgNPs induce weak ER stress in zebrafish embryos. • AgNPs induce oxidative stress and transcripts of pro-apoptosis genes.

  16. Role of endoplasmic reticulum stress in the loss of retinal ganglion cells in diabetic retinopathy

    Institute of Scientific and Technical Information of China (English)

    Liping Yang; Lemeng Wu; Dongmei Wang; Ying Li; Hongliang Dou; Mark OMTso; Zhizhong Ma


    Endoplasmic reticulum stress is closely involved in the early stage of diabetic retinopathy. In the present study, a streptozotocin-induced diabetic animal model was given an intraperitoneal injection of tauroursodeoxycholic acid. Results from immunofluorescent co-localization experiments showed that both caspase-12 protein and c-Jun N-terminal kinase 1 phosphorylation levels significantly in-creased, which was associated with retinal ganglion celldeath in diabetic retinas. The C/ERB ho-mologous protein pathway directly contributed to glial reactivity, and was subsequently responsible for neuronal loss and vascular abnormalities in diabetic retinopathy. Our experimental findings in-dicate that endoplasmic reticulum stress plays an important role in diabetes-induced retinal neu-ronal loss and vascular abnormalities, and that inhibiting the activation of the endoplasmic reticulum stress pathway provides effective protection against diabetic retinopathy.

  17. Fructus Broussonetae extract improves cognitive function and endoplasmic reticulum stress in Alzheimer's disease models

    Institute of Scientific and Technical Information of China (English)

    Yinghong Li; Li Hu; Zhengzhi Wu; Zhiling Yu; Meiqun Cao; Kehuan Sun; Yu Jin; Anmin Wu; Andrew CJ Huang


    This study investigated the effects and possible targets of Fructus Broussonetiae extract, a traditional Chinese medicinal herb, on a model of Alzheimer's disease induced by beta-amyloid peptide 25-35 and D-galactose. The results revealed that intragastric administration of Fructus Broussonetiae significantly increased the expression of immunoglobulin-binding protein, a key factor in the endoplasmic reticulum stress-signaling pathway in rat hippocampus. In contrast, the treatment significantly decreased expression levels of PKR-like endoplasmic reticulum kinase and C/EBP homologous protein, and substantially improved learning, memory and spatial recognition dysfunction in rats. This evidence indicates that Fructus Broussonetiae extract improves spatial learning and memory abilities in rats by affecting the regulation of hippocampal endoplasmic reticulum stress and activation of the apoptosis pathway.

  18. Dark matter annihilation and decay profiles for the Reticulum II dwarf spheroidal galaxy

    CERN Document Server

    Bonnivard, V; Maurin, D; Geringer-Sameth, A; Koushiappas, S M; Walker, M G; Mateo, M; Olszewski, E; Bailey, J I


    The dwarf spheroidal galaxies (dSph) of the Milky Way are among the most attractive targets for indirect searches of dark matter. In this work, we reconstruct the dark matter annihilation (J-factor) and decay profiles for the newly discovered dSph Reticulum~II. This is done using an optimized spherical Jeans analysis of kinematic data obtained from the Michigan/Magellan Fiber System (M2FS). We find Reticulum~II to have one of the highest J-factor when compared to the other Milky Way dSphs. We have also checked the robustness of this result against several ingredients of the analysis. Unless it suffers from tidal disruption or significant inflation of its velocity dispersion from binary stars, Reticulum~II may provide a unique window on dark matter particle properties.

  19. Dark Matter Annihilation and Decay Profiles for the Reticulum II Dwarf Spheroidal Galaxy (United States)

    Bonnivard, Vincent; Combet, Céline; Maurin, David; Geringer-Sameth, Alex; Koushiappas, Savvas M.; Walker, Matthew G.; Mateo, Mario; Olszewski, Edward W.; Bailey, John I., III


    The dwarf spheroidal galaxies (dSph) of the Milky Way are among the most attractive targets for indirect searches of dark matter (DM). In this work, we reconstruct the DM annihilation (J-factor) and decay profiles for the newly discovered dSph Reticulum II. Using an optimized spherical Jeans analysis of kinematic data obtained from the Michigan/Magellan Fiber System, we find Reticulum II’s J-factor to be among the largest of any Milky Way dSph. We have checked the robustness of this result against several ingredients of the analysis. Unless it suffers from tidal disruption or significant inflation of its velocity dispersion from binary stars, Reticulum II may provide a unique window on DM particle properties.

  20. Physics of Cardiac Arrhythmogenesis (United States)

    Karma, Alain


    A normal heartbeat is orchestrated by the stable propagation of an excitation wave that produces an orderly contraction. In contrast, wave turbulence in the ventricles, clinically known as ventricular fibrillation (VF), stops the heart from pumping and is lethal without prompt defibrillation. I review experimental, computational, and theoretical studies that have shed light on complex dynamical phenomena linked to the initiation, maintenance, and control of wave turbulence. I first discuss advances made to understand the precursor state to a reentrant arrhythmia where the refractory period of cardiac tissue becomes spatiotemporally disordered; this is known as an arrhythmogenic tissue substrate. I describe observed patterns of transmembrane voltage and intracellular calcium signaling that can contribute to this substrate, and symmetry breaking instabilities to explain their formation. I then survey mechanisms of wave turbulence and discuss novel methods that exploit electrical pacing stimuli to control precursor patterns and low-energy pulsed electric fields to control turbulence.

  1. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong


    Full Text Available Sudden cardiac death remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g. serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products.

  2. Mediastinitis after cardiac transplantation

    Directory of Open Access Journals (Sweden)

    Noedir A. G. Stolf


    Full Text Available OBJECTIVE: Assessment of incidence and behavior of mediastinitis after cardiac transplantation. METHODS: From 1985 to 1999, 214 cardiac transplantations were performed, 12 (5.6% of the transplanted patients developed confirmed mediastinitis. Patient's ages ranged from 42 to 66 years (mean of 52.3±10.0 years and 10 (83.3% patients were males. Seven (58.3% patients showed sternal stability on palpation, 4 (33.3% patients had pleural empyema, and 2 (16.7% patients did not show purulent secretion draining through the wound. RESULTS: Staphylococcus aureus was the infectious agent identified in the wound secretion or in the mediastinum, or both, in 8 (66.7% patients. Staphylococcus epidermidis was identified in 2 (16.7% patients, Enterococcus faecalis in 1 (8.3% patient, and the cause of mediastinitis could not be determined in 1 (8.3% patient. Surgical treatment was performed on an emergency basis, and the extension of the débridement varied with local conditions. In 2 (16.7% patients, we chose to leave the surgical wound open and performed daily dressings with granulated sugar. Total sternal resection was performed in only 1 (8.3% patient. Out of this series, 5 (41.7% patients died, and the causes of death were related to the infection. Autopsy revealed persistence of mediastinitis in 1 (8.3% patient. CONCLUSION: Promptness in diagnosing mediastinitis and precocious surgical drainage have changed the natural evolution of this disease. Nevertheless, observance of the basic precepts of prophylaxis of infection is still the best way to treat mediastinitis.

  3. Cellular mechanisms for the slow phase of the Frank-Starling response. (United States)

    Bluhm, W F; Sung, D; Lew, W Y; Garfinkel, A; McCulloch, A D


    Following a step increase in sarcomere length, isometric cardiac muscle tension increases instantaneously by the Frank-Starling mechanism. In isolated papillary muscle and myocytes, there is an additional significant rise in developed tension over the following 15 min due to an unknown mechanism. This slow change in tension could not be explained by mechanical heterogeneity of the muscle preparations or by an increase in myofilament sensitivity to Ca2+. The slow change in tension was not dependent on sarcoplasmic reticulum Ca2+ loading assessed with rapid cooling contractures, and was not significantly altered by sarcoplasmic reticulum Ca2+ depletion (ryanodine) or inhibition of sarcoplasmic reticulum Ca2+ reuptake (cyclopiazonic acid). We used the Luo-Rudy ionic model of the ventricular myocyte together with a model of the length-dependent myofilament activation by Ca2+ to examine the effects of step changes in the parameters of sarcolemmal ion fluxes as possible mechanisms for the slow change in stress. The slow increase in tension was simulated by step changes in the Na+-K+ pump or Na+ leak currents, suggesting that the slow change in stress may be caused by length induced changes in Na+ fluxes. The model also predicted a slow increase in the magnitude of the initial repolarization during phase 1 of the action potential. The combination of experimental and computational models used in this investigation represents a valuable technique in elucidating the cellular mechanisms of fundamental processes in cardiac excitation-contraction coupling.

  4. Metoclopramide-induced cardiac arrest

    Directory of Open Access Journals (Sweden)

    Martha M. Rumore


    Full Text Available The authors report a case of cardiac arrest in a patient receiving intravenous (IV metoclopramide and review the pertinent literature. A 62-year-old morbidly obese female admitted for a gastric sleeve procedure, developed cardiac arrest within one minute of receiving metoclopramide 10 mg via slow intravenous (IV injection. Bradycardia at 4 beats/min immediately appeared, progressing rapidly to asystole. Chest compressions restored vital function. Electrocardiogram (ECG revealed ST depression indicative of myocardial injury. Following intubation, the patient was transferred to the intensive care unit. Various cardiac dysrrhythmias including supraventricular tachycardia (SVT associated with hypertension and atrial fibrillation occurred. Following IV esmolol and metoprolol, the patient reverted to normal sinus rhythm. Repeat ECGs revealed ST depression resolution without pre-admission changes. Metoclopramide is a non-specific dopamine receptor antagonist. Seven cases of cardiac arrest and one of sinus arrest with metoclopramide were found in the literature. The metoclopramide prescribing information does not list precautions or adverse drug reactions (ADRs related to cardiac arrest. The reaction is not dose related but may relate to the IV administration route. Coronary artery disease was the sole risk factor identified. According to Naranjo, the association was possible. Other reports of cardiac arrest, severe bradycardia, and SVT were reviewed. In one case, five separate IV doses of 10 mg metoclopramide were immediately followed by asystole repeatedly. The mechanism(s underlying metoclopramide’s cardiac arrest-inducing effects is unknown. Structural similarities to procainamide may play a role. In view of eight previous cases of cardiac arrest from metoclopramide having been reported, further elucidation of this ADR and patient monitoring is needed. Our report should alert clinicians to monitor patients and remain diligent in surveillance and

  5. Fetal cardiac rhabdomyoma: case report

    Directory of Open Access Journals (Sweden)

    Seyed Mostafa Ghavami


    Full Text Available Background: The primary manifestation of cardiac tumors in embryonic period is a very rare condition. Cardiac rhabdomyomas most frequently arise in the ventricular myocardium, they may also occur in the atria and the epicardial surface. In spite of its benign nature, the critical location of the tumor inside the heart can lead to lethal arrhythmias and chamber obstruction. Multiple rhabdomyomas are strongly associated with tuberous sclerosis which is associated with mental retardation and epilepsy of variable severity. Ultrasonography as a part of routine prenatal screening, is the best method for the diagnosis of cardiac rhabdomyomas. In the review of articles published in Iran, fetal cardiac rhabdomyoma was not reported. Case presentation: We report a case of cardiac rhabdomyoma on a 24-year-old gravid 1, referred to Day Medical Imaging Center for routine evaluation of fetal abnormalities at 31 weeks of her gestational age. Ultrasonographic examination displayed a homogenous echogenic mass (13×9mm, originating from the left ventricle of the fetal heart. It was a normal pregnancy without any specific complications. Other organs of the fetus were found normal and no cardiac abnormalities were appeared. No Pericardial fluid effusion was found. The parents did not have consanguineous marriage. They did not also have any specific disease such as tuberous sclerosis. Conclusion: The clinical features of cardiac rhabdomyomas vary widely, depending on the location, size, and number of tumors in the heart. Although cardiac rhabdomyoma is a benign tumor in many affected fetuses, an early prenatal diagnosis of the tumor is of great significance in making efficient planning and providing adequate follow up visits of the patients and the complications such as, heart failure and outlet obstruction of cardiac chambers.

  6. Sarco(endoplasmic Reticulum Ca2+-ATPase-2 Gene: Structure and Transcriptional Regulation of the Human Gene

    Directory of Open Access Journals (Sweden)

    Angel Zarain-Herzberg


    Full Text Available The sarco(endoplasmic reticulum Ca2+-ATPases (SERCAs belong to a family of active calcium transport enzymes encoded by the SERCA1, 2, and 3 genes. In this study, we describe the complete structure of the human SERCA2 gene and its 5’ -regulatory region. The hSERCA2 gene is located in chromosome 12 position q24.1 in Contig NT_009770.8, spans 70 kb, and is organized in 21 exons intervened by 20 introns. The last two exons of the pre-mRNA produce by alternatively splicing the cardiac/slow-twitch muscle-specific SERCA2a isoform and the ubiquitous SERCA2b isoform. The sequence of the proximal 225-bp regulatory region of the SERCA2 genes is 80% G+C-rich and is conserved among human, rabbit, rat, and mouse species. It contains a TATA-like-box, an E-box/USF sequence, a CAAT-box, four Sp1 binding sites, and a thyroid hormone responsive element (TRE. There are two other conserved regulatory regions located between positions -410 to -661 bp and from -919 to -1410 bp. Among the DNA cis-elements present in these two regulatory regions there are potential binding sites for: GATA-4, -5, -6, Nkx-2.5/Csx, OTF-1, USF, MEF-2, SRF, PPAR/RXR, AP-2, and TREs. Upstream from position -1.5 kb, there is no significant homology among the SERCA2 genes cloned. In addition, the human gene has several repeated sequences mainly of the Alu and L2 type located upstream from position -1.7 kb, spanning in a continuous fashion for more than 40 kb. In this study, we report the cloning of 2.4 kb of 5’-regulatory region and demonstrate that the proximal promoter region is sufficient for expression in cardiac myocytes, and the region from -225 to -1232 bp contains regulatory DNA elements which down-regulate the expression of the SERCA2 gene in neonatal cardiomyocytes.

  7. The endoplasmic reticulum:A dynamic and well-connected organelle

    Institute of Scientific and Technical Information of China (English)

    Chris Hawes; Petra Kiviniemi; Verena Kriechbaumer


    The endoplasmic reticulum forms the first compart-ment in a series of organel es which comprise the secretory pathway. It takes the form of an extremely dynamic and pleomorphic membrane-bounded network of tubules and cisternae which have numerous different cel ular functions. In this review, we discuss the nature of endoplasmic reticulum structure and dynamics, its relationship with closely associated organel es, and its possible function as a highway for the distribution and delivery of a diverse range of structures from metabolic complexes to viral particles.

  8. Epigenetic regulation in cardiac fibrosis

    Institute of Scientific and Technical Information of China (English)

    Li-Ming; Yu; Yong; Xu


    Cardiac fibrosis represents an adoptive response in the heart exposed to various stress cues. While resolution of the fibrogenic response heralds normalization of heart function, persistent fibrogenesis is usually associated with progressive loss of heart function and eventually heart failure. Cardiac fibrosis is regulated by a myriad of factors that converge on the transcription of genes encoding extracellular matrix proteins, a process the epigenetic machinery plays a pivotal role. In this minireview, we summarize recent advances regarding the epigenetic regulation of cardiac fibrosis focusing on the role of histone and DNA modifications and non-coding RNAs.

  9. Cardiac Involvement in Ankylosing Spondylitis (United States)

    Ozkan, Yasemin


    Ankylosing spondylitis is one of the subgroup of diseases called “seronegative spondyloarthropathy”. Frequently, it affects the vertebral colon and sacroiliac joint primarily and affects the peripheral joints less often. This chronic, inflammatory and rheumatic disease can also affect the extraarticular regions of the body. The extraarticular affections can be ophthalmologic, cardiac, pulmonary or neurologic. The cardiac affection can be 2-10% in all patients. Cardiac complications such as left ventricular dysfunction, aortitis, aortic regurgitation, pericarditis and cardiomegaly are reviewed. PMID:27222669

  10. Acupuncture therapy related cardiac injury. (United States)

    Li, Xue-feng; Wang, Xian


    Cardiac injury is the most serious adverse event in acupuncture therapy. The causes include needling chest points near the heart, the cardiac enlargement and pericardial effusion that will enlarge the projected area on the body surface and make the proper depth of needling shorter, and the incorrect needling method of the points. Therefore, acupuncture practitioners must be familiar with the points of the heart projected area on the chest and the correct needling methods in order to reduce the risk of acupuncture therapy related cardiac injury.

  11. Normal cardiac function in mice with supraphysiological cardiac creatine levels. (United States)

    Santacruz, Lucia; Hernandez, Alejandro; Nienaber, Jeffrey; Mishra, Rajashree; Pinilla, Miguel; Burchette, James; Mao, Lan; Rockman, Howard A; Jacobs, Danny O


    Creatine and phosphocreatine levels are decreased in heart failure, and reductions in myocellular phosphocreatine levels predict the severity of the disease and portend adverse outcomes. Previous studies of transgenic mouse models with increased creatine content higher than two times baseline showed the development of heart failure and shortened lifespan. Given phosphocreatine's role in buffering ATP content, we tested the hypothesis whether elevated cardiac creatine content would alter cardiac function under normal physiological conditions. Here, we report the creation of transgenic mice that overexpress the human creatine transporter (CrT) in cardiac muscle under the control of the α-myosin heavy chain promoter. Cardiac transgene expression was quantified by qRT-PCR, and human CrT protein expression was documented on Western blots and immunohistochemistry using a specific anti-CrT antibody. High-energy phosphate metabolites and cardiac function were measured in transgenic animals and compared with age-matched, wild-type controls. Adult transgenic animals showed increases of 5.7- and 4.7-fold in the content of creatine and free ADP, respectively. Phosphocreatine and ATP levels were two times as high in young transgenic animals but declined to control levels by the time the animals reached 8 wk of age. Transgenic mice appeared to be healthy and had normal life spans. Cardiac morphometry, conscious echocardiography, and pressure-volume loop studies demonstrated mild hypertrophy but normal function. Based on our characterization of the human CrT protein expression, creatine and phosphocreatine content, and cardiac morphometry and function, these transgenic mice provide an in vivo model for examining the therapeutic value of elevated creatine content for cardiac pathologies.

  12. Use of cardiac biomarkers in neonatology. (United States)

    Vijlbrief, Daniel C; Benders, Manon J N L; Kemperman, Hans; van Bel, Frank; de Vries, Willem B


    Cardiac biomarkers are used to identify cardiac disease in term and preterm infants. This review discusses the roles of natriuretic peptides and cardiac troponins. Natriuretic peptide levels are elevated during atrial strain (atrial natriuretic peptide (ANP)) or ventricular strain (B-type natriuretic peptide (BNP)). These markers correspond well with cardiac function and can be used to identify cardiac disease. Cardiac troponins are used to assess cardiomyocyte compromise. Affected cardiomyocytes release troponin into the bloodstream, resulting in elevated levels of cardiac troponin. Cardiac biomarkers are being increasingly incorporated into clinical trials as indicators of myocardial strain. Furthermore, cardiac biomarkers can possibly be used to guide therapy and improve outcome. Natriuretic peptides and cardiac troponins are potential tools in the diagnosis and treatment of neonatal disease that is complicated by circulatory compromise. However, clear reference ranges need to be set and validation needs to be carried out in a population of interest.

  13. Recent developments in cardiac pacing. (United States)

    Rodak, D J


    Indications for cardiac pacing continue to expand. Pacing to improve functional capacity, which is now common, relies on careful patient selection and technical improvements, such as complex software algorithms and diagnostic capabilities.

  14. Robotic Applications in Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Alan P. Kypson


    Full Text Available Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery.

  15. Cardiac manifestations in systemic sclerosis

    Institute of Scientific and Technical Information of China (English)

    Sevdalina; Lambova


    Primary cardiac involvement, which develops as a direct consequence of systemic sclerosis(SSc), may manifest as myocardial damage, fibrosis of the conduction system, pericardial and, less frequently, as valvular disease. In addition, cardiac complications in SSc may develop as a secondary phenomenon due to pulmonary arterial hypertension and kidney pathology. The prevalence of primary cardiac involvement in SSc is variable and difficult to determine because of the diversity of cardiac manifestations, the presence of subclinical periods, the type of diagnostic tools applied, and the diversity of patient populations. When clinically manifested, cardiac involvement is thought to be an important prognostic factor. Profound microvascular disease is a pathognomonic feature of SSc, as both vasospasm and structural alterations are present. Such alterations are thought to predict macrovascular atherosclerosis over time. There are contradictory reports regarding the prevalence of atherosclerosis in SSc. According to some authors, the prevalence of atherosclerosis of the large epicardial coronary arteries is similar to that of the general population, in contrast with other rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the level of inflammation in SSc is inferior. Thus, the atherosclerotic process may not be as aggressive and not easily detectable in smaller studies. Echocardiography(especially tissue Doppler imaging), single-photon emission computed tomography, magnetic resonance imaging and cardiac computed tomography are sensitive techniques for earlier detection of both structural and functional scleroderma-related cardiac pathologies. Screening for subclinical cardiac involvement via modern, sensitive tools provides an opportunity for early diagnosis and treatment, which is of crucial importance for a positive outcome.

  16. Cardiac transplantation in Friedreich ataxia. (United States)

    Yoon, Grace; Soman, Teesta; Wilson, Judith; George, Kristen; Mital, Seema; Dipchand, Anne I; McCabe, Jane; Logan, William; Kantor, Paul


    In this article, we describe a 14-year-old boy with a confirmed diagnosis of Friedreich ataxia who underwent cardiac transplantation for left ventricular failure secondary to dilated cardiomyopathy with restrictive physiology. His neurological status prior to transplantation reflected early signs of neurological disease, with evidence of dysarthria, weakness, mild gait impairment, and limb ataxia. We review the ethical issues considered during the process leading to the decision to offer cardiac transplantation.

  17. Cardiac Transplantation in Friedreich Ataxia


    Yoon, Grace; Soman, Teesta; Wilson, Judith; George, Kristen; Mital, Seema; Dipchand, Anne I; McCabe, Jane; Logan, William; Kantor, Paul


    In this paper, we describe a 14-year-old boy with a confirmed diagnosis of Friedreich ataxia who underwent cardiac transplantation for left ventricular failure secondary to dilated cardiomyopathy with restrictive physiology. His neurological status prior to transplantation reflected early signs of neurologic disease, with evidence of dysarthria, weakness, mild gait impairment, and limb ataxia. We review the ethical issues considered during the process leading to the decision to offer cardiac ...

  18. [Stem cells and cardiac regeneration]. (United States)

    Perez Millan, Maria Ines; Lorenti, Alicia


    Stem cells are defined by virtue of their functional attributes: absence of tissue specific differentitated markers, capable of proliferation, able to self-maintain the population, able to produce a large number of differentiated, functional progeny, able to regenerate the tissue after injury. Cell therapy is an alternative for the treatment of several diseases, like cardiac diseases (cell cardiomyoplasty). A variety of stem cells could be used for cardiac repair: from cardiac and extracardiac sources. Each cell type has its own profile of advantages, limitations, and practicability issues in specific clinical settings. Differentiation of bone marrow stem cells to cardiomyocyte-like cells have been observed under different culture conditions. The presence of resident cardiac stem cell population capable of differentiation into cardiomyocyte or vascular lineage suggests that these cells could be used for cardiac tissue repair, and represent a great promise for clinical application. Stem cells mobilization by cytokines may also offer a strategy for cardiac regeneration. The use of stem cells (embryonic and adult) may hold the key to replacing cells lost in many devastating diseases. This potential benefit is a major focus for stem cell research.

  19. Cardiac Regeneration and Stem Cells. (United States)

    Zhang, Yiqiang; Mignone, John; MacLellan, W Robb


    After decades of believing the heart loses the ability to regenerate soon after birth, numerous studies are now reporting that the adult heart may indeed be capable of regeneration, although the magnitude of new cardiac myocyte formation varies greatly. While this debate has energized the field of cardiac regeneration and led to a dramatic increase in our understanding of cardiac growth and repair, it has left much confusion in the field as to the prospects of regenerating the heart. Studies applying modern techniques of genetic lineage tracing and carbon-14 dating have begun to establish limits on the amount of endogenous regeneration after cardiac injury, but the underlying cellular mechanisms of this regeneration remained unclear. These same studies have also revealed an astonishing capacity for cardiac repair early in life that is largely lost with adult differentiation and maturation. Regardless, this renewed focus on cardiac regeneration as a therapeutic goal holds great promise as a novel strategy to address the leading cause of death in the developed world.

  20. Cardiac imaging. A multimodality approach

    Energy Technology Data Exchange (ETDEWEB)

    Thelen, Manfred [Johannes Gutenberg University Hospital, Mainz (Germany); Erbel, Raimund [University Hospital Essen (Germany). Dept. of Cardiology; Kreitner, Karl-Friedrich [Johannes Gutenberg University Hospital, Mainz (Germany). Clinic and Polyclinic for Diagnostic and Interventional Radiology; Barkhausen, Joerg (eds.) [University Hospital Schleswig-Holstein, Luebeck (Germany). Dept. of Radiology and Nuclear Medicine


    An excellent atlas on modern diagnostic imaging of the heart Written by an interdisciplinary team of experts, Cardiac Imaging: A Multimodality Approach features an in-depth introduction to all current imaging modalities for the diagnostic assessment of the heart as well as a clinical overview of cardiac diseases and main indications for cardiac imaging. With a particular emphasis on CT and MRI, the first part of the atlas also covers conventional radiography, echocardiography, angiography and nuclear medicine imaging. Leading specialists demonstrate the latest advances in the field, and compare the strengths and weaknesses of each modality. The book's second part features clinical chapters on heart defects, endocarditis, coronary heart disease, cardiomyopathies, myocarditis, cardiac tumors, pericardial diseases, pulmonary vascular diseases, and diseases of the thoracic aorta. The authors address anatomy, pathophysiology, and clinical features, and evaluate the various diagnostic options. Key features: - Highly regarded experts in cardiology and radiology off er image-based teaching of the latest techniques - Readers learn how to decide which modality to use for which indication - Visually highlighted tables and essential points allow for easy navigation through the text - More than 600 outstanding images show up-to-date technology and current imaging protocols Cardiac Imaging: A Multimodality Approach is a must-have desk reference for cardiologists and radiologists in practice, as well as a study guide for residents in both fields. It will also appeal to cardiac surgeons, general practitioners, and medical physicists with a special interest in imaging of the heart. (orig.)

  1. Recurrent late cardiac tamponade following cardiac surgery : a deceiving and potentially lethal complication

    NARCIS (Netherlands)

    Harskamp, Ralf E.; Meuzelaar, Jacobus J.


    Background - Cardiac tamponade, characterized by inflow obstruction of the heart chambers by extracardiac compression, is a potentially lethal complication following cardiac surgery. Case report - We present a case of recurrent cardiac tamponade following valve surgery. At first presentation, diagno

  2. Risk factors and the effect of cardiac resynchronization therapy on cardiac and non-cardiac mortality in MADIT-CRT

    DEFF Research Database (Denmark)

    Perkiomaki, Juha S; Ruwald, Anne-Christine; Kutyifa, Valentina;


    causes, 108 (63.9%) deemed cardiac, and 61 (36.1%) non-cardiac. In multivariate analysis, increased baseline creatinine was significantly associated with both cardiac and non-cardiac deaths [hazard ratio (HR) 2.97, P ...AIMS: To understand modes of death and factors associated with the risk for cardiac and non-cardiac deaths in patients with cardiac resynchronization therapy with implantable cardioverter-defibrillator (CRT-D) vs. implantable cardioverter-defibrillator (ICD) therapy, which may help clarify...... the action and limitations of cardiac resynchronization therapy (CRT) in relieving myocardial dysfunction. METHODS AND RESULTS: In Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy (MADIT-CRT), during 4 years of follow-up, 169 (9.3%) of 1820 patients died of known...

  3. Cardiac output during exercise

    DEFF Research Database (Denmark)

    Siebenmann, C; Rasmussen, P.; Sørensen, H.


    Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from...... the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2  = 12%). While all four methods reported...... a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO2) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q(Fick-M), Q(Inn), QP hys and Q(Pulse), respectively; P = 0...

  4. [Calpains and cardiac diseases]. (United States)

    Perrin, C; Vergely, C; Rochette, L


    Calpains are a large family of cytosolic cysteine proteases composed of at least fourteen distinct isoforms. The family can be divided into two groups on the basis of distribution: ubiquitous and tissue-specific. Our current knowledge about calpains properties apply mainly to the ubiquitous isozymes, micro- and milli-calpain (classic calpains). These forms are activated after autolysis. Translocation and subsequent interactions with phospholipids of these enzymes increase their activity. Calpains are able to cleave a subset of substrates, as enzymes, structural and signalling proteins. Cardiac pathologies, such as heart failure, atrial fibrillation or clinical states particularly ischemia reperfusion, are associated with an increase of cytosolic calcium and in this regards, calpain activation has been evoked as one of the mediators leading to myocardial damage. Calpain activities have been shown to be increased in hearts experimentally subjected to ischemia reperfusion or during hypertrophy, but also in atrial tissue harvested from patients suffering from atrial fibrillations. These activities have been related to an increase of the proteolysis of different myocardial components, particularly, troponins, which are major regulators of the contraction of cardiomyocytes. Moreover, recent works have demonstrated that calpains are involved in the development of myocardial cell death by necrosis or apoptosis.

  5. Cardiac Imaging System (United States)


    Although not available to all patients with narrowed arteries, balloon angioplasty has expanded dramatically since its introduction with an estimated further growth to 562,000 procedures in the U.S. alone by 1992. Growth has fueled demand for higher quality imaging systems that allow the cardiologist to be more accurate and increase the chances of a successful procedure. A major advance is the Digital Cardiac Imaging (DCI) System designed by Philips Medical Systems International, Best, The Netherlands and marketed in the U.S. by Philips Medical Systems North America Company. The key benefit is significantly improved real-time imaging and the ability to employ image enhancement techniques to bring out added details. Using a cordless control unit, the cardiologist can manipulate images to make immediate assessment, compare live x-ray and roadmap images by placing them side-by-side on monitor screens, or compare pre-procedure and post procedure conditions. The Philips DCI improves the cardiologist's precision by expanding the information available to him.

  6. Grab a Golgi: Laser trapping of golgi bodies reveals in vivo Interactions with the endoplasmic reticulum

    NARCIS (Netherlands)

    Sparkes, I.A.; Ketelaar, T.; Ruijter, de N.C.A.; Hawes, C.


    In many vacuolate plant cells individual Golgi bodies appear to be attached to tubules of the pleiomorphic cortical endoplasmic reticulum (ER) network. Such observations culminated in the controversial mobile secretory unit hypothesis to explain transport of cargo from the ER to Golgi via Golgi atta

  7. Ceramide transport from endoplasmic reticulum to Golgi apparatus is not vesicle-mediated

    NARCIS (Netherlands)

    Kok, JW; Babia, T; Klappe, K; Egea, G; Hoekstra, D


    Ceramide (Cer) transfer from the endoplasmic reticulum (ER) to the Golgi apparatus was measured under conditions that block vesicle-mediated protein transfer. This was done either in intact cells by reducing the incubation temperature to 15 degrees C, or in streptolysin O-permeabilized cells by mani

  8. Effects of ginger extract on smooth muscle activity of sheep reticulum and rumen

    Directory of Open Access Journals (Sweden)

    Amin Mamaghani


    Full Text Available Reticulorumen hypomotility leads to the impaired physiologic functions of the digestive tract. Prokinetic action of ginger has been demonstrated in the laboratory animals and human. The aim of this study was to evaluate the effect of hydroalcoholic extract of ginger on contraction and motility of reticulum and rumen of ruminants. Collected samples of reticulum and rumen from eight sheep were investigated in vitro. The extract at the concentration of 0.1 and 1.0 mg L-1 had no effect on any preparations. Contraction of reticulum and rumen preparations was occurred at 10.0 and 100 mg L-1 concentrations (p < 0.05. Concentration of 1000 mg L-1 caused a relaxation in preparations contracted with 10.0 and 100 mg L-1. Likewise, the concentration of 1000 mg L-1 significantly (p < 0.05 inhibited ACh-induced contraction in both tissues. Six sheep were involved in electromyographic study. Administration of 40 mg kg-1 of the extract increased the overall frequency of contractions of the reticulum and rumen at the subsequent three days with the prominent increase at the second day (p < 0.05. Results of in vitro study indicated that hydroalcoholic extract of ginger contained spasmogenic and spasmolytic constituents. The results in vivo study represented evidences that the extract may have stimulant effect on reticulorumen motility in 40 mg kg-1 concentration.

  9. Water-mediated interactions influence the binding of thapsigargin to sarco/endoplasmic reticulum calcium adenosinetriphosphatase

    DEFF Research Database (Denmark)

    Paulsen, Eleonora S.; Villadsen, Jesper; Tenori, Eleonora;


    A crystal structure suggests four water molecules are present in the binding cavity of thapsigargin in sarco/endoplasmic reticulum calcium ATPase (SERCA). Computational chemistry indicates that three of these water molecules mediate an extensive hydrogen-bonding network between thapsigargin...

  10. Endoplasmic Reticulum Stress and Unfolded Protein Response in Cartilage Pathophysiology; Contributing Factors to Apoptosis and Osteoarthritis. (United States)

    Hughes, Alexandria; Oxford, Alexandra E; Tawara, Ken; Jorcyk, Cheryl L; Oxford, Julia Thom


    Chondrocytes of the growth plate undergo apoptosis during the process of endochondral ossification, as well as during the progression of osteoarthritis. Although the regulation of this process is not completely understood, alterations in the precisely orchestrated programmed cell death during development can have catastrophic results, as exemplified by several chondrodystrophies which are frequently accompanied by early onset osteoarthritis. Understanding the mechanisms that underlie chondrocyte apoptosis during endochondral ossification in the growth plate has the potential to impact the development of therapeutic applications for chondrodystrophies and associated early onset osteoarthritis. In recent years, several chondrodysplasias and collagenopathies have been recognized as protein-folding diseases that lead to endoplasmic reticulum stress, endoplasmic reticulum associated degradation, and the unfolded protein response. Under conditions of prolonged endoplasmic reticulum stress in which the protein folding load outweighs the folding capacity of the endoplasmic reticulum, cellular dysfunction and death often occur. However, unfolded protein response (UPR) signaling is also required for the normal maturation of chondrocytes and osteoblasts. Understanding how UPR signaling may contribute to cartilage pathophysiology is an essential step toward therapeutic modulation of skeletal disorders that lead to osteoarthritis.

  11. Management of the endoplasmic reticulum stress by activation of the heat shock response in yeast

    DEFF Research Database (Denmark)

    Hou, Jin; Tang, Hongting; Liu, Zihe;


    In yeast Saccharomyces cerevisiae, accumulation of misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates the unfolded protein response (UPR), which is mediated by Hac1p. The heat shock response (HSR) mediated by Hsf1p, mainly regulates cytosolic processes and protect...

  12. Comparing Galactic Center MSSM dark matter solutions to the Reticulum II gamma-ray data

    NARCIS (Netherlands)

    Achterberg, A.; van Beekveld, M.; Beenakker, W.; Caron, S.; Hendriks, L.


    Observations with the Fermi Large Area Telescope (LAT) indicate a possible small photon signal originating from the dwarf galaxy Reticulum II that exceeds the expected background between 2 GeV and 10 GeV . We have investigated two specific scenarios for annihilating WIMP dark matter within the pheno

  13. Respiratory metabolism and calorie restriction relieve persistent endoplasmic reticulum stress induced by calcium shortage in yeast

    DEFF Research Database (Denmark)

    Busti, Stefano; Mapelli, Valeria; Tripodi, Farida


    Calcium homeostasis is crucial to eukaryotic cell survival. By acting as an enzyme cofactor and a second messenger in several signal transduction pathways, the calcium ion controls many essential biological processes. Inside the endoplasmic reticulum (ER) calcium concentration is carefully regula...

  14. Increased cardiac workload by closure of the ductus arteriosus leads to hypertrophy and apoptosis rather than to hyperplasia in the late fetal period. (United States)

    van den Hoff, Maurice J B; Deprez, Ronald H Lekanne; Ruijter, Jan M; de Boer, Piet A J; Tesink-Taekema, Sabina; Buffing, Anita A; Lamers, Wouter H; Moorman, Antoon F M


    It is generally thought that adult mammalian cardiomyocytes compensate for an increased workload by hypertrophy, whereas fetal myocardium grows by cellular proliferation. We analyzed the response of late-fetal rat hearts upon an increased workload imposed by premature constriction of the ductus arteriosus with indomethacin. Initially the fetal heart responds by proliferative growth, as both wet weight and labeling index (bromodeoxyuridine incorporation) of the ventricles increased, whereas neither a change in the fibroblast fraction, ploidy and nucleation in the ventricles is observed. However, this hyperplastic growth is abrogated by a subsequent burst in apoptosis and followed by a hypertrophic response as based on a decrease in DNA and increase in both RNA and protein concentration. This hypertrophic growth was accompanied by a 1.4-fold increase in the volume of the cardiomyocytes. Changes in the molecular phenotype characteristic of pressure-overload hypertrophic growth accompany the process. Thus, the levels of expression of beta-myosin heavy chain and atrial natriuretic factor mRNA increased, of sarcoplasmic/endoplasmic reticulum ATPase (SERCA2) mRNA decreased, and of alpha-myosin heavy chain, phospholamban, and calsequestrin mRNA did not change. In situ hybridization showed that the pattern of mRNA expression changed first in the right ventricular wall and subsequently in the left ventricular free wall as well. It is concluded that pressure-overload imposed on the late-fetal heart induces limited proliferative growth complemented by extensive hypertrophic growth.

  15. Compensatory up-regulation of cardiac SR Ca2+-pump by heat-shock counteracts SR Ca2+-channel activation by ischemia/reperfusion. (United States)

    O'Brien, P J; Li, G O; Locke, M; Klabunde, R E; Ianuzzo, C D


    We tested the hypothesis that heat-shock protected myocardial Ca2+-cycling by sarcoplasmic reticulum from ischemia and reperfusion (I/R) injury. Twenty-four hours after increasing body temperature to 42 degrees C for 15 min, rat hearts were isolated, Langendorff-perfused, and subjected to 30 min ischemia then 30 min reperfusion. Left ventricles were homogenized and their ionized Ca2+ concentration monitored with indo- during Ca2+-uptake in the presence and absence of the Ca2+-release channel (CRC) modulator ryanodine. Tissue content of heat-shock protein 72 (HSP 72) was analyzed. Exposure to I/R resulted in a 37% enhancement of CRC activity but no effect on Ca2+-pumping activity, resulting in 25% decreased net Ca2+-uptake activity. Pre-exposure to heat-shock resulted in a 10-fold increase in HSP 72, and a 25% enhancement of maximal Ca2+-pumping activity which counteracted the effect of I/R on CRC and net Ca2+-uptake activities. This protection of SR Ca2+-cycling was associated with partial protection of myocardial physiological performance. Net Ca2+-uptake activity was correlated with the left ventricular developed pressure and its rate of change. We conclude that one of the mechanisms by which heat-shock protects myocardium from I/R injury is to upregulate SR Ca2+-pumping activity to counteract the enhanced SR Ca2+-release produced by I/R.

  16. Temperature sensitivity of cardiac function in pelagic fishes with different vertical mobilities: yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus), mahimahi (Coryphaena hippurus), and swordfish (Xiphias gladius). (United States)

    Galli, Gina L J; Shiels, Holly A; Brill, Richard W


    We measured the temperature sensitivity, adrenergic sensitivity, and dependence on sarcoplasmic reticulum (SR) Ca(2+) of ventricular muscle from pelagic fishes with different vertical mobility patterns: bigeye tuna (Thunnus obesus), yellowfin tuna (Thunnus albacares), and mahimahi (Coryphaena hippurus) and a single specimen from swordfish (Xiphias gladius). Ventricular muscle from the bigeye tuna and mahimahi exhibited a biphasic response to an acute decrease in temperature (from 26 degrees to 7 degrees C); twitch force and kinetic parameters initially increased and then declined. The magnitude of this response was larger in the bigeye tuna than in the mahimahi. Under steady state conditions at 26 degrees C, inhibition of SR Ca(2+) release and reuptake with ryanodine and thapsigargin decreased twitch force and kinetic parameters, respectively, in the bigeye tuna only. However, the initial inotropy associated with decreasing temperature was abolished by SR inhibition in both the bigeye tuna and the mahimahi. Application of adrenaline completely reversed the effects of ryanodine and thapsigargin, but this effect was diminished at cold temperatures. In the yellowfin tuna, temperature and SR inhibition had minor effects on twitch force and kinetics, while adrenaline significantly increased these parameters. Limited data suggest that swordfish ventricular muscle responds to acute temperature reduction, SR inhibition, and adrenergic stimulation in a manner similar to that of bigeye tuna ventricular muscle. In aggregate, our results show that the temperature sensitivity, SR dependence, and adrenergic sensitivity of pelagic fish hearts are species specific and that these differences reflect species-specific vertical mobility patterns.

  17. Dying from cardiac tamponade

    Directory of Open Access Journals (Sweden)

    Powari Manish


    Full Text Available Abstract Background To determine the causes of cardiac tamponade (CT, focussing especially on haemopericardium (HP, as a terminal mode of death, within a 430,000 rural English population. Methods Our hospital mortuary register and, all postmortem reports between 1995 and 2004 inclusive, were interrogated for patients dying of CT or HP. The causes of CT/HP and selected morphological characteristics were then determined. Results 14,368 postmortems were performed in this period: of these, 461 patients died of CT. Three cases were due to non-haemorrhagic pericardial effusion. HP accounted for the remaining 458 cases of which, five were post-traumatic, 311 followed rupture of an acute myocardial infarction (RAMI, 138 after intra-pericardial rupture of dissecting ascending aortic aneurysms (RD3A and four were due to miscellaneous causes. HP was more commonly due to RAMI. Men tended to die from RAMI or RD3A earlier than women. RAMI or RD3A were commoner in men Two thirds of RAMI were associated with coronary artery thrombosis. Anterior free wall rupture was commonest overall, and in women, but posterior free wall rupture was commoner in men. The volume of intrapericardial blood in RAMI (mean = 440 ml and RD3A (mean = 498 ml varied between 150 and 1000 ml: intrapericardial blood volume was greater in men than in women dying from either RAMI or RD3A. Conclusion At postmortem, CT is most often related to HP, attributable to either RAMI or intrapericardial RD3A. Post-traumatic and other causes of CT are infrequent.

  18. Cardiac output monitoring

    Directory of Open Access Journals (Sweden)

    Mathews Lailu


    Full Text Available Minimally invasive and non-invasive methods of estimation of cardiac output (CO were developed to overcome the limitations of invasive nature of pulmonary artery catheterization (PAC and direct Fick method used for the measurement of stroke volume (SV. The important minimally invasive techniques available are: oesophageal Doppler monitoring (ODM, the derivative Fick method (using partial carbon dioxide (CO 2 breathing, transpulmonary thermodilution, lithium indicator dilution, pulse contour and pulse power analysis. Impedance cardiography is probably the only non-invasive technique in true sense. It provides information about haemodynamic status without the risk, cost and skill associated with the other invasive or minimally invasive techniques. It is important to understand what is really being measured and what assumptions and calculations have been incorporated with respect to a monitoring device. Understanding the basic principles of the above techniques as well as their advantages and limitations may be useful. In addition, the clinical validation of new techniques is necessary to convince that these new tools provide reliable measurements. In this review the physics behind the working of ODM, partial CO 2 breathing, transpulmonary thermodilution and lithium dilution techniques are dealt with. The physical and the physiological aspects underlying the pulse contour and pulse power analyses, various pulse contour techniques, their development, advantages and limitations are also covered. The principle of thoracic bioimpedance along with computation of CO from changes in thoracic impedance is explained. The purpose of the review is to help us minimize the dogmatic nature of practice favouring one technique or the other.

  19. Patch in Cardiac Surgery

    Directory of Open Access Journals (Sweden)

    Alireza Alizadeh Ghavidel


    Full Text Available Introduction: Excessive bleeding presents a risk for the patient in cardiovascular surgery. Local haemostatic agents are of great value to reduce bleeding and related complications. TachoSil (Nycomed, Linz, Austria is a sterile, haemostatic agent that consists of an equine collagen patchcoated with human fibrinogen and thrombin. This study evaluated the safety and efficacy of TachoSil compared to conventional technique.Methods: Forty-two patients scheduled for open heart surgeries, were entered to this study from August 2010 to May 2011. After primary haemostatic measures, patients divided in two groups based on surgeon’s judgment. Group A: 20 patients for whom TachoSil was applied and group B: 22 patients that conventional method using Surgicel (13 patients or wait and see method (9 cases, were performed in order to control the bleeding. In group A, 10 patients were male with mean age of 56.95±15.67 years and in group B, 9 cases were male with mean age of 49.95±14.41 years. In case group 70% (14/20 of the surgeries were redo surgeries versus 100% (22/22 in control group.Results: Baseline characteristics were similar in both groups. In TachoSil group 75% of patients required transfusion versus 90.90% in group B (P=0.03.Most transfusions consisted of packed red blood cell; 2±1.13 units in group A versus 3.11±1.44 in group B (P=0.01, however there were no significant differences between two groups regarding the mean total volume of intra and post-operative bleeding. Re-exploration was required in 10% in group A versus 13.63% in group B (P=0.67.Conclusion: TachoSil may act as a superior alternative in different types of cardiac surgery in order to control the bleeding and therefore reducing transfusion requirement.

  20. Nuclear imaging in cardiac amyloidosis

    Energy Technology Data Exchange (ETDEWEB)

    Glaudemans, A.W.J.M.; Slart, R.H.J.A.; Veltman, N.C.; Dierckx, R.A.J.O. [University Medical Center Groningen, Department of Nuclear Medicine and Molecular Imaging, Hanzeplein 1, P.O. Box 30001, Groningen (Netherlands); Zeebregts, C.J. [University Medical Center Groningen, Department of Surgery (Division of Vascular Surgery), Groningen (Netherlands); Tio, R.A. [University Medical Center Groningen, Department of Cardiology, Groningen (Netherlands); Hazenberg, B.P.C. [University Medical Center Groningen, Department of Rheumatology and Clinical Immunology, Groningen (Netherlands)


    Amyloidosis is a disease characterized by depositions of amyloid in organs and tissues. It can be localized (in just one organ) or systemic. Cardiac amyloidosis is a debilitating disease and can lead to arrhythmias, deterioration of heart function and even sudden death. We reviewed PubMed/Medline, without time constraints, on the different nuclear imaging modalities that are used to visualize myocardial amyloid involvement. Several SPECT tracers have been used for this purpose. The results with these tracers in the evaluation of myocardial amyloidosis and their mechanisms of action are described. Most clinical evidence was found for the use of {sup 123}I-MIBG. Myocardial defects in MIBG activity seem to correlate well with impaired cardiac sympathetic nerve endings due to amyloid deposits. {sup 123}I-MIBG is an attractive option for objective evaluation of cardiac sympathetic level and may play an important role in the indirect measurement of the effect of amyloid myocardial infiltration. Other, less sensitive, options are {sup 99m}Tc-aprotinin for imaging amyloid deposits and perhaps {sup 99m}Tc-labelled phosphate derivatives, especially in the differential diagnosis of the aetiology of cardiac amyloidosis. PET tracers, despite the advantage of absolute quantification and higher resolution, are not yet well evaluated for the study of cardiac amyloidosis. Because of these advantages, there is still the need for further research in this field. (orig.)

  1. Cardiac Penetrating Injuries and Pseudoaneurysm

    Institute of Scientific and Technical Information of China (English)

    CHEN Shifeng


    Objective To discuss the early diagnosis and treatment of cardiac penetrating injuries and pseudoaneurysm. Methods 18 cases of cardiac penetrating injuries, in which 2 cases were complicated with pseudoaneurysm, were diagnosed by emergency operation and color Doppler echocardiography between May 1973 and Dec. 2001 in our hospital. The basis for emergency operation is the injured path locating in cardiac dangerous zone, severe shock or pericardial tamponade. ResultsAmong 18 cases of this study, 17 cases underwent emergency operation. During the operation, 11 cases were found injured in right ventricle, 2 cases were found injured in right atrium, 1 case was found injured in pulmonary artery,4 cases were found injured in left ventricle, 2 cases were found complicated with pseudoaneurysm. 17cases underwent cardiac repair including 1 case of rupture of aneurysm. 1 case underwent elective aneurysm resection. In whole group, 15 cases survived(83.33% ), 3 cases died( 16.67%). The cause of death is mainly hemorrhagic shock. Conclusion Highly suspicious cardiac penetrating injuries or hemopericaridium should undergo direct operative exploration. Pseudoaneurysm should be resected early,which can prevent severe complications.

  2. Cell-specific promoter in adenovirus vector for transgenic expression of SERCA1 ATPase in cardiac myocytes. (United States)

    Inesi, G; Lewis, D; Sumbilla, C; Nandi, A; Strock, C; Huff, K W; Rogers, T B; Johns, D C; Kessler, P D; Ordahl, C P


    Adenovirus-mediated transfer of cDNA encoding the chicken skeletal muscle sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA1) yielded selective expression in cultured chick embryo cardiac myocytes under control of a segment (-268 base pair) of the cell-specific cardiac troponin T (cTnT) promoter or nonselective expression in myocytes and fibroblasts under control of a constitutive viral [cytomegalovirus (CMV)] promoter. Under optimal conditions nearly all cardiac myocytes in culture were shown to express transgenic SERCA1 ATPase. Expression was targeted to intracellular membranes and was recovered in subcellular fractions with a pattern identical to that of the endogenous SERCA2a ATPase. Relative to control myocytes, transgenic SERCA1 expression increased up to four times the rates of ATP-dependent (and thapsigargin-sensitive) Ca2+ transport activity of cell homogenates. Although the CMV promoter was more active than the cTnT promoter, an upper limit for transgenic expression of functional enzyme was reached under control of either promoter by adjustment of the adenovirus plaque-forming unit titer of infection media. Cytosolic Ca2+ concentration transients and tension development of whole myocytes were also influenced to a similar limit by transgenic expression of SERCA1 under control of either promoter. Our experiments demonstrate that a cell-specific protein promoter in recombinant adenovirus vectors yields highly efficient and selective transgene expression of a membrane-bound and functional enzyme in cardiac myocytes.

  3. Exercise-induced cardiac remodeling. (United States)

    Weiner, Rory B; Baggish, Aaron L


    Early investigations in the late 1890s and early 1900s documented cardiac enlargement in athletes with above-normal exercise capacity and no evidence of cardiovascular disease. Such findings have been reported for more than a century and continue to intrigue scientists and clinicians. It is well recognized that repetitive participation in vigorous physical exercise results in significant changes in myocardial structure and function. This process, termed exercise-induced cardiac remodeling (EICR), is characterized by structural cardiac changes including left ventricular hypertrophy with sport-specific geometry (eccentric vs concentric). Associated alterations in both systolic and diastolic functions are emerging as recognized components of EICR. The increasing popularity of recreational exercise and competitive athletics has led to a growing number of individuals exhibiting these findings in routine clinical practice. This review will provide an overview of EICR in athletes.

  4. [Ectopia cordis and cardiac anomalies]. (United States)

    Cabrera, Alberto; Rodrigo, David; Luis, María Teresa; Pastor, Esteban; Galdeano, José Miguel; Esteban, Susana


    Ectopia cordis is a rare disease that occurs in 5.5 to 7.9 per million live births. Only 267 cases had been reported as of 2001, most (95%) associated with other cardiac anomalies. We studied the cardiac malformations associated in 6 patients with ectopia cordis. Depending on where the defect was located, the cases of ectopia were classified into four groups: cervical, thoracic, thoraco-abdominal, and abdominal. All 6 patients died before the third day of life, 4 during delivery. Three of the patients were included in the thoracic group, whereas the other 3 belonged to the thoraco-abdominal group. All the patients had associated ventricular septal defects, 3 double-outlet right ventricle (50%) and the rest (50%) tetralogy of Fallot-pulmonary atresia. Two patients with double-outlet right ventricle presented mitral-valve pathology, a parachute valve and an atresic mitral valve. None of these cardiac anomalies have been reported to date.

  5. Electrophysiological Cardiac Modeling: A Review. (United States)

    Beheshti, Mohammadali; Umapathy, Karthikeyan; Krishnan, Sridhar


    Cardiac electrophysiological modeling in conjunction with experimental and clinical findings has contributed to better understanding of electrophysiological phenomena in various species. As our knowledge on underlying electrical, mechanical, and chemical processes has improved over time, mathematical models of the cardiac electrophysiology have become more realistic and detailed. These models have provided a testbed for various hypotheses and conditions that may not be easy to implement experimentally. In addition to the limitations in experimentally validating various scenarios implemented by the models, one of the major obstacles for these models is computational complexity. However, the ever-increasing computational power of supercomputers facilitates the clinical application of cardiac electrophysiological models. The potential clinical applications include testing and predicting effects of pharmaceutical agents and performing patient-specific ablation and defibrillation. A review of studies involving these models and their major findings are provided.

  6. Sodium Butyrate Induces Endoplasmic Reticulum Stress and Autophagy in Colorectal Cells: Implications for Apoptosis.

    Directory of Open Access Journals (Sweden)

    Jintao Zhang

    Full Text Available Butyrate, a short-chain fatty acid derived from dietary fiber, inhibits proliferation and induces cell death in colorectal cancer cells. However, clinical trials have shown mixed results regarding the anti-tumor activities of butyrate. We have previously shown that sodium butyrate increases endoplasmic reticulum stress by altering intracellular calcium levels, a well-known autophagy trigger. Here, we investigated whether sodium butyrate-induced endoplasmic reticulum stress mediated autophagy, and whether there was crosstalk between autophagy and the sodium butyrate-induced apoptotic response in human colorectal cancer cells.Human colorectal cancer cell lines (HCT-116 and HT-29 were treated with sodium butyrate at concentrations ranging from 0.5-5mM. Cell proliferation was assessed using MTT tetrazolium salt formation. Autophagy induction was confirmed through a combination of Western blotting for associated proteins, acridine orange staining for acidic vesicles, detection of autolysosomes (MDC staining, and electron microscopy. Apoptosis was quantified by flow cytometry using standard annexinV/propidium iodide staining and by assessing PARP-1 cleavage by Western blot.Sodium butyrate suppressed colorectal cancer cell proliferation, induced autophagy, and resulted in apoptotic cell death. The induction of autophagy was supported by the accumulation of acidic vesicular organelles and autolysosomes, and the expression of autophagy-associated proteins, including microtubule-associated protein II light chain 3 (LC3-II, beclin-1, and autophagocytosis-associated protein (Atg3. The autophagy inhibitors 3-methyladenine (3-MA and chloroquine inhibited sodium butyrate induced autophagy. Furthermore, sodium butyrate treatment markedly enhanced the expression of endoplasmic reticulum stress-associated proteins, including BIP, CHOP, PDI, and IRE-1a. When endoplasmic reticulum stress was inhibited by pharmacological (cycloheximide and mithramycin and genetic

  7. An update on insertable cardiac monitors

    DEFF Research Database (Denmark)

    Olsen, Flemming J; Biering-Sørensen, Tor; Krieger, Derk W


    Continuous cardiac rhythm monitoring has undergone compelling progress over the past decades. Cardiac monitoring has emerged from 12-lead electrocardiograms being performed at the discretion of the treating physician to in-hospital telemetry, Holter monitoring, prolonged external event monitoring...

  8. Complications after cardiac implantable electronic device implantations

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard;


    Complications after cardiac implantable electronic device (CIED) treatment, including permanent pacemakers (PMs), cardiac resynchronization therapy devices with defibrillators (CRT-Ds) or without (CRT-Ps), and implantable cardioverter defibrillators (ICDs), are associated with increased patient...

  9. Clinical advances on Cardiac Insuffiency

    Directory of Open Access Journals (Sweden)

    Angel Julio Romero Cabrera


    Full Text Available Cardiac insuffiency is a complex clinical syndrome which constitutes a common final path to get in by the majority of the cardiac diseases. Studies based on the communitarian surveys shows that from 30 to 40 % of the patients decease within the first year of the diagnosis. The rest of the patients (from 60 to 70 % die within the 5 years after being diagnosed. For this reason it has been called as the ¨cancer of cardiology¨. The objective of this article is to update the advances reached in the clinical and therapeutic aspects of this important syndrome.

  10. TBHQ Alleviated Endoplasmic Reticulum Stress-Apoptosis and Oxidative Stress by PERK-Nrf2 Crosstalk in Methamphetamine-Induced Chronic Pulmonary Toxicity

    Directory of Open Access Journals (Sweden)

    Yun Wang


    Full Text Available Methamphetamine (MA leads to cardiac and pulmonary toxicity expressed as increases in inflammatory responses and oxidative stress. However, some interactions may exist between oxidative stress and endoplasmic reticulum stress (ERS. The current study is designed to investigate if both oxidative stress and ERS are involved in MA-induced chronic pulmonary toxicity and if antioxidant tertiary butylhydroquinone (TBHQ alleviated ERS-apoptosis and oxidative stress by PERK-Nrf2 crosstalk. In this study, the rats were randomly divided into control group, MA-treated group (MA, and MA plus TBHQ-treated group (MA + TBHQ. Chronic exposure to MA resulted in slower growth of weight and pulmonary toxicity of the rats by increasing the pulmonary arterial pressure, promoting the hypertrophy of right ventricle and the remodeling of pulmonary arteries. MA inhibited the Nrf2-mediated antioxidative stress by downregulation of Nrf2, GCS, and HO-1 and upregulation of SOD2. MA increased GRP78 to induce ERS. Overexpression and phosphorylation of PERK rapidly phosphorylated eIF2α, increased ATF4, CHOP, bax, caspase 3, and caspase 12, and decreased bcl-2. These changes can be reversed by antioxidant TBHQ through upregulating expression of Nrf2. The above results indicated that TBHQ can alleviate MA-induced oxidative stress which can accelerate ERS to initiate PERK-dependent apoptosis and that PERK/Nrf2 is likely to be the key crosstalk between oxidative stress and ERS in MA-induced chronic pulmonary toxicity.

  11. TBHQ Alleviated Endoplasmic Reticulum Stress-Apoptosis and Oxidative Stress by PERK-Nrf2 Crosstalk in Methamphetamine-Induced Chronic Pulmonary Toxicity (United States)

    Gu, Yu-Han; Liu, Ming; Bai, Yang; Liang, Li-Ye; Wang, Huai-Liang


    Methamphetamine (MA) leads to cardiac and pulmonary toxicity expressed as increases in inflammatory responses and oxidative stress. However, some interactions may exist between oxidative stress and endoplasmic reticulum stress (ERS). The current study is designed to investigate if both oxidative stress and ERS are involved in MA-induced chronic pulmonary toxicity and if antioxidant tertiary butylhydroquinone (TBHQ) alleviated ERS-apoptosis and oxidative stress by PERK-Nrf2 crosstalk. In this study, the rats were randomly divided into control group, MA-treated group (MA), and MA plus TBHQ-treated group (MA + TBHQ). Chronic exposure to MA resulted in slower growth of weight and pulmonary toxicity of the rats by increasing the pulmonary arterial pressure, promoting the hypertrophy of right ventricle and the remodeling of pulmonary arteries. MA inhibited the Nrf2-mediated antioxidative stress by downregulation of Nrf2, GCS, and HO-1 and upregulation of SOD2. MA increased GRP78 to induce ERS. Overexpression and phosphorylation of PERK rapidly phosphorylated eIF2α, increased ATF4, CHOP, bax, caspase 3, and caspase 12, and decreased bcl-2. These changes can be reversed by antioxidant TBHQ through upregulating expression of Nrf2. The above results indicated that TBHQ can alleviate MA-induced oxidative stress which can accelerate ERS to initiate PERK-dependent apoptosis and that PERK/Nrf2 is likely to be the key crosstalk between oxidative stress and ERS in MA-induced chronic pulmonary toxicity. PMID:28303170

  12. Elevated sensitivity to cardiac ischemia in proteinuric rats is independent of adverse cardiac remodeling

    NARCIS (Netherlands)

    Szymanski, Mariusz K.; Hillege, Hans L.; Danser, A. H. Jan; Garrelds, Ingrid M.; Schoemaker, Regien G.


    Objectives: Chronic renal dysfunction severely increases cardiovascular risk. Adverse cardiac remodeling is suggested to play a major role as predisposition for increased cardiac ischemic vulnerability. The aim of the present study was to examine the role of adverse cardiac remodeling in cardiac sen

  13. Pregnancy as a cardiac stress model



    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women witho...

  14. Bifid cardiac apex in a 25-year-old male with sudden cardiac death. (United States)

    Wu, Annie; Kay, Deborah; Fishbein, Michael C


    Although a bifid cardiac apex is common in certain marine animals, it is an uncommon finding in humans. When present, bifid cardiac apex is usually associated with other congenital heart anomalies. We present a case of bifid cardiac apex that was an incidental finding in a 25-year-old male with sudden cardiac death from combined drug toxicity. On gross examination, there was a bifid cardiac apex with a 2-cm long cleft. There were no other significant gross or microscopic abnormalities. This case represents the very rare occurrence of a bifid cardiac apex as an isolated cardiac anomaly.

  15. Structural insights into the human RyR2 N-terminal region involved in cardiac arrhythmias

    Energy Technology Data Exchange (ETDEWEB)

    Borko, Ľubomír; Bauerová-Hlinková, Vladena, E-mail:; Hostinová, Eva; Gašperík, Juraj [Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava (Slovakia); Beck, Konrad [Cardiff University School of Dentistry, Heath Park, Cardiff CF14 4XY Wales (United Kingdom); Lai, F. Anthony [Cardiff University School of Medicine, Cardiff CF14 4XN Wales (United Kingdom); Zahradníková, Alexandra, E-mail: [Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava (Slovakia); Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, 833 34 Bratislava (Slovakia); Ševčík, Jozef, E-mail: [Institute of Molecular Biology, Slovak Academy of Sciences, Dúbravská cesta 21, 845 51 Bratislava (Slovakia)


    X-ray and solution structures of the human RyR2 N-terminal region were obtained under near-physiological conditions. The structure exhibits a unique network of interactions between its three domains, revealing an important stabilizing role of the central helix. Human ryanodine receptor 2 (hRyR2) mediates calcium release from the sarcoplasmic reticulum, enabling cardiomyocyte contraction. The N-terminal region of hRyR2 (amino acids 1–606) is the target of >30 arrhythmogenic mutations and contains a binding site for phosphoprotein phosphatase 1. Here, the solution and crystal structures determined under near-physiological conditions, as well as a homology model of the hRyR2 N-terminal region, are presented. The N-terminus is held together by a unique network of interactions among its three domains, A, B and C, in which the central helix (amino acids 410–437) plays a prominent stabilizing role. Importantly, the anion-binding site reported for the mouse RyR2 N-terminal region is notably absent from the human RyR2. The structure concurs with the differential stability of arrhythmogenic mutations in the central helix (R420W, I419F and I419F/R420W) which are owing to disparities in the propensity of mutated residues to form energetically favourable or unfavourable contacts. In solution, the N-terminus adopts a globular shape with a prominent tail that is likely to involve residues 545–606, which are unresolved in the crystal structure. Docking the N-terminal domains into cryo-electron microscopy maps of the closed and open RyR1 conformations reveals C{sup α} atom movements of up to 8 Å upon channel gating, and predicts the location of the leucine–isoleucine zipper segment and the interaction site for spinophilin and phosphoprotein phosphatase 1 on the RyR surface.

  16. Discovery and progress of direct cardiac reprogramming. (United States)

    Kojima, Hidenori; Ieda, Masaki


    Cardiac disease remains a major cause of death worldwide. Direct cardiac reprogramming has emerged as a promising approach for cardiac regenerative therapy. After the discovery of MyoD, a master regulator for skeletal muscle, other single cardiac reprogramming factors (master regulators) have been sought. Discovery of cardiac reprogramming factors was inspired by the finding that multiple, but not single, transcription factors were needed to generate induced pluripotent stem cells (iPSCs) from fibroblasts. We first reported a combination of cardiac-specific transcription factors, Gata4, Mef2c, and Tbx5 (GMT), that could convert mouse fibroblasts into cardiomyocyte-like cells, which were designated as induced cardiomyocyte-like cells (iCMs). Following our first report of cardiac reprogramming, many researchers, including ourselves, demonstrated an improvement in cardiac reprogramming efficiency, in vivo direct cardiac reprogramming for heart regeneration, and cardiac reprogramming in human cells. However, cardiac reprogramming in human cells and adult fibroblasts remains inefficient, and further efforts are needed. We believe that future research elucidating epigenetic barriers and molecular mechanisms of direct cardiac reprogramming will improve the reprogramming efficiency, and that this new technology has great potential for clinical applications.

  17. Multimodality imaging to guide cardiac interventional procedures

    NARCIS (Netherlands)

    Tops, Laurens Franciscus


    In recent years, a number of new cardiac interventional procedures have been introduced. Catheter ablation procedures for atrial fibrillation (AF) have been refined and are now considered a good treatment option in patients with drug-refractory AF. In cardiac pacing, cardiac resynchronization therap

  18. Regulation of Cardiac Hypertrophy: the nuclear option

    NARCIS (Netherlands)

    D.W.D. Kuster (Diederik)


    textabstractCardiac hypertrophy is the response of the heart to an increased workload. After myocardial infarction (MI) the surviving muscle tissue has to work harder to maintain cardiac output. This sustained increase in workload leads to cardiac hypertrophy. Despite its apparent appropriateness, c

  19. Cardiac manifestations of myotonic dystrophy type 1

    DEFF Research Database (Denmark)

    Petri, Helle; Vissing, John; Witting, Nanna;


    To estimate the degree of cardiac involvement regarding left ventricular ejection fraction, conduction abnormalities, arrhythmia, risk of sudden cardiac death (SCD) and the associations between cardiac involvement and cytosine-thymine-guanine (CTG)-repeat, neuromuscular involvement, age and gende...... in patients with myotonic dystrophy type 1 (MD1)....

  20. Cardiac anatomy and physiology: a review. (United States)

    Gavaghan, M


    This article reviews the normal anatomy and physiology of the heart. Understanding the normal anatomic and physiologic relationships described in this article will help perioperative nurses care for patients who are undergoing cardiac procedures. Such knowledge also assists nurses in educating patients about cardiac procedures and about activities that can prevent, reverse, or improve cardiac illness.

  1. Sulindac sulfide inhibits sarcoendoplasmic reticulum Ca2+ ATPase, induces endoplasmic reticulum stress response, and exerts toxicity in glioma cells: relevant similarities to and important differences from celecoxib. (United States)

    White, M C; Johnson, G G; Zhang, W; Hobrath, J V; Piazza, G A; Grimaldi, M


    Malignant gliomas have low survival expectations regardless of current treatments. Nonsteroidal anti-inflammatory drugs (NSAIDs) prevent cell transformation and slow cancer cell growth by mechanisms independent of cyclooxygenase (COX) inhibition. Certain NSAIDs trigger the endoplasmic reticulum stress response (ERSR), as revealed by upregulation of molecular chaperones such as GRP78 and C/EBP homologous protein (CHOP). Although celecoxib (CELE) inhibits the sarcoendoplasmic reticulum Ca(2+) ATPase (SERCA), an effect known to induce ERSR, sulindac sulfide (SS) has not been reported to affect SERCA. Here, we investigated these two drugs for their effects on Ca(2+) homeostasis, ERSR, and glioma cell survival. Our findings indicate that SS is a reversible inhibitor of SERCA and that both SS and CELE bind SERCA at its cyclopiazonic acid binding site. Furthermore, CELE releases additional Ca(2+) from the mitochondria. In glioma cells, both NSAIDS upregulate GRP78 and activate ER-associated caspase-4 and caspase-3. Although only CELE upregulates the expression of CHOP, it appears that CHOP induction could be associated with mitochondrial poisoning. In addition, CHOP induction appears to be uncorrelated with the gliotoxicity of these NSAIDS in our experiments. Our data suggest that activation of ERSR is primarily responsible for the gliotoxic effect of these NSAIDS. Because SS has good brain bioavailability, has lower COX-2 inhibition, and has no mitochondrial effects, it represents a more appealing molecular candidate than CELE to achieve gliotoxicity via activation of ERSR.

  2. CSB ablation induced apoptosis is mediated by increased endoplasmic reticulum stress response (United States)

    Caputo, Manuela; Balzerano, Alessio; Arisi, Ivan; D’Onofrio, Mara; Brandi, Rossella; Bongiorni, Silvia; Brancorsini, Stefano; Frontini, Mattia; Proietti-De-Santis, Luca


    The DNA repair protein Cockayne syndrome group B (CSB) has been recently identified as a promising anticancer target. Suppression, by antisense technology, of this protein causes devastating effects on tumor cells viability, through a massive induction of apoptosis, while being non-toxic to non-transformed cells. To gain insights into the mechanisms underlying the pro-apoptotic effects observed after CSB ablation, global gene expression patterns were determined, to identify genes that were significantly differentially regulated as a function of CSB expression. Our findings revealed that response to endoplasmic reticulum stress and response to unfolded proteins were ranked top amongst the cellular processes affected by CSB suppression. The major components of the endoplasmic reticulum stress-mediated apoptosis pathway, including pro-apoptotic factors downstream of the ATF3-CHOP cascade, were dramatically up-regulated. Altogether our findings add new pieces to the understanding of CSB mechanisms of action and to the molecular basis of CS syndrome. PMID:28253359

  3. Organization of the cytoplasmic reticulum in the central vacuole of parenchyma cells in Allium cepa L.

    Directory of Open Access Journals (Sweden)

    Tomasz J. Wodzicki


    Full Text Available An elaborate and complex cytoplasmic reticulum composed of fine filaments and lamellae ranging from 0.1 to 4 microns in size is revealed by viewing the central vacuole of onion bulb parenchyma cells with the scanning election microscope. The larger cytoplasmic strands, visible with the light microscope, are composed of numerous smaller filaments (some tubular which might explain the observed bidirectional movement of particles in these larger strands. The finely divided cytoplasmic network of filaments is continuous with the parietal cytoplasm inclosing the vacuolar sap. In these highly vacuolated cells the mass of the protoplast is in the form of an intravacuolar reticulum immersed in the cell sap. The probable significance of the vacuolar sap in relation to physiological processes of the cell is discussed.


    Energy Technology Data Exchange (ETDEWEB)

    Rubin, Philip; Levitt, Seymour H.


    Case histories of two patients treated with colloidal radiogold for diffuse reticulum cell sarcoma are presented. Further analysis of the method is suggested by the unusually long survival time of one of the patients. It was concluded that, although external radiotherapy remains the treatment of choice in localized reticulum cell sarcoma, intravenous colloidal radiogold may be a useful agent in lymphosarcomas with diffuse minute neoplastic liver and spleen involvements. Intravenous colloidal radiogold can produce bone marrow depression and thrombocytopenia which can lead to death. This factor tends to argue against therapeutic use of the agent. It is suggested that no more than 50 mC Au/sup 198/ intravenously should be used for treatment of this disease. (R.M.G.)

  5. Sch proteins are localized on endoplasmic reticulum membranes and are redistributed after tyrosine kinase receptor activation

    DEFF Research Database (Denmark)

    Lotti, L V; Lanfrancone, L; Migliaccio, E;


    area of the cell and mostly associated with the cytosolic side of rough endoplasmic reticulum membranes. Upon epidermal growth factor treatment and receptor tyrosine kinase activation, the immunolabeling became peripheral and was found to be associated with the cytosolic surface of the plasma membrane......The intracellular localization of Shc proteins was analyzed by immunofluorescence and immunoelectron microscopy in normal cells and cells expressing the epidermal growth factor receptor or the EGFR/erbB2 chimera. In unstimulated cells, the immunolabeling was localized in the central perinuclear....... The rough endoplasmic reticulum localization of Shc proteins in unstimulated cells and their massive recruitment to the plasma membrane, endocytic structures, and peripheral cytosol following receptor tyrosine kinase activation could account for multiple putative functions of the adaptor protein....

  6. Sphingosine inhibits the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) activity. (United States)

    Benaim, Gustavo; Pimentel, Adriana A; Felibertt, Pimali; Mayora, Adriana; Colman, Laura; Sojo, Felipe; Rojas, Héctor; De Sanctis, Juan B


    The increase in the intracellular Ca(2+) concentration ([Ca(2+)]i) is the key variable for many different processes, ranging from regulation of cell proliferation to apoptosis. In this work we demonstrated that the sphingolipid sphingosine (Sph) increases the [Ca(2+)]i by inhibiting the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), in a similar manner to thapsigargin (Tg), a specific inhibitor of this Ca(2+) pump. The results showed that addition of sphingosine produced a release of Ca(2+) from the endoplasmic reticulum followed by a Ca(2+) entrance from the outside mileu. The results presented in this work support that this sphingolipid could control the activity of the SERCA, and hence sphingosine may participate in the regulation of [Ca(2+)]I in mammalian cells.

  7. Cardiac tumors: optimal cardiac MR sequences and spectrum of imaging appearances.

    LENUS (Irish Health Repository)

    O'Donnell, David H


    OBJECTIVE: This article reviews the optimal cardiac MRI sequences for and the spectrum of imaging appearances of cardiac tumors. CONCLUSION: Recent technologic advances in cardiac MRI have resulted in the rapid acquisition of images of the heart with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MRI provides optimal assessment of the location, functional characteristics, and soft-tissue features of cardiac tumors, allowing accurate differentiation of benign and malignant lesions.

  8. Ultrafast glycerophospholipid-selective transbilayer motion mediated by a protein in the endoplasmic reticulum membrane. (United States)

    Buton, X; Morrot, G; Fellmann, P; Seigneuret, M


    A relatively rapid transbilayer motion of phospholipids in the microsomal membrane seems to be required due to their asymmetric synthesis in the cytoplasmic leaflet. Marked discrepancies exist with regard to the rate and specificity of this flip-flop process. To reinvestigate this problem, we have used both spin-labeled and radioactively labeled long chain phospholipids with a new fast translocation assay. Identical results were obtained with both types of probes. Transbilayer motion of glycerophospholipids was found to be much more rapid than previously reported (half-time less than 25 s) and to occur identically for phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine. Such transport is nonvectorial and leads to a symmetric transbilayer distribution of phospholipids. In contrast, transverse diffusion of sphingomyelin was 1 order of magnitude slower. Phospholipid flip-flop appears to occur by a protein-mediated transport process displaying saturable and competitive behavior. Proteolysis, chemical modification, and competition experiments suggest that this transport process may be related to that previously described in the endoplasmic reticulum for short-chain phosphatidylcholine (Bishop, W. R., and Bell, R. M. (1985) Cell 42, 51-60). The relationship between phospholipid flip-flop and nonbilayer structures occurring in the endoplasmic reticulum was also investigated by 31P-NMR. Several conditions were found under which the 31P isotropic NMR signal previously attributed to nonbilayer structures is decreased or abolished, whereas transbilayer diffusion is unaffected, suggesting that the flip-flop process is independent of such structures. It is concluded that flip-flop in the endoplasmic reticulum is mediated by a bidirectional protein transporter with a high efficiency for glycerophospholipids and a low efficiency for sphingomyelin. In vivo, the activity of this transporter would be able to redistribute all changes in phospholipid composition due

  9. Endoplasmic Reticulum Stress and the Related Signaling Networks in Severe Asthma



    The endoplasmic reticulum (ER) is a specialized organelle that plays a central role in biosynthesis, correct protein folding, and posttranslational modifications of secretory and membrane proteins. Loss of homeostasis in ER functions triggers the ER stress response, resulting in activation of unfolded protein response (UPR), a hallmark of many inflammatory diseases. These pathways have been reported as critical players in the pathogenesis of various pulmonary disorders, including pulmonary fi...

  10. Glucose-6-phosphate Reduces Calcium Accumulation in Rat Brain Endoplasmic Reticulum (United States)


    low millimolar range. Most Ca2+ is sequestered within organelles , including the endoplasmic reticulum (ER), Golgi, mitochondria , and nucleus (Carafoli...G6P and thapsigargin caused generalized reduction in Ca2+ accumulation in remarkably similar patterns with no apparent gray matter regional...with glucose-6-phosphate (10 mM) or thapsigargin (1 µM), revealed very similar pattern of generalized reduction in 45Ca2+ accumulation in gray and

  11. Thapsigargin-induced transport of cholera toxin to the endoplasmic reticulum.


    Sandvig, K.; Garred, O; van Deurs, B.


    Cholera toxin is normally observed only in the Golgi apparatus and not in the endoplasmic reticulum (ER) although the enzymatically active A subunit of cholera toxin has a KDEL sequence. Here we demonstrate transport of horseradish peroxidase-labeled cholera toxin to the ER by electron microscopy in thapsigargin-treated A431 cells. Thapsigargin treatment strongly increased cholera toxin-induced cAMP production, and the formation of the catalytically active A1 fragment was somewhat increased. ...

  12. The Endoplasmic Reticulum Stress Protein Calreticulin in Diabetic Chronic Kidney Disease (United States)


    TECHNOLOGY? These studies identify a new target for the treatment of diabetic nephropathy . Studies with the NFAT inhibitor 11R- VIVIT will provide further...cells. In Aim 2, we will determine the role of CRT in mouse models of diabetic nephropathy . In year 2, we developed stably transduced HK-2 cells western blot for fibronectin. 15. SUBJECT TERMS Diabetic nephropathy , calreticulin, TGF-beta, endoplasmic reticulum stress, fibrosis 16. SECURITY

  13. The quality control of glycoprotein folding in the endoplasmic reticulum, a trip from trypanosomes to mammals

    Directory of Open Access Journals (Sweden)

    A.J. Parodi


    Full Text Available The present review deals with the stages of synthesis and processing of asparagine-linked oligosaccharides occurring in the lumen of the endoplasmic reticulum and their relationship to the acquisition by glycoproteins of their proper tertiary structures. Special emphasis is placed on reactions taking place in trypanosomatid protozoa since their study has allowed the detection of the transient glucosylation of glycoproteins catalyzed by UDP-Glc:glycoprotein glucosyltransferase and glucosidase II. The former enzyme has the unique property of covalently tagging improperly folded conformations by catalyzing the formation of protein-linked Glc1Man7GlcNAc2, Glc1Man8GlcNac2 and Glc1Man9GlcNAc2 from the unglucosylated proteins. Glucosyltransferase is a soluble protein of the endoplasmic reticulum that recognizes protein domains exposed in denatured but not in native conformations (probably hydrophobic amino acids and the innermost N-acetylglucosamine unit that is hidden from macromolecular probes in most native glycoproteins. In vivo, the glucose units are removed by glucosidase II. The influence of oligosaccharides in glycoprotein folding is reviewed as well as the participation of endoplasmic reticulum chaperones (calnexin and calreticulin that recognize monoglucosylated species in the same process. A model for the quality control of glycoprotein folding in the endoplasmic reticulum, i.e., the mechanism by which cells recognize the tertiary structure of glycoproteins and only allow transit to the Golgi apparatus of properly folded species, is discussed. The main elements of this control are calnexin and calreticulin as retaining components, the UDP-Glc:glycoprotein glucosyltransferase as a sensor of tertiary structures and glucosidase II as the releasing agent.

  14. Six new chrysophycean stomatocysts ornamented with reticulum from the Great Xing'an Mountains, China

    Institute of Scientific and Technical Information of China (English)

    PANG Wanting; WANG Youfang; WANG Quanxi


    Six new chrysophycean stomatocysts ornamented with reticulum were illustrated based on SEM observation.They were described following the guidelines of the International Statospore Working Group (ISWG).All samples were collected from the Great Xing'an Mountains,China.Their taxonomic characteristics and habitats were described to provide new information on the biodiversity of chrysophycean stomatocysts.As is common with many morphotypes,their biological affinities remain unknown.

  15. Voltage-Independent Calcium Release in Heart Muscle (United States)

    Niggli, Ernst; Lederer, W. Jonathan


    The Ca2+ that activates contraction in heart muscle is regulated as in skeletal muscle by processes that depend on voltage and intracellular Ca2+ and involve a positive feedback system. How the initial electrical signal is amplified in heart muscle has remained controversial, however. Analogous protein structures from skeletal muscle and heart muscle have been identified physiologically and sequenced; these include the Ca2+ channel of the sarcolemma and the Ca2+ release channel of the sarcoplasmic reticulum. Although the parallels found in cardiac and skeletal muscles have provoked valuable experiments in both tissues, separation of the effects of voltage and intracellular Ca2+ on sarcoplasmic reticulum Ca2+ release in heart muscle has been imperfect. With the use of caged Ca2+ and flash photolysis in voltage-clamped heart myocytes, effects of membrane potential in heart muscle cells on Ca2+ release from intracellular stores have been studied. Unlike the response in skeletal muscle, voltage across the sarcolemma of heart muscle does not affect the release of Ca2+ from the sarcoplasmic reticulum, suggesting that other regulatory processes are needed to control Ca2+-induced Ca2+ release.

  16. Neuroprotective effects of atorvastatin against cerebral ischemia/reperfusion injury through the inhibition of endoplasmic reticulum stress

    Institute of Scientific and Technical Information of China (English)

    Jian-wen Yang; Zhi-ping Hu


    Cerebral ischemia triggers secondary ischemia/reperfusion injury and endoplasmic reticulum stress initiates cell apoptosis. However, the regulatory mechanism of the signaling pathway remains unclear. We hypothesize that the regulatory mechanisms are mediated by the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α in the endoplasmic reticulum stress signaling pathway. To verify this hypothesis, we occluded the middle cere-bral artery in rats to establish focal cerebral ischemia/reperfusion model. Results showed that the expression levels of protein kinase-like endoplasmic reticulum kinase and caspase-3, as well as the phosphorylation of eukaryotic initiation factor 2α, were increased after ischemia/reperfusion. Administration of atorvastatin decreased the expression of protein kinase-like endoplasmic reticulum kinase, caspase-3 and phosphorylated eukaryotic initiation factor 2α, reduced the infarct volume and improved ultrastructure in the rat brain. After salubrinal, the speciifc inhibitor of phosphorylated eukaryotic initiation factor 2α was given into the rats in-tragastrically, the expression levels of caspase-3 and phosphorylated eukaryotic initiation factor 2α in the were decreased, a reduction of the infarct volume and less ultrastructural damage were observed than the untreated, ischemic brain. However, salubrinal had no impact on the expression of protein kinase-like endoplasmic reticulum kinase. Experimental ifndings indi-cate that atorvastatin inhibits endoplasmic reticulum stress and exerts neuroprotective effects. The underlying mechanisms of attenuating ischemia/reperfusion injury are associated with the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α/caspase-3 pathway.

  17. Molecular therapies for cardiac arrhythmias

    NARCIS (Netherlands)

    Boink, G.J.J.


    Despite the ongoing advances in pharmacology, devices and surgical approaches to treat heart rhythm disturbances, arrhythmias are still a significant cause of death and morbidity. With the introduction of gene and cell therapy, new avenues have arrived for the local modulation of cardiac disease. Th

  18. The cardiac patient in Ramadan. (United States)

    Chamsi-Pasha, Majed; Chamsi-Pasha, Hassan


    Ramadan is one of the five fundamental pillars of Islam. During this month, the majority of the 1.6 billion Muslims worldwide observe an absolute fast from dawn to sunset without any drink or food. Our review shows that the impact of fasting during Ramadan on patients with stable cardiac disease is minimal and does not lead to any increase in acute events. Most patients with the stable cardiac disease can fast safely. Most of the drug doses and their regimen are easily manageable during this month and may need not to be changed. Ramadan fasting is a healthy nonpharmacological means for improving cardiovascular risk factors. Most of the Muslims, who suffer from chronic diseases, insist on fasting Ramadan despite being exempted by religion. The Holy Quran specifically exempts the sick from fasting. This is particularly relevant if fasting worsens one's illness or delays recovery. Patients with unstable angina, recent myocardial infarction, uncontrolled hypertension, decompensated heart failure, recent cardiac intervention or cardiac surgery or any debilitating diseases should avoid fasting.

  19. Pseudothrombocytopenia in cardiac surgical practice. (United States)

    Nair, Sukumaran K; Shah, Roma; Petko, Matus; Keogh, Bruce E


    Pseudothrombocytopenia is observed occasionally in post-cardiac surgical patients. It is commonly due to EDTA-mediated immunological mechanisms, which lead to agglutination of functionally intact platelets. This condition is harmless and does not warrant platelet transfusion. We describe an instance of pseudothrombocytopenia in our practice and discuss its clinical relevance.

  20. Thoracocentesis in cardiac surgery patients. (United States)

    Wickbom, Anders; Cha, Soon Ok; Ahlsson, Anders


    Pleural effusion following cardiac surgery is a common complication that sometimes requires invasive treatment. Conventional methods for evacuation include needle aspiration and chest tube insertion. We present an effective, easy and potentially time-saving method of thoracocentesis, using a single-lumen central venous catheter.

  1. Reninoma presenting as cardiac syncope

    Directory of Open Access Journals (Sweden)

    Tak Shahid


    Full Text Available Reninoma, a renin-secreting tumor of the juxta-glomerular cells of the kidney, is a rare but surgically treatable cause of secondary hypertension in children. We report a case of reninoma presenting as cardiac syncope with long QTc on electrocardiogram due to hypokalemia.

  2. Cardiac leiomyosarcoma, a case report

    DEFF Research Database (Denmark)

    Andersen, Rikke; Kristensen, Bjarne W; Gill, Sabine


    In this case report we present the history of a patient admitted with recurrent pulmonary edema. Transesophageal chocardiography showed a tumour in the left atrium, occluding the ostium of the mitral valve and mimicking intermittent mitral stenosis. Cardiac surgery followed by pathological...

  3. Cardiac connexins and impulse propagation

    NARCIS (Netherlands)

    J.A. Jansen; T.A.B. van Veen; J.M.T. de Bakker; H.V.M. van Rijen


    Gap junctions form the intercellular pathway for cell-to-cell transmission of the cardiac impulse from its site of origin, the sinoatrial node, along the atria, the atrioventricular conduction system to the ventricular myocardium. The component parts of gap junctions are proteins called connexins (C

  4. [Acute cardiac failure in pheochromocytoma.

    DEFF Research Database (Denmark)

    Jønler, Morten; Munk, Kim


    Pheochromocytoma (P) is an endocrine catecholamine-secreting tumor. Classical symptoms like hypertension, attacks of sweating, palpitations, headache and palor are related to catecholamine discharge. We provide a case of P in a 71 year-old man presenting with acute cardiac failure, severe reduction...

  5. Cardiac resynchronization therapy in China

    Institute of Scientific and Technical Information of China (English)

    Wei HUA


    @@ Congestive heart failure (HF) is a major and growing public health problem. The therapeutic approach includes non-pharmacological measures, pharmacological therapy,mechanical devices, and surgery. Despite the benefits of optimal pharmacologic therapy, the prognosis is still not ideal. At this time, cardiac resynchronization therapy (CRT)has gained wide acceptance as an alternative treatment for HF patients with conduction delay.1

  6. Cardiac abnormalities after subarachnoid hemorrhage

    NARCIS (Netherlands)

    Bilt, I.A.C. van der


    Aneurysmal subarachnoid hemorrhage(aSAH) is a devastating neurological disease. During the course of the aSAH several neurological and medical complications may occur. Cardiac abnormalities after aSAH are observed often and resemble stress cardiomyopathy or Tako-tsubo cardiomyopathy(Broken Heart Syn

  7. Response to cardiac resynchronization therapy

    DEFF Research Database (Denmark)

    Versteeg, Henneke; Schiffer, Angélique A; Widdershoven, Jos W


    Cardiac resynchronization therapy (CRT) is a promising treatment for a subgroup of patients with advanced congestive heart failure and a prolonged QRS interval. Despite the majority of patients benefiting from CRT, 10-40% of patients do not respond to this treatment and are labeled as nonresponders...

  8. Caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress. (United States)

    Zhang, Qiang; Liu, Jianing; Chen, Shulan; Liu, Jing; Liu, Lijuan; Liu, Guirong; Wang, Fang; Jiang, Wenxin; Zhang, Caixia; Wang, Shuangyu; Yuan, Xiao


    It is well recognized that mandibular growth, which is caused by a variety of functional appliances, is considered to be the result of both neuromuscular and skeletal adaptations. Accumulating evidence has demonstrated that apoptosis plays an important role in the adaptation of skeletal muscle function. However, the underlying mechanism of apoptosis that is induced by stretch continues to be incompletely understood. Endoplasmic reticulum stress (ERS), a newly defined signaling pathway, initiates apoptosis. This study seeks to determine if caspase-12 is involved in stretch-induced apoptosis mediated endoplasmic reticulum stress in myoblast and its underlying mechanism. Apoptosis was assessed by Hochest staining, DAPI staining and annexin V binding and PI staining. ER chaperones, such as GRP78, CHOP and caspase-12, were determined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Furthermore, caspase-12 inhibitor was used to value the mechanism of the caspase-12 pathway. Apoptosis of myoblast, which is subjected to cyclic stretch, was observed in a time-dependent manner. We found that GRP78 mRNA and protein were significantly increased and CHOP and caspase-12 were activated in myoblast that was exposed to cyclic stretch. Caspase-12 inhibition reduced stretch-induced apoptosis, and caspase-12 activated caspase-3 to induce apoptosis. We concluded that caspase-12 played an important role in stretch-induced apoptosis that is associated by endoplasmic reticulum stress by activating caspase-3.

  9. Evidence for Gamma-ray Emission from the Newly Discovered Dwarf Galaxy Reticulum 2

    CERN Document Server

    Geringer-Sameth, Alex; Koushiappas, Savvas M; Koposov, Sergey E; Belokurov, Vasily; Torrealba, Gabriel; Evans, N Wyn


    We present a search for gamma-ray emission from the direction of the newly discovered dwarf galaxy Reticulum 2. Using Fermi-LAT data, we detect a signal that exceeds expected backgrounds between ~2-10 GeV and is consistent with annihilation of dark matter for particle masses less than a few x 10^2 GeV. Modeling the background as a Poisson process based on Fermi-LAT diffuse models, and taking into account trials factors, we detect emission with p-value less than 9.8 x 10^-5 (>3.7 sigma). An alternative, model-independent treatment of background reduces the significance, raising the p-value to 9.7 x 10^-3 (2.3 sigma). Even in this case, however, Reticulum 2 has the most significant gamma-ray signal of any known dwarf galaxy. If Reticulum 2 has a dark matter halo that is similar to those inferred for other nearby dwarfs, the signal is consistent with the s-wave relic abundance cross section for annihilation.

  10. Molecular Modeling of Cardiac Troponin (United States)

    Manning, Edward P.

    The cardiac thin filament regulates interactions of actin and myosin, the force-generating elements of muscular contraction. Over the past several decades many details have been discovered regarding the structure and function of the cardiac thin filament and its components, including cardiac troponin (cTn). My hypothesis is that signal propagation occurs between distant ends of the cardiac troponin complex through calcium-dependent alterations in the dynamics of cTn and tropomyosin (Tm). I propose a model of the thin filament that encompasses known structures of cTn, Tm and actin to gain insight into cardiac troponin's allosteric regulation of thin filament dynamics. By performing molecular dynamics simulations of cTn in conjunction with overlapping Tm in two conditions, with and without calcium bound to site II of cardiac troponin C (cTnC), I found a combination of calcium-dependent changes in secondary structure and dynamics throughout the cTn-Tm complex. I then applied this model to investigate familial hypertrophic cardiomyopathy (FHC), a disease of the sarcomere that is one of the most commonly occurring genetic causes of heart disease. Approximately 15% of known FHC-related mutations are found in cardiac troponin T (cTnT), most of which are in or flank the alpha-helical N-tail domain TNT1. TNT1 directly interacts with overlapping Tm coiled coils. Using this model I identified effects of TNT1 mutations that propagate to the cTn core where site II of cTnC, the regulatory site of calcium binding in the thin filament, is located. Specifically, I found that mutations in TNT1 alter the flexibility of TNT1 and that the flexibility of TNT1 is inversely proportional to the cooperativity of calcium activation of the thin filament. Further, I identified a pathway of propagation of structural and dynamic changes linking TNT1 to site II of cTnC. Mutation-induced changes at site II cTnC alter calcium coordination which corresponds to biophysical measurements of calcium

  11. Changes in sarcoplasmic metabolite concentrations and pH associated with the catch contraction and relaxation of the anterior byssus retractor muscle of Mytilus edulis measured by phosphorus-31 nuclear magnetic resonance. (United States)

    Ishii, N; Mitsumori, F; Takahashi, K


    The sarcoplasmic concentrations of phosphorus metabolites and pH (pHin) were measured in the anterior byssus retractor muscle (ABRM) of Mytilus edulis by 31P nuclear magnetic resonance spectroscopy. During an active contraction induced by 10(-3) acetylcholine, the concentration of arginine phosphate ([Arg-P]in) decreased from the resting value of 7.47 +/- 0.26 (mean +/- SE, n = 8) to 6.67 +/- 0.29 (n = 6) mumol g-1, and that of inorganic phosphate (Pi) consistently increased from 0.84 +/- 0.06 (n = 7) to 1.61 +/- 0.12 (n = 5) mumol g-1. In the 'catch' state following the active contraction, these concentrations were close to their resting levels, indicating that the catch is an inactive state. 5-hydroxytryptamine caused a rapid relaxation of the catch, which was associated with a slight decrease in [Arg-P]in and an increase in pHin by ca 0.2 units. The sarcoplasmic concentration of ATP (mean, 1.6 mumol g-1) did not change throughout the contraction-relaxation cycle.

  12. Can cardiac surgery cause hypopituitarism? (United States)

    Francis, Flverly; Burger, Ines; Poll, Eva Maria; Reineke, Andrea; Strasburger, Christian J; Dohmen, Guido; Gilsbach, Joachim M; Kreitschmann-Andermahr, Ilonka


    Apoplexy of pituitary adenomas with subsequent hypopituitarism is a rare but well recognized complication following cardiac surgery. The nature of cardiac on-pump surgery provides a risk of damage to the pituitary because the vascular supply of the pituitary is not included in the cerebral autoregulation. Thus, pituitary tissue may exhibit an increased susceptibility to hypoperfusion, ischemia or intraoperative embolism. After on-pump procedures, patients often present with physical and psychosocial impairments which resemble symptoms of hypopituitarism. Therefore, we analyzed whether on-pump cardiac surgery may cause pituitary dysfunction also in the absence of pre-existing pituitary disease. Twenty-five patients were examined 3-12 months after on-pump cardiac surgery. Basal hormone levels for all four anterior pituitary hormone axes were measured and a short synacthen test and a growth hormone releasing hormone plus arginine (GHRH-ARG)-test were performed. Quality of life (QoL), depression, subjective distress for a specific life event, sleep quality and fatigue were assessed by means of self-rating questionnaires. Hormonal alterations were only slight and no signs of anterior hypopituitarism were found except for an insufficient growth hormone rise in two overweight patients in the GHRH-ARG-test. Psychosocial impairment was pronounced, including symptoms of moderate to severe depression in 9, reduced mental QoL in 8, dysfunctional coping in 6 and pronounced sleep disturbances in 16 patients. Hormone levels did not correlate with psychosocial impairment. On-pump cardiac surgery did not cause relevant hypopituitarism in our sample of patients and does not serve to explain the psychosocial symptoms of these patients.

  13. Cardiac energetics: sense and nonsense. (United States)

    Gibbs, Colin L


    1. The background to current ideas in cardiac energetics is outlined and, in the genomic era, the need is stressed for detailed knowledge of mouse heart mechanics and energetics. 2. The mouse heart is clearly different to the rat in terms of its excitation-contraction (EC) coupling and the common assumption that heart rate difference between mice and humans will account for the eightfold difference in myocardial oxygen consumption is wrong, because the energy per beat of the mouse heart is approximately one-third that of the human heart. 3. In vivo evidence suggests that there may well be an eightfold species difference in the non-beating metabolism of mice and human hearts. It is speculated that the magnitude of basal metabolism in the heart is regulatable and that, in the absence of perfusion, it falls to approximately one-quarter of its in vivo rate and that in clinical conditions, such as hibernation, it probably decreases; its magnitude may be controlled by the endothelium. 4. The active energy balance sheet is briefly discussed and it is suggested that the activation heat accounts for 20-25% of the active energy per beat and cross-bridge turnover accounts for the balance. It is argued that force, not shortening, is the major determinant of cardiac energy usage. 5. The outcome of recent cardiac modelling with variants of the Huxley and Hill/Eisenberg models is described. It has been necessary to invoke 'loose coupling' to replicate the low cardiac energy flux measured at low afterloads (medium to high velocities of shortening). 6. Lastly, some of the unexplained or 'nonsense' energetic data are outlined and eight unsolved problems in cardiac energetics are discussed.

  14. Effects of Weak Magnetic Field on Ca2+ Modulation of Skeletal Muscle Sarcoplamic Reticulum%弱磁场对骨骼肌肌质网钙调控作用的研究

    Institute of Scientific and Technical Information of China (English)

    刘仁臣; 吴永刚; 程和平; 谢国秋; 陆静; 夏子奂


    目的:探讨弱磁场对提取的骨骼肌肌质网系(SR)Ca2+转运、钙泵(Ca2 - Mg2+ -ATPase)及钙释放通道(RyR)活性的影响,从分子水平和细胞信号系统的角度来解释生物电磁效应.方法:利用动态光谱法检测0.4 mT弱磁场辐照过的SR Ca2+转运、Ca2 -ATPase活性,还原型辅酶(NADH)的氧化初速率和超氧(O2)产率,以及用同位素标记方法检测[3H] -Ryanodine与RyR的平衡结合度.结果:弱磁场辐照引起SR的Ca2+摄取功能和Ca2 -ATPase的活性明显下降,Ca2+释放和[3H] -Ryanodine平衡结合度上升,同时上调了NADH的氧化初速率和O2的产率.结论:提示0.4 mT弱磁场辐照30 min对SR Ca2 -ATPase活性有明显抑制,对RyR有一定的激活效果.%Objective: Discuss the effects of weak magnetic field on isolated sarcoplasmic reticulum (SR) Ca2+ modulation, calcium pump (Ca2+-Mg2+-ATPase) and Ca2 + release channel (Ryanodine Receptor, RyR) activity, so as to explain the mechanism of biological effects caused by electromagnetic fields in terms of molecular level and signal transduction system. Methods;The Ca + modulation and Ca + -ATPase activity, NADH oxidation initial rates and superoxide production of SR exposed to 0. 4 mT weak magnetic field ( MF) were investigated with dynamic Ca2 * dye spectrum method, [3 H ] -Ryanodine binding assay was investigated by isotope Labeling. Results: Weak MF exposure decreased SR Ca + uptake and Ca2 + -ATPase activity obviously, increased SR Ca2 + release and [3 H ] -Rryanodine binding, up-regulated the initial rates of NADH oxidation and the production of superoxide. Conclusion: It is indicated that 0. 4 mT weak magnetic field exposure for 30 min inhibited Ca2 + -ATPase activity and promoted the RyR channel function.

  15. Cardiac troponin: an emerging cardiac biomarker in animal health

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    Vishal V. Undhad

    Full Text Available Analysis of cardiac troponin I (cTn I and T (cTnT are considered the “gold standard” for the non-invasive diagnosis of myocardial injury in human and animals. It has replaced traditionally used cardiac biomarkers such as myoglobin, lactate dehydrogenase (LDH, creatine kinase (CK and CK-MB due to its high sensitivity and specificity for the detection of myocardial injury. Cardiac troponins are proteins that control the calcium-mediated interaction between actin and myosin, allowing contraction at the sarcomere level. Concentration of the cTn can be correlated microscopic lesion and loss of immunolabeling in myocardium damage. Troponin concentration remains elevated in blood for 1-2wks so that wide window is available for diagnosis of myocardial damage. The cTn test has >95% specificity and sensitivity and test is less time consuming (10 to 15 minutes and less costly (INR 200 to INR 500. [Vet. World 2012; 5(8.000: 508-511

  16. [Cardiac cephalgia: an underdiagnosed condition? ]. (United States)

    Gutiérrez Morlote, Jesús; Fernández García, José M; Timiraos Fernández, Juan J; Llano Cardenal, Miguel; Llano Catedral, Miguel; Rodríguez Rodríguez, Eloy; Pascual Gómez, Julio


    Cardiac cephalgia, or headache occurring as manifestation of myocardial ischemia, has only recently been recognized as a distinct entity. In patients with known ischemic cardiopathy, its diagnosis depends on the presence of severe headache that is accompanied by nausea, worsened by physical exercise, and only ceases with nitrate administration. We report on two patients who met diagnostic criteria for this entity. In both, headache was the only symptom of coronary ischemia, and delayed its diagnosis. Headache occurred both at rest and during exertion, and resolved only after the administration of nitrates. Cardiac cephalgia should be suspected in patients with a history of ischemic cardiopathy who present with de novo headache, even when thoracic pain is absent, especially if the headache improves with nitrates. Differential diagnosis with migraine is crucial to avoid the administration of vasoconstrictors.

  17. [Cardiac toxicity of 5-fluorouracil]. (United States)

    Fournier, C; Benahmed, M; Blondeau, M


    A 67 year-old patient receives 5-fluorouracil for vocal chord cancer. During the perfusion, atypical angina pain occurs, accompanied with offset of ST above the baseline in standard leads and in V4 through V6. The pain subsides spontaneously in 45 minutes. These ECG alterations are followed 48 hours later by diffuse inverted T waves with lengthened QT. Cardiac ultrasonography and isotopic angiography do not show any abnormality of the left ventricular function, but myocardial tomoscintigraphy with labelled thallium show a lower hypofixation on exertion. The cardiac toxicity of 5-fluorouracil is in frequent. It is usually believed that it involves a coronary spasm, as suggested by the ECG tracing in the reported cases. The incident, which may be painful or painless, may result in a myocardial infarction or even sudden death during the perfusion. Therefore, it is advisable to discontinue the treatment as soon as an angina-type pain occurs.

  18. Progeria syndrome with cardiac complications. (United States)

    Ilyas, Saadia; Ilyas, Hajira; Hameed, Abdul; Ilyas, Muhammad


    A case report of 6-year-old boy with progeria syndrome, with marked cardiac complications is presented. The boy had cardiorespiratory failure. Discoloured purpuric skin patches, alopecia, prominent forehead, protuberant eyes, flattened nasal cartilage, malformed mandible, hypodentition, and deformed rigid fingers and toes were observed on examination. The boy was unable to speak. A sclerotic systolic murmur was audible over the mitral and aortic areas. Chest x-rays showed cardiac enlargement and the electrocardiogram (ECG) showed giant peaked P waves (right atrial hypertrophy) and right ventricular hypertrophy. Atherosclerotic dilated ascending aorta, thickened sclerotic aortic, mitral, and tricuspid valves with increased echo texture, left and right atrial and right ventricular dilatation, reduced left ventricular cavity, and thickened speckled atrial and ventricular septa were observed on echocardiography.

  19. Sudden cardiac death in athletes

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    Fábio Camilo Pellegrino dos Santos


    Full Text Available ABSTRACT The most accepted definition of sudden cardiac death nowadays is an unexplained death occurred suddenly within one hour of symptom onset. If it was not witnessed, individuals need to had been observed for at least 24 hours before the event and should be discarded the possibility of non cardiac causes of sudden death, pulmonary embolism or extensive malignancy. The term athlete refers to individuals of any age who participate in collective or individual regular physical activity, as well as physical training program for regular competitions. The sudden death of a young athlete, whether amateur or professional, especially during competitions, is always dramatic, with strong negative social impact and in the media. The fact that sports are recommended as a formula for longevity and quality of life makes these events a cause for concern in sports and society in general.

  20. Heart fields and cardiac morphogenesis. (United States)

    Kelly, Robert G; Buckingham, Margaret E; Moorman, Antoon F


    In this review, we focus on two important steps in the formation of the embryonic heart: (i) the progressive addition of late differentiating progenitor cells from the second heart field that drives heart tube extension during looping morphogenesis, and (ii) the emergence of patterned proliferation within the embryonic myocardium that generates distinct cardiac chambers. During the transition between these steps, the major site of proliferation switches from progenitor cells outside the early heart to proliferation within the embryonic myocardium. The second heart field and ballooning morphogenesis concepts have major repercussions on our understanding of human heart development and disease. In particular, they provide a framework to dissect the origin of congenital heart defects and the regulation of myocardial proliferation and differentiation of relevance for cardiac repair.

  1. Respiratory gating in cardiac PET

    DEFF Research Database (Denmark)

    Lassen, Martin Lyngby; Rasmussen, Thomas; Christensen, Thomas E


    of our study was to compare the resulting imaging quality by the use of a time-based respiratory gating system in two groups administered either adenosine or dipyridamole as the pharmacological stress agent. METHODS AND RESULTS: Forty-eight patients were randomized to adenosine or dipyridamole cardiac...... stress (82)RB-PET. Respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. Patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4......BACKGROUND: Respiratory motion due to breathing during cardiac positron emission tomography (PET) results in spatial blurring and erroneous tracer quantification. Respiratory gating might represent a solution by dividing the PET coincidence dataset into smaller respiratory phase subsets. The aim...

  2. Systems biology and cardiac arrhythmias. (United States)

    Grace, Andrew A; Roden, Dan M


    During the past few years, the development of effective, empirical technologies for treatment of cardiac arrhythmias has exceeded the pace at which detailed knowledge of the underlying biology has accumulated. As a result, although some clinical arrhythmias can be cured with techniques such as catheter ablation, drug treatment and prediction of the risk of sudden death remain fairly primitive. The identification of key candidate genes for monogenic arrhythmia syndromes shows that to bring basic biology to the clinic is a powerful approach. Increasingly sophisticated experimental models and methods of measurement, including stem cell-based models of human cardiac arrhythmias, are being deployed to study how perturbations in several biologic pathways can result in an arrhythmia-prone heart. The biology of arrhythmia is largely quantifiable, which allows for systematic analysis that could transform treatment strategies that are often still empirical into management based on molecular evidence.

  3. Nutritional Status and Cardiac Autophagy

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    Jihyun Ahn


    Full Text Available Autophagy is necessary for the degradation of long-lasting proteins and nonfunctional organelles, and is activated to promote cellular survival. However, overactivation of autophagy may deplete essential molecules and organelles responsible for cellular survival. Lifelong calorie restriction by 40% has been shown to increase the cardiac expression of autophagic markers, which suggests that it may have a cardioprotective effect by decreasing oxidative damage brought on by aging and cardiovascular diseases. Although cardiac autophagy is critical to regulating protein quality and maintaining cellular function and survival, increased or excessive autophagy may have deleterious effects on the heart under some circumstances, including pressure overload-induced heart failure. The importance of autophagy has been shown in nutrient supply and preservation of energy in times of limitation, such as ischemia. Some studies have suggested that a transition from obesity to metabolic syndrome may involve progressive changes in myocardial inflammation, mitochondrial dysfunction, fibrosis, apoptosis, and myocardial autophagy.

  4. Ca(2+ release events in cardiac myocytes up close: insights from fast confocal imaging.

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    Vyacheslav M Shkryl

    Full Text Available The spatio-temporal properties of Ca(2+ transients during excitation-contraction coupling and elementary Ca(2+ release events (Ca(2+ sparks were studied in atrial and ventricular myocytes with ultra-fast confocal microscopy using a Zeiss LSM 5 LIVE system that allows sampling rates of up to 60 kHz. Ca(2+ sparks which originated from subsarcolemmal junctional sarcoplasmic reticulum (j-SR release sites in atrial myocytes were anisotropic and elongated in the longitudinal direction of the cell. Ca(2+ sparks in atrial cells originating from non-junctional SR and in ventricular myocytes were symmetrical. Ca(2+ spark recording in line scan mode at 40,000 lines/s uncovered step-like increases of [Ca(2+]i. 2-D imaging of Ca(2+ transients revealed an asynchronous activation of release sites and allowed the sequential recording of Ca(2+ entry through surface membrane Ca(2+ channels and subsequent activation of Ca(2+-induced Ca(2+ release. With a latency of 2.5 ms after application of an electrical stimulus, Ca(2+ entry could be detected that was followed by SR Ca(2+ release after an additional 3 ms delay. Maximum Ca(2+ release was observed 4 ms after the beginning of release. The timing of Ca(2+ entry and release was confirmed by simultaneous [Ca(2+]i and membrane current measurements using the whole cell voltage-clamp technique. In atrial cells activation of discrete individual release sites of the j-SR led to spatially restricted Ca(2+ release events that fused into a peripheral ring of elevated [Ca(2+]i that subsequently propagated in a wave-like fashion towards the center of the cell. In ventricular myocytes asynchronous Ca(2+ release signals from discrete sites with no preferential subcellular location preceded the whole-cell Ca(2+ transient. In summary, ultra-fast confocal imaging allows investigation of Ca(2+ signals with a time resolution similar to patch clamp technique, however in a less invasive fashion.

  5. Pregnancy as a cardiac stress model. (United States)

    Chung, Eunhee; Leinwand, Leslie A


    Cardiac hypertrophy occurs during pregnancy as a consequence of both volume overload and hormonal changes. Both pregnancy- and exercise-induced cardiac hypertrophy are generally thought to be similar and physiological. Despite the fact that there are shared transcriptional responses in both forms of cardiac adaptation, pregnancy results in a distinct signature of gene expression in the heart. In some cases, however, pregnancy can induce adverse cardiac events in previously healthy women without any known cardiovascular disease. Peripartum cardiomyopathy is the leading cause of non-obstetric mortality during pregnancy. To understand how pregnancy can cause heart disease, it is first important to understand cardiac adaptation during normal pregnancy. This review provides an overview of the cardiac consequences of pregnancy, including haemodynamic, functional, structural, and morphological adaptations, as well as molecular phenotypes. In addition, this review describes the signalling pathways responsible for pregnancy-induced cardiac hypertrophy and angiogenesis. We also compare and contrast cardiac adaptation in response to disease, exercise, and pregnancy. The comparisons of these settings of cardiac hypertrophy provide insight into pregnancy-associated cardiac adaptation.


    Directory of Open Access Journals (Sweden)



    Full Text Available : Heart transplantation has emerged as the definitive therapy for patients with end-stage cardiomyopathy. The two most common forms of cardiac disease that lead to transplantation are ischemic cardiomyopathy and dilated cardiomyopathy, which together comprise approximately 90% of cases. The other less common forms of heart disease include viral cardiomyopathy, infiltrative cardiomyopathy, postpartum cardiomyopathy, valvular heart disease and congenital heart disease

  7. Chaos control of cardiac arrhythmias. (United States)

    Garfinkel, A; Weiss, J N; Ditto, W L; Spano, M L


    Chaos theory has shown that many disordered and erratic phenomena are in fact deterministic, and can be understood causally and controlled. The prospect that cardiac arrhythmias might be instances of deterministic chaos is therefore intriguing. We used a recently developed method of chaos control to stabilize a ouabain-induced arrhythmia in rabbit ventricular tissue in vitro. Extension of these results to clinically significant arrhythmias such as fibrillation will require overcoming the additional obstacles of spatiotemporal complexity.

  8. Cardiac autonomic nerve distribution and arrhythmia

    Institute of Scientific and Technical Information of China (English)

    Quan Liu; Dongmei Chen; Yonggang Wang; Xin Zhao; Yang Zheng


    OBJECTIVE: To analyze the distribution characteristics of cardiac autonomic nerves and to explore the correlation between cardiac autonomic nerve distribution and arrhythmia.DATA RETRIEVAL: A computer-based retrieval was performed for papers examining the distribution of cardiac autonomic nerves, using "heart, autonomic nerve, sympathetic nerve, vagus nerve, nerve distribution, rhythm and atrial fibrillation" as the key words.SELECTION CRITERIA: A total of 165 studies examining the distribution of cardiac autonomic nerve were screened, and 46 of them were eventually included.MAIN OUTCOME MEASURES: The distribution and characteristics of cardiac autonomic nerves were observed, and immunohistochemical staining was applied to determine the levels of tyrosine hydroxylase and acetylcholine transferase (main markers of cardiac autonomic nerve distribution). In addition, the correlation between cardiac autonomic nerve distribution and cardiac arrhythmia was investigated.RESULTS: Cardiac autonomic nerves were reported to exhibit a disordered distribution in different sites, mainly at the surface of the cardiac atrium and pulmonary vein, forming a ganglia plexus. The distribution of the pulmonary vein autonomic nerve was prominent at the proximal end rather than the distal end, at the upper left rather than the lower right, at the epicardial membrane rather than the endocardial membrane, at the left atrium rather than the right atrium, and at the posterior wall rather than the anterior wall. The main markers used for cardiac autonomic nerves were tyrosine hydroxylase and acetylcholine transferase. Protein gene product 9.5 was used to label the immunoreactive nerve distribution, and the distribution density of autonomic nerves was determined using a computer-aided morphometric analysis system.CONCLUSION: The uneven distribution of the cardiac autonomic nerves is the leading cause of the occurrence of arrhythmia, and the cardiac autonomic nerves play an important role in the

  9. Mechanical modulation of cardiac microtubules. (United States)

    White, Ed


    Microtubules are a major component of the cardiac myocyte cytoskeleton. Interventions that alter it may influence cardiac mechanical and electrical activity by disrupting the trafficking of proteins to and from the surface membrane by molecular motors such as dynein, which use microtubules as tracks to step along. Free tubulin dimers may transfer GTP to the α-subunits of G-proteins, thus an increase in free tubulin could increase the activity of G-proteins; evidence for and against such a role exists. There is more general agreement that microtubules act as compression-resisting structures within myocytes, influencing visco-elasticity of myocytes and increasing resistance to shortening when proliferated and resisting deformation from longitudinal shear stress. In response to pressure overload, there can be post-translational modifications resulting in more stable microtubules and an increase in microtubule density. This is accompanied by contractile dysfunction of myocytes which can be reversed by microtubule disruption. There are reports of mechanically induced changes in electrical activity that are dependent upon microtubules, but at present, a consensus is lacking on whether disruption or proliferation would be beneficial in the prevention of arrhythmias. Microtubules certainly play a role in the response of cardiac myocytes to mechanical stimulation, the exact nature and significance of this role is still to be fully determined.

  10. Review Article of Cardiac Amyloidosis

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    Jittiporn PURATTANAMAL


    Full Text Available Cardiac amyloidosis is a term that means the deposit of abnormal proteins in the myocardium leading to global thickening of the heart walls. The clinical character is that of infiltrative cardiomyopathy. AL amyloidosis is the most common type that involves cardiac failure. Cardiac amyloid precedes clinical congestive heart failure, especially right-sided heart failure. Laboratory investigations have identified the amyloid fibril proteins deposited in the organ tissues. Immunofixation tests are the most sensitive that recognize the paraprotein mean light chain protein or immunoglobulin subtype deposit. Prognosis is poor if AL amyloidosis is untreated. Treatment of systemic involvement in AL amyloidosis is via chemotherapy such as melphalan and prednisolone. UK experts have reported the results of treatment in AL amyloidosis. Regardless of the use of adjunctive chemotherapy, the five-year survival after heart transplantation was generally poorer for AL (20 % at five years, but similar for non-AL amyloidosis (64 % at five years, than heart transplants in other cases. Progression of the systemic disease contributed to increased mortality. A specific treatment that increases the chances of survival is unknown.

  11. Sudden cardiac death risk stratification. (United States)

    Deyell, Marc W; Krahn, Andrew D; Goldberger, Jeffrey J


    Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

  12. Neurologic management following cardiac arrest. (United States)

    Bircher, N G


    Optimal neurologic outcome after cardiac arrest requires careful attention to the details of both intracranial and extracranial homeostasis. A high index of suspicion regarding the potential causes and complications of cardiac arrest facilitates discovery and treatment of problems before they adversely affect neurologic outcome. The future is bright for resuscitation research: Our fundamental understanding of cerebral ischemia and its consequences has dramatically improved, and this knowledge can hopefully be transferred to clinical useful modes of therapy. However, the transition from a promising, therapeutically effective intervention in animals to the demonstration that treatment is effective following cardiac arrest in humans is an important and difficult step. The patient population is heterogeneous before the insult, the duration and severity of the insult are variable, and the effectiveness of cardiopulmonary resuscitation varies among institutions. Therefore, the only means of demonstrating clinical efficacy is the performance of a large clinical trial. The Resuscitation Research Center at the University of Pittsburgh has developed and coordinated a multicenter, multinational team of investigators who have completed one definitive trial of postarrest barbiturate therapy and are currently completing a similar trial using a calcium entry blocker. Despite the formidable obstacles posed by such comprehensive efforts, they provide the mechanism for determining whether the cost of a new treatment modality is justified by the likelihood of improved mortality or morbidity.

  13. Inherited arrhythmias: The cardiac channelopathies

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    Shashank P Behere


    Full Text Available Ion channels in the myocardial cellular membrane are responsible for allowing the cardiac action potential. Genetic abnormalities in these channels can predispose to life-threatening arrhythmias. We discuss the basic science of the cardiac action potential; outline the different clinical entities, including information regarding overlapping diagnoses, touching upon relevant genetics, new innovations in screening, diagnosis, risk stratification, and management. The special considerations of sudden unexplained death and sudden infant death syndrome are discussed. Scientists and clinicians continue to reconcile the rapidly growing body of knowledge regarding the molecular mechanisms and genetics while continuing to improve our understanding of the various clinical entities and their diagnosis and management in clinical setting. Two separate searches were run on the National Center for Biotechnology Information′s website. The first using the term cardiac channelopathies was run on the PubMed database using filters for time (published in past 5 years and age (birth-18 years, yielding 47 results. The second search using the medical subject headings (MeSH database with the search terms "Long QT Syndrome" (MeSH and "Short QT Syndrome" (MeSH and "Brugada Syndrome" (MeSH and "Catecholaminergic Polymorphic Ventricular Tachycardia" (MeSH, applying the same filters yielded 467 results. The abstracts of these articles were studied, and the articles were categorized and organized. Articles of relevance were read in full. As and where applicable, relevant references and citations from the primary articles where further explored and read in full.

  14. The involvement of SMILE/TMTC3 in endoplasmic reticulum stress response.

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    Maud Racapé

    Full Text Available BACKGROUND: The state of operational tolerance has been detected sporadically in some renal transplanted patients that stopped immunosuppressive drugs, demonstrating that allograft tolerance might exist in humans. Several years ago, a study by Brouard et al. identified a molecular signature of several genes that were significantly differentially expressed in the blood of such patients compared with patients with other clinical situations. The aim of the present study is to analyze the role of one of these molecules over-expressed in the blood of operationally tolerant patients, SMILE or TMTC3, a protein whose function is still unknown. METHODOLOGY/PRINCIPAL FINDINGS: We first confirmed that SMILE mRNA is differentially expressed in the blood of operationally tolerant patients with drug-free long term graft function compared to stable and rejecting patients. Using a yeast two-hybrid approach and a colocalization study by confocal microscopy we furthermore report an interaction of SMILE with PDIA3, a molecule resident in the endoplasmic reticulum (ER. In accordance with this observation, SMILE silencing in HeLa cells correlated with the modulation of several transcripts involved in proteolysis and a decrease in proteasome activity. Finally, SMILE silencing increased HeLa cell sensitivity to the proteasome inhibitor Bortezomib, a drug that induces ER stress via protein overload, and increased transcript expression of a stress response protein, XBP-1, in HeLa cells and keratinocytes. CONCLUSION/SIGNIFICANCE: In this study we showed that SMILE is involved in the endoplasmic reticulum stress response, by modulating proteasome activity and XBP-1 transcript expression. This function of SMILE may influence immune cell behavior in the context of transplantation, and the analysis of endoplasmic reticulum stress in transplantation may reveal new pathways of regulation in long-term graft acceptance thereby increasing our understanding of tolerance.

  15. Cardiac tamponade: contrast reflux as an indicator of cardiac chamber equalization

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    Nauta Foeke Jacob


    Full Text Available Abstract Background Traumatic hemopericardium remains a rare entity; it does however commonly cause cardiac tamponade which remains a major cause of death in traumatic blunt cardiac injury. Objectives We present a case of blunt chest trauma complicated by cardiac tamponade causing cardiac chamber equalization revealed by reflux of contrast. Case report A 29-year-old unidentified male suffered blunt chest trauma in a motor vehicle collision. Computed tomography (CT demonstrated a periaortic hematoma and hemopericardium. Significant contrast reflux was seen in the inferior vena cava and hepatic veins suggesting a change in cardiac chamber pressures. After intensive treatment including cardiac massage this patient expired of cardiac arrest. Conclusion Reflux of contrast on CT imaging can be an indicator of traumatic cardiac tamponade.

  16. Sensing Cardiac Electrical Activity With a Cardiac Myocyte--Targeted Optogenetic Voltage Indicator

    NARCIS (Netherlands)

    Chang Liao, Mei-Ling; de Boer, Teun P; Mutoh, Hiroki; Raad, Nour; Richter, Claudia; Wagner, Eva; Downie, Bryan R; Unsöld, Bernhard; Arooj, Iqra; Streckfuss-Bömeke, Katrin; Döker, Stephan; Luther, Stefan; Guan, Kaomei; Wagner, Stefan; Lehnart, Stephan E; Maier, Lars S; Stühmer, Walter; Wettwer, Erich; van Veen, Toon; Morlock, Michael M; Knöpfel, Thomas; Zimmermann, Wolfram-Hubertus


    RATIONALE: Monitoring and controlling cardiac myocyte activity with optogenetic tools offer exciting possibilities for fundamental and translational cardiovascular research. Genetically encoded voltage indicators may be particularly attractive for minimal invasive and repeated assessments of cardiac

  17. Melatonin Induces Anti-Inflammatory Effects to Play a Protective Role via Endoplasmic Reticulum Stress in Acute Pancreatitis

    Directory of Open Access Journals (Sweden)

    Yina Chen


    Full Text Available Background/Aims: Melatonin, which is mainly secreted by the pineal gland and released into blood, has anti-inflammatory properties in acute pancreatitis. Many studies show that melatonin can relieve inflammation in taurocholate-induced acute pancreatitis. However, the mechanisms of its anti-inflammatory effects are still undefined, especially the relationship between melatonin and endoplasmic reticulum stress. We explored the anti-inflammatory activity of melatonin in AR42J and rat models. Methods: The CCK-8 assay was used to assess effects of melatonin on AR42J cell viability. Inflammatory degree and the expressions of endoplasmic reticulum stress related molecules were examined by quantitative RT-PCR and western blotting. The degree of inflammation in the tissue was also accessed by pathological grading. Finally, we used the western blotting method to verify apoptosis and autophagy. Results: Endoplasmic reticulum stress was obviously activated in early stage inflammation in AR42J and rat models. Melatonin could induce anti-inflammatory effects via endoplasmic reticulum stress. Melatonin significantly inhibited inflammatory cytokines and the expression of ERS-related molecules. Finally, it played a protective role by promoting apoptosis and autophagy of the cells, which were damaged in the process of inflammatory reaction. Conclusion: Melatonin induces anti-inflammatory effects via endoplasmic reticulum stress in acute pancreatitis to play a protective role.

  18. Endoplasmic reticulum stress-induced apoptosis in the penumbra aggravates secondary damage in rats with traumatic brain injur y

    Institute of Scientific and Technical Information of China (English)

    Guo-zhu Sun; Fen-fei Gao; Zong-mao Zhao; Hai Sun; Wei Xu; Li-wei Wu; Yong-chang He


    Neuronal apoptosis is mediated by intrinsic and extrinsic signaling pathways such as the membrane-mediated, mitochondrial, and endo-plasmic reticulum stress pathways. Few studies have examined the endoplasmic reticulum-mediated apoptosis pathway in the penumbra after traumatic brain injury, and it remains unclear whether endoplasmic reticulum stress can activate the caspase-12-dependent apoptotic pathway in the traumatic penumbra. Here, we established rat models of lfuid percussion-induced traumatic brain injury and found that protein expression of caspase-12, caspase-3 and the endoplasmic reticulum stress marker 78 kDa glucose-regulated protein increased in the traumatic penumbra 6 hours after injury and peaked at 24 hours. Furthermore, numbers of terminal deoxynucleotidyl transferase-mediat-ed dUTP nick end labeling-positive cells in the traumatic penumbra also reached peak levels 24 hours after injury. These ifndings suggest that caspase-12-mediated endoplasmic reticulum-related apoptosis is activated in the traumatic penumbra, and may play an important role in the pathophysiology of secondary brain injury.

  19. [From endoplasmic reticulum to Golgi apparatus: a secretory pathway controlled by signal molecules]. (United States)

    Wang, Jiasheng; Luo, Jianhong; Zhang, Xiaomin


    Protein transport from endoplasmic reticulum (ER) to Golgi apparatus has long been known to be a central process for protein quality control and sorting. Recent studies have revealed that a large number of signal molecules are involved in regulation of membrane trafficking through ER, ER-Golgi intermediate compartment and Golgi apparatus. These molecules can significantly change the transport rate of proteins by regulating vesicle budding and fusion. Protein transport from ER to Golgi apparatus is not only controlled by signal pathways triggered from outside the cell, it is also regulated by feedback signals from the transport pathway.

  20. Comparative ultrastructural study of endoplasmic reticulum in colorectal carcinoma cell lines with different degrees of differentiation

    Institute of Scientific and Technical Information of China (English)

    Shu Feng; Jin Dan Song


    The endoplasmic reticulum (ER) consists of a complex system of tubules, lamellae, and flattened vesicles, and has a variety of morphologies in different cells. It is believed to play a central role in the biosynthesis of cholesterol, phospholipids, steroids, prostaglandins, membrane and secretory proteins[1]. Cancer cells have different functions and ultrastmcture from their original cells[2-4]. The studies on ER membrane system of cancer cells are of great significance in understanding their malignant behavior. In the present work, the ultrastructural characteristics of ER in human colorectal carcinoma cell lines with different differentiation degrees were investigated.

  1. A postmortem study on indigestible foreign bodies in the rumen and reticulum of ruminants, eastern Ethiopia

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    Seifu Negash


    Full Text Available A cross-sectional study was conducted on ruminants (cattle, sheep and goats slaughtered at Haramaya University and Haramaya municipal abattoirs from November 2013 to April 2014 in Haramaya, eastern Ethiopia. The objective of the study was to identify types and estimate the prevalence of foreign bodies in the rumen and reticulum of domestic ruminants in the area. From 810 randomly selected study animals, 422 (52.1% were found to have foreign bodies. Of the 332 cattle, 193 sheep and 285 goats examined, 144 (43.4%, 109 (56.5% and 169 (59.3% respectively were found with various types of foreign bodies. The prevalence of foreign bodies was significantly (χ2 = 17.53, p < 0.05 higher in sheep (59.3% and goats (56.7% than in cattle (43.4%. Overall the prevalence of foreign bodies in study animals with poor body condition was significantly higher (χ2 = 38.57, p < 0.05 than in those with medium and good body condition. A higher percentage of foreign bodies occurred in the rumen alone (87.9% than in the reticulum alone (5.0%, with the rest present in both. Significantly higher proportions of foreign bodies were observed in the rumen of cattle (χ2 = 332, p < 0.05, sheep (χ2 = 193, p < 0.05 and goats (χ2 = 285.0, p = 0.000 than in the reticulum. Plastic was the most commonly encountered (79.2% foreign body, followed by cloth (15.3% and rope (12.3%. In addition, metal (0.9% and calcified material and/or stone (1.0% were found in the reticulum of cattle. Lack of a plastic waste disposal system in the area as well as communal/free grazing of livestock in highly waste-polluted areas seemed to be major factors in the high occurrence of foreign bodies in ruminants. To change this, collaborative intervention schemes involving professionals, policy makers, livestock keepers and environmental activists are needed.

  2. Survival and death of endoplasmic-reticulum-stressed cells:Role of autophagy

    Institute of Scientific and Technical Information of China (English)


    Accumulation of unfolded proteins in the endoplasmic reticulum (ER) results in ER stress, which subsequently activates the unfolded protein response that induces a transcriptional program to alleviate the stress. Another cellular process that is activated during ER stress is autophagy, a mechanism of enclosing intracellular compo- nents in a double-membrane autophagosome, and then delivering it to the lysosome for degradation. Here, we discuss the role of autophagy in cellular response to ER stress, the signaling pathways linking ER stress to autophagy, and the possible implication of modulating autophagy in treatment of diseases such as cancer.

  3. The metabolomic signature of Leber's hereditary optic neuropathy reveals endoplasmic reticulum stress. (United States)

    Chao de la Barca, Juan Manuel; Simard, Gilles; Amati-Bonneau, Patrizia; Safiedeen, Zainab; Prunier-Mirebeau, Delphine; Chupin, Stéphanie; Gadras, Cédric; Tessier, Lydie; Gueguen, Naïg; Chevrollier, Arnaud; Desquiret-Dumas, Valérie; Ferré, Marc; Bris, Céline; Kouassi Nzoughet, Judith; Bocca, Cinzia; Leruez, Stéphanie; Verny, Christophe; Miléa, Dan; Bonneau, Dominique; Lenaers, Guy; Martinez, M Carmen; Procaccio, Vincent; Reynier, Pascal


    Leber's hereditary optic neuropathy (MIM#535000), the commonest mitochondrial DNA-related disease, is caused by mutations affecting mitochondrial complex I. The clinical expression of the disorder, usually occurring in young adults, is typically characterized by subacute, usually sequential, bilateral visual loss, resulting from the degeneration of retinal ganglion cells. As the precise action of mitochondrial DNA mutations on the overall cell metabolism in Leber's hereditary optic neuropathy is unknown, we investigated the metabolomic profile of the disease. High performance liquid chromatography coupled with tandem mass spectrometry was used to quantify 188 metabolites in fibroblasts from 16 patients with Leber's hereditary optic neuropathy and eight healthy control subjects. Latent variable-based statistical methods were used to identify discriminating metabolites. One hundred and twenty-four of the metabolites were considered to be accurately quantified. A supervised orthogonal partial least squares discriminant analysis model separating patients with Leber's hereditary optic neuropathy from control subjects showed good predictive capability (Q(2)cumulated = 0.57). Thirty-eight metabolites appeared to be the most significant variables, defining a Leber's hereditary optic neuropathy metabolic signature that revealed decreased concentrations of all proteinogenic amino acids, spermidine, putrescine, isovaleryl-carnitine, propionyl-carnitine and five sphingomyelin species, together with increased concentrations of 10 phosphatidylcholine species. This signature was not reproduced by the inhibition of complex I with rotenone or piericidin A in control fibroblasts. The importance of sphingomyelins and phosphatidylcholines in the Leber's hereditary optic neuropathy signature, together with the decreased amino acid pool, suggested an involvement of the endoplasmic reticulum. This was confirmed by the significantly increased phosphorylation of PERK and eIF2α, as well as

  4. Endoplasmic reticulum (ER) stress-suppressive compounds from scrap cultivation beds of the mushroom Hericium erinaceum. (United States)

    Ueda, Keiko; Kodani, Shinya; Kubo, Masakazu; Masuno, Kazuhiko; Sekiya, Atsushi; Nagai, Kaoru; Kawagishi, Hirokazu


    Four compounds were isolated from scrap cultivation beds of the mushroom, Hericium erinaceum. Compounds 1-4 were identified as methyl 4-hydroxy-3-(3-methylbutanoyl) benzoate, 2-chloro-1,3-dimethoxy-5-methylbenzene, methyl 4-chloro-3,5-dimethoxybenzoate, and 4-chloro-3,5-dimethoxybenzaldehyde by an interpretation of the NMR and MS data, respectively. This is the first reported isolation of 1 from a natural source. All the compounds showed protective activity against endoplasmic reticulum stress-dependent cell death.

  5. Analysis of site-specific N-glycan remodeling in the endoplasmic reticulum and the Golgi (United States)

    Hang, Ivan; Lin, Chia-wei; Grant, Oliver C; Fleurkens, Susanna; Villiger, Thomas K; Soos, Miroslav; Morbidelli, Massimo; Woods, Robert J; Gauss, Robert; Aebi, Markus


    The hallmark of N-linked protein glycosylation is the generation of diverse glycan structures in the secretory pathway. Dynamic, non-template-driven processes of N-glycan remodeling in the endoplasmic reticulum and the Golgi provide the cellular setting for structural diversity. We applied newly developed mass spectrometry-based analytics to quantify site-specific N-glycan remodeling of the model protein Pdi1p expressed in insect cells. Molecular dynamics simulation, mutational analysis, kinetic studies of in vitro processing events and glycan flux analysis supported the defining role of the protein in N-glycan processing. PMID:26240167

  6. ERIS, an endoplasmic reticulum IFN stimulator, activates innate immune signaling through dimerization



    We report here the identification and characterization of a protein, ERIS, an endoplasmic reticulum (ER) IFN stimulator, which is a strong type I IFN stimulator and plays a pivotal role in response to both non–self-cytosolic RNA and dsDNA. ERIS (also known as STING or MITA) resided exclusively on ER membrane. The ER retention/retrieval sequence RIR was found to be critical to retain the protein on ER membrane and to maintain its integrity. ERIS was dimerized on innate immune challenges. Coume...

  7. ERIS, an endoplasmic reticulum IFN stimulator, activates innate immune signaling through dimerization. (United States)

    Sun, Wenxiang; Li, Yang; Chen, Lu; Chen, Huihui; You, Fuping; Zhou, Xiang; Zhou, Yi; Zhai, Zhonghe; Chen, Danying; Jiang, Zhengfan


    We report here the identification and characterization of a protein, ERIS, an endoplasmic reticulum (ER) IFN stimulator, which is a strong type I IFN stimulator and plays a pivotal role in response to both non-self-cytosolic RNA and dsDNA. ERIS (also known as STING or MITA) resided exclusively on ER membrane. The ER retention/retrieval sequence RIR was found to be critical to retain the protein on ER membrane and to maintain its integrity. ERIS was dimerized on innate immune challenges. Coumermycin-induced ERIS dimerization led to strong and fast IFN induction, suggesting that dimerization of ERIS was critical for self-activation and subsequent downstream signaling.

  8. The endoplasmic reticulum exerts control over organelle streaming during cell expansion. (United States)

    Stefano, Giovanni; Renna, Luciana; Brandizzi, Federica


    Cytoplasmic streaming is crucial for cell homeostasis and expansion but the precise driving forces are largely unknown. In plants, partial loss of cytoplasmic streaming due to chemical and genetic ablation of myosins supports the existence of yet-unknown motors for organelle movement. Here we tested a role of the endoplasmic reticulum (ER) as propelling force for cytoplasmic streaming during cell expansion. Through quantitative live-cell analyses in wild-type Arabidopsis thaliana cells and mutants with compromised ER structure and streaming, we demonstrate that cytoplasmic streaming undergoes profound changes during cell expansion and that it depends on motor forces co-exerted by the ER and the cytoskeleton.

  9. Cognitive impairment after sudden cardiac arrest


    Jaszke-Psonka, Magdalena; Piegza, Magdalena; Ścisło, Piotr; Pudlo, Robert; Piegza, Jacek; Badura-Brzoza, Karina; Leksowska, Aleksandra; Hese, Robert T.; Gorczyca, Piotr W.


    Aim To evaluate the incidence and severity of the impairment of selected cognitive functions in patients after sudden cardiac arrest (SCA) in comparison to patients after myocardial infarction without SCA and healthy subjects and to analyze the influence of sociodemographic and clinical parameters and the duration of cardiac arrest on the presence and severity of the described disorders. Material and methods The study group comprised 30 cardiac arrest survivors, the reference group comprised ...

  10. Surgical resection of a giant cardiac fibroma. (United States)

    Stamp, Nikki L; Larbalestier, Robert I


    A 42-year-old woman presented to a regional hospital emergency room with palpitations and was found to be in ventricular tachycardia. Chest radiography demonstrated a massively enlarged cardiac silhouette. Echocardiography and cardiac magnetic resonance imaging demonstrated a mass within the left ventricular free wall, consistent with a cardiac fibroma. The patient proceeded to have surgical resection of the mass. Left ventricular function was preserved postoperatively.

  11. Modeling Catecholaminergic Polymorphic Ventricular Tachycardia using Induced Pluripotent Stem Cell-derived Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Atara Novak


    Full Text Available Catecholaminergic polymorphic ventricular tachycardia (CPVT is an inherited arrhythmogenic cardiac disorder characterized by life-threatening arrhythmias induced by physical or emotional stress, in the absence structural heart abnormalities. The arrhythmias may cause syncope or degenerate into cardiac arrest and sudden death which usually occurs during childhood. Recent studies have shown that CPVT is caused by mutations in the cardiac ryanodine receptor type 2 (RyR2 or calsequestrin 2 (CASQ2 genes. Both proteins are key contributors to the intracellular Ca2+ handling process and play a pivotal role in Ca2+ release from the sarcoplasmic reticulum to the cytosol during systole. Although the molecular pathogenesis of CPVT is not entirely clear, it was suggested that the CPVT mutations promote excessive sarcoplasmic reticulum Ca2+ leak, which initiates delayed afterdepolarizations (DADs and triggered arrhythmias in cardiac myocytes. The recent breakthrough discovery of induced pluripotent stem cells (iPSC generated from somatic cells (e.g. fibroblasts, keratinocytes now enables researches to investigate mutated cardiomyocytes generated from the patient’s iPSC. To this end, in the present article we review recent studies on CPVT iPSC-derived cardiomyocytes, thus demonstrating in the mutated cells catecholamine-induced DADs and triggered arrhythmias.

  12. Cardiac Arrhythmias: Diagnosis, Symptoms, and Treatments. (United States)

    Fu, Du-Guan


    The cardiac arrhythmia is characterized by irregular rhythm of heartbeat which could be either too slow (100 beats/min) and can happen at any age. The use of pacemaker and defibrillators devices has been suggested for heart arrhythmias patients. The antiarrhythmic medications have been reported for the treatment of cardiac arrhythmias or irregular heartbeats. The diagnosis, symptoms, and treatments of cardiac arrhythmias as well as the radiofrequency ablation, tachycardia, Brugada syndrome, arterial fibrillation, and recent research on the genetics of cardiac arrhythmias have been described here.

  13. Multimodality imaging for resuscitated sudden cardiac death. (United States)

    Chen, Yingming Amy; Deva, Djeven; Kirpalani, Anish; Prabhudesai, Vikram; Marcuzzi, Danny W; Graham, John J; Verma, Subodh; Jimenez-Juan, Laura; Yan, Andrew T


    We present a case that elegantly illustrates the utility of two novel noninvasive imaging techniques, computed tomography (CT) coronary angiography and cardiac MRI, in the diagnosis and management of a 27-year-old man with exertion-induced cardiac arrest caused by an anomalous right coronary artery. CT coronary angiography with 3D reformatting delineated the interarterial course of an anomalous right coronary artery compressed between the aorta and pulmonary artery, whereas cardiac MRI showed a small myocardial infarction in the right coronary artery territory not detected on echocardiography. This case highlights the value of novel multimodality imaging techniques in the risk stratification and management of patients with resuscitated cardiac arrest.

  14. Tumors of the cardiac conduction system: are they an explanation for otherwise unexplained sudden cardiac death?

    Institute of Scientific and Technical Information of China (English)


    @@ Cardiac tumors are well described in the literature. The first reports of cardiac tumors date back hundreds of years.The prevalence of primary cardiac tumors at autopsy ranges from 0.001% to 0.3% with secondary tumors more common than in primary tumors.

  15. 硫氢化钠对慢性心力衰竭大鼠心功能及心脏结构的影响%Sodium hydrosulfide improves cardiac functions and structures in rats with chronic heart failure

    Institute of Scientific and Technical Information of China (English)

    李晓惠; 张超英; 张霆


    Objective To explore the effects of sodium hydrosulfide ( NaHS),a hydrogen sulphide (H2S) donor,on cardiac functions and structures in rats with chronic heart failure induced by volume overload and examine its influence on cardiac remodelling.Methods A total of 47 SD rats ( 120 - 140 g) were randomly divided into 5 groups:shunt group ( n =11 ),sham group ( n =8),shunt + NaHS group ( n =10),sham + NaHS group ( n =8) and shunt + phentolamine group (n =10).The rat model of chronic heart failure was induced by abdominal aorta-inferior vena cava puncture.At Week 8 post-operation,hemodynamic parameters,microstructures and ultrastructures of myocardial tissues were analyzed.Extracellular collagen content in myocardial tissues was analyzed after Sirius red staining.Right ventricular hydroxyproline concentration was determined and compared.Results At Week 8 post-operation,compared with the sham operation and shunt + NaHS groups,the shunt group showed significantly increased right ventricular systolic pressure (RVSP) and right ventricular end diastolic pressure (RVEDP) ( mm Hg:35.2 ±3.9 vs 21.4 ±3.7 and 28.1 ±2.7,32 ±5 vs 21 ±4 and 26 ±4,all P <0.05,1 mm Hg =0.133 kPa).The RV peak rate of contraction and relaxation markedly decreased ( RV ± dp/dt max) ( mm Hg/s:1528 ± 113 vs 2336 ± 185 and 1835 ± 132,1331 ± 107 vs 2213 ± 212 and 1768 ± 116,all P < 0.05).It was found microscopically that myocardial fibers in the shunt group were irregularly arranged,partially cytolyzed and infiltrated by inflammatory cells.Electron microscopy revealed that myocardial fibers thickened non-uniformly in the shunt group,some fiber mitochondria were highly swollen and contained vacuoles.And sarcoplasmic reticulum appeared slightly dilated.Polarized microscopy indicated that,collagen content (particularly type-Ⅰ collagen) increased in the shunt group compared with the sham operation group.Additionally,compared with the shunt group,the shunt and NaHS treatment groups showed an

  16. DSCR2, a Down syndrome critical region protein, is localized to the endoplasmic reticulum of mammalian cells

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    PA Possik


    Full Text Available We used immunocytochemical and fluorescence assays to investigate the subcellular location of the protein encoded by Down syndrome critical region gene 2 (DSCR2 in transfected cells. It was previously suggested that DSCR2 is located in the plasma membrane as an integral membrane protein. Interestingly, we observed this protein in the endoplasmic reticulum (ER of cells.We also studied whether the truncated forms of DSCR2 showed different subcellular distributions. Our observations indicate that DSCR2 probably is not inserted into the membrane of the endoplasmic reticulum since the fragments lacking the predicted transmembrane (TM helices remained associated with the ER. Our analyses suggest that, although DSCR2 is associated with the endoplasmic reticulum, it is not an integral membrane protein and it is maintained on the cytoplasmic side of the ER by indirect interaction with the ER membrane or with another protein.


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    Full Text Available Cardiovascular malformations are the most common cause of congenital malformations, the diagnosis of which requires a close observation in the neonatal period. Early recognition of CHD is important in the neonatal period, as many of them may be fatal if undiagnosed and may require immediate intervention. The objectives of this study are to study the epidemiology of neonatal cardiac murmurs, to identify clinical characteristics which differentiate pathological murmur from functional murmurs and to assess the reliability of clinical evaluation in diagnosing CHD. Method of study included all neonates admitted to the NICU, postnatal ward, attending pediatric OPD or neonatal follow up clinic and were detected to have cardiac murmurs. It was a cross sectional study over a period of 16months. A clinical diagnosis was made based on history and clinical examination. Then Chest X-ray and ECG, Echocardiography was done in all neonates for confirmation of the diagnosis. These neonates were again examined daily till they were in hospital and during the follow-up visit at 6 weeks. The results of 70 neonates in this study conducted over a period of 24 months included the incidence of cardiac murmurs among intramural neonates which was 13.5 for 1000 live births. Most frequent symptom was fast breathing in 10(14.3% cases. VSD was the most common diagnosis clinically in 23 (33% babies. The most frequent Echo diagnosis was acyanotic complex congenital heart disease in 25(36% cases followed by 12(17% cases each of VSD and ASD respectively. Overall in our study 77.1% (54cases of the murmurs were diagnosed correctly and confirmed by Echocardiography The study concluded that it is possible to make clinical diagnosis in many cases of congenital heart diseases, the functional murmurs could be differentiated from those arising from structural heart disease and evaluation of the infants based only on murmurs, few congenital heart diseases can be missed.

  18. ECLS in Pediatric Cardiac Patients (United States)

    Di Nardo, Matteo; MacLaren, Graeme; Marano, Marco; Cecchetti, Corrado; Bernaschi, Paola; Amodeo, Antonio


    Extracorporeal life support (ECLS) is an important device in the management of children with severe refractory cardiac and or pulmonary failure. Actually, two forms of ECLS are available for neonates and children: extracorporeal membrane oxygenation (ECMO) and use of a ventricular assist device (VAD). Both these techniques have their own advantages and disadvantages. The intra-aortic balloon pump is another ECLS device that has been successfully used in larger children, adolescents, and adults, but has found limited applicability in smaller children. In this review, we will present the “state of art” of ECMO in neonate and children with heart failure. ECMO is commonly used in a variety of settings to provide support to critically ill patients with cardiac disease. However, a strict selection of patients and timing of intervention should be performed to avoid the increase in mortality and morbidity of these patients. Therefore, every attempt should be done to start ECLS “urgently” rather than “emergently,” before the presence of dysfunction of end organs or circulatory collapse. Even though exciting progress is being made in the development of VADs for long-term mechanical support in children, ECMO remains the mainstay of mechanical circulatory support in children with complex anatomy, particularly those needing rapid resuscitation and those with a functionally univentricular circulation. With the increase in familiarity with ECMO, new indications have been added, such as extracorporeal cardiopulmonary resuscitation (ECPR). The literature supporting ECPR is increasing in children. Reasonable survival rates have been achieved after initiation of support during active compressions of the chest following in-hospital cardiac arrest. Contraindications to ECLS have reduced in the last 5 years and many centers support patients with functionally univentricular circulations. Improved results have been recently achieved in this complex subset of patients. PMID

  19. Sudden Cardiac Death and Post Cardiac Arrest Syndrome. An Overview

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    Zima Endre


    Full Text Available A satisfactory neurologic outcome is the key factor for survival in patients with sudden cardiac death (SCD, however this is highly dependent on the haemodynamic status. Short term cardiopulmonary resuscitation and regained consciousness on the return of spontaneous circulation (ROSC is indicative of a better prognosis. The evaluation and treatment of SCD triggering factors and of underlying acute and chronic diseases will facilitate prevention and lower the risk of cardiac arrest. Long term CPR and a prolonged unconscious status after ROSC, in the Intensive Care Units or Coronary Care Units, indicates the need for specific treatment and supportive therapy including efforts to prevent hyperthermia. The prognosis of these patients is unpredictable within the first seventy two hours, due to unknown responses to therapeutic management and the lack of specific prognostic factors. Patients in these circumstances require the highest level of intensive care and aetiology driven treatment without any delay, independently of their coma state. Current guidelines sugest the use of multiple procedures in arriving at a diagnosis and prognosis of these critical cases.

  20. [Morgagni hernia causing cardiac tamponade]. (United States)

    S Breinig; Paranon, S; Le Mandat, A; Galinier, P; Dulac, Y; Acar, P


    Morgagni hernia is a rare malformation (3% of diaphragmatic hernias). This hernia is usually asymptomatic in children. We report on a case revealed by an unusual complication. Severe cyanosis was due to right-to-left atrial shunt through the foramen ovale assessed by 2D echocardiography. Diagnosis of the Morgagni hernia was made with CT scan. The intrathoracic liver compressed the right chambers of the heart causing tamponade. Cardiac compression was reversed after surgery and replacement of the liver in the abdomen. Six months after the surgery, the infant was symptom-free with normal size right chambers of the heart.