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Sample records for calcium channel blocker

  1. Calcium channel blockers and Alzheimer's disease

    Institute of Scientific and Technical Information of China (English)

    Yi Tan; Yulin Deng; Hong Qing

    2012-01-01

    Alzheimer's disease is characterized by two pathological hallmarks: amyloid plaques and neurofi-brillary tangles. In addition, calcium homeostasis is disrupted in the course of human aging. Recent research shows that dense plaques can cause functional alteration of calcium signals in mice with Alzheimer's disease. Calcium channel blockers are effective therapeutics for treating Alzheimer's disease. This review provides an overview of the current research of calcium channel blockers in-volved in Alzheimer's disease therapy.

  2. Calcium channel blockers in cardiovascular pharmacotherapy.

    Science.gov (United States)

    Godfraind, Theophile

    2014-11-01

    This paper summarizes the pharmacological properties of calcium channel blockers (CCBs), their established therapeutic uses for cardiovascular disorders and the current improvement of their clinical effects through drug combinations. Their identification resulted from study of small molecules including coronary dilators, which were named calcium antagonists. Further experiments showed that they reduced contraction of arteries by inhibiting calcium entry and by interacting with binding sites identified on voltage-dependent calcium channels. This led to the denomination calcium channel blockers. In short-term studies, by decreasing total peripheral resistance, CCBs lower arterial pressure. By unloading the heart and increasing coronary blood flow, CCBs improve myocardial oxygenation. In long-term treatment, the decrease in blood pressure is more pronounced in hypertensive than in normotensive patients. A controversy on the safety of CCBs ended after a large antihypertensive trial (ALLHAT) sponsored by the National Heart, Lung, and Blood Institute. There are two main types of CCBs: dihydopyridine and non-dihydropyridine; the first type is vascular selective. Dihydropyrines are indicated for hypertension, chronic, stable and vasospastic angina. Non-dihydropyridines have the same indications plus antiarrythmic effects in atrial fibrillation or flutter and paroxysmal supraventricular tachycardia. In addition, CCBs reduced newly formed coronary lesions in atherosclerosis. In order to reach recommended blood pressure goals, there is a recent therapeutic move by combination of CCBs with other antihypertensive agents particularly with inhibitors acting at the level of the renin-angiotensin system. They are also combined with statins. Prevention of dementia has been reported in hypertensive patients treated with nitrendipine, opening a way for further studies on CCBs' beneficial effect in cognitive deterioration associated with aging.

  3. Renal vascular effects of calcium channel blockers in hypertension.

    Science.gov (United States)

    Benstein, J A; Dworkin, L D

    1990-12-01

    Recent evidence suggests that calcium channel blockers have specific effects on renal hemodynamics in patients with hypertension and may also slow the progression of chronic renal failure. When these agents are studied in vitro, their predominant effect is to reverse afferent arteriolar vasoconstriction induced by catecholamines or angiotensin II. Because efferent resistance may remain high, glomerular filtration rate rises while renal blood flow remains low. The effects in vivo are less consistent. In human hypertension, calcium channel blockers lower renal resistance and may raise both renal blood flow and glomerular filtration rate. In experimental models of chronic renal disease, calcium channel blockers slow the progression of renal damage; however, variable effects on renal hemodynamics have been found. Other factors implicated in the progression of renal damage, including compensatory renal hypertrophy, platelet aggregation, and calcium deposition, may also be favorably influenced by these agents. Recent studies suggest that calcium channel blockers may have similar protective effects in patients with hypertension and chronic renal disease.

  4. A combined role of calcium channel blockers and angiotensin receptor blockers in stroke prevention

    Directory of Open Access Journals (Sweden)

    Ji-Guang Wang

    2009-07-01

    Full Text Available Ji-Guang WangCentre for Epidemiological Studies and Clinical Trials, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, ChinaAbstract: Stroke is a leading cause of death and disability worldwide. The importance of lowering blood pressure for reducing the risk of stroke is well established. However, not all the benefits of antihypertensive treatments in stroke can be accounted for by reductions in BP and there may be differences between antihypertensive classes as to which provides optimal protection. Dihydropyridine calcium channel blockers, such as amlodipine, and angiotensin receptor blockers, such as valsartan, represent the two antihypertensive drug classes with the strongest supportive data for the prevention of stroke. Therefore, when combination therapy is required, a combination of these two antihypertensive classes represents a logical approach.Keywords: stroke, angiotensin, calcium channel, cerebrovascular, hypertension, blood pressure

  5. End organ protection by calcium-channel blockers.

    Science.gov (United States)

    Tzivoni, D

    2001-02-01

    In recent years, much attention has been given to end organ protection by antihypertensive, anti-heart failure, and anti-ischemic medications. This review describes the available information on end organ protection by calcium-channel blockers (CCBs). In normotensive patients and patients with hypertension treated with long-acting dihydropyridines, medial thickness was thinner than in patients treated with atenolol or in untreated hypertensive patients. Long-term treatment was associated with significant reduction in left ventricular mass. Calcium-channel blockers also improved endothelial-dependent relaxation and reversed the vasoconstrictive response to nitric oxide inhibitors. In diabetic patients, CCBs were effective in preserving kidney function and microalbuminurea. The combination of angiotensin-converting enzyme (ACE) inhibitors and CCBs was more effective than ACE inhibitors alone in preserving kidney function. In animal experiments, CCBs prevented development of coronary atheroschlerosis; however, in humans only limited data are available on their antiatherogenic effect. Some studies suggest that CCBs exert antiplatelets properties and may therefore be beneficial in patients with coronary artery disease.

  6. High-dose insulin therapy in beta-blocker and calcium channel-blocker poisoning.

    Science.gov (United States)

    Engebretsen, Kristin M; Kaczmarek, Kathleen M; Morgan, Jenifer; Holger, Joel S

    2011-04-01

    INTRODUCTION. High-dose insulin therapy, along with glucose supplementation, has emerged as an effective treatment for severe beta-blocker and calcium channel-blocker poisoning. We review the experimental data and clinical experience that suggests high-dose insulin is superior to conventional therapies for these poisonings. PRESENTATION AND GENERAL MANAGEMENT. Hypotension, bradycardia, decreased systemic vascular resistance (SVR), and cardiogenic shock are characteristic features of beta-blocker and calcium-channel blocker poisoning. Initial treatment is primarily supportive and includes saline fluid resuscitation which is essential to correct vasodilation and low cardiac filling pressures. Conventional therapies such as atropine, glucagon and calcium often fail to improve hemodynamic status in severely poisoned patients. Catecholamines can increase blood pressure and heart rate, but they also increase SVR which may result in decreases in cardiac output and perfusion of vascular beds. The increased myocardial oxygen demand that results from catecholamines and vasopressors may be deleterious in the setting of hypotension and decreased coronary perfusion. METHODS. The Medline, Embase, Toxnet, and Google Scholar databases were searched for the years 1975-2010 using the terms: high-dose insulin, hyperinsulinemia-euglycemia, beta-blocker, calcium-channel blocker, toxicology, poisoning, antidote, toxin-induced cardiovascular shock, and overdose. In addition, a manual search of the Abstracts of the North American Congress of Clinical Toxicology and the Congress of the European Association of Poisons Centres and Clinical Toxicologists published in Clinical Toxicology for the years 1996-2010 was undertaken. These searches identified 485 articles of which 72 were considered relevant. MECHANISMS OF HIGH-DOSE INSULIN BENEFIT. There are three main mechanisms of benefit: increased inotropy, increased intracellular glucose transport, and vascular dilatation. EFFICACY OF HIGH

  7. LERCANIDIPINE, CALCIUM CHANNEL BLOCKER OF THE THIRD GENERATION: NEW POSSIBILITIES IN THE TREATMENT OF ARTERIAL HYPERTENSION

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    O. D. Ostroumova

    2013-01-01

    Full Text Available Classification, modes of action and clinical effects of calcium channel blockers are presented. Advantages of the third generation of dihydropyridine calcium channel blockers are considered. Clinical pharmacology, studies on the efficacy, safety and prevention of hypertensive complications with lercanidipine are detailed.

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

    Science.gov (United States)

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

    1998-08-01

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

  9. A different dihydropyridine calcium channel blocker in hypertensive patients who developed pedal edema on dihydropyridine calcium channel blocker therapy

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    Ayşe Yüksel

    2014-03-01

    Full Text Available Abstract Aim. Dihydropyridine calcium channel blockers (CCB are widely preferred for the treatment of hypertension for their efficacy, metabolic neutrality and low side effect profile. However pedal edema formation limits their usage. The aim of the present study is to evaluate the incidence of pedal edema formation with a different dihydropyridine CCB in hypertensive patients who developed pedal edema during a dihydropyridine CCB therapy. Method. Fifty-eight hypertensive patients (34 female, 24 male, mean age: 65.3±10.5 in whom pedal edema developed during treatment with a dihydropyridine CCB (amlodipine 10mg/day in 40 patients, amlodipine 5mg/day in 14 patients, nifedipine GITS 30mg/day in 4 patients were enrolled. CCB which caused pedal edema was withdrawn and a different CCB (felodipine or lacidipine were initiated after the resolution of the pedal edema. CCB therapy was continued as long as the patient tolerated pedal edema. Results. At the end of one year, 44 out of 58 patients (36 [81.8%] free of pedal edema, 8 [19.2%] with pedal edema continued CCB therapy. Eleven (37.9% patients in the felodipine group and 9 (31.0% patients in the lacidipine group developed pedal edema. In 7 patients in felodipine group and in 5 patients in the lacidipine group the study drug was withdrawn due to pedal edema. In two patients, study drug was withdrawn due to intractable headache (felodipine group or due to flushing (lacidipine group. Conclusion. A different group of dihydropyridine CCB be used as an alternative therapy for hypertension whenever pedal edema develops during treatment with a dihydropyridine CCB.

  10. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate

    OpenAIRE

    Ivanov, Vadim; Ivanova, Svetlana; KALINOVSKY, TATIANA; NIEDZWIECKI, ALEKSANDRA; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition...

  11. Calcium channel blockers and cancer : A risk analysis using the UK Clinical Practice Research Datalink (CPRD)

    NARCIS (Netherlands)

    Grimaldi-Bensouda, Lamiae; Klungel, Olaf; Kurz, Xavier; De Groot, Mark C H; Afonso, Ana S Maciel; De Bruin, Marie L.; Reynolds, Robert; Rossignol, Michel

    2016-01-01

    OBJECTIVE: The evidence of an association between calcium channel blockers (CCBs) and cancer is conflicting. The objective of the present study was to evaluate the risk of cancer (all, breast, prostate and colon cancers) in association with exposure to CCB. METHODS: This is a population-based cohort

  12. [Influence of rifampicin on antihypertensive effects of dihydropiridine calcium-channel blockers in four elderly patients].

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    Yoshimoto, H; Takahashi, M; Saima, S

    1996-09-01

    Rifamicin, an antituberculosis agent, is one of the most potent inducers of hepatic drug-oxidation enzymes. Rifampicin can reduce the efficacy of several therapeutically important drugs (including verapamil and diltiazem) by accelerating systemic elimination or by increasing hepatic first-pass metabolism. Because dihydropyridine calcium-channel blockers are mainly metabolized by the liver, rifampicin may also increase the extraction of these drugs and thereby reduce their antihypertensive effects. Here we report four possible cases of interaction between rifampicin and dihydropiridine calcium-channel blockers. Rifampicin was given to treat tuberculosis in four elderly hypertensive patients whose blood pressure was well-controlled by one or more dihydropiridine calcium-channel blockers (nisoldipine, nifedipine, or barnidipine and manidipine), shortly after the start of antituberculosis therapy, their blood pressures rose. Either much greater doses of dihydropyridines or additional antihypertensive agents had to be given to keep blood pressure under control. After withdrawal of rifampicin, blood pressure fell in all patients and the doses of the antihypertensive agents had to be reduced. These findings indicate that rifampicin may lessen the antihypertensive effects of dihydropiridine calcium-channel blockers.

  13. Aging Reduces L-type Calcium Channel Current and the Vasodilatory Response of Small Mesenteric Arteries to Calcium Channel Blockers

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    Sulayma A Albarwani

    2016-05-01

    Full Text Available Calcium channel blockers are widely used to treat cardiovascular disease (CVD including hypertension. As aging is an independent risk factor for CVD, the use of calcium channel blockers increases with increasing age. Hence, this study was designed to evaluate the effect of aging on the sensitivity of small mesenteric arteries to L-type voltage-gated calcium channel (LTCC blockers and also to investigate whether there was a concomitant change in calcium current density. Third order mesenteric arteries from male F344 rats, aged 2.5 - 3 months (young and 22 - 26 months (old were mounted on wire myograph to measure the tension during isometric contraction. Arteries were contracted with 100 mM KCl and were then relaxed in a cumulative concentration-response dependent manner with nifedipine (0.1nM - 10 µM, verapamil (0.1nM-10 µM or diltiazem (0.1nM - 10µM. Relaxation-concentration response curves produced by cumulative concentrations of three different calcium channel blockers (CCBs in arteries of old rats were shifted to the right with statistically significant IC50s. pEC50 ± s.e.m: (8.37 ± 0.06 vs 8.04 ± 0.05 , 7.40 ± 0.07 vs 6.81 ± 0.04 and 6.58 ± 0.07 vs 6.34 ± 0.06 in young vs old. It was observed that the maximal contractions induced by 100 mM KCl, phenylephrine and reversed by sodium nitroprusside were not different between young and old groups. However, Bay K 8644 increased resting tension by 23±4.8% in young arteries and 4.7±1.6% in old arteries. LTCC current density were also significantly lower in old arteries (-2.77 ± 0.45 pA/pF compared to young arteries (-4.5 ± 0.40 pA/pF; with similar steady-state activation and inactivation curves. Parallel to this reduction, the expression of Cav1.2 protein was reduced by 57 ± 5% in arteries from old rats compared to those from young rats. In conclusion, our results suggest that aging reduces the response of small mesenteric arteries to the vasodilatory effect of the CCBs and this may

  14. Calcium-channel blockers for the prevention of stroke: from scientific evidences to the clinical practice

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    S. Taddei

    2013-05-01

    Full Text Available AIM OF THE REVIEW The present review aims to analyze the role of calcium-channel blockers, and particularly newer molecules, as first-line therapy for cerebrovascular disease. BACKGROUND Stroke is the leading cause of disability in the general population. Among traditional cardiovascular risk factors, hypertension has a key role in the genesis of both hemorrhagic and ischemic stroke and a direct correlation exists between blood pressure values and the risk of stroke. Moreover, blood pressure reduction has been demonstrated to be the most important route to reduce stroke incidence and recurrence. However, the mere reduction of blood pressure values does not normalize the cardiovascular risk of the hypertensive patient. It is therefore necessary to use drug classes that beyond their blood pressure-lowering effect have also an additional effect in terms of organ protection. Among these, calcium-channel blockers have a crucial profile. Firstly, they are effective in inducing left ventricular hypertrophy regression, with a strength at least equal to that of ACE-inhibitors. Secondly, they have an antithrombotic and an endothelium-protecting effect, mediated by their antioxidant activity. Finally, calcium-channel blockers are the most powerful drugs in preventing vascular remodeling. For these reasons this drug class has probably the strongest antiatherosclerotic effect, and it is the first-choice treatment mainly for cerebrovascular disease. Among different available calcium-channel blockers, the newer ones seem to possess pharmacokinetic characteristics allowing a more homogeneous 24 hours coverage as compared to older molecules, and preliminary data seem to suggest a greater beneficial effect also on left ventricular hypertrophy and lower incidence of side effects. CONCLUSIONS Although blood pressure reduction is the main tool to reduce cerebrovascular risk in hypertensive patients, some drug classes, such as calciumchannel blockers, seem to provide

  15. Applying Theoretical Approach for Predicting the Selective Calcium Channel Blockers Pharmacological Parameter by Biopartitioning Micellar Chromatography

    Institute of Scientific and Technical Information of China (English)

    WANG Su-Min; YANG Geng-Liang; LI Zhi-Wei; LIU Hai-Yan; GUO Hui-Juan

    2006-01-01

    The usefulness of biopartitioning micellar chromatography (BMC) for predicting oral drug acute toxicity and apparent bioavailability was demonstrated. A logarithmic model (an LD50 model) and the second order polynomial models (apparent bioavailability model) have been obtained using the retention data of the selective calcium channel blockers to predict pharmacological properties of compounds. The use of BMC is simple, reproducible and can provide key information about the acute toxicity and transport properties of new compounds during the drug discovery process.

  16. Calcium channel blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors: Effectiveness in combination with diuretics or β-blockers for treating hypertension

    Science.gov (United States)

    Bisognano, John D; McLaughlin, Trent; Roberts, Craig S; Tang, Simon SK

    2007-01-01

    This retrospective database analysis compared the effectiveness of dihydropyridine calcium channel blockers (DHPs), angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor blockers (ARBs) added to diuretics or β-blockers. Adults with hypertension treated with diuretic or β-blocker monotherapy between 1998 and 2001 were identified from a large US electronic medical records database of primary care practices. Patients were required to have a baseline blood pressure (BP) ≥140/90 mmHg (≥130/80 mmHg for diabetes mellitus) and recorded BP measurements within 6 months before and 1–12 months following index date. Patients were matched 1:1:1 by propensity score to correct for differences in baseline characteristics. 1875 patients met study criteria and 660 (220 in each cohort) were matched based on propensity scores. Matched cohorts had no significant differences in baseline characteristics. Mean changes in systolic/diastolic BP were −17.5/−8.8, −15.7/−6.3, and −13.0/−8.0 mmHg with DHPs, ACE inhibitors, and ARBs, respectively. Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High BP 6/7 goal attainment for each regimen was 47.3%, 40.0%, and 32.2%, respectively. DHPs, ACE inhibitors, and ARBs improved BP when added to patients’ β-blocker or diuretic therapy. The greatest benefits were observed with DHPs, followed by ACE inhibitors, then ARBs. PMID:18078009

  17. Barnidipine: a new calcium channel blocker for hypertension treatment.

    Science.gov (United States)

    Liau, Chiau-Suong

    2005-03-01

    Although it is commonly agreed that all antihypertensive medications have similar efficacy, there are important differences related to safety, tolerability, patient adherence, cost effectiveness and effects on the prevention or retardation of associated disease progression. It is desirable for antihypertensives to have a long duration of action so that once-daily dosing is possible. In addition, antihypertensive medication must be able to be administered concomitantly with other drugs likely to be taken by the patients. This is particularly critical in the elderly population. Barnidipine, a novel, long-acting calcium antagonist, has met these challenges of modern pharmacotherapy. Its once-daily dosing, good tolerability and durable antihypertensive effect contribute to excellent patient adherence and make this drug a valuable addition to the antihypertensive formulary.

  18. Experts Consensus Recommendations for the Management of Calcium Channel Blocker Poisoning in Adults

    Science.gov (United States)

    Anseeuw, Kurt; Cantrell, Frank Lee; Gilchrist, Ian C.; Hantson, Philippe; Bailey, Benoit; Lavergne, Valéry; Gosselin, Sophie; Kerns, William; Laliberté, Martin; Lavonas, Eric J.; Juurlink, David N.; Muscedere, John; Yang, Chen-Chang; Sinuff, Tasnim; Rieder, Michael; Mégarbane, Bruno

    2017-01-01

    Objective: To provide a management approach for adults with calcium channel blocker poisoning. Data Sources, Study Selection, and Data Extraction: Following the Appraisal of Guidelines for Research & Evaluation II instrument, initial voting statements were constructed based on summaries outlining the evidence, risks, and benefits. Data Synthesis: We recommend 1) for asymptomatic patients, observation and consideration of decontamination following a potentially toxic calcium channel blocker ingestion (1D); 2) as first-line therapies (prioritized based on desired effect), IV calcium (1D), high-dose insulin therapy (1D–2D), and norepinephrine and/or epinephrine (1D). We also suggest dobutamine or epinephrine in the presence of cardiogenic shock (2D) and atropine in the presence of symptomatic bradycardia or conduction disturbance (2D); 3) in patients refractory to the first-line treatments, we suggest incremental doses of high-dose insulin therapy if myocardial dysfunction is present (2D), IV lipid-emulsion therapy (2D), and using a pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block without significant alteration in cardiac inotropism (2D); 4) in patients with refractory shock or who are periarrest, we recommend incremental doses of high-dose insulin (1D) and IV lipid-emulsion therapy (1D) if not already tried. We suggest venoarterial extracorporeal membrane oxygenation, if available, when refractory shock has a significant cardiogenic component (2D), and using pacemaker in the presence of unstable bradycardia or high-grade arteriovenous block in the absence of myocardial dysfunction (2D) if not already tried; 5) in patients with cardiac arrest, we recommend IV calcium in addition to the standard advanced cardiac life-support (1D), lipid-emulsion therapy (1D), and we suggest venoarterial extracorporeal membrane oxygenation if available (2D). Conclusion: We offer recommendations for the stepwise management of calcium channel blocker

  19. THE ROLE OF S-AMLODIPINE IN ARTERIAL HYPERTENSION THERAPY WITH COMBINATION OF CALCIUM CHANNEL BLOCKERS AND BETA-BLOCKERS

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    M. A. Maksimova

    2013-01-01

    Full Text Available Aim. To study efficacy and safety of calcium channel blocker, S-amlodipine, in combination with β-blocker, atenolol, in patients with arterial hypertension (HT 1-2 degree com- pared to fixed combination of racemic amlodipine and atenolol.Material and methods. Patients (n=31, 7 men and 24 women with HT 1–2 degree were included into the study. The patients were randomized into two groups by the com- binations sequence. Treatment with each combination lasted 4 weeks. Office blood pressure (BP was assessed at baseline and at the end of the treatment periods, possible side effects were registered.Results. All patients completed the study. Both combination of S-amlodipine+atenolol and fixed combination of racemic amlodipine+atenolol reduced systolic (in average, -15.9 and -12.7 mm Hg, respectively and diastolic (in average, -7.3 and -5.3 mmHg, respectively BP significantly. Heart rate also decreased during therapy (in average, -3 and -4 bt/min, respectively. The differences between combinations BP and heart rate effects were not significant. 8 and 16 adverse events were registered during S-amlodipine+atenolol and racemic amlodipine+atenolol therapies, respectively Conclusion. Combination of S-amlodipine+atenolol, as well as combination of racemic amlodipine+atenolol are effective in the treatment of patients with HT 1-2 degree, however combination with S-amlodipine has less number of adverse events.

  20. Calcium channel blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors: Effectiveness in combination with diuretics or β-blockers for treating hypertension

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    John D Bisognano

    2007-11-01

    Full Text Available John D Bisognano1, Trent McLaughlin2, Craig S Roberts3, Simon SK Tang31Internal Medicine Department, Cardiology Division, the University of Rochester Medical Center, Rochester, NY, USA; 2NDC Health, Phoenix, Arizona, USA; 3Pfizer Inc, New York, NY, USAAbstract: This retrospective database analysis compared the effectiveness of dihydropyridine calcium channel blockers (DHPs, angiotensin-converting enzyme (ACE inhibitors, and angiotensin receptor blockers (ARBs added to diuretics or β-blockers. Adults with hypertension treated with diuretic or β-blocker monotherapy between 1998 and 2001 were identified from a large US electronic medical records database of primary care practices. Patients were required to have a baseline blood pressure (BP ≥140/90 mmHg (≥130/80 mmHg for diabetes mellitus and recorded BP measurements within 6 months before and 1–12 months following index date. Patients were matched 1:1:1 by propensity score to correct for differences in baseline characteristics. 1875 patients met study criteria and 660 (220 in each cohort were matched based on propensity scores. Matched cohorts had no significant differences in baseline characteristics. Mean changes in systolic/diastolic BP were –17.5/–8.8, –15.7/–6.3, and –13.0/–8.0 mmHg with DHPs, ACE inhibitors, and ARBs, respectively. Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High BP 6/7 goal attainment for each regimen was 47.3%, 40.0%, and 32.2%, respectively. DHPs, ACE inhibitors, and ARBs improved BP when added to patients’ β-blocker or diuretic therapy. The greatest benefits were observed with DHPs, followed by ACE inhibitors, then ARBs.Keywords: hypertension, amlodipine besylate, lisinopril, valsartan, Joint National Committee (JNC 6 and 7

  1. COMPUTER AIDED DESIGN OF SELECTIVE CALCIUM CHANNEL BLOCKERS: USING PHARMACOPHORE - BASED AND DOCKING SIMULATIONS

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    Reetu

    2012-03-01

    Full Text Available In the present study, 3-D QSAR analysis was performed on the previously synthesized and evaluated derivatives of novel 2-arylthiazolidinones as selective analgesic N-type calcium channel blockers. Calcium Channel blockers is the molecular target responsible for the treatment of neuropathic and inflammatory pain. The 3D-QSAR study based on the principle of the alignment of pharmacophoric features by PHASE module of Schrodinger suite has been carried out on the same set of calcium channel blockers. Statistically significant 3-D QSAR model (R2=0.9288 were generated using 21 molecules in the training set. The predictive ability of model was determined using a randomly chosen test set of 6 molecules which gave predictive correlation coefficients (R2pred of 0.946 for 3-D models, indicating good predictive power. PHASE pharmacophore hypothesis AAHR.13 may correspond very closely to the interactions recorded in the active site of the ligand bound complex. These studies produced models with high correlation coefficient and good predictive abilities. Docking studies were also carried out wherein these analogues were docked into the active sites of COX-2 to analyze the receptor-ligand interactions that confer selectivity for COX-2. Compound 2 have the highest dock score (-7.28. In the active site, there are some strong hydrogen-bonding interactions observed between residues GLU67, ALA103, ASP96, SER184 and ASP22. Additionally a correlation of the quantitative structure –activity relationship data and the docking results is found to validate each other and suggest the importance of the binding step in overall drug action.

  2. Aging Reduces L-Type Calcium Channel Current and the Vasodilatory Response of Small Mesenteric Arteries to Calcium Channel Blockers

    Science.gov (United States)

    Albarwani, Sulayma A.; Mansour, Fathi; Khan, Abdul Aleem; Al-Lawati, Intisar; Al-Kaabi, Abdulla; Al-Busaidi, Al-Manar; Al-Hadhrami, Safa; Al-Husseini, Isehaq; Al-Siyabi, Sultan; Tanira, Musbah O.

    2016-01-01

    Calcium channel blockers (CCBs) are widely used to treat cardiovascular disease (CVD) including hypertension. As aging is an independent risk factor for CVD, the use of CCBs increases with increasing age. Hence, this study was designed to evaluate the effect of aging on the sensitivity of small mesenteric arteries to L-type voltage-gated calcium channel (LTCC) blockers and also to investigate whether there was a concomitant change in calcium current density. Third order mesenteric arteries from male F344 rats, aged 2.5–3 months (young) and 22–26 months (old) were mounted on wire myograph to measure the tension during isometric contraction. Arteries were contracted with 100 mM KCl and were then relaxed in a cumulative concentration-response dependent manner with nifedipine (0.1 nM–1 μM), verapamil (0.1 nM–10 μM), or diltiazem (0.1 nM–10 μM). Relaxation-concentration response curves produced by cumulative concentrations of three different CCBs in arteries of old rats were shifted to the right with statistically significant IC50s. pIC50 ± s.e.m: (8.37 ± 0.06 vs. 8.04 ± 0.05, 7.40 ± 0.07 vs. 6.81 ± 0.04, and 6.58 ± 0.07 vs. 6.34 ± 0.06) in young vs. old. It was observed that the maximal contractions induced by phenylephrine and reversed by sodium nitroprusside were not different between young and old groups. However, Bay K 8644 (1 μM) increased resting tension by 23 ± 4.8% in young arteries and 4.7 ± 1.6% in old arteries. LTCC current density were also significantly lower in old arteries (−2.77 ± 0.45 pA/pF) compared to young arteries (−4.5 ± 0.40 pA/pF); with similar steady-state activation and inactivation curves. Parallel to this reduction, the expression of Cav1.2 protein was reduced by 57 ± 5% in arteries from old rats compared to those from young rats. In conclusion, our results suggest that aging reduces the response of small mesenteric arteries to the vasodilatory effect of the CCBs and this may be due to, at least in part, reduced

  3. POSITIONS OF CALCIUM CHANNEL BLOCKER LERCANIDIPINE ACCORDING TO EVIDENCE BASED CARDIOLOGY

    Directory of Open Access Journals (Sweden)

    Yu. V. Lukina

    2010-01-01

    Full Text Available Data of evidence based cardiology including results of international clinical trials on efficacy and safety of the modern calcium channel blocker (CCB, lercanidipine, are presented. Results of these trials show the firm position of lercanidipine in the modern cardiology and confirm that treatment with lercanidipine leads to significant reduction of systolic and diastolic blood pressure (BP with no effect on heart rate (HR. Peripheral edema (the common side effect of CCBs occurs rarer with lercanidipine treatment than this with any other CCB treatment. Lercanidipine can be recommended to patients with concomitant diseases due to its additional features.

  4. Effects of Calcium Channel Blockers on Antidepressant Action of Alprazolam and Imipramine

    Directory of Open Access Journals (Sweden)

    Gorash ZM

    2007-01-01

    Full Text Available Alprazolam is effective as an anxiolytic and in the adjunct treatment of depression. In this study, the effects of calcium channel antagonists on the antidepressant action of alprazolam and imipramine were investigated. A forced swimming maze was used to study behavioral despair in albino mice. Mice were divided into nine groups (n = 7 per group. One group received a single dose of 1% Tween 80; two groups each received a single dose of the antidepressant alone (alprazolam or imipramine; two groups each received a single dose of the calcium channel blocker (nifedipine or verapamil; four groups each received a single dose of the calcium channel blocker followed by a single dose of the antidepressant (with same doses used for either in the previous four groups. Drug administration was performed concurrently on the nine groups. Our data confirmed the antidepressant action of alprazolam and imipramine. Both nifedipine and verapamil produced a significant antidepressant effect (delay the onset of immobility when administered separately. Verapamil augmented the antidepressant effects of alprazolam and imipramine (additive antidepressant effect. This may be due to the possibility that verapamil might have antidepressant-like effect through different mechanism. Nifedipine and imipramine combined led to a delay in the onset of immobility greater than their single use but less than the sum of their independent administration. This may be due to the fact that nifedipine on its own might act as an antidepressant but blocks one imipramine mechanism that depends on L-type calcium channel activation. Combining nifedipine with alprazolam produced additional antidepressant effects, which indicates that they exert antidepressant effects through different mechanisms.

  5. Effects of calcium ion, calpains, and calcium channel blockers on retinitis pigmentosa.

    Science.gov (United States)

    Nakazawa, Mitsuru

    2011-01-01

    Recent advances in molecular genetic studies have revealed many of the causative genes of retinitis pigmentosa (RP). These achievements have provided clues to the mechanisms of photoreceptor degeneration in RP. Apoptosis is known to be a final common pathway in RP and, therefore, a possible therapeutic target for photoreceptor rescue. However, apoptosis is not a single molecular cascade, but consists of many different reactions such as caspase-dependent and caspase-independent pathways commonly leading to DNA fractionation and cell death. The intracellular concentration of calcium ions is also known to increase in apoptosis. These findings suggest that calpains, one of the calcium-dependent proteinases, play some roles in the process of photoreceptor apoptosis and that calcium channel antagonists may potentially inhibit photoreceptor apoptosis. Herein, the effects of calpains and calcium channel antagonists on photoreceptor degeneration are reviewed.

  6. Effects of Calcium Ion, Calpains, and Calcium Channel Blockers on Retinitis Pigmentosa

    Directory of Open Access Journals (Sweden)

    Mitsuru Nakazawa

    2011-01-01

    Full Text Available Recent advances in molecular genetic studies have revealed many of the causative genes of retinitis pigmentosa (RP. These achievements have provided clues to the mechanisms of photoreceptor degeneration in RP. Apoptosis is known to be a final common pathway in RP and, therefore, a possible therapeutic target for photoreceptor rescue. However, apoptosis is not a single molecular cascade, but consists of many different reactions such as caspase-dependent and caspase-independent pathways commonly leading to DNA fractionation and cell death. The intracellular concentration of calcium ions is also known to increase in apoptosis. These findings suggest that calpains, one of the calcium-dependent proteinases, play some roles in the process of photoreceptor apoptosis and that calcium channel antagonists may potentially inhibit photoreceptor apoptosis. Herein, the effects of calpains and calcium channel antagonists on photoreceptor degeneration are reviewed.

  7. Antioxidant effect of T-type calcium channel blockers in gastric injury.

    Science.gov (United States)

    Bilici, Dilek; Banoğlu, Z Nur; Kiziltunç, Ahmet; Avci, Bahattin; Ciftçioğlu, Akif; Bilici, Sefa

    2002-04-01

    It is known that calcium ion has an important role in the cellular function. For this reason, calcium channel blockers may have a protective action against gastric injury which is induced by various stimuli. In this study, the influence of mibefradil on ethanol-induced gastric injury was investigated in rats. Mibefradil was given at a dose 50 mg/kg intraperitoneally 30 min before administration of 1 ml absolute ethanol given by gavage. We compared this effect of mibefradil with that of omeprazol. Ethanol-induced mucosal damage was evaluated using three different approaches: analysis of biochemical parameters and pathologic and macroscopic investigation. It was found that pretreatment with mibefradil significantly reduced ethanol-induced macroscopic, pathologic, and biochemical changes in the gastric mucosa. In conclusion, it is speculated that this findings may prove important in the development of new and improved therapies for the treatment and prevention of gastric ulcers in humans.

  8. Calcium Channel Blockers, More than Diuretics, Enhance Vascular Protective Effects of Angiotensin Receptor Blockers in Salt-Loaded Hypertensive Rats

    Science.gov (United States)

    Yamamoto, Eiichiro; Kataoka, Keiichiro; Dong, Yi-Fei; Koibuchi, Nobutaka; Toyama, Kensuke; Sueta, Daisuke; Katayama, Tetsuji; Yasuda, Osamu; Ogawa, Hisao; Kim-Mitsuyama, Shokei

    2012-01-01

    The combination therapy of an angiotensin receptor blocker (ARB) with a calcium channel blocker (CCB) or with a diuretic is favorably recommended for the treatment of hypertension. However, the difference between these two combination therapies is unclear. The present work was undertaken to examine the possible difference between the two combination therapies in vascular protection. Salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP) were divided into 6 groups, and they were orally administered (1) vehicle, (2) olmesartan, an ARB, (3) azelnidipine, a CCB, (4) hydrochlorothiazide, a diuretic, (5) olmesartan combined with azelnidipine, or (6) olmesartan combined with hydrochlorothiazide. Olmesartan combined with either azelnidipine or hydrochlorothiazide ameliorated vascular endothelial dysfunction and remodeling in SHRSP more than did monotherapy with either agent. However, despite a comparable blood pressure lowering effect between the two treatments, azelnidipine enhanced the amelioration of vascular endothelial dysfunction and remodeling by olmesartan to a greater extent than did hydrochlorothiazide in salt-loaded SHRSP. The increased enhancement by azelnidipine of olmesartan-induced vascular protection than by hydrochlorothiazide was associated with a greater amelioration of vascular nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, superoxide, mitogen-activated protein kinase activation, and with a greater activation of the Akt/endothelial nitric oxide synthase (eNOS) pathway. These results provided the first evidence that a CCB potentiates the vascular protective effects of an ARB in salt-sensitive hypertension, compared with a diuretic, and provided a novel rationale explaining the benefit of the combination therapy with an ARB and a CCB. PMID:22720058

  9. Calcium channel blockers, more than diuretics, enhance vascular protective effects of angiotensin receptor blockers in salt-loaded hypertensive rats.

    Directory of Open Access Journals (Sweden)

    Eiichiro Yamamoto

    Full Text Available The combination therapy of an angiotensin receptor blocker (ARB with a calcium channel blocker (CCB or with a diuretic is favorably recommended for the treatment of hypertension. However, the difference between these two combination therapies is unclear. The present work was undertaken to examine the possible difference between the two combination therapies in vascular protection. Salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP were divided into 6 groups, and they were orally administered (1 vehicle, (2 olmesartan, an ARB, (3 azelnidipine, a CCB, (4 hydrochlorothiazide, a diuretic, (5 olmesartan combined with azelnidipine, or (6 olmesartan combined with hydrochlorothiazide. Olmesartan combined with either azelnidipine or hydrochlorothiazide ameliorated vascular endothelial dysfunction and remodeling in SHRSP more than did monotherapy with either agent. However, despite a comparable blood pressure lowering effect between the two treatments, azelnidipine enhanced the amelioration of vascular endothelial dysfunction and remodeling by olmesartan to a greater extent than did hydrochlorothiazide in salt-loaded SHRSP. The increased enhancement by azelnidipine of olmesartan-induced vascular protection than by hydrochlorothiazide was associated with a greater amelioration of vascular nicotinamide adenine dinucleotide phosphate (NADPH oxidase activation, superoxide, mitogen-activated protein kinase activation, and with a greater activation of the Akt/endothelial nitric oxide synthase (eNOS pathway. These results provided the first evidence that a CCB potentiates the vascular protective effects of an ARB in salt-sensitive hypertension, compared with a diuretic, and provided a novel rationale explaining the benefit of the combination therapy with an ARB and a CCB.

  10. The omega-atracotoxins: selective blockers of insect M-LVA and HVA calcium channels.

    Science.gov (United States)

    Chong, Youmie; Hayes, Jessica L; Sollod, Brianna; Wen, Suping; Wilson, David T; Hains, Peter G; Hodgson, Wayne C; Broady, Kevin W; King, Glenn F; Nicholson, Graham M

    2007-08-15

    The omega-atracotoxins (omega-ACTX) are a family of arthropod-selective peptide neurotoxins from Australian funnel-web spider venoms (Hexathelidae: Atracinae) that are candidates for development as biopesticides. We isolated a 37-residue insect-selective neurotoxin, omega-ACTX-Ar1a, from the venom of the Sydney funnel-web spider Atrax robustus, with high homology to several previously characterized members of the omega-ACTX-1 family. The peptide induced potent excitatory symptoms, followed by flaccid paralysis leading to death, in acute toxicity tests in house crickets. Using isolated smooth and skeletal nerve-muscle preparations, the toxin was shown to lack overt vertebrate toxicity at concentrations up to 1 microM. To further characterize the target of the omega-ACTXs, voltage-clamp analysis using the whole-cell patch-clamp technique was undertaken using cockroach dorsal unpaired median neurons. It is shown here for the first time that omega-ACTX-Ar1a, and its homolog omega-ACTX-Hv1a from Hadronyche versuta, reversibly block both mid-low- (M-LVA) and high-voltage-activated (HVA) insect calcium channel (Ca(v)) currents. This block occurred in the absence of alterations in the voltage-dependence of Ca(v) channel activation, and was voltage-independent, suggesting that omega-ACTX-1 family toxins are pore blockers rather than gating modifiers. At a concentration of 1 microM omega-ACTX-Ar1a failed to significantly affect global K(v) channel currents. However, 1 microM omega-ACTX-Ar1a caused a modest 18% block of insect Na(v) channel currents, similar to the minor block of Na(v) channels reported for other insect Ca(v) channel blockers such as omega-agatoxin IVA. These findings validate both M-LVA and HVA Ca(v) channels as potential targets for insecticides.

  11. Comparison of electrophysiological effects of calcium channel blockers on cardiac repolarization.

    Science.gov (United States)

    Lee, Hyang-Ae; Hyun, Sung-Ae; Park, Sung-Gurl; Kim, Ki-Suk; Kim, Sung Joon

    2016-01-01

    Dihydropyridine (DHP) calcium channel blockers (CCBs) have been widely used to treat of several cardiovascular diseases. An excessive shortening of action potential duration (APD) due to the reduction of Ca(2+) channel current (I Ca) might increase the risk of arrhythmia. In this study we investigated the electrophysiological effects of nicardipine (NIC), isradipine (ISR), and amlodipine (AML) on the cardiac APD in rabbit Purkinje fibers, voltage-gated K(+) channel currents (I Kr, I Ks) and voltage-gated Na(+) channel current (I Na). The concentration-dependent inhibition of Ca(2+) channel currents (I Ca) was examined in rat cardiomyocytes; these CCBs have similar potency on I Ca channel blocking with IC50 (the half-maximum inhibiting concentration) values of 0.142, 0.229, and 0.227 nM on NIC, ISR, and AML, respectively. However, ISR shortened both APD50 and APD90 already at 1 µM whereas NIC and AML shortened APD50 but not APD90 up to 30 µM. According to ion channel studies, NIC and AML concentration-dependently inhibited I Kr and I Ks while ISR had only partial inhibitory effects (NIC and AML could compensate for the AP shortening effects due to the block of I Ca.

  12. [Effect of calcium channel blockers on developing nervous syndrome of high pressure and nitrogen narcosis in mice].

    Science.gov (United States)

    Sledkov, A I

    1997-01-01

    In the experiments conducted on mice which prior to compression in a heliox environment have been injected the blockers of various types of calcium channels (flunarezine, verapramil and nifedipine) as well as bemethyl (actoprotector) and oxymethacye (antioxidant) there escaped detection of noticeable effect of these drugs on developing the high pressure nervous syndrome (HPNS). On exposure to the hyperbaric nitrogen-oxygen environment verapromil (phenylalkulamine blocker of L-type calcium channels) had a protection effect with respect to a convulsive component of the nitrogen narcosis.

  13. A deleterious gene-by-environment interaction imposed by calcium channel blockers in Marfan syndrome.

    Science.gov (United States)

    Doyle, Jefferson J; Doyle, Alexander J; Wilson, Nicole K; Habashi, Jennifer P; Bedja, Djahida; Whitworth, Ryan E; Lindsay, Mark E; Schoenhoff, Florian; Myers, Loretha; Huso, Nick; Bachir, Suha; Squires, Oliver; Rusholme, Benjamin; Ehsan, Hamid; Huso, David; Thomas, Craig J; Caulfield, Mark J; Van Eyk, Jennifer E; Judge, Daniel P; Dietz, Harry C

    2015-10-27

    Calcium channel blockers (CCBs) are prescribed to patients with Marfan syndrome for prophylaxis against aortic aneurysm progression, despite limited evidence for their efficacy and safety in the disorder. Unexpectedly, Marfan mice treated with CCBs show accelerated aneurysm expansion, rupture, and premature lethality. This effect is both extracellular signal-regulated kinase (ERK1/2) dependent and angiotensin-II type 1 receptor (AT1R) dependent. We have identified protein kinase C beta (PKCβ) as a critical mediator of this pathway and demonstrate that the PKCβ inhibitor enzastaurin, and the clinically available anti-hypertensive agent hydralazine, both normalize aortic growth in Marfan mice, in association with reduced PKCβ and ERK1/2 activation. Furthermore, patients with Marfan syndrome and other forms of inherited thoracic aortic aneurysm taking CCBs display increased risk of aortic dissection and need for aortic surgery, compared to patients on other antihypertensive agents.

  14. Use of clopidogrel and calcium channel blockers and risk of major adverse cardiovascular events

    DEFF Research Database (Denmark)

    Schmidt, Morten; Johansen, Martin B; Robertson, Douglas J

    2012-01-01

    Eur J Clin Invest 2011 ABSTRACT: Background  The CYP3A4 inhibition by calcium channel blockers (CCBs) may attenuate the effectiveness of clopidogrel. Using time-varying drug exposure ascertainment, we examined whether CCB use modified the association between clopidogrel use and major adverse......-month follow-up, we tracked the use of clopidogrel and CCBs and the rate of MACE (composite of myocardial infarction, ischaemic stroke, stent thrombosis, target lesion revascularization, or cardiac death). We used Cox regression to compute hazard ratios, controlling for potential confounders. Results......  Overall, the 12-month risk for MACE was 14·5%. The rate was 130 per 1000 person years for concomitant clopidogrel and CCB use, 106 for clopidogrel without CCB use, 213 for CCB without clopidogrel use, and 248 for no use of either drug. The adjusted hazard ratio for MACE comparing clopidogrel use...

  15. Synergistic Effect of Fluconazole and Calcium Channel Blockers against Resistant Candida albicans.

    Science.gov (United States)

    Liu, Shuyuan; Yue, Longtao; Gu, Wenrui; Li, Xiuyun; Zhang, Liuping; Sun, Shujuan

    2016-01-01

    Candidiasis has increased significantly recently that threatens patients with low immunity. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of fungal resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapy is one of the most widely used and effective strategy to alleviate this problem. In this paper, we were aimed to evaluate the combined antifungal effects of four CCBs (calcium channel blockers), amlodipine (AML), nifedipine (NIF), benidipine (BEN) and flunarizine (FNZ) with fluconazole against C. albicans by checkerboard and time-killing method. In addition, we determined gene (CCH1, MID1, CNA1, CNB1, YVC1, CDR1, CDR2 and MDR1) expression by quantitative PCR and investigated the efflux pump activity of resistant candida albicans by rhodamine 6G assay to reveal the potential mechanisms. Finally, we concluded that there was a synergy when fluconazole combined with the four tested CCBs against resistant strains, with fractional inhibitory concentration index (FICI) fluconazole plus amlodipine caused down-regulating of CNA1, CNB1 (encoding calcineurin) and YVC1 (encoding calcium channel protein in vacuole membrane).

  16. Synergistic Effect of Fluconazole and Calcium Channel Blockers against Resistant Candida albicans.

    Directory of Open Access Journals (Sweden)

    Shuyuan Liu

    Full Text Available Candidiasis has increased significantly recently that threatens patients with low immunity. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of fungal resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapy is one of the most widely used and effective strategy to alleviate this problem. In this paper, we were aimed to evaluate the combined antifungal effects of four CCBs (calcium channel blockers, amlodipine (AML, nifedipine (NIF, benidipine (BEN and flunarizine (FNZ with fluconazole against C. albicans by checkerboard and time-killing method. In addition, we determined gene (CCH1, MID1, CNA1, CNB1, YVC1, CDR1, CDR2 and MDR1 expression by quantitative PCR and investigated the efflux pump activity of resistant candida albicans by rhodamine 6G assay to reveal the potential mechanisms. Finally, we concluded that there was a synergy when fluconazole combined with the four tested CCBs against resistant strains, with fractional inhibitory concentration index (FICI <0.5, but no interaction against sensitive strains (FICI = 0.56 ~ 2. The mechanism studies revealed that fluconazole plus amlodipine caused down-regulating of CNA1, CNB1 (encoding calcineurin and YVC1 (encoding calcium channel protein in vacuole membrane.

  17. Statin, Calcium Channel Blocker and Beta Blocker Therapy May Decrease the Incidence of Tuberculosis Infection in Elderly Taiwanese Patients with Type 2 Diabetes

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    Mei-Yueh Lee

    2015-05-01

    Full Text Available Background: It is well known that diabetes mellitus impairs immunity and therefore is an independent risk factor for tuberculosis. However, the influence of associated metabolic factors, such as hypertension, dyslipidemia and gout has yet to be confirmed. This study aimed to investigate whether the strong association between tuberculosis and diabetes mellitus is independent from the influence of hypertension and dyslipidemia, and its treatment in elderly Taiwanese patients. Methods: A total of 27,958 patients aged more than 65 years were identified from the National Health Insurance Research Database (NIHRD in 1997 and were followed from 1998 to 2009. The demographic characteristics between the patients with and without diabetes were analyzed using the χ2 test. A total of 13,981 patients with type 2 diabetes were included in this study. Cox proportional hazard regression models were used to determine the independent effects of diabetes on the risk of tuberculosis. Results: After adjusting for age, sex, other co-morbidities and medications, calcium channel blocker, beta blocker and statin users had a lower independent association, with risk ratios of 0.76 (95% CI, 0.58–0.98, 0.72 (95% CI, 0.58–0.91 and 0.76 (95% CI, 0.60–0.97, respectively. Conclusion: Calcium channel blocker, beta blocker and statin therapy may decrease the incidence of tuberculosis infection in elderly Taiwanese patients with type 2 diabetes.

  18. L—type calcium channel blockers inhibit the development but not the expression of sensitization to morphine in mice

    Institute of Scientific and Technical Information of China (English)

    ZhanQ; ZhenJW

    2002-01-01

    The relationship between opioid actions and L-type calcium channel blockers has been well documented.However,there is no report relevant to L-type calcium channel blockers and morphinesensitization,which is suggested to be an analog of behaviors that are the characteristics of drug addiction.Here the effects of three L-type calcium channel blockers,nimodipine,nifedipine and verapamil,on morphine-induced locomotor activity,the development and the expression of sensitization to morphine were studied systematically.The results showed that both nimodipine and verapamil attenuated,while nifedipine had only a tendency to decrease morphine-induced locomotor activity.All the three drugs inhibited the development of sensitization to morphine.However,none of them showed any effects on the expression of morphine sensitization.These results indicate that blocking L-tpye calcium channel attenuates the locomotor stimulating effects of morphine and inhibits the development but not the expression of morphine-sensitization.

  19. Effects of calcium channel blockers on proteinuria in patients with diabetic nephropathy.

    Science.gov (United States)

    Toto, Robert D; Tian, Min; Fakouhi, Kaffa; Champion, Annette; Bacher, Peter

    2008-10-01

    Diabetic nephropathy management should include the use of an angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker with additional antihypertensive medications to reduce proteinuria and cardiovascular events. Some studies suggest that adding a nondihydropyridine rather than a dihydropyridine calcium channel blocker (CCB) may more effectively lower proteinuria. We hypothesized that a trandolapril/verapamil SR (T/V) fixed-dose combination (FDC) was superior to a benazepril/amlodipine (B/A) FDC for reducing albuminuria in 304 hypertensive diabetic nephropathy patients when treated for 36 weeks. No statistically significant differences were observed between groups in the primary end point; adjusted percentage change in urinary albumin/creatinine ratio (UACR), which increased (mean T/V, 29.29%; mean B/A, 8.49%; difference, 20.80%; P=.34); or in change in absolute UACR, which decreased (mean [g/g] T/V, -0.11; mean [g/g] B/A, -0.08; difference -0.03; P=.78). There were significant reductions in log UACR (mean change in T/V, -0.28; P<.01; mean change in B/A, -0.31; P<.001) and diastolic blood pressure in both groups and in systolic blood pressure in the B/A group. T/V was not superior to B/A for reducing UACR. Both ACEI/CCB FDCs may reduce albuminuria; in the case of T/V, this appears to be independent of systolic blood pressure reduction in patients who had previously been treated and had baseline blood pressure levels of 142/77 mm Hg.

  20. Degradation kinetics and pathways of three calcium channel blockers under UV irradiation.

    Science.gov (United States)

    Zhu, Bing; Zonja, Bozo; Gonzalez, Oscar; Sans, Carme; Pérez, Sandra; Barceló, Damia; Esplugas, Santiago; Xu, Ke; Qiang, Zhimin

    2015-12-01

    Calcium channel blockers (CCBs) are a group of pharmaceuticals widely prescribed to lower blood pressure and treat heart diseases. They have been frequently detected in wastewater treatment plant (WWTP) effluents and downstream river waters, thus inducing a potential risk to aquatic ecosystems. However, little is known about the behavior and fate of CCBs under UV irradiation, which has been adopted as a primary disinfection method for WWTP effluents. This study investigated the degradation kinetics and pathways of three commonly-used CCBs, including amlodipine (AML), diltiazem (DIL), and verapamil (VER), under UV (254 nm) irradiation. The chemical structures of transformation byproducts (TBPs) were first identified to assess the potential ecological hazards. On that basis, a generic solid-phase extraction method, which simultaneously used four different cartridges, was adopted to extract and enrich the TBPs. Thereafter, the photo-degradation of target CCBs was performed under UV fluences typical for WWTP effluent disinfection. The degradation of all three CCBs conformed to the pseudo-first-order kinetics, with rate constants of 0.031, 0.044 and 0.011 min(-1) for AML, DIL and VER, respectively. By comparing the MS(2) fragments and the evolution (i.e., formation or decay) trends of identified TBPs, the degradation pathways were proposed. In the WWTP effluent, although the target CCBs could be degraded, several TBPs still contained the functional pharmacophores and reached peak concentrations under UV fluences of 40-100 mJ cm(-2).

  1. Efficacy and safety of calcium channel blockers in hypertensive patients with concomitant left ventricular dysfunction.

    Science.gov (United States)

    Parmley, W W

    1992-04-01

    The use of calcium channel blockers (CCBs) in the treatment of hypertension and concomitant left ventricular dysfunction is reviewed. Some CCBs, particularly second-generation dihydropyridine agents such as felodipine, isradipine, nicardipine, nimodipine, and nitrendipine, have properties that enhance their usefulness in these patients. All CCBs have a similar mechanism of action. Differences in their selective action at various tissue sites determine which are most appropriate for patients with concomitant hypertension and left ventricular dysfunction. Most CCBs do not produce reflex stimulation of the heart or induce intravascular expansion. While all CCBs produce arteriolar dilation, all local beds and regional circulations in target organs are not affected equally. Most CCBs can decrease cardiac mass, and second-generation CCBs tend to have little or no negative inotropic effects at therapeutic dosages. In addition, they increase blood flow and reduce myocardial oxygen requirements. Because of differences in functional and electrophysiologic effects, specific CCBs may not be appropriate for all patients. Since second-generation dihydropyridine CCBs lack clinically relevant negative inotropic effects, and have been shown to improve exercise tolerance and coronary artery perfusion, they are appropriate for hypertensive patients with left ventricular dysfunction, angina, and coronary heart disease. Second-generation CCBs tend to lack cardiodepressant side effects and are less likely to react with digoxin than are first-generation CCBs.

  2. Inhibition of collagen synthesis by select calcium and sodium channel blockers can be mitigated by ascorbic acid and ascorbyl palmitate.

    Science.gov (United States)

    Ivanov, Vadim; Ivanova, Svetlana; Kalinovsky, Tatiana; Niedzwiecki, Aleksandra; Rath, Matthias

    2016-01-01

    Calcium, sodium and potassium channel blockers are widely prescribed medications for a variety of health problems, most frequently for cardiac arrhythmias, hypertension, angina pectoris and other disorders. However, chronic application of channel blockers is associated with numerous side effects, including worsening cardiac pathology. For example, nifedipine, a calcium-channel blocker was found to be associated with increased mortality and increased risk for myocardial infarction. In addition to the side effects mentioned above by different channel blockers, these drugs can cause arterial wall damage, thereby contributing to vascular wall structure destabilization and promoting events facilitating rupture of plaques. Collagen synthesis is regulated by ascorbic acid, which is also essential for its optimum structure as a cofactor in lysine and proline hydroxylation, a precondition for optimum crosslinking of collagen and elastin. Therefore, the main objective in this study was to evaluate effects of various types of channel blockers on intracellular accumulation and cellular functions of ascorbate, specifically in relation to formation and extracellular deposition of major collagen types relevant for vascular function. Effects of select Na- and Ca- channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen I ECM deposition. Nifedipine (50 µM), a representative of channel blockers tested, significantly reduced ascorbic acid and ascorbyl palmitate-dependent ECM deposition of collagen type l and collagen type lV by cultured aortic smooth muscle cells. In addition, nifedipine (50 µM) significantly reduced ascorbate-dependent collagen type l and type lV synthesis by cultured aortic smooth

  3. Inhibitory effects of calcium channel blockers on thyroid hormone uptake in neonatal rat cardiomyocytes

    NARCIS (Netherlands)

    F.A. Verhoeven; E.P.C.M. Moerings (Ellis); J.M.J. Lamers (Jos); G. Hennemann; T.J. Visser (Theo); M.E. Everts (Maria)

    2001-01-01

    textabstractThe effects of the Ca2+ channel blockers verapamil, nifedipine, and diltiazem on triiodothyronine (T3) and thyroxine (T4) uptake were tested in cultured cardiomyocytes from 2-day-old rats. Experiments were performed at 37 degrees C in medium with 0.5% BSA for [125I]T3 (

  4. N-type calcium channel blockers: novel therapeutics for the treatment of pain.

    Science.gov (United States)

    Schroeder, C I; Doering, C J; Zamponi, G W; Lewis, R J

    2006-09-01

    Highly selective Ca(v)2.2 voltage-gated calcium channel (VGCC) inhibitors have emerged as a new class of therapeutics for the treatment of chronic and neuropathic pain. Cone snail venoms provided the first drug in class with FDA approval granted in 2005 to Prialt (omega-conotoxin MVIIA, Elan) for the treatment of neuropathic pain. Since this pioneering work, major efforts underway to develop alternative small molecule inhibitors of Ca(v)2.2 calcium channel have met with varied success. This review focuses on the properties of the Ca(v)2.2 calcium channel in different pain states, the action of omega-conotoxins GVIA, MVIIA and CVID, describing their structure-activity relationships and potential as leads for the design of improved Ca(v)2.2 calcium channel therapeutics, and finally the development of small molecules for the treatment of chronic pain.

  5. Rationale for triple fixed-dose combination therapy with an angiotensin II receptor blocker, a calcium channel blocker, and a thiazide diuretic

    Directory of Open Access Journals (Sweden)

    Volpe M

    2012-06-01

    Full Text Available Massimo Volpe,1,2 Giuliano Tocci21Division of Cardiology, Department of Clinical and Molecular Medicine, University of Rome, Sapienza, Sant'Andrea Hospital, Rome, 2IRCCS Neuromed, Pozzilli, ItalyAbstract: Hypertension is a growing global health problem, and is predicted to affect 1.56 billion people by 2025. Treatment remains suboptimal, with control of blood pressure achieved in only 20%–35% of patients, and the majority requiring two or more antihypertensive drugs to achieve recommended blood pressure goals. To improve blood pressure control, the European hypertension guidelines recommend that angiotensin II receptor blockers (ARBs or angiotensin-converting enzyme inhibitors (ACEIs are combined with calcium channel blockers (CCBs and/or thiazide diuretics. The rationale for this strategy is based, in part, on their different effects on the renin-angiotensin system, which improves antihypertensive efficacy. Data from a large number of trials support the efficacy of ACEIs or ARBs in combination with CCBs and/or hydrochlorothiazide (HCTZ. Combining two different classes of antihypertensive drugs has an additive effect on lowering of blood pressure, and does not increase adverse events, with the ARBs showing a tolerability advantage over the ACEIs. Among the different ARBs, olmesartan medoxomil is available as a dual fixed-dose combination with either amlodipine or HCTZ, and the increased blood pressure-lowering efficacy of these two combinations is proven. Triple therapy is required in 15%–20% of treated uncontrolled hypertensive patients, with a renin-angiotensin system blocker, CCB, and thiazide diuretic considered to be a rational combination according to the European guidelines. Olmesartan, amlodipine, and HCTZ are available as a triple fixed-dose combination, and significant blood pressure reductions have been observed with this regimen compared with the possible dual combinations. The availability of these fixed-dose combinations should

  6. Neuroprotective effect of gadolinium: a stretch-activated calcium channel blocker in mouse model of ischemia-reperfusion injury.

    Science.gov (United States)

    Gulati, Puja; Muthuraman, Arunachalam; Jaggi, Amteshwar S; Singh, Nirmal

    2013-03-01

    The present study was designed to investigate the potential of gadolinium, a stretch-activated calcium channel blocker in ischemic reperfusion (I/R)-induced brain injury in mice. Bilateral carotid artery occlusion of 12 min followed by reperfusion for 24 h was given to induce cerebral injury in male Swiss mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using Morris water maze test and motor incoordination was evaluated using rota-rod, lateral push, and inclined beam walking tests. In addition, total calcium, thiobarbituric acid reactive substance (TBARS), reduced glutathione (GSH), and acetylcholinesterase (AChE) activity were also estimated in brain tissue. I/R injury produced a significant increase in cerebral infarct size. A significant loss of memory along with impairment of motor performance was also noted. Furthermore, I/R injury also produced a significant increase in levels of TBARS, total calcium, AChE activity, and a decrease in GSH levels. Pretreatment of gadolinium significantly attenuated I/R-induced infarct size, behavioral and biochemical changes. On the basis of the present findings, we can suggest that opening of stretch-activated calcium channel may play a critical role in ischemic reperfusion-induced brain injury and that gadolinium has neuroprotective potential in I/R-induced injury.

  7. Efficacy and Safety of Combination Therapy Consisting of Angiotensin II Type 1 Receptor Blocker, Calcium Channel Blocker and Hydrochlorothiazide in Patients With Hypertension

    Science.gov (United States)

    Shiga, Yuhei; Miura, Shin-ichiro; Motozato, Kota; Yoshimine, Yuka; Norimatsu, Kenji; Arimura, Tadaaki; Koyoshi, Rie; Morii, Joji; Kuwano, Takashi; Inoue, Ken; Shirotani, Tetsuro; Fujisawa, Kazuaki; Matsunaga, Eiyu; Saku, Keijiro

    2017-01-01

    Background Many patients continue to have high blood pressure (BP) even after treatment with high-dose (H)-angiotensin II type 1 receptor blocker (ARB)/calcium channel blocker (CCB) or middle-dose (M)-ARB/CCB/hydrochlorothiazide (HCTZ). Methods Thirty-two hypertensive patients who had the use of H-ARB/CCB or M-ARB/CCB/HCTZ were enrolled in this study. We applied a changeover with a switch to H-ARB (telmisartan 80 mg/day)/CCB (amlodipine 5 mg/day or nifedipine CR 40 mg/day)/HCTZ (12.5 mg/day). Results Systolic BP (SBP) and diastolic BP (DBP) were significantly decreased in all patients and in the H-ARB/CCB and M-ARB/CCB/HCTZ groups after 3 months. Percentage (%) of patients who reached the target BP after 3 months (72%) in all patients was significantly higher than that at 0 months (19%). There were no serious adverse effects in any of the patients. Conclusions Combination therapy with H-ARB/CCB/HCTZ was associated with a significant reduction of BP. PMID:28090225

  8. Calcium-activated potassium channels sustain calcium signaling in T lymphocytes. Selective blockers and manipulated channel expression levels.

    Science.gov (United States)

    Fanger, C M; Rauer, H; Neben, A L; Miller, M J; Rauer, H; Wulff, H; Rosa, J C; Ganellin, C R; Chandy, K G; Cahalan, M D

    2001-04-13

    To maintain Ca(2+) entry during T lymphocyte activation, a balancing efflux of cations is necessary. Using three approaches, we demonstrate that this cation efflux is mediated by Ca(2+)-activated K(+) (K(Ca)) channels, hSKCa2 in the human leukemic T cell line Jurkat and hIKCa1 in mitogen-activated human T cells. First, several recently developed, selective and potent pharmacological inhibitors of K(Ca) channels but not K(V) channels reduce Ca(2+) entry in Jurkat and in mitogen-activated human T cells. Second, dominant-negative suppression of the native K(Ca) channel in Jurkat T cells by overexpression of a truncated fragment of the cloned hSKCa2 channel decreases Ca(2+) influx. Finally, introduction of the hIKCa1 channel into Jurkat T cells maintains rapid Ca(2+) entry despite pharmacological inhibition of the native small conductance K(Ca) channel. Thus, K(Ca) channels play a vital role in T cell Ca(2+) signaling.

  9. Current concepts in combination therapy for the treatment of hypertension: combined calcium channel blockers and RAAS inhibitors

    Directory of Open Access Journals (Sweden)

    Alberto F Rubio-Guerra

    2009-11-01

    Full Text Available Alberto F Rubio-Guerra1, David Castro-Serna2, Cesar I Elizalde Barrera2, Luz M Ramos-Brizuela21Metabolic and Research Clinic, 2Internal Medicine Department, Hospital General de Ticomán SS DF, MéxicoAbstract: Recent guidelines for the management of hypertension recommend target blood pressures <140/90 mmHg in hypertensive patients, or <130/80 mmHg in subjects with diabetes, chronic kidney disease, or coronary artery disease. Despite the availability and efficacy of antihypertensive drugs, most hypertensive patients do not reach the recommended treatment targets with monotherapy, making combination therapy necessary to achieve the therapeutic goal. Combination therapy with 2 or more agents is the most effective method for achieving strict blood pressure goals. Fixed-dose combination simplifies treatment, reduces costs, and improves adherence. There are many drug choices for combination therapy, but few data are available about the efficacy and safety of some specific combinations. Combination therapy of calcium antagonists and inhibitors of the renin-angiotensin-aldosterone system (RAAS are efficacious and safe, and have been considered rational by both the JNC 7 and the 2007 European Society of Hypertension – European Society of Cardiology guidelines for the management of arterial hypertension. The aim of this review is to discuss some relevant issues about the use of combinations with calcium channel blockers and RAAS inhibitors in the treatment of hypertension.Keywords: hypertension, calcium channel blockers, renin-angiotensin-aldosterone system inhibitors, fixed-dose combination, adherence

  10. Calcium Channel Blockers and Esophageal Sclerosis: Should We Expect Exacerbation of Interstitial Lung Disease

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    Charalampos Seretis

    2012-01-01

    Full Text Available Esophageal sclerosis is the most common visceral manifestation of systemic sclerosis, resulting in impaired esophageal clearance and retention of ingested food; in addition, co-existence of lung fibrosis with esophageal scleroderma is not uncommon. Both the progression of generalized connective tissue disorders and the damaging effect of chronic aspiration due to esophageal dysmotility appear to be involved in this procedure of interstitial fibrosis. Nifedipine is a widely prescribed calcium antagonist in a significant percentage of rheumatologic patients suffering from Raynaud syndrome, in order to inhibit peripheral vasospasm. Nevertheless, blocking calcium channels has proven to contribute to exacerbation of gastroesophageal reflux, which consequently can lead to chronic aspiration. We describe the case of severe exacerbation of interstitial lung disease in a 76-year-old female with esophageal sclerosis who was treated with oral nifedipine for Raynaud syndrome.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-06-01

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

  12. Potentiation of Opioid-Induced Analgesia by L-Type Calcium Channel Blockers: Need for Clinical Trial in Cancer Pain

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    S Basu Ray

    2008-01-01

    Full Text Available Previous reports indicate that the analgesic effect of opioids is due to both closure of specific voltage-gated calcium channels (N- and P/Q-types and opening of G protein-coupled inwardly rectifying potassium channels (GIRKs in neurons concerned with transmission of pain. However, administration of opioids leads to unacceptable levels of side effects, particularly at high doses. Thus, current research is directed towards simultaneously targeting other voltage-gated calcium channels (VGCCs like the L-type VGCCs or even other cell signaling mechanisms, which would aug-ment opioid-mediated analgesic effect without a concurrent increase in the side effects. Unfortunately, the results of these studies are often conflicting considering the different experimental paradigms (variable drug selection and their doses and also the specific pain test used for studying analgesia adopted by researchers. The present review focuses on some of the interesting findings regarding the analgesic effect of Opioids + L-VGCC blockers and suggests that time has come for a clinical trial of this combination of drugs in the treatment of cancer pain.

  13. Calcium-channel blockers and other factors influencing delayed function in renal allografts.

    Science.gov (United States)

    Ferguson, C J; Hillis, A N; Williams, J D; Griffin, P J; Salaman, J R

    1990-01-01

    A retrospective analysis was undertaken to examine the influence of calcium-channel blocking drugs on early renal allograft function. Delayed function was defined as the need for dialysis or a reduction in serum creatinine of less than 15% within 4 days of transplantation. The drug histories of 172 patients were examined. After exclusions, the data from 138 patients were analysed. No patient was taking any calcium-channel blocking drug other than nifedipine. Thirty-one patients were taking nifedipine at the time of transplantation and these had a delayed function rate of 16% compared with 40% for 107 patients not taking nifedipine (chi 2, P less than 0.05). Delayed function occurred in 61% of cases when the donor age was over 50 years compared with 29% with younger donors (chi 2, P less than 0.05). A total ischaemic time of longer than 24 h and administration of inotropic support to the donor were associated with delayed function (chi 2, P less than 0.05). Administration to the donor of mannitol, steroids, phenoxybenzamine and heparin had no effect on the rate of delayed function. Recipients treated with low-dose dopamine in the perioperative period had no advantage. Elevated trough whole blood concentrations of cyclosporin in the first week after transplant were associated with delayed function (Mann-Whitney U, P less than 0.05).

  14. Calcium-channel blockers do not alter the clinical efficacy of clopidogrel after myocardial infarction: a nationwide cohort study

    DEFF Research Database (Denmark)

    Olesen, Jonas B; Gislason, Gunnar H; Charlot, Mette G

    2011-01-01

    Objectives The purpose of this study was to determine the risk of adverse cardiovascular events associated with concomitant use of clopidogrel and calcium-channel blockers (CCBs) in patients with myocardial infarction (MI). Background CCBs inhibit a variety of cytochrome P-450 enzymes, some...... of which contribute to clopidogrel metabolic activation. This interaction may diminish the efficacy of clopidogrel. Methods All patients surviving 30 days after a first-time MI in the period 2000 to 2006 in Denmark were identified by individual-level linkage of nationwide administrative registers....... The cohort was divided into patients treated with and without clopidogrel and followed for 1 year after discharge. The risk of a composite of cardiovascular death, MI, or stroke and the risk of the individual components of the composite end point and all-cause death associated with CCBs were analyzed...

  15. Comparative effect of angiotensin II type I receptor blockers and calcium channel blockers on laboratory parameters in hypertensive patients with type 2 diabetes

    Directory of Open Access Journals (Sweden)

    Nishida Yayoi

    2012-05-01

    Full Text Available Abstract Background Both angiotensin II type I receptor blockers (ARBs and calcium channel blockers (CCBs are widely used antihypertensive drugs. Many clinical studies have demonstrated and compared the organ-protection effects and adverse events of these drugs. However, few large-scale studies have focused on the effect of these drugs as monotherapy on laboratory parameters. We evaluated and compared the effects of ARB and CCB monotherapy on clinical laboratory parameters in patients with concomitant hypertension and type 2 diabetes mellitus. Methods We used data from the Clinical Data Warehouse of Nihon University School of Medicine obtained between Nov 1, 2004 and July 31, 2011, to identify cohorts of new ARB users (n = 601 and propensity-score matched new CCB users (n = 601, with concomitant mild to moderate hypertension and type 2 diabetes mellitus. We used a multivariate-adjusted regression model to adjust for differences between ARB and CCB users, and compared laboratory parameters including serum levels of triglyceride (TG, total cholesterol (TC, non-fasting blood glucose, hemoglobin A1c (HbA1c, sodium, potassium, creatinine, alanine aminotransferase (ALT, aspartate aminotransferase (AST, gamma-glutamyltransferase (GGT, hemoglobin and hematocrit, and white blood cell (WBC, red blood cell (RBC and platelet (PLT counts up to 12 months after the start of ARB or CCB monotherapy. Results We found a significant reduction of serum TC, HbA1c, hemoglobin and hematocrit and RBC count and a significant increase of serum potassium in ARB users, and a reduction of serum TC and hemoglobin in CCB users, from the baseline period to the exposure period. The reductions of RBC count, hemoglobin and hematocrit in ARB users were significantly greater than those in CCB users. The increase of serum potassium in ARB users was significantly greater than that in CCB users. Conclusions Our study suggested that hematological adverse effects and

  16. Regression of glomerular and tubulointerstitial injuries by dietary salt reduction with combination therapy of angiotensin II receptor blocker and calcium channel blocker in Dahl salt-sensitive rats.

    Directory of Open Access Journals (Sweden)

    Kazi Rafiq

    Full Text Available A growing body of evidence indicates that renal tissue injuries are reversible. We investigated whether dietary salt reduction with the combination therapy of angiotensin II type 1 receptor blocker (ARB plus calcium channel blocker (CCB reverses renal tissue injury in Dahl salt-sensitive (DSS hypertensive rats. DSS rats were fed a high-salt diet (HS; 4% NaCl for 4 weeks. Then, DSS rats were given one of the following for 10 weeks: HS diet; normal-salt diet (NS; 0.5% NaCl, NS + an ARB (olmesartan, 10 mg/kg/day, NS + a CCB (azelnidipine, 3 mg/kg/day, NS + olmesartan + azelnidipine or NS + hydralazine (50 mg/kg/day. Four weeks of treatment with HS diet induced hypertension, proteinuria, glomerular sclerosis and hypertrophy, glomerular podocyte injury, and tubulointerstitial fibrosis in DSS rats. A continued HS diet progressed hypertension, proteinuria and renal tissue injury, which was associated with inflammatory cell infiltration and increased proinflammatory cytokine mRNA levels, NADPH oxidase activity and NADPH oxidase-dependent superoxide production in the kidney. In contrast, switching to NS halted the progression of hypertension, renal glomerular and tubular injuries. Dietary salt reduction with ARB or with CCB treatment further reduced blood pressure and partially reversed renal tissues injury. Furthermore, dietary salt reduction with the combination of ARB plus CCB elicited a strong recovery from HS-induced renal tissue injury including the attenuation of inflammation and oxidative stress. These data support the hypothesis that dietary salt reduction with combination therapy of an ARB plus CCB restores glomerular and tubulointerstitial injury in DSS rats.

  17. Lipid Rescue Therapy and High-Dose insulin Euglycemic Therapy are Effective for Severe Refractory Calcium Channel Blocker Overdose: Case Report and Review of Literature

    Directory of Open Access Journals (Sweden)

    Niko Bekjarovski

    2013-09-01

    How to cite this article: Bekjarovski NG. Lipid Rescue Therapy and High-Dose insulin Euglycemic Therapy are Effective for Severe Refractory Calcium Channel Blocker Overdose: Case Report and Review of Literature. Asia Pac J Med Toxicol 2013;2:114-6.

  18. Calcium channel antagonist and beta-blocker overdose: antidotes and adjunct therapies.

    Science.gov (United States)

    Graudins, Andis; Lee, Hwee Min; Druda, Dino

    2016-03-01

    Management of cardiovascular instability resulting from calcium channel antagonist (CCB) or beta-adrenergic receptor antagonist (BB) poisoning follows similar principles. Significant myocardial depression, bradycardia and hypotension result in both cases. CCBs can also produce vasodilatory shock. Additionally, CCBs, such as verapamil and diltiazem, are commonly ingested in sustained-release formulations. This can also be the case for some BBs. Peak toxicity can be delayed by several hours. Provision of early gastrointestinal decontamination with activated charcoal and whole-bowel irrigation might mitigate this. Treatment of shock requires a multimodal approach to inotropic therapy that can be guided by echocardiographic or invasive haemodynamic assessment of myocardial function. High-dose insulin euglycaemia is commonly recommended as a first-line treatment in these poisonings, to improve myocardial contractility, and should be instituted early when myocardial dysfunction is suspected. Catecholamine infusions are complementary to this therapy for both inotropic and chronotropic support. Catecholamine vasopressors and vasopressin are used in the treatment of vasodilatory shock. Optimizing serum calcium concentration can confer some benefit to improving myocardial function and vascular tone after CCB poisoning. High-dose glucagon infusions have provided moderate chronotropic and inotropic benefits in BB poisoning. Phosphodiesterase inhibitors and levosimendan have positive inotropic effects but also produce peripheral vasodilation, which can limit blood pressure improvement. In cases of severe cardiogenic shock and/or cardiac arrest post-poisoning, extracorporeal cardiac assist devices have resulted in successful recovery. Other treatments used in refractory hypotension include intravenous lipid emulsion for lipophilic CCB and BB poisoning and methylene blue for refractory vasodilatory shock.

  19. Short-term exposure to L-type calcium channel blocker, verapamil, alters the expression pattern of calcium-binding proteins in the brain of goldfish, Carassius auratus.

    Science.gov (United States)

    Palande, Nikhil V; Bhoyar, Rahul C; Biswas, Saikat P; Jadhao, Arun G

    2015-01-01

    The influx of calcium ions (Ca(2+)) is responsible for various physiological events including neurotransmitter release and synaptic modulation. The L-type voltage dependent calcium channels (L-type VDCCs) transport Ca(2+) across the membrane. Calcium-binding proteins (CaBPs) bind free cytosolic Ca(2+) and prevent excitotoxicity caused by sudden increase in cytoplasmic Ca(2+). The present study was aimed to understand the regulation of expression of neuronal CaBPs, namely, calretinin (CR) and parvalbumin (PV) following blockade of L-type VDCCs in the CNS of Carassius auratus. Verapamil (VRP), a potent L-type VDCC blocker, selectively blocks Ca(2+) entry at the plasma membrane level. VRP present in the aquatic environment at a very low residual concentration has shown ecotoxicological effects on aquatic animals. Following acute exposure for 96h, median lethal concentration (LC50) for VRP was found to be 1.22mg/L for goldfish. At various doses of VRP, the behavioral alterations were observed in the form of respiratory difficulty and loss of body balance confirming the cardiovascular toxicity caused by VRP at higher doses. In addition to affecting the cardiovascular system, VRP also showed effects on the nervous system in the form of altered expression of PV. When compared with controls, the pattern of CR expression did not show any variations, while PV expression showed significant alterations in few neuronal populations such as the pretectal nucleus, inferior lobes, and the rostral corpus cerebellum. Our result suggests possible regulatory effect of calcium channel blockers on the expression of PV.

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

    Science.gov (United States)

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

    2013-01-01

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

  1. Dose calcium channel blocker verapamil decrease urinary VMA levels in sympathoadrenal hyperactive patients with posttraumatic stress disorder?

    Institute of Scientific and Technical Information of China (English)

    Munawar Alam Ansari; Shahida PAhmed; Zahida Memon

    2008-01-01

    Objective:The majority of the patients with posttraumatic stress disorders (PTSD)embrace augmented urina-ry flow of Vanillylmandelic Acid (VMA)than normal subjects owing to superior sympathetic doings,which steer to cardiovascular catastrophe.Urinary flow of VMA was evaluated as sympathoadrenal bustle marker in patients with posttraumatic stress disorder.Calcium ion shows a noteworthy dependability in nervousness owing to its special effects on brain synaptosomes.So this study was conducted to explore the effects of Verapamil on sympathoadrenal motion in patients with PTSD.Methods:Placebo controlled clinical tryout was conducted. At first hundred (100)PTSD patients were chosen and enrolled in the study,from department of Psychological Medicine Dow University of Health Sciences,Karachi.Verapamil 120 mg/day was specified in divided doses to group-I (n =50)patients and group-II (n =50)patients received placebo therapy on a daily basis for nine weeks.Each and every patient was monitored weekly,all the way through extent of study.Results:Under-neath the posttraumatic stress disorder,urinary excretion of VMA was greater.Calcium channel blocker vera-pamil additionally abolished the embellished retort in urinary flow of VMA appreciably in patients with PTSD. Conclusion:Verapamil was experiential to be exceedingly effectual treatment.It reduces VMA levels in u-rine,and on the whole cardiovascular threat in PTSD patients.

  2. [Clinical efficacy of calcium channel blockers slow the third generation of lercanidipine in the treatment of patients with arterial hypertension and metabolic disorders (review)].

    Science.gov (United States)

    Tabidze, G A; Gezeli, T D; Tsibadze, T A; Dolidze, N M

    2015-02-01

    Arterial hypertension is the most common risk factor in patients with metabolic disorders. In the selection of antihypertensive therapy it is necessary to consider not only the anti-hypertensive and organoprotective effects of drugs and their metabolic effects, which has prognostic value. Calcium antaginists, along. Lercanidipine related to the third generation dihydripyridine calcium antagonist, has been much more selective for the so-called slow calcium channels of vascular smooth muscle cells, which is associated with a good hypertensive, organo and metabolic action. Combination therapy with an ACE inhibitor and a calcium channel blocker is also a justified tactic for the management of patients with high-risk cardiovascular and metabolic disorders. Attention is paid new fixed combinations, including angiotensin converting enzyme inhibitors and calcium antagonists.

  3. Investigation of Calcium Channel Blockers as Antiprotozoal Agents and Their Interference in the Metabolism of Leishmania (L. infantum

    Directory of Open Access Journals (Sweden)

    Juliana Quero Reimão

    2016-01-01

    Full Text Available Leishmaniasis and Chagas disease are neglected parasitic diseases endemic in developing countries; efforts to find new therapies remain a priority. Calcium channel blockers (CCBs are drugs in clinical use for hypertension and other heart pathologies. Based on previous reports about the antileishmanial activity of dihydropyridine-CCBs, this work aimed to investigate whether the in vitro anti-Leishmania infantum and anti-Trypanosoma cruzi activities of this therapeutic class would be shared by other non-dihydropyridine-CCBs. Except for amrinone, our results demonstrated antiprotozoal activity for fendiline, mibefradil, and lidoflazine, with IC50 values in a range between 2 and 16 μM and Selectivity Index between 4 and 10. Fendiline demonstrated depolarization of mitochondrial membrane potential, with increased reactive oxygen species production in amlodipine and fendiline treated Leishmania, but without plasma membrane disruption. Finally, in vitro combinations of amphotericin B, miltefosine, and pentamidine against L. infantum showed in isobolograms an additive interaction when these drugs were combined with fendiline, resulting in overall mean sum of fractional inhibitory concentrations between 0.99 and 1.10. These data demonstrated that non-dihydropyridine-CCBs present antiprotozoal activity and could be useful candidates for future in vivo efficacy studies against Leishmaniasis and Chagas’ disease.

  4. Investigation into in vitro anti-leishmanial combinations of calcium channel blockers and current anti-leishmanial drugs

    Directory of Open Access Journals (Sweden)

    Juliana Quero Reimão

    2011-12-01

    Full Text Available The need for drug combinations to treat visceral leishmaniasis (VL arose because of resistance to antimonials, the toxicity of current treatments and the length of the course of therapy. Calcium channel blockers (CCBs have shown anti-leishmanial activity; therefore their use in combination with standard drugs could provide new alternatives for the treatment of VL. In this work, in vitro isobolograms of Leishmania (Leishmania chagasi using promastigotes or intracellular amastigotes were utilised to identify the interactions between five CCBs and the standard drugs pentamidine, amphotericin B and glucantime. The drug interactions were assessed with a fixed ratio isobologram method and the fractional inhibitory concentrations (FICs, sum of FICs (ΣFICs and the overall mean ΣFIC were calculated for each combination. Graphical isobologram analysis showed that the combination of nimodipine and glucantime was the most promising in amastigotes with an overall mean ΣFIC value of 0.79. Interactions between CCBs and the anti-leishmanial drugs were classified as indifferent according to the overall mean ΣFIC and the isobologram graphic analysis.

  5. Cost containment for treating hypertension in African Americans: impact of a combined ACE inhibitor-calcium channel blocker.

    Science.gov (United States)

    Kountz, D S

    1997-07-01

    The use of calcium channel blockers (CCBs) and angiotensin-converting enzyme (ACE) inhibitors has increased dramatically over the last 10 years and now accounts for 60% to 70% of all new antihypertensive prescriptions. Even though these two classes are efficacious, they are costly. Combined ACE inhibitor/CCB therapy (amlodipine-benazepril) was introduced in 1995. An analysis was done to assess the potential financial impact of substituting this agent for patients being treated with on ACE inhibitor/CCB combination. A pharmaceutical profile review of prescriptions during October 1995 was performed on 219 randomly selected patients enrolled in a Medicaid managed care program. Eighty-four profiles were analyzed; 24% of patients were on a combination ACE inhibitor/CCB regimen with an average monthly cost of $135. If the single agent amlodipine-benazepril with an average monthly cost of $45 (all strengths) was substituted, the savings would be considerable: $1080 per patient per year and $1,080,000 annualized for the calculated number of hypertensives on combination therapy in our network of 15,000 patients. Therapeutic substitution is one method of achieving cost containment in managed care. The cost differential between separately prescribed CCBs and ACE inhibitors and amlodipine-benazepril is significant. Compliance also should be enhanced as the patient would need to take only one pill daily. Once a patient has been maintained on a stable dose of a CCB/ACE inhibitor, substitution with amlodipine-benazepril should be considered.

  6. Effects of the long-acting calcium channel blocker barnidipine hydrochloride on 24-h ambulatory blood pressure.

    Science.gov (United States)

    Kuwajima, Iwao; Abe, Keishi

    2002-02-01

    The effect of the long acting calcium channel blocker, barnidipine hydrochloride (barnidipine) on 24-h ambulatory blood pressure (ABP) was evaluated in J-MUBA (Japanese Multicentre Study on Barnidipine with Ambulatory Blood Pressure Monitoring). Following an observation period of two weeks, antihypertensive treatment with barnidipine was continued for at least six months. At the end of each period, ABP were measured. The patients were divided into high- and low-range groups based on ABP measurement. Throughout the 24 h, barnidipine exerted an excellent antihypertensive effect in the high-range group, but not in the low-range group. Barnidipine had comparable effects in the daytime and nighttime in inverted dippers and non-dippers, but it was more effective on daytime ABP than on nighttime ABP in dippers and in extreme dippers. Morning blood pressure before and after waking was evaluated before and after barnidipine administration in 233 patients. Barnidipine inhibited increases in blood pressure before and after waking, especially in surge-type patients whose blood pressure increased rapidly after waking. A positive correlation among 24-h ABP, daytime and night time ABP, morning blood pressure, and clinic blood pressure during the observation period and the antihypertensive effect of barnidipine was observed, with barnidipine exhibiting stronger antihypertensive effects in patients with persistently high blood pressure. It was concluded that the antihypertensive effects of barnidipine are maintained for 24 h but it has no excessive hypotensive effects on lower blood pressure and is thus a safe antihypertensive agent.

  7. Preadmission Use of Calcium Channel Blockers and Outcomes After Hospitalization With Pneumonia: A Retrospective Propensity-Matched Cohort Study.

    Science.gov (United States)

    Zheng, Lin; Hunter, Krystal; Gaughan, John; Poddar, Sameer

    In sepsis, an overwhelming immune response, as mediated by the release of various inflammatory mediators, can lead to shock, multiple organ damage, and even death. Pneumonia is the leading cause of sepsis. In animal septic models, sepsis could induce uncontrolled calcium (Ca) leaking, raising cytosolic Ca to a toxic level, causing irreversible cellular injuries and organ failure. All types of calcium channel blockers (CCBs), by inhibiting Ca influx, have been shown to decrease overall mortality in various septic animal models. However, to our best knowledge, no clinical study had been conducted to investigate the beneficial effect(s) of CCBs in sepsis. We conducted a retrospective propensity-matched cohort study after screening 2214 patients hospitalized for pneumonia from year 2012 to 2014 at our institution. We identified 387 preadmission CCB users and 387 nonusers by propensity score matching. Logistic regression analysis was then used to determine the association between preadmission CCB use and outcomes in pneumonia. Our study showed that the odds for development of severe sepsis was significantly lower in the CCB user group [odds ratio (OR), 0.466; 95% confidence interval (CI), 0.311-0.697; P = 0.002]. Preadmission CCB use was associated with a lower risk of contracting bacteremia (OR, 0.498; 95% CI, 0.262-0.99; P = 0.0327), lower risk of acute respiratory insufficiency (OR, 0.573; 95% CI, 0.412-0.798; P = 0.001), lower risk of intensive care unit admission (OR, 0.602; 95% CI, 0.432-0.840; P = 0.0028). In conclusion, our study suggested preadmission CCB use was associated with a reduction in the risks of development of respiratory insufficiency, bacteremia, and severe sepsis in patients admitted to the hospital with pneumonia.

  8. The calcium channel blocker amlodipine exerts its anti-proliferative action via p21(Waf1/Cip1) gene activation.

    Science.gov (United States)

    Ziesche, Rolf; Petkov, Ventzislav; Lambers, Christopher; Erne, Paul; Block, Lutz-Henning

    2004-10-01

    Proliferation of vascular smooth muscle cells (VSMC) contributes to the progression of atherosclerotic plaques. Calcium channel blockers have been shown to reduce VSMC proliferation, but the underlying molecular mechanism remains unclear. p21(Waf1/Cip1) is a potent inhibitor of cell cycle progression. Here, we demonstrate that amlodipine (10(-6) to 10(-8) M) activates de novo synthesis of p21(Waf1/Cip1) in vitro. We show that amlodipine-dependent activation of p21(Waf1/Cip1) involves the action of the glucocorticoid receptor (GR) and C/EBP-alpha. The underlying pathway apparently involves the action of mitogen-activated protein kinase or protein kinase C, but not of extracellular signal-related kinase or changes of intracellular calcium. Amlodipine-induced p21(Waf1/Cip1) promoter activity and expression were abrogated by C/EBP-alpha antisense oligonucleotide or by the GR antagonist RU486. Amlodipine-dependent inhibition of cell proliferation was partially reversed by RU486 at 10(-8) M (58%+/-29%), antisense oligonucleotides targeting C/EBP-alpha (91%+/-26%), or antisense mRNAs targeting p21(Waf1/Cip1) (96%+/-32%, n=6); scrambled antisense oligonucleotides or those directed against C/EBP-beta were ineffective. The data suggest that the anti-proliferative action of amlodipine is achieved by induction of the p21 (Waf1/Cip1) gene, which may explain beneficial covert effects of this widely used cardiovascular therapeutic drug beyond a more limited role as a vascular relaxant.

  9. Parathyroid Hormone and the Use of Diuretics and Calcium-Channel Blockers: The Multi-Ethnic Study of Atherosclerosis.

    Science.gov (United States)

    Zaheer, Sarah; de Boer, Ian; Allison, Matthew; Brown, Jenifer M; Psaty, Bruce M; Robinson-Cohen, Cassianne; Ix, Joachim H; Kestenbaum, Bryan; Siscovick, David; Vaidya, Anand

    2016-06-01

    Thiazide diuretic (TZ) use is associated with higher bone mineral density, whereas loop diuretic (LD) use is associated with lower bone density and incident fracture. Dihydropyridine-sensitive calcium channels are expressed on parathyroid cells and may play a role in parathyroid hormone (PTH) regulation. The potential for diuretics and calcium-channel blockers (CCBs) to modulate PTH and calcium homeostasis may represent a mechanism by which they influence skeletal outcomes. We hypothesized that the use of LD and dihydropyridine CCBs is associated with higher PTH, and TZ use is associated with lower PTH. We conducted cross-sectional analyses of participants treated for hypertension in the Multi-Ethnic Study of Atherosclerosis who did not have primary hyperparathyroidism or chronic kidney disease (n = 1888). We used adjusted regression models to evaluate the independent association between TZ, LD, and CCB medication classes and PTH. TZ use was associated with lower PTH when compared with non-TZ use (44.4 versus 46.9 pg/mL, p = 0.02), whereas the use of LD and CCBs was associated with higher PTH when compared with non-users of each medication class (LD: 60.7 versus 45.5 pg/mL, p < 0.0001; CCB: 49.5 versus. 44.4 pg/mL, p < 0.0001). Adjusted regression models confirmed independent associations between TZ use and lower PTH (β = -3.2 pg/mL, p = 0.0007), and LD or CCB use and higher PTH (LD: β = +12.0 pg/mL, p < 0.0001; CCB: +3.7 pg/mL, p < 0.0001). Among CCB users, the use of dihydropyridines was independently associated with higher PTH (β = +5.0 pg/mL, p < 0.0001), whereas non-dihydropyridine use was not (β = +0.58 pg/mL, p = 0.68). We conclude that in a large community-based cohort with normal kidney function, TZ use is associated with lower PTH, whereas LD and dihydropyridine CCB use is associated with higher PTH. These associations may provide a mechanistic explanation linking use of these

  10. Effect of fixed-dose ACE-inhibitor/calcium channel blocker combination therapy vs. ACE-inhibitor monotherapy on arterial compliance in hypertensive patients with type 2 diabetes.

    Science.gov (United States)

    Winer, Nathaniel; Folker, Amy; Murphy, Julie A; Hung, Elena; Bard, Mara; Perkelvald, Alexander; Sowers, James R; Bakris, George L

    2005-01-01

    Assessment of vascular compliance may be a useful measurement of the clinical effects of antihypertensive treatment. Both angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers are known to improve vascular elasticity. A study was performed to test the hypothesis that combined therapy with an ACE inhibitor and a calcium channel blocker would have additive benefits on vascular compliance at similar levels of blood pressure (BP), as compared with monotherapy with an ACE inhibitor. This 12-week, double-blind study was a substudy of a larger clinical hypertension study conducted in patients with hypertension and type 2 diabetes. Subjects (N = 20) were randomized to either a fixed-dose combination of amlodipine besylate/benazepril HCl or to enalapril monotherapy. BP, heart rate, large- and small-vessel compliance, systemic vascular resistance, and urinary microalbumin excretion were assessed at baseline and after treatment. Both treatments were similarly effective in lowering BP, reducing systemic vascular resistance, and decreasing urinary microalbumin excretion. Improvement in large-vessel compliance was significantly greater among subjects who received ACE-inhibitor/calcium channel blocker combination therapy (52%) as compared with those who received ACE-inhibitor monotherapy (32%; p < 0.05). No significant change in small-vessel compliance was observed with either treatment. Greater improvement in large-vessel compliance with combination therapy was independent of BP lowering.

  11. Pharmacokinetics of barnidipine hydrochloride, a new dihydropyridine calcium channel blocker, in the rat, dog and human.

    Science.gov (United States)

    Teramura, T; Watanabe, T; Higuchi, S; Hashimoto, K

    1995-11-01

    1. The pharmacokinetics of a new calcium antagonist barnidipine hydrochloride, a stereochemically pure enantiomer, was studied after intravenous and oral dosing to the rat and dog, and oral to man. 2. After intravenous dosing, plasma concentrations of barnidipine hydrochloride declined bi-exponentially with the terminal half-lives of 0.6 h in the rat and 4.1 h in the dog. The blood clearance was 5.2 l/h/kg in the rat and 3.3 l/h/kg in the dog, and was comparable with hepatic blood flow in both species. 3. After oral dosing, plasma concentrations of barnidipine hydrochloride peaked rapidly (0.3-0.4 h in the rat and dog, 1.0-1.6 h in man). Cmax and AUC rose non-linearly with increasing doses in all three species. 4. The absolute bioavailability was low (11-18% in the rat and 6-9% in the dog), suggesting a marked first-pass metabolism.

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

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  13. Quantitative Structure-Activity Relationship Studies of 4-Imidazolyl- 1,4-dihydropyridines as Calcium Channel Blockers

    Directory of Open Access Journals (Sweden)

    Farzin Hadizadeh

    2013-08-01

    Conclusion: The predictive ability of the model was found to be satisfactory and could be used for designing a similar group of 1,4- dihydropyridines , based on a pyridine structure core which can block calcium channels.

  14. Effects of glycoprotein Ⅱb/Ⅲa antagonists and chloride channel blockers on platelet cytoplasmic free calcium

    Institute of Scientific and Technical Information of China (English)

    YIN Song-mei; XIE Shuang-feng; NIE Da-nian; LI Yi-qing; LI Hai-ming; MA Li-ping; WANG Xiu-ju; WU Yu-dan; FENG Jian-hong

    2005-01-01

    @@ Platelet activation plays an important role in thrombosis. Platelet glycoprotein Ⅱb/Ⅲa (GP Ⅱb/Ⅲa) is the receptor of fibrinogen. Platelet cross-linking with fibrinogen through GPⅡb/Ⅲa is the process of thrombosis. Ca2+ is an important intracellular second messenger in platelet activation. It has been reported that GPⅡb/Ⅲa receptors were involved in the calcium influx of activated platelet, and GPⅡb/Ⅲa receptor had characteristics of calcium channel or an adjacent calcium channel.

  15. Efficacy and safety of calcium channel blockers in heart failure : Focus on recent trials with second-generation dihydropyridines

    NARCIS (Netherlands)

    de Vries, RJM; van Veldhuisen, DJ; Dunselman, PHJM

    2000-01-01

    Background Chronic heart failure (CHF) has high morbidity and mortality rates despite treatment with angiotensin-converting-enzyme inhibitors, diuretics, and digoxin. Adjunctive-vasodilation through calcium channel blockade has been suggested as potentially useful, However, the first-generation calc

  16. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  17. Non-cardiogenic pulmonary edema and life-threatening shock due to calcium channel blocker overdose: a case report and clinical review.

    Science.gov (United States)

    Siddiqi, Tauseef Afaq; Hill, Jennifer; Huckleberry, Yvonne; Parthasarathy, Sairam

    2014-02-01

    Calcium channel blockers (CCBs) overdose can be life-threatening when manifest as catastrophic shock and non-cardiogenic pulmonary edema. We describe a case of massive overdose of multiple medications, including sustained-release verapamil, which was resistant to conventional support. Initial treatment for CCB overdose is primarily supportive, and includes fluid resuscitation. The mechanism of non-cardiogenic pulmonary edema is not well known, and reported cases have been successfully treated with mechanical ventilation. Circulatory shock may fail to respond to atropine, glucagon, and calcium in severely poisoned patients, and vasopressors are usually required. Attempting to overcome calcium-channel antagonism with the supra-therapeutic doses of calcium salts is clinically indicated to reverse hypotension and bradycardia. There is evidence that hyperinsulinemia-euglycemia therapy is superior to other therapies for CCB poisoning, and the mechanism is thought to be the insulin-mediated active transport of glucose into the cells, which counters the CCB-induced intra-cellular carbohydrate-deficient state. Conventional decontamination measures are ineffective in accelerating clearance of CCB. Experience with intravenous lipid emulsion for lipophilic drug overdose, such as verapamil, is limited, but has been proposed as a rescue therapy and might improve cardiac inotropy through intravascular sequestration of the lipophilic CCB.

  18. Synthesis and Effects of Novel Dihydropyridines as Dual Calcium Channel Blocker and Angiotensin Antagonist on Isolated Rat Aorta

    Directory of Open Access Journals (Sweden)

    Farzin Hadizadeh

    2010-01-01

    Full Text Available Four novel losartan analogues 5a-d were synthesized by connecting a dihydropyridine nucleus to imidazole ring. The effects of 5a and 5b on angiotensin receptors (AT1 and L-type calcium channels were investigated on isolated rat aorta. Materials and MethodsAortic rings were pre-contracted with 1 µM Angiotensin II or 80 mM KCl and relaxant effects of losartan, nifedipine, 5a and 5b were evaluated by cumulative addition of these drugs to the bath solution.ResultsThe results showed that compounds 5a and 5b have both L-type calcium channel and AT1 receptor blocking activity. Their effects on AT1 receptors are 1000 and 100,000 times more than losartan respectively. The activity of compound 5b on L-type calcium channel is significantly less than nifedipine but compound 5a has comparable effect with nifedipine. ConclusionFinally we concluded that these two new Compounds can be potential candidates to be used as effective antihypertensive agents.

  19. In vivo and ex vivo evaluation of L-type calcium channel blockers on acid beta-glucosidase in Gaucher disease mouse models.

    Directory of Open Access Journals (Sweden)

    Ying Sun

    Full Text Available Gaucher disease is a lysosomal storage disease caused by mutations in acid beta-glucosidase (GCase leading to defective hydrolysis and accumulation of its substrates. Two L-type calcium channel (LTCC blockers-verapamil and diltiazem-have been reported to modulate endoplasmic reticulum (ER folding, trafficking, and activity of GCase in human Gaucher disease fibroblasts. Similarly, these LTCC blockers were tested with cultured skin fibroblasts from homozygous point-mutated GCase mice (V394L, D409H, D409V, and N370S with the effect of enhancing of GCase activity. Correspondingly, diltiazem increased GCase protein and facilitated GCase trafficking to the lysosomes of these cells. The in vivo effects of diltiazem on GCase were evaluated in mice homozygous wild-type (WT, V394L and D409H. In D409H homozygotes diltiazem (10 mg/kg/d via drinking water or 50-200 mg/kg/d intraperitoneally had minor effects on increasing GCase activity in brain and liver (1.2-fold. Diltiazem treatment (10 mg/kg/d had essentially no effect on WT and V394L GCase protein or activity levels (<1.2-fold in liver. These results show that LTCC blockers had the ex vivo effects of increasing GCase activity and protein in the mouse fibroblasts, but these effects did not translate into similar changes in vivo even at very high drug doses.

  20. The effects of a sodium and a calcium channel blocker on lethality of mice injected with the yellow scorpion (Leiurus quinquestriatus venom

    Directory of Open Access Journals (Sweden)

    A. R. Al-Shanawani

    2005-06-01

    Full Text Available Scorpion venom toxins generally produce similar effects by mainly acting on sodium channels, and to a lesser extent, on potassium, calcium, and chloride channels. This leads to increased release of neurotransmitters and mediators, resulting in a cascade of pathological events, involving the central nervous system, the autonomic nervous system, the cardiovascular and the respiratory system, eventually leading to death. The objective of this paper was to discover whether a sodium channel blocker, lidocaine, or a calcium channel blocker, verapamil, would prolong the survival of mice injected with the venom from the common yellow scorpion Leiurus quinquestriatus quinquestriatus (LQQ. For this purpose, mice were divided into 2 groups, each injected with a different venom dose (250 or 300 µg.kg-1, s.c.. Subgroups (n=10 from each group were given venom alone; different doses of lidocaine (4, 10, 15, or 20 mg.kg-1; or several doses of verapamil (0.01, 0.03, 0.1, 0.3, or 1 mg.kg-1. All doses of lidocaine and verapamil were intravenously administered 3 minutes before, 1, 5, and 15 minutes after venom injection. Percent surviving after 24 hours was recorded in addition to the time of death. In general, lidocaine significantly prolonged survival at the dose of 10 mg.kg-1 (P<0.05 and P<0.01, versus low and high dose of venom, respectively or 15 mg.kg-1 (P<0.01 and P<0.001, versus low and high dose of venom, respectively; Covariance Wilcoxon survival statistics, especially when injected before the venom or in the early stages of envenomation. On the other hand, in all doses administered, verapamil was either toxic or showed non-significant results. Lidocaine, the sodium channel blocker, appears to play an important role in the protection from lethality of mice injected with LQQ venom, and significantly prolonged the survival time of mice whether injected before or in the early stages of envenomation.

  1. Study on combined antiepileptic effect of Topmax(TPM) and Calcium channel blockers(CCB)%CCB辅助TPM抗痫的探讨

    Institute of Scientific and Technical Information of China (English)

    程百学; 高唯一; 张新华; 赵宗彦; 李文浩; 邢玉栋

    2002-01-01

    目的:观察钙通道阻滞剂(Calcium channel blocker,CCB)辅助妥泰(Topmax,TPM)抗癫痫的效果.方法:将服用TPM治疗癫痫的患者分为TPM组及TPM加CCB组,观察癫痫发作频率的变化及不良反应发生率.结果:西比灵、尼莫地平辅助TPM组临床癫痫控制率(76.15%)明显优于未用CCB组(18.18%);不良反应发生率TPM加CCB组(10.09%)低于TPM组(33.3%).结论:CCB辅助TPM可提高癫痫控制率、降低TPM的不良反应发生率.

  2. Characterisation of marrubenol, a diterpene extracted from Marrubium vulgare, as an L-type calcium channel blocker.

    Science.gov (United States)

    El-Bardai, Sanae; Wibo, Maurice; Hamaide, Marie-Christine; Lyoussi, Badiaa; Quetin-Leclercq, Joelle; Morel, Nicole

    2003-12-01

    1. The objective of the present study was to investigate the mechanism of the relaxant activity of marrubenol, a diterpenoid extracted from Marrubium vulgare. In rat aorta, marrubenol was a more potent inhibitor of the contraction evoked by 100 mM KCl (IC50: 11.8+/-0.3 microM, maximum relaxation: 93+/-0.6%) than of the contraction evoked by noradrenaline (maximum relaxation: 30+/-1.5%). 2. In fura-2-loaded aorta, marrubenol simultaneously inhibited the Ca2+ signal and the contraction evoked by 100 mM KCl, and decreased the quenching rate of fura-2 fluorescence by Mn2+. 3. Patch-clamp data obtained in aortic smooth muscle cells (A7r5) indicated that marrubenol inhibited Ba2+ inward current in a voltage-dependent manner (KD: 8+/-2 and 40+/-6 microM at holding potentials of -50 and -100 mV, respectively). 4. These results showed that marrubenol inhibits smooth muscle contraction by blocking L-type calcium channels.

  3. FIXED COMBINATION OF THE CALCIUM CHANNEL BLOCKER LERCANIDIPINE AND ANGIOTENSIN CONVERTING ENZYME INHIBITOR ENALAPRIL: POSSIBILITY OF USAGE

    Directory of Open Access Journals (Sweden)

    O. D. Ostroumova

    2013-01-01

    Full Text Available Data on the updated approach to the choice of two-component antihypertensive combinations for different clinical situations are presented. Advantages and indications for combination of an angiotensin converting enzyme (ACE inhibitor and dihydropyridine calcium antagonist are considered. Data on the efficacy and safety of the combination of calcium antagonist of the third generation, lercanidipine, and ACE inhibitor, enalapril, are presented.

  4. Influence of calcium blockers on the SPR of erythrocytes

    Science.gov (United States)

    Shynkarenko, Olena V.; Tril, Orest; Wojnarowska, Renata; Prohorenko, Sergiy; Shergii, E. M.

    2016-12-01

    One of the promising areas of research is the impact of calcium channel blockers (CB) of biological fluids. This paper shows that the CB impact on a biological fluid can be efficiently combine with the surface plasmon resonance (SPR). It is shown that the addition of CB at the SPR measurements affect the stability of membranes and acts differently on the kinetics of erythrocytes ligament in the different groups of people.

  5. Effects of first and second generation calcium channel blockers on diastolic function of the failing hamster heart: relationship with coronary flow changes.

    Science.gov (United States)

    Beaucage, Pierre; Massicotte, Julie; Boileau, Jean-François; Dumont, Louis

    2003-07-01

    Calcium channel blockers (CCBs) have variable efficacy in the treatment of heart failure. We hypothesized that modulation of left ventricular diastolic pressure (LVDP) may play a role in the variable efficacy of CCBs in this condition. Isolated perfused hearts from 200- to 250-day-old UM-X7.1 cardiomyopathic hamsters (failing hearts) and age-matched Syrian hamsters (normal hearts) were studied. After recording of heart rate, coronary flow (CF), LVDP and left ventricular systolic pressure (LVSP), hearts were exposed either to verapamil or diltiazem (1 nM-10 microM), mibefradil (1 nM-1 microM) or clentiazem (1 nM-10 microM). Mechanical increase in CF (+2 to +10 ml/min) was carried out using a roller pump. Mechanically-augmented flow led to an increase in coronary perfusion pressure (+40 to +90 mm Hg), LVSP (+5 to +40 mm Hg) and LVDP (+5 to +25 mm Hg). CCBs-induced increment of coronary flow led to a difference in their cardiac response. In normal hearts, the negative inotropic response was more important with diltiazem and verapamil. Failing hearts did not demonstrate increased inotropic sensitivity to first-generation CCBs. On the contrary, at clinically relevant concentrations, verapamil resulted in the most pronounced impairment of LVDP followed by diltiazem while mibefradil and clentiazem, at clinically relevant concentrations, preserved LVDP. Such findings provide an additional explanation for the variable efficacy of CCBs in heart failure.

  6. Simultaneous determination of a novel diphenylpiperazine calcium channel blocker and its four metabolites in rat liver microsomes by liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Guo, Wei; Kong, Dezhi; Du, Yingfeng; Shi, Xiaowei; Wang, Wei; Wang, Yongli

    2012-01-01

    Dipfluzine hydrochloride (Dip), a novel diphenylpiperazine calcium channel blocker, has revealed the characteristics of a promising candidate for the treatment of cerebral vascular diseases in preclinical studies. Our research identified and quantified Dip and its 4 metabolites (M1, M2, M4 and M5) in rat liver microsomes by liquid chromatography tandem mass spectrometry. The results showed that Dip was firstly metabolized to M1 and M5 by 1- and 4-dealkylation from a piperazine nitrogen, and then the latter was subsequently metabolized to M2 and M4. The concentrations of Dip, M1, M2 and M5 were 557.3 ± 26.3, 854.3 ± 46.0, 2796.7± 126.9, 2473.3 ± 82.6 and 4.0 ± 0.4, 2.4 ± 0.1, 318.2 ± 8.7 and 27.4 ± 1.5 ng/ml in male and female rats, respectively. M4 (404.2 ± 22.2 ng/ml) was detected only in males not in females, suggesting that there is gender difference in the metabolism of Dip.

  7. Combination therapy of renin-angiotensin system inhibitors plus calcium channel blockers versus other two-drug combinations for hypertension: a systematic review and meta-analysis.

    Science.gov (United States)

    Lu, Z; Chen, Y; Li, L; Wang, G; Xue, H; Tang, W

    2017-01-01

    Many randomized clinical trials (RCTs) have investigated the efficacy and safety of renin-angiotensin system inhibitors (RASIs) plus calcium channel blockers (CCBs), compared with other two-drug combinations, but systematic assessment in this aspect is still lacking. We carried out the present meta-analysis of randomized controlled trials to evaluate the long-term effect and safety of RASIs plus CCBs. Literatures were searched in MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials in September 2014. A fixed-effect model was used to estimate the pooled effect of trials identified. Thirty-four trials with 41 694 patients were included. Compared with RASIs plus diuretics, RASIs plus CCBs decreased total cardiovascular (CV) events (relative risk (RR) 0.82, 95% confidence interval (CI): 0.75, 0.91, adjusted RR (ARR) 1.7%) and withdrawals due to adverse effect (WDAE) (RR 0.87, 95% CI: 0.80, 0.94, ARR 1.3%). Compared with CCBs plus diuretics, RASIs plus CCBs decreased WDAE (RR 0.63, 95% CI: 0.45, 0.90, ARR 1.1%). Our meta-analysis indicates that RASIs plus CCBs provide a superior safety and prevention of CV events to RASIs plus diuretics, whereas this combination is also safer than CCBs plus diuretics. We also raise a new hypothesis. More high-quality RCTs focused on hard end points with CV, cerebrovascular and renal events are needed to confirm the hypothesis we have brought out.

  8. Optical isomers of dihydropyridine calcium channel blockers display enantiospecific effects on the expression and enzyme activities of human xenobiotics-metabolizing cytochromes P450.

    Science.gov (United States)

    Štěpánková, Martina; Krasulová, Kristýna; Dořičáková, Aneta; Kurka, Ondřej; Anzenbacher, Pavel; Dvořák, Zdeněk

    2016-11-16

    Dihydropyridine calcium channel blockers (CCBs) are used as anti-hypertensives and in the treatment of angina pectoris. Structurally, CCBs have at least one chiral center in the molecule, thereby existing in two or more different enantiomers. In the current paper we examined effects of benidipine, felodipine and isradipine enantiomers on the expression and enzyme activities of human xenobiotics-metabolizing cytochromes P450. All CCBs dose-dependently activated aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR), as revealed by gene reporter assays. Activation of AhR, but not PXR, was enantiospecific. Consistently, CCBs induced CYP1A1 and CYP1A2 mRNAs, but not protein, in human hepatocytes and HepG2 cells, with following pattern: benidipine (-)>(+), isradipine (-)>(+) and felodipine (+)>(-). All CCBs induced CYP2A6, CYP2B6 and CYP3A4 mRNA and protein in human hepatocytes, and there were not differences between the enantiomers. All CCBs transformed AhR in its DNA-binding form, as revealed by electromobility shift assay. Tested CCBs inhibited enzyme activities of CYP3A4 (benidipine (+)>(-); felodipine (-)>(+); isradipine (-)-(+)) and CYP2C9 (benidipine (-)>(+); felodipine (+)>(-); isradipine (-)>(+)). The data presented here might be of toxicological and clinical importance.

  9. Renoprotective Effect of the Combination of Renin-angiotensin System Inhibitor and Calcium Channel Blocker in Patients with Hypertension and Chronic Kidney Disease

    Institute of Scientific and Technical Information of China (English)

    Rong-Shuang Huang; Yi-Ming Cheng; Xiao-Xi Zeng; Sehee Kim; Ping Fu

    2016-01-01

    Background:Renin-angiotensin system inhibitor and calcium channel blocker (CCB) are widely used in controlling blood pressure (BP) in patients with chronic kidney disease (CKD).We carried out a meta-analysis to compare the renoprotective effect of the combination of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) and CCB (i.e.,ACEI/ARB + CCB) with ACEI/ ARB monotherapy in patients with hypertension and CKD.Methods:Publications were identified from PubMed,Embase,Medline,and Cochrane databases.Only randomized controlled trials (RCTs) of BP lowering treatment for patients with hypertension and CKD were considered.The outcomes of end-stage renal disease (ESRD),cardiovascular events,BP,urinary protein measures,estimated glomerular filtration rate (GFR),and adverse events were extracted.Results:Based on seven RCTs with 628 patients,ACEI/ARB + CCB did not show additional benefit for the incidence of ESRD (risk ratio [RR] =0.84;95% confidence interval [CI]:0.52-1.33) and cardiovascular events (RR =0.58;95% CI:0.21-1.63) significantly,compared with ACEI/ARB monotherapy.There were no significant differences in change from baseline to the end points in diastolic BP (weighted mean difference [WMD] =-1.28 mmHg;95% CI:-3.18 to-0.62),proteinuria (standard mean difference =-0.55;95% CI:-1.41 to-0.30),GFR (WMD =-0.32 ml/min;95% CI:-1.53 to-0.89),and occurrence of adverse events (RR =1.05;95% CI:0.72-1.53).However,ACEI/ARB + CCB showed a greater reduction in systolic BP (WMD =-4.46 mmHg;95% CI:-6.95 to-1.97),compared with ACEI/ARB monotherapy.Conclusion:ACEI/ARB + CCB had no additional renoprotective benefit beyond than what could be achieved with ACEI/ARB monotherapy.

  10. Effects of the 1, 4-dihydropyridine L-type calcium channel blocker benidipine on bone marrow stromal cells.

    Science.gov (United States)

    Ma, Zhong-ping; Liao, Jia-cheng; Zhao, Chang; Cai, Dao-zhang

    2015-08-01

    Osteoporosis (OP) often increases the risk of bone fracture and other complications and is a major clinical problem. Previous studies have found that high blood pressure is associated with bone formation abnormalities, resulting in increased calcium loss. We have investigated the effect of the antihypertensive drug benidipine on bone marrow stromal cell (BMSC) differentiation into osteoblasts and bone formation under osteoporotic conditions. We used a combination of in vitro and in vivo approaches to test the hypothesis that benidipine promotes murine BMSC differentiation into osteoblasts. Alkaline phosphatase (ALP), osteocalcin (OCN), runt-related transcription factor 2 (RUNX2), β-catenin, and low-density lipoprotein receptor-related protein 5 (LRP5) protein expression was evaluated in primary femoral BMSCs from C57/BL6 mice cultured under osteogenic conditions for 2 weeks to examine the effects of benidipine. An ovariectomized (OVX) mouse model was used to investigate the effect of benidipine treatment for 3 months in vivo. We found that ALP, OCN, and RUNX2 expression was up-regulated and WNT/β-catenin signaling was enhanced in vitro and in vivo. In OVX mice that were intragastrically administered benidipine, bone parameters (trabecular thickness, bone mineral density, and trabecular number) in the distal femoral metaphysis were significantly increased compared with control OVX mice. Consistently, benidipine promoted BMSC differentiation into osteoblasts and protected against bone loss in OVX mice. Therefore, benidipine might be a suitable candidate for the treatment of patients with postmenopausal osteoporosis and hypertension.

  11. Metabolism and pharmacokinetics of barnidipine hydrochloride, a calcium channel blocker, in man following oral administration of its sustained release formulation.

    Science.gov (United States)

    Teramura, T; Watanabe, T; Higuchi, S; Hashimoto, K

    1997-02-01

    1. The metabolism and pharmacokinetics of barnidipine hydrochloride, a 1, 4-dihydropyridine calcium antagonist were evaluated following single oral administration of a sustained release formulation (SR) capsule comprising of quick and slow release pellets to healthy male volunteers. 2. Various metabolites were identified and quantitated by newly established GC-MS analytical methods. Major metabolites were the hydrolyzed product of the benzyl-pyrrolidinyl ester (M-3) in plasma and its oxidized pyridine product (M-4) in plasma and urine. The pyridine form of unchanged barnidipine and the N-debenzylated product were observed as minor metabolites. Therefore, the primary metabolic pathways in man are (a) hydrolysis of the benzylpyrrolidine ester, (b) N-debenzylation, and (c) oxidation of the dihydropyridine ring. 3. When the SR and normal capsules were administered at a dose of 10 mg to six subjects in a crossover design, AUC 0-infinity of unchanged drug, M-3 and 4 in each subject receiving the SR were 97 +/- 15, 85 +/- 31 and 76 +/- 21% respectively of those subjects receiving the normal formulation. The sum of the excretion of urinary metabolites for the SR formulation was 65 +/- 6% of that for the normal formulation. These data suggest that the absorption of the SR formulation is slightly reduced but that its bioavailability is comparable to that of the normal formulation.

  12. Extent of use of immediate-release formulations of calcium channel blockers as antihypertensive monotherapy by primary care physicians: multicentric study from Bahrain.

    Directory of Open Access Journals (Sweden)

    Sequeira R

    2002-07-01

    Full Text Available BACKGROUND: The issue of cardiovascular safety of calcium channel blockers (CCBs has been widely debated in view of reflex increase in sympathetic activity induced by immediate release (IR / short acting formulations. It is generally agreed that such CCBs should not be used alone in the management of hypertension. AIMS: We have determined the extent to which primary care physicians prescribe CCBs as monotherapy, especially the immediate release formulations, in the management of uncomplicated hypertension and diabetic hypertension - with an emphasis upon the age of the patients. SETTING, DESIGN AND METHODS: A retrospective prescription-based study was carried out in seven out of 18 Health Centres in Bahrain. The study involved a registered population of 229,300 representing 46% of registered individuals, and 35 physicians representing 43% of all primary care physicians. The data was collected between November 1998 and January 1999 using chronic dispensing cards. RESULTS: In all categories CCBs were the third commonly prescribed antihypertensive as monotherapy, with a prescription rate of 11.1% in uncomplicated hypertension, 18% in diabetic hypertension and 20.1% in elderly patients above 65 years of age. Nifedipine formulations were the most extensively prescribed CCBs. Almost half of the CCB-treated patients were on IR-nifedipine, whereas IR-diltiazem and IR-verapamil, and amlodipine were infrequently prescribed. CONCLUSION: Prescription of IR-formulations of CCBs as monotherapy by primary care physicians does not conform with recommended guidelines. In view of concerns about the safety of such practice, measures to change the prescribing pattern are required.

  13. The use of amlodipine, but not of P-glycoprotein inhibiting calcium channel blockers is associated with clopidogrel poor-response.

    Science.gov (United States)

    Harmsze, Ankie M; Robijns, Karen; van Werkum, Jochem W; Breet, Nicoline J; Hackeng, Christian M; Ten Berg, Jurrien M; Ruven, Hendrik J T; Klungel, Olaf H; de Boer, Anthonius; Deneer, Vera H M

    2010-05-01

    Clopidogrel is a prodrug that has to be converted in vivo to its active metabolite by cytochrome (CYP)P450 iso-enzymes. As calcium channel blockers (CCBs) are inhibitors of CYP3A4, concomitant use of these drugs might play a role in the wide inter-individual variability in the response to clopidogrel. However, some CCBs also have strong inhibitory effects on the drug transporter P-glycoprotein (Pgp), which mediates clopidogrel's intestinal absorption. It was the aim of this study to evaluate the effect of co-administration of Pgp-inhibiting and non-Pgp-inhibiting CCBs on on-clopidogrel platelet reactivity in patients on dual antiplatelet therapy undergoing elective percutaneous coronary intervention (PCI). In a total of 623 consecutive patients undergoing elective PCI treated with clopidogrel and aspirin, platelet reactivity to 5 and 20 muM adenosine diphospate (ADP) and clopidogrel poor-response (defined as > 70% platelet aggregation to 20 muM ADP) were evaluated by light transmittance aggregometry. A total of 222 patients (35.6%) were on CCB treatment, of which 98 used Pgp-inhibiting CCBs (verapamil, nifedipine, diltiazem, barnidipine) and 124 patients used the non-Pgp-inhibiting CCB amlodipine. Adjusted mean ADP-induced on-clopidogrel platelet reactivity was significantly higher in both users of Pgp-inhibiting CCBs and amlodipine as compared to CCB non-users (all p<0.05). However, only the use of amlodipine was significantly associated with a 2.3-fold increased risk of clopidogrel poor-response. This study demonstrates that concomitant use of Pgp-inhibiting CCBs and amlodipine increases on-clopidogrel platelet reactivity. Only amlodipine was associated with clopidogrel poor-response. The drug-drug interaction between clopidogrel and amlodipine might be more clinically relevant as compared to P-glycoprotein-inhibiting CCBs.

  14. Reduced myocardial {sup 18}F-FDG uptake after calcium channel blocker administration. Initial observation for a potential new method to improve plaque detection

    Energy Technology Data Exchange (ETDEWEB)

    Gaeta, Chiara; Flotats, Albert; Artigas, Carles; Deportos, Jordi; Geraldo, Llanos; Carrio, Ignasi [Sant Pau Hospital, PET Unit, Department of Nuclear Medicine, Barcelona (Spain); Fernandez, Yolanda [Center for Experimental Molecular Imaging (CIME), CETIR-ERESA, Barcelona (Spain); Pavia, Javier [Center for Experimental Molecular Imaging (CIME), CETIR-ERESA, Barcelona (Spain); Networking Research Centre on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona (Spain)

    2011-11-15

    Physiological glucose uptake by the myocardium may hamper visualization of coronary atherosclerotic plaques in {sup 18}F-FDG PET studies. Intracellular myocardial calcium relates to glucose influx. We assessed whether administration of a calcium channel blocker such as verapamil could decrease myocardial {sup 18}F-FDG uptake in mice. Experiments were conducted on ten male C57BL/6JOlaHsd mice. The mice were studied by {sup 18}F-FDG PET/CT under basal conditions and after a single administration of verapamil injected 1 h prior to {sup 18}F-FDG administration at doses of 1 mg/kg (group A, n = 5) and 20 mg/kg (group B, n = 5). PET scanning was started 60 min after injection of {sup 18}F-FDG employing a dedicated small-animal PET/CT system (ARGUS-CT). In each mouse, post-verapamil PET images were coregistered with the basal PET images. Volumetric regions of interest (VOI) were drawn on the basal study containing the myocardium of the whole left ventricle and quantitatively compared with the same VOI applied to the post-verapamil scan. The SUV{sub mean} was used to express the mean myocardial {sup 18}F-FDG uptake. The relative coefficient of variation (RV) between the basal and post-verapamil conditions was calculated. Verapamil administration decreased myocardial {sup 18}F-FDG uptake in all animals. The median (range) SUV{sub mean} values in group A were 2.6 (1.6-4.1) under basal conditions and 1.7 (1.1-2.9) after verapamil administration (p = 0.043), and in group B were 1.6 (1.3-2.0) under basal conditions and 1.0 (0.9-1.4) after verapamil administration (p = 0.043). The median (range) RV values were -31% (-5%, -50%) in group A, and -37% (-10%, -51%) in group B (p = 0.6). In this animal model there was a significant reduction in {sup 18}F-FDG uptake in the myocardium following verapamil administration. This type of intervention could facilitate the definition of coronary atherosclerotic plaque inflammation on {sup 18}F-FDG PET scans. (orig.)

  15. Rapid changes in skeletal muscle calcium uptake induced in vitro by 1,25-dihydroxyvitamin D/sub 3/ are suppressed by calcium channel blockers

    Energy Technology Data Exchange (ETDEWEB)

    de Boland, A.R.; Boland, R.L.

    1987-05-01

    Previous investigations have shown that 1,25-dihydroxyvitamin D/sub 3/ (1,25-(OH)/sub 2/D/sub 3/) stimulates muscle Ca uptake through a nuclear mechanism. The possibility that 1,25-(OH)/sub 2/D/sub 3/ would induce rapid changes in muscle Ca fluxes independent of de novo protein synthesis was investigated in the present work. In vitro preparations of soleus muscles obtained from vitamin D-deficient chicks were used. A significant increase in /sup 45/Ca labeling of the tissue was already observed after 3-min treatment with 2.4 X 10(-10) M 1,25-(OH)/sub 2/D/sub 3/. This early stimulation in muscle Ca uptake became maximal at 10-15 min. Cycloheximide (50 microM) did not block the effect of the metabolite at 15 and 30 min. However, the antibiotic effectively blocked the increase in Ca uptake induced by 1,25-(OH)/sub 2/D/sub 3/ after 1-h treatment. The rapid 1,25-(OH)/sub 2/D/sub 3/-dependent stimulation of /sup 45/Ca labeling of soleus muscle was not associated to changes in lipid synthesis as assessed by measurements of /sup 3/H-glycerol incorporation into the tissue lipids. However, the calcium antagonists verapamil and nifedipine (50 microM) abolished the stimulation in Ca uptake produced by 1,25-(OH)/sub 2/D/sub 3/ in 5 min. These results suggest that 1,25-(OH)/sub 2/D/sub 3/ can act directly at the muscle membrane level affecting Ca fluxes through Ca channels.

  16. Phenylalkylamines as calcium channel blockers

    Indian Academy of Sciences (India)

    Anamika Awasthi; Arpita Yadav

    2007-09-01

    In this study we present ab initio Hartree Fock molecular orbital calculations with complete geometry optimizations on some phenylalkylamines (PAAs) that are clinically used as antiarrhythmic drugs. Pharmacophoric features of PAAs have been derived. An explanation of potency regulation in PAAs has been suggested based on ion capturing vs. ion holding by the drug. Ion capturing by the drug is always electrostatically highly favourable but has to be analysed in terms of conformational changes required and physiological accessibility of the situation. Our results also seem to offer an explanation for inhibitory effect of Ca2+ ion concentration on binding affinity of PAAs.

  17. An open-label, randomized, controlled, 4-week comparative clinical trial of barnidipine hydrochloride, a calcium-channel blocker, and benazepril, an angiotensin-converting enzyme inhibitor, in Chinese patients with renal parenchymal hypertension.

    Science.gov (United States)

    Chen, X; Zheng, F; Chen, P; Tang, L; Wei, R; Yu, Y; Su, Y; Kikkawa, T; Yamamoto, M

    2006-01-01

    This study compared barnidipine, a calcium-channel blocker, and benazepril, an angiotensin-converting enzyme inhibitor, in 85 Chinese patients with renal parenchymal hypertension (diastolic blood pressure range 95 - 110 mmHg). Patients were randomly assigned to receive either 10 mg barnidipine or 10 mg benazepril orally daily for 4 weeks. In patients with diastolic blood pressure > 90 mmHg after 2 weeks of treatment, the dose of barnidipine or benazepril was increased by 5 or 10 mg, respectively. Both the barnidipine-treated group (n = 43) and the benazepril-treated group (n = 42) showed significant mean reductions from baseline in sitting systolic and diastolic blood pressures. The decrease in diastolic blood pressure with benazepril was significantly greater than with barnidipine treatment. Sitting heart rate was not changed by either drug. There was no significant difference in adverse events between the two groups. Barnidipine is similar to benazepril for the treatment of renal parenchymal hypertension.

  18. Meta Analysis of the Effects of Calcium Channel Blockers or Renin-Angiotensin System Blockers on Arterial Stiffness in Hypertension%钙离子拮抗剂和肾素-血管紧张素系统阻断剂对高血压动脉僵硬度作用差异的荟萃分析

    Institute of Scientific and Technical Information of China (English)

    张艺军; 裴静娴; 王月刚; 吴平生

    2012-01-01

    目的 系统评价钙离子拮抗剂和肾素-血管紧张素系统阻断剂在高血压治疗中,动脉僵硬度变化的差异.方法 按循证医学的要求,制定相应的纳入、排除标准及其检索策略.通过PubMed、EMBASE、Ovid EMBReviews、中周期刊全文数据库、中文科技期刊全文数据库、万方数据库检索相关的随机对照临床研究,计算机检索时间从各数据库建库至2012年1月;同时辅助其他检索,纳入经过钙离子拮抗剂和肾素-血管紧张素系统阻断剂治疗原发性高血压患者的随机对照试验,治疗时间至少12周.采用RevMan5.0软件进行统计分析.结果 纳入7篇随机对照研究,共计524例高血压患者.荟萃分析结果显示:肾素-血管紧张素系统阻断剂在改善动脉僵硬度方面优于钙离子拮抗剂(均数差=160.15,95%可信区间57.10~263.21),差异有统计学意义.但是在降低收缩压(均数差=-2.94,95%可信区间-4.59~-1.29)和舒张压(均数差=-6.63,95%可信区间-9.56~-3.70)方面,较钙离子拮抗剂弱,在降低脉压差(均数差=-6.12,95%可信区间-2.3~14.55)方面与钙离子拮抗剂相比无显著性差异.结论 肾素-血管紧张素系统阻断剂在改善高血压患者动脉僵硬度方面优于钙离子拮抗剂,该作用与其降压作用无关.%Objective To evaluate the differences of the changes of pulse wave velocity(PWV) of hypertension patients with the treatment of calcium channel blockers or Renin-angiotensin system blockers. Methods Based on the principles of evidence-based medicine, corresponding inclusion and exclusion criteria, along with search strategies were developed. We searched the Ovid EMB Reviews, PubMed, EMBASE, Chinese Biomedical Literature Database, Chinese Scientific Journal Full-text Database, and Chinese Journal Full-text Database up to January 2012 to identify randomized controlled trials comparing the effects of calcium channel hlockers with that of Renin

  19. The effects of calcium channel blockers in the prevention of stroke in adults with hypertension: a meta-analysis of data from 273,543 participants in 31 randomized controlled trials.

    Directory of Open Access Journals (Sweden)

    Gui Jv Chen

    Full Text Available BACKGROUND: Hypertension is a major risk factor for the development of stroke. It is well known that lowering blood pressure decreases the risk of stroke in people with moderate to severe hypertension. However, the specific effects of calcium channel blockers (CCBs against stroke in patients with hypertension as compared to no treatment and other antihypertensive drug classes are not known. METHODS AND FINDINGS: This systematic review and meta-analysis of randomized controlled trials (RCTs evaluated CCBs effect on stroke in patients with hypertension in studies of CCBs versus placebo, angiotensin-converting-enzyme inhibitors (ACEIs, β-adrenergic blockers, and diuretics. The PUBMED, MEDLINE, EMBASE, OVID, CNKI, MEDCH, and WANFANG databases were searched for trials published in English or Chinese during the period January 1, 1996 to July 31, 2012. A total of 177 reports were collected, among them 31 RCTs with 273,543 participants (including 130,466 experimental subjects and 143,077 controls met the inclusion criteria. In these trials a total of 9,550 stroke events (4,145 in experimental group and 5,405 in control group were reported. CCBs significantly decreased the incidence of stroke compared with placebo (OR = 0.68, 95% CI 0.61-0.75, p<1×10(-5, β-adrenergic blockers combined with diuretics (OR = 0.89, 95% CI 0.83-0.95, p = 7×10(-5 and β-adrenergic blockers (OR = 0.79, 95% CI 0.72-0.87, p<1×10(-5, statistically significant difference was not found between CCBs and ACEIs (OR = 0.92, 95% CI 0.8-1.02, p = 0.12 or diuretics (OR = 0.95, 95% CI 0.84-1.07, p = 0.39. CONCLUSION: In a pooled analysis of data of 31 RCTs measuring the effect of CCBs on stroke, CCBs reduced stroke more than placebo and β-adrenergic blockers, but were not different than ACEIs and diuretics. More head to head RCTs are warranted.

  20. Angiotensin System Blockade Combined With Calcium Channel Blockers Is Superior to Other Combinations in Cardiovascular Protection With Similar Blood Pressure Reduction: A Meta-Analysis in 20,451 Hypertensive Patients.

    Science.gov (United States)

    Chi, Chen; Tai, Chenhui; Bai, Bin; Yu, Shikai; Karamanou, Marianna; Wang, Jiguang; Protogerou, Athanase; Blacher, Jacques; Safar, Michel E; Zhang, Yi; Xu, Yawei

    2016-08-01

    The authors aimed to investigate the superiority of angiotensin system blockade (angiotensin-converting enzyme [ACE] inhibitor/angiotensin receptor blocker [ARB]) plus a calcium channel blocker (CCB) (A+C) over other combination therapies in antihypertensive treatment. A meta-analysis in 20,451 hypertensive patients from eight randomized controlled trials was conducted to compare the A+C treatment with other combination therapies in terms of blood pressure (BP) reduction, clinical outcomes, and adverse events. The results showed that BP reduction did not differ significantly among the A+C therapy and other combination therapies in systolic and diastolic BP (P=.87 and P=.56, respectively). However, A+C therapy, compared with other combination therapies, achieved a significantly lower incidence of cardiovascular composite endpoints, including cardiovascular mortality, nonfatal myocardial infarction, and nonfatal stroke (risk ratio [RR], 0.80; 95% confidence interval [CI], 0.70-0.91; Pother combinations (Pother combination therapies (P=.34) but presented a significantly lower incidence of serious adverse events (RR, 0.85; 95% CI, 0.73-0.98; P=.03). In conclusion, A+C therapy is superior to other combinations of antihypertensive treatment as it shows a lower incidence of cardiovascular events and adverse events, while it has similar effects in lowering BP and preserving renal function.

  1. Effects of calcium channel blockers on growth cone and their clinical implications%钙离子通道调节剂在神经元的生长锥的作用及临床意义

    Institute of Scientific and Technical Information of China (English)

    Ji-Sun KIM; Vivian Y SZETO; 冯中平

    2016-01-01

    钙是神经发育过程中重要的信号分子,其生物学功能通过众多的钙离子通道、交换蛋白及钙结合蛋白来实现。在神经发育过程中,神经元的生长锥利用钙离子的浓度差来进行正确爬行,并最终引导轴突向正确的方向生长。然而,如果钙离子通道出现功能障碍,将会引起生长锥错误地爬行,从而导致神经发育相关疾病的发生。了解特异性表达于生长锥的钙通道,并获得能调控这些钙通道的调节剂对于治疗神经发育相关疾病至关重要。这些调节剂可能已广泛用于其他组织病变,如心血管疾病的治疗。但它们对生长锥上钙通道的调控仍有待进一步研究。最近的研究表明,离子通道调节剂可以作为治疗神经发育相关疾病的药物靶标。本文讨论钙通道调节剂在生长锥引导轴突生长过程中的潜在作用。%Calcium signaling is a critical component of neuronal development, and is mediated by numerous calcium channels, exchangers and calcium-binding proteins. Growth cones use calcium gradient as a tool to pathfind correctly, ultimately directing the appropriate growth of axons. Conse⁃quently, dysfunctions of calcium channels could lead to incorrect pathfinding, thus resulting in develop⁃mental disorders. It is important to understand the pharmacological modulators of the calcium channels present in the growth cone-some already widely used in other tissue pathologies, like cardiovascular disease. Further, L-type channel blockers such as dihydropyridines have been instrumental in under⁃standing the properties of L-type channels as well as their heterogeneous nature. Investigation of channel property often uses pharmacological inhibition to reveal their functionality. Recent studies show the channel modulators as promising drug targets in the treatment of neurodevelopmental disorders. The goal of this article is to discuss the potential effects of

  2. Application of ab initio theory to QSAR study of 1,4-dihydropyridine-based calcium channel blockers using GA-MLR and PC-GA-ANN procedures.

    Science.gov (United States)

    Hemmateenejad, Bahram; Safarpour, Mohammad A; Miri, Ramin; Taghavi, Fariba

    2004-09-01

    The usefulness of the quantum chemical descriptors, calculated at the level of the RHF theory using 6-31G basis set for QSAR study of 1,4-dihydropyridine-based calcium channel antagonist was examined. A data set containing 45 dihydropyridine derivatives with known activity was used. Multiple linear regressions combined with genetic algorithm for variable selection and an artificial neural network model combined with principal component analysis for dimension reduction and genetic algorithm for factor selection (PC-GA-ANN) were employed. Some multiparametric MLR equations with good statistical quality were obtained for different classes of dihydropyridine derivatives. The resulting equations suggest that the electronic properties of the atoms belonging to the backbone of the molecules as well as the conformation of the molecules affect the binding of these molecules with their receptor. In the PC-GA-ANN, The principal components of the descriptors data matrix were used as the input of the neural network and then genetic algorithm was applied to select the most relevant set of principal components. Two ANN models with five selected principal components were obtained. These models, which have high statistical qualities, can predict the activity of the molecules with prediction errors lower than +/-5%.

  3. 钙离子拮抗剂致药物性牙龈增生的危险因素分析%Analysis of risk factors for gingival hyperplasia induced by calcium channel blockers

    Institute of Scientific and Technical Information of China (English)

    李行懿; 陈娜

    2012-01-01

    目的 调查高血压患者服用钙离子拮抗剂后引起药物性牙龈增生的患病率,并分析其危险因素.方法 将北京医院心血管内科的681例高血压或冠心病患者纳入本研究,其中330例服用钙离子拮抗剂(CCB组),351例未服用钙离子拮抗剂(对照组).记录患者的性别、年龄、用药种类、持续时间、剂量、是否联合用药.临床检查牙龈出血指数(BI)、菌斑指数(PLI)、牙龈增生指数(HI).结果 服用钙离子拮抗剂组牙龈增生的患病率为4l.21%,显著高于对照组4.84%(P <0.05).对调查的各种因素进行Logistic回归分析,结果显示:BI(OR=2.17,95%可信区间:1.60-2.94)PLI(OR=1.99,95%可信区间:1.38-2.87)是患者出现牙龈增生的危险因素.结论 口腔卫生状况和牙龈炎症反应是药物性牙龈增生的危险因素.%Objective Tu investigate the prevalence and risk factors of calcium channel blockers induced gingival overgrowth in hypertensive patients. Methods A cross-sectional survey was conducted in 681 hypertensive patients. Among them 330 patients took calcium channel blockers and 351 patients who had never received calcium channel bloclers were recruited as controls. The pharmacological and demographic data fnr each subject were recorded. Degree of gingival hyperplasia、plaque index and probing bleeding index were studied Results The prevalence of gingival overgrowth was 41.21% in CCB group which was statistically higher than that (4.84%) in the control group. By Logistic regression analysis BI ( OR=2.17,95% CI:1.60-2.94 ) and PL1 ( OR=1.99,95% CI:1.38-2.87 ) were found to be risk factors. Conclusion The gingivaJ inflammation and oral hygiene are important risk factors for the occurrence of gingival hyperplasia induced by calciun channel blockers.

  4. Nifedipine, a calcium channel blocker, inhibits advanced glycation end product (AGE)-elicited mesangial cell damage by suppressing AGE receptor (RAGE) expression via peroxisome proliferator-activated receptor-gamma activation

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Takanori [Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011 (Japan); Yamagishi, Sho-ichi, E-mail: shoichi@med.kurume-u.ac.jp [Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011 (Japan); Takeuchi, Masayoshi [Department of Pathophysiological Science, Faculty of Pharmaceutical Science, Hokuriku University, Kanazawa (Japan); Ueda, Seiji; Fukami, Kei; Okuda, Seiya [Department of Medicine, Kurume University School of Medicine, Kurume (Japan)

    2009-07-24

    The interaction between advanced glycation end products (AGE) and their receptor RAGE mediates the progressive alteration in renal architecture and loss of renal function in diabetic nephropathy. Oxidative stress generation and inflammation also play a central role in diabetic nephropathy. This study investigated whether and how nifedipine, a calcium channel blocker (CCB), blocked the AGE-elicited mesangial cell damage in vitro. Nifedipine, but not amlodipine, a control CCB, down-regulated RAGE mRNA levels and subsequently reduced reactive oxygen species (ROS) generation in AGE-exposed mesangial cells. AGE increased mRNA levels of vascular cell adhesion molecule-1 (VCAM-1) and induced monocyte chemoattractant protein-1 (MCP-1) production in mesangial cells, both of which were prevented by the treatment with nifedipine, but not amlodipine. The beneficial effects of nifedipine on AGE-exposed mesangial cells were blocked by the simultaneous treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma} (PPAR-{gamma}). Although nifedipine did not affect expression levels of PPAR-{gamma}, it increased the PPAR-{gamma} transcriptional activity in mesangial cells. Our present study provides a unique beneficial aspect of nifedipine on diabetic nephropathy; it could work as an anti-inflammatory agent against AGE by suppressing RAGE expression in cultured mesangial cells via PPAR-{gamma} activation.

  5. ADVANTAGES OF COMBINATION THERAPY OF HYPERTENSION WITH CALCIUM CHANNEL BLOCKER AND ANGIOTENSIN-CONVERTING ENZYME INHIBITOR IN PATIENTS WITH IMPAIRED RENAL FUNCTION

    Directory of Open Access Journals (Sweden)

    N. A. Dzhaiani

    2014-01-01

    Full Text Available Up-to-date data on combination therapy of arterial hypertension in patients with chronic kidney disease are presented. Special attention is paid to the fixed combination of calcium antagonist lercanidipine and angiotensin-converting enzyme inhibitor enalapril.

  6. Rational application of antihypertensive calcium channel blockers in renal diseases%钙离子拮抗剂类降压药在肾脏病中的合理应用

    Institute of Scientific and Technical Information of China (English)

    王伟铭; 徐丽梨

    2014-01-01

    中国人群高血压发病率较高,其中继发性高血压第一位的病因就是慢性肾脏病(CKD)。对于CKD高血压患者首选血管紧张素转换酶抑制剂(ACEI)或血管紧张素II 受体拮抗剂(ARB)类药物,而单药治疗往往血压控制不佳,需联合其它降压药物治疗。钙离子拮抗剂(CCB)是一线降压药物,既往考虑其对肾脏副作用而较少应用于CKD患者。随着研究进展及新型制剂的研发, CCB类药物在CKD高血压治疗中亦有一定地位及优势,合理的应用可改善肾脏病预后,给患者带来益处。%The incidence of hypertension is high in the Chinese population.And the first cause of secondary hypertension is chronic kidney disease (CKD).To control the hypertension in CKD patients, angiotensin converting enzyme inhibitor (ACEI)or angiotensin receptor blocker (ARB)is the first choice. However,as single drug use of ACEI or ARB does not have satisfactory effect in controlling the hypertension of CKD patients,combination of other antihypertensive drugs is usually needed.Calcium channel blockers (CCB)are first-line antihypertensive drugs,but were less used in CKD patients previously due to their adverse effects.With the research progress and the development of new preparations,CCB have their certain places and advantages in treatment of hypertension patients with CKD.Rational application of CCB can improve prognosis of the kidney so as to benefit the patients.

  7. 钙通道阻滞剂对神经损伤后瘢痕处血管分布的影响%Effects of calcium channel blockers on the distribution of blood vessels around the scar after nerve injury

    Institute of Scientific and Technical Information of China (English)

    刘冲; 刘晓峰; 陈涛平; 王云飞; 任宝; 郭召; 薛金伟; 刘双立

    2015-01-01

    目的:探讨钙通道阻滞剂对大鼠坐骨神经损伤后瘢痕处血管分布的实验研究。方法选用SD大鼠96只,随机4组,每组24只,制作大鼠坐骨神经损伤模型,实验组及对照组每天分别给予腹腔注射维拉帕米和生理盐水(4 mg/kg),分别于术后第4、8周进行免疫组化染色及血管灌注,观察损伤后瘢痕处血管分布情况。结果术后4、8周实验组瘢痕处血管数量多、密度高,血管分布较均匀,血管走形较规律。对照组血管数量少,密度低,血管分布不均,血管走形紊乱。结论钙通道阻滞剂能够改变损伤处血管分布状况,改善损伤处神经组织的血液供应。%Objective To investigate the correlation between the calcium channel blockers on the distribution of blood vessels scar after sciatic nerve injury in rats.Methods 96 SD rats were divided into 4 group at random, 24 rats in each group. The experimental rats were made sciatic nerve injury model, the experimental group and control group were given respectively a intraperitoneal injection of verapamil and physiological saline(4 mg/kg), in 4, 8 weeks after surgery immunohistochemical staining and vascular perfusion were conducted to observe the scar after injury of vascular distribution.Results In 4, 8 weeks after surgery, the blood vessel numbers were increased and the density of the nerve lesions became higher, the vascular distributions were more uniform in the rats of the experimental group. However, the results of the controls indicated that the blood vessels numbers were decreased, the density of the nerve lesions became lower, the vascular distributions were in the state of disorder.Conclusion Calcium channel blockers can be used to reduce the formation of collagen ifbers to soften the scars, and thus improve the distribution of the lesions of blood vessels and promote the blood supply of nerve tissue damage, and make the damaged nerve bundle membrane and blood

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

    Science.gov (United States)

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

    2003-01-01

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

  9. Comparative effects of sodium channel blockers in short term rat whole embryo culture

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, Mats F, E-mail: Mats.Nilsson@farmbio.uu.se [Department of Pharmaceutical Biosciences, Uppsala University (Sweden); Sköld, Anna-Carin; Ericson, Ann-Christin; Annas, Anita; Villar, Rodrigo Palma [AstraZeneca R and D Södertälje (Sweden); Cebers, Gvido [AstraZeneca R and D, iMed, 141 Portland Street, Cambridge, MA 02139 (United States); Hellmold, Heike; Gustafson, Anne-Lee [AstraZeneca R and D Södertälje (Sweden); Webster, William S [Department of Anatomy and Histology, University of Sydney (Australia)

    2013-10-15

    This study was undertaken to examine the effect on the rat embryonic heart of two experimental drugs (AZA and AZB) which are known to block the sodium channel Nav1.5, the hERG potassium channel and the L-type calcium channel. The sodium channel blockers bupivacaine, lidocaine, and the L-type calcium channel blocker nifedipine were used as reference substances. The experimental model was the gestational day (GD) 13 rat embryo cultured in vitro. In this model the embryonic heart activity can be directly observed, recorded and analyzed using computer assisted image analysis as it responds to the addition of test drugs. The effect on the heart was studied for a range of concentrations and for a duration up to 3 h. The results showed that AZA and AZB caused a concentration-dependent bradycardia of the embryonic heart and at high concentrations heart block. These effects were reversible on washout. In terms of potency to cause bradycardia the compounds were ranked AZB > bupivacaine > AZA > lidocaine > nifedipine. Comparison with results from previous studies with more specific ion channel blockers suggests that the primary effect of AZA and AZB was sodium channel blockage. The study shows that the short-term rat whole embryo culture (WEC) is a suitable system to detect substances hazardous to the embryonic heart. - Highlights: • Study of the effect of sodium channel blocking drugs on embryonic heart function • We used a modified method rat whole embryo culture with image analysis. • The drugs tested caused a concentration dependent bradycardia and heart block. • The effect of drugs acting on multiple ion channels is difficult to predict. • This method may be used to detect cardiotoxicity in prenatal development.

  10. Clinical events in high-risk hypertensive patients randomly assigned to calcium channel blocker versus angiotensin-converting enzyme inhibitor in the antihypertensive and lipid-lowering treatment to prevent heart attack trial.

    Science.gov (United States)

    Leenen, Frans H H; Nwachuku, Chuke E; Black, Henry R; Cushman, William C; Davis, Barry R; Simpson, Lara M; Alderman, Michael H; Atlas, Steven A; Basile, Jan N; Cuyjet, Aloysius B; Dart, Richard; Felicetta, James V; Grimm, Richard H; Haywood, L Julian; Jafri, Syed Z A; Proschan, Michael A; Thadani, Udho; Whelton, Paul K; Wright, Jackson T

    2006-09-01

    The Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) provides a unique opportunity to compare the long-term relative safety and efficacy of angiotensin-converting enzyme inhibitor and calcium channel blocker-initiated therapy in older hypertensive individuals. Patients were randomized to amlodipine (n=9048) or lisinopril (n=9054). The primary outcome was combined fatal coronary heart disease or nonfatal myocardial infarction, analyzed by intention-to-treat. Secondary outcomes included all-cause mortality, stroke, combined cardiovascular disease (CVD), end-stage renal disease (ESRD), cancer, and gastrointestinal bleeding. Mean follow-up was 4.9 years. Blood pressure control was similar in nonblacks, but not in blacks. No significant differences were found between treatment groups for the primary outcome, all-cause mortality, ESRD, or cancer. Stroke rates were higher on lisinopril in blacks (RR=1.51, 95% CI 1.22 to 1.86) but not in nonblacks (RR=1.07, 95% CI 0.89 to 1.28), and in women (RR=1.45, 95% CI 1.17 to 1.79), but not in men (RR=1.10, 95% CI 0.92 to 1.31). Rates of combined CVD were higher (RR=1.06, 95% CI 1.00 to 1.12) because of higher rates for strokes, peripheral arterial disease, and angina, which were partly offset by lower rates for heart failure (RR=0.87, 95% CI 0.78 to 0.96) on lisinopril compared with amlodipine. Gastrointestinal bleeds and angioedema were higher on lisinopril. Patients with and without baseline coronary heart disease showed similar outcome patterns. We conclude that in hypertensive patients, the risks for coronary events are similar, but for stroke, combined CVD, gastrointestinal bleeding, and angioedema are higher and for heart failure are lower for lisinopril-based compared with amlodipine-based therapy. Some, but not all, of these differences may be explained by less effective blood pressure control in the lisinopril arm.

  11. Calcium channel antagonists in hypertension.

    Science.gov (United States)

    Ambrosioni, E; Borghi, C

    1989-02-01

    The clinical usefulness of calcium entry-blockers for the treatment of high blood pressure is related to their capacity to act upon the primary hemodynamic derangement in hypertension: the increased peripheral vascular resistance. They can be used alone or in combination with other antihypertensive agents for the treatment of various forms of hypertensive disease. The calcium entry-blockers appear to be the most useful agents for the treatment of hypertension in the elderly and for the treatment of hypertension associated with ischemic heart disease, pulmonary obstructive disease, peripheral vascular disease, and supraventricular arrhythmias. They are effective in reducing blood pressure in pregnancy-associated hypertension and must be considered as first-line therapy for the treatment of hypertensive crisis.

  12. Potassium Channels Blockers from the Venom of Androctonus mauretanicus mauretanicus

    Directory of Open Access Journals (Sweden)

    Marie-France Martin-Eauclaire

    2012-01-01

    Full Text Available K+ channels selectively transport K+ ions across cell membranes and play a key role in regulating the physiology of excitable and nonexcitable cells. Their activation allows the cell to repolarize after action potential firing and reduces excitability, whereas channel inhibition increases excitability. In eukaryotes, the pharmacology and pore topology of several structural classes of K+ channels have been well characterized in the past two decades. This information has come about through the extensive use of scorpion toxins. We have participated in the isolation and in the characterization of several structurally distinct families of scorpion toxin peptides exhibiting different K+ channel blocking functions. In particular, the venom from the Moroccan scorpion Androctonus mauretanicus mauretanicus provided several high-affinity blockers selective for diverse K+ channels  (SKCa,  Kv4.x, and  Kv1.x K+ channel families. In this paper, we summarize our work on these toxin/channel interactions.

  13. Electrical Heart Defibrillation with Ion Channel Blockers

    Science.gov (United States)

    Feeney, Erin; Clark, Courtney; Puwal, Steffan

    Heart disease is the leading cause of mortality in the United States. Rotary electrical waves within heart muscle underlie electrical disorders of the heart termed fibrillation; their propagation and breakup leads to a complex distribution of electrical activation of the tissue (and of the ensuing mechanical contraction that comes from electrical activation). Successful heart defibrillation has, thus far, been limited to delivering large electrical shocks to activate the entire heart and reset its electrical activity. In theory, defibrillation of a system this nonlinear should be possible with small electrical perturbations (stimulations). A successful algorithm for such a low-energy defibrillator continues to elude researchers. We propose to examine in silica whether low-energy electrical stimulations can be combined with antiarrhythmic, ion channel-blocking drugs to achieve a higher rate of defibrillation and whether the antiarrhythmic drugs should be delivered before or after electrical stimulation has commenced. Progress toward a more successful, low-energy defibrillator will greatly minimize the adverse effects noted in defibrillation and will assist in the development of pediatric defibrillators.

  14. The genetic background affects the vascular response in T-type calcium channels 3.2 deficient mice

    DEFF Research Database (Denmark)

    Svenningsen, Per; Hansen, Pernille B L

    2016-01-01

    Voltage-gated calcium channels (Cav ) are important regulators of vascular tone and are attractive targets for pharmacological treatment of hypertension. The clinical used calcium blockers are often not selective for one channel but affect several types of calcium channels (Hansen 2015). L...

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

    Institute of Scientific and Technical Information of China (English)

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

    2011-01-01

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

  16. Role of L-type calcium-channel modulation in nonconvulsive epilepsy in rats

    NARCIS (Netherlands)

    Luijtelaar, E.L.J.M. van; Ates, N.; Coenen, A.M.L.

    1995-01-01

    Old male Wistar rats spontaneously showing hundreds of spike-wave discharges daily were used to investigate the role of calcium ions in nonconvulsive epilepsy. The effects of the L-type calcium channel blocker nimodipine and the L-type channel opener BAY K 8644 on number and duration of these spike-

  17. Towards evidence-based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 4: Alpha blockers v calcium blockers to increase spontaneous passage of renal calculi.

    Science.gov (United States)

    Stewart, Alexander; Ferguson, Craig

    2013-02-01

    A short cut review was carried out to establish the administration of an alpha-1 receptor antagonist or a calcium channel blocker would facilitate the most rapid and successful expulsion of a stone from a patient with uncomplicated renal colic. 597 articles were found using the reported search, of which five trials were selected as providing the best evidence to answer this question. The authors, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. It is concluded that in a patient with an uncomplicated ureteric calculus tamsulosin is more effective than nifedipine in promoting speedy and successful expulsion of the stone.

  18. Acute effect of calcium blocker on renal hemodynamics in diabetic spontaneously hypertensive rat.

    Science.gov (United States)

    Kaizu, K; Ling, Q Y; Uriu, K; Ikeda, M; Eto, S

    1995-01-01

    This study was done to examine the acute effect of a calcium channel blocker on renal hemodynamics in the diabetic spontaneously hypertensive rat (SHR). Streptozotocin was used to induce diabetes, and barnidipine (B) was used as a calcium blocker. Renal blood flow (RBF) and glomerular filtration rate (GFR) were measured by a clearance method with paraaminohypurate (PAH) and inulin, respectively. Rats were divided into two groups: nondiabetic SHR, N-SHR; diabetic SHR, DM-SHR. B increased RBF in N-SHR (7.44 +/- 1.99 versus 8.50 +/- 1.97 mL/min/g.kw) while there was no change in DM-SHR. B reduced renovascular resistance (RVR) in DM-SHR and N-SHR. B increased GFR in N-SHR (1.15 +/- 0.24 versus 1.34 +/- 0.25 mL/min/g.kw), in spite of no changes in DM-SHR. B did not modify filtration fraction (FF) in both groups. These results indicate (1) in SHR, B exerts beneficial effects on hypertensive renal damage by reducing mean arterial pressure (MAP), RVR, RBF, and GFR; (2) in diabetic SHR, B is less effective in restoring renal hyperfiltration in spite of reducing RVR.

  19. A potent potassium channel blocker from Mesobuthus eupeus scorpion venom.

    Science.gov (United States)

    Gao, Bin; Peigneur, Steve; Tytgat, Jan; Zhu, Shunyi

    2010-12-01

    Scorpion venom-derived peptidyl toxins are valuable pharmacological tools for investigating the structure-function relationship of ion channels. Here, we report the purification, sequencing and functional characterization of a new K(+) channel blocker (MeuKTX) from the venom of the scorpion Mesobuthus eupeus. Effects of MeuKTX on ten cloned potassium channels in Xenopus oocytes were evaluated using two-electrode voltage-clamp recordings. MeuKTX is the orthologue of BmKTX (α-KTx3.6), a known Kv1.3 blocker from the scorpion Mesobuthus martensii, and classified as α-KTx3.13. MeuKTX potently blocks rKv1.1, rKv1.2 and hKv1.3 channels with 50% inhibitory concentration (IC(50)) of 203.15 ± 4.06 pM, 8.92 ± 2.3 nM and 171 ± 8.56 pM, respectively, but does not affect rKv1.4, rKv1.5, hKv3.1, rKv4.3, and hERG channels even at 2 μM concentration. At this high concentration, MeuKTX is also active on rKv1.6 and Shaker IR. Our results also demonstrate that MeuKTX and BmKTX have the same channel spectrum and similar pharmacological potency. Analysis of the structure-function relationships of α-KTx3 subfamily toxins allows us to recognize several key sites which may be useful for designing toxins with improved activity on hKv1.3, an attractive target for T-cell mediated autoimmune diseases.

  20. Pulmonary vasoconstrictor action of KCNQ potassium channel blockers

    Directory of Open Access Journals (Sweden)

    Balan Prabhu

    2006-02-01

    Full Text Available Abstract Background KCNQ channels have been widely studied in the nervous system, heart and inner ear, where they have important physiological functions. Recent reports indicate that KCNQ channels may also be expressed in portal vein where they are suggested to influence spontaneous contractile activity. The biophysical properties of K+ currents mediated by KCNQ channels resemble a current underlying the resting K+ conductance and resting potential of pulmonary artery smooth muscle cells. We therefore investigated a possible role of KCNQ channels in regulating the function of pulmonary arteries by determining the ability of the selective KCNQ channel blockers, linopirdine and XE991, to promote pulmonary vasoconstriction. Methods The tension developed by rat and mouse intrapulmonary or mesenteric arteries was measured using small vessel myography. Contractile responses to linopirdine and XE991 were measured in intact and endothelium denuded vessels. Experiments were also carried out under conditions that prevent the contractile effects of nerve released noradrenaline or ATP, or block various Ca2+ influx pathways, in order to investigate the mechanisms underlying contraction. Results Linopirdine and XE991 both contracted rat and mouse pulmonary arteries but had little effect on mesenteric arteries. In each case the maximum contraction was almost as large as the response to 50 mM K+. Linopirdine had an EC50 of around 1 μM and XE991 was almost 10-fold more potent. Neither removal of the endothelium nor exposure to phentolamine or α,β-methylene ATP, to block α1-adrenoceptors or P2X receptors, respectively, affected the contraction. Contraction was abolished in Ca2+-free solution and in the presence of 1 μM nifedipine or 10 μM levcromakalim. Conclusion The KCNQ channel blockers are potent and powerful constrictors of pulmonary arteries. This action may be selective for the pulmonary circulation as mesenteric arteries showed little response. The

  1. 钙通道阻滞剂在危重烧伤脓毒症防治中的应用%Study of calcium channel blockers on prevention and treatment of patients with severe burn sepsis

    Institute of Scientific and Technical Information of China (English)

    吴祖煌; 宋斌; 陈国养; 王光毅

    2010-01-01

    (t = 2.20,2.17,2.19,2.17,2.61) (P <0.01 or 0.05). Plasma Ca2+ and iCa2+ levels were decreased. However,MAP were increased in the two groups, although no difference was found between the two group(P >0.05). Conclusions Early applying of calcium channel blockers (CCB) can markedly inhibit the degree of inflammatory medium in serum, thereby preventing the development of excessive inflammation response and subsequent multiple organ dysfunction syndrome associated with severely burned sepsis. It can effectively inhibit intracellular Ca2+ overload caused by myocadial infection injury,which may contribute to the effect of acupuncture in reducing myocardial injury and protecting myocardial performance and improving prognosis.%目的 探讨尼莫地平在危重烧伤脓毒症防治中的作用.方法 将28例危重烧伤脓毒症病例随机分为2组:治疗组(n=14)和对照组(n=14).2组除实施相同的脓毒症综合治疗方案外,治疗组应用微量泵持续给予生理盐水+尼莫地平注射液15 μg/(kg·h)进行治疗,对照组给予相同剂量的生理盐水治疗.观察2组血浆肿瘤坏死因子-α(TNF-α)、白细胞介素6(IL-6)、C-反应蛋白(CRP)、前降钙素(PCT)、脑钠肽(BNP)、血钙、离子钙水平变化和血流动力学变化.结果 ①血流动力学指标明显改善(ABF、ACC、LVET、TSVR对照组治疗前后t值分别为3.93、3.37、3.75、7.02,治疗组治疗前后t值分别为6.46、4.98、6.29、4.60,P<0.01或P<0.05),平均动脉压无明显变化(P>0.05).与对照组比较,治疗组主动脉血流量(ABF)、左心室血流最大流速(ACC)、左心室射血分数时间(LVET)、外周血管阻力(TSVR)改善更为明显(t值分别为2.29、2.07、2.23、2.14,P<0.01或P<0.05).②血浆TNF-α、IL-6、CRP浓度明显下降(TNF-α、IL-6、CRP对照组治疗前后t值分别为2.38、2.29、2.45,治疗组治疗前后t值分别为4.04、4.04、2.56,P<0.01或P<0.05).PCT、BNP治疗组更明显(PCT、BNP治疗

  2. Calcium signaling and T-type calcium channels in cancer cell cycling

    Institute of Scientific and Technical Information of China (English)

    James T Taylor; Xiang-Bin Zeng; Jonathan E Pottle; Kevin Lee; Alun R Wang; Stephenie G Yi; Jennifer A S Scruggs; Suresh S Sikka; Ming Li

    2008-01-01

    Regulation of intracellular calcium is an important signaling mechanism for cell proliferation in both normal and cancerous cells. In normal epithelial cells,free calcium concentration is essential for cells to enter and accomplish the S phase and the M phase of the cell cycle. In contrast, cancerous cells can pass these phases of the cell cycle with much lower cytoplasmic free calcium concentrations, indicating an alternative mechanism has developed for fulfilling the intracellular calcium requirement for an increased rate of DNA synthesis and mitosis of fast replicating cancerous cells. The detailed mechanism underlying the altered calcium loading pathway remains unclear;however, there is a growing body of evidence that suggests the T-type Ca2+ channel is abnormally expressed in cancerous cells and that blockade of these channels may reduce cell proliferation in addition to inducing apoptosis. Recent studies also show that the expression of T-type Ca2+ channels in breast cancer cells is proliferation state dependent, i.e. the channels are expressed at higher levels during the fast-replication period, and once the cells are in a non-proliferation state, expression of this channel isminimal. Therefore, selectively blocking calcium entry into cancerous cells may be a valuable approach for preventing tumor growth. Since T-type Ca2+ channels are not expressed in epithelial cells, selective T-type Ca2+ channel blockers may be useful in the treatment of certain types of cancers.

  3. 3种长效钙拮抗剂对血压季节变异的影响%Effect of three long-acting calcium channel blockers on the seasonal variability of blood pressure

    Institute of Scientific and Technical Information of China (English)

    曹平良; 唐琼珍; 陈早芳; 卢寅辉; 刘建萍; 邱元芝; 葛郁芝

    2011-01-01

    of cardiovascular events independent of mean blood pressure, and it has become an attentional focus. The seasonal blood pressure variability is closely related to cardiovascular events, but there are few studies about the effects of an-tihypertensive medications on its variability at home and abroad. Objective To explore the effect of three types of long-acting calcium channel blockers on seasonal variability of blood pressure. Methods One hundred fifty-nine patients with mild-to-moderate essential hypertension were randomly treated with felodipine extended-release tablet 5 mg/d(FEL group, n=53), nifedipine controlled-release tablet 30 mg/d(NIF group, n = 53) or amlodipine besylate tablet 5 mg/d( AML group, rc=53). All subjects were recruited in the same autumn. Office blood pressures was detected two to four times monthly and the daily mean temperature was recorded contemporarily for 12 months. 24 h ambulatory blood-pressure monitoring was also performed in summer and winter. Results The office mean systolic blood pressure (oSBP), 24 hours mean systolic blood pressure (24hSBP), diurnal mean systolic blood pressure (dSBP) and nocturnal mean systolic blood pressure (nSBP) in the three groups were significantly higher in winter than those in summer, and the variations between summer and winter were more obvious in group FEL[(8. 6i 3.7), (9.8 + 3.3), (10.9 + 3.6), (7.5 + 2.7) mm Hg] and group NIF [(7. 5±2. 8), (9.0 + 2.9), (10.2±3. 3), (7. 1±2. 5) mm Hg] than those in group AML [(4. 6 +1. 3), (5.4 + 1.9), (6. 2±2. 4), (4.9 + 1. 7)mm Hg] (all P<0. 05). In winter, the attainment rates of office and diurnal BP were higher in group AML (60.0%, 72. 2% )than those in group FEL (40.0%, 42.2%) and group NIF (38.3%, 44. 1%) (all P < 0. 05 ) , respectively. The standard deviations and variation coefficients of visit-to-visit office systolic and diastolic blood pressure were significantly lower in group AML than those in group FEL and group NIF (all P<0. 05). The office

  4. Store-Operated Calcium Channels.

    Science.gov (United States)

    Prakriya, Murali; Lewis, Richard S

    2015-10-01

    Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.

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

    Science.gov (United States)

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

    2008-02-19

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

  6. Transport of beta-blockers and calcium antagonists by diffusion in cat myocardium

    DEFF Research Database (Denmark)

    Haunsø, Stig; Sejrsen, Per; Svendsen, Jesper Hastrup

    1991-01-01

    Beta-blockers and calcium antagonists have been claimed to possess cardioprotective properties. This study addresses the question of whether a significant amount of these drugs will reach the cardiac myocytes during no-flow ischemia, where solute transport depends solely on diffusion. In anesthet......Beta-blockers and calcium antagonists have been claimed to possess cardioprotective properties. This study addresses the question of whether a significant amount of these drugs will reach the cardiac myocytes during no-flow ischemia, where solute transport depends solely on diffusion...

  7. A multiple ion channel blocker, NIP-142, for the treatment of atrial fibrillation.

    Science.gov (United States)

    Tanaka, Hikaru; Hashimoto, Norio

    2007-01-01

    Atrial fibrillation (AF) is one of the most frequent cardiac arrhythmia and is associated with increased cardiovascular morbidity and mortality, and the risk of stroke. Although currently available antiarrhythmic drugs are moderately effective in restoring normal sinus rhythm in patients with AF, excessive delay of ventricular repolarization by these agents may be associated with increased risk of proarrhythmia. Therefore, selective blockers of cardiac ion channel(s) that are exclusively present in the atria are highly desirable. NIP-142 is a novel benzopyrane derivative, which blocks potassium, calcium, and sodium channels and shows atrial specific action potential duration prolongation. NIP-142 preferentially blocks the ultrarapid delayed rectifier potassium current (I Kur) and the acetylcholine-activated potassium current (I KACh). Since I Kur and I KACh have been shown to be expressed more abundantly in the atrial than in the ventricular myocardium, the atrial-specific repolarization prolonging effect of NIP-142 is considered to be due to the blockade of these potassium currents. In canine models, NIP-142 was shown to terminate the microreentry type AF induced by vagal nerve stimulation and the macroreentry type atrial flutter induced by an intercaval crush. These effects of NIP-142 have been attributed to the prolongation of atrial effective refractory period (ERP), because this compound prolonged atrial ERP without affecting intraatrial and interatrial conduction times in these models. The ERP prolongation by NIP-142 was greater in the atrium than in the ventricle. NIP-142 also terminated the focal activity type AF induced by aconitine. In addition, NIP-142 reversed the atrial ERP shortening and the loss of rate adaptation induced by short-term rapid atrial pacing in anesthetized dogs. Thus, although clinical trials are required to provide evidence for its efficacy and safety, the novel multiple ion channel blocker, NIP-142, appears to be a useful agent for

  8. Modeling of the Binding of Peptide Blockers to Voltage-Gated Potassium Channels: Approaches and Evidence.

    Science.gov (United States)

    Novoseletsky, V N; Volyntseva, A D; Shaitan, K V; Kirpichnikov, M P; Feofanov, A V

    2016-01-01

    Modeling of the structure of voltage-gated potassium (KV) channels bound to peptide blockers aims to identify the key amino acid residues dictating affinity and provide insights into the toxin-channel interface. Computational approaches open up possibilities for in silico rational design of selective blockers, new molecular tools to study the cellular distribution and functional roles of potassium channels. It is anticipated that optimized blockers will advance the development of drugs that reduce over activation of potassium channels and attenuate the associated malfunction. Starting with an overview of the recent advances in computational simulation strategies to predict the bound state orientations of peptide pore blockers relative to KV-channels, we go on to review algorithms for the analysis of intermolecular interactions, and then take a look at the results of their application.

  9. 维拉帕米联合5-氟脲嘧啶腹腔内化疗对荷肝癌大鼠的抗肿瘤作用%Antineoplastic Effect of Calcium Channel Blocker-Verapamil and 5-Fluorouracil Intraperitoneal Chemotherapy on Hepatocarcinoma-Bearing Rats

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Department of General Surgery, Huadu District People's Hospital, Guangzhou 510800, ChinaObjective To study the antineoplastic effect of the calcium channel blocker verapamil and 5-fluorouracil intraperitoneal chemotherapy on hepatocarcinoma-bearing rats, and examine the action between calcium channel blockers and cytotoxic drugs.Methods We adopted the method of subcapsular implantation of carcinoma tissues of walker-256 in the left liver lobe as a model of liver carcinoma-bearing rats. All experimental animals were divided into four groups. On the sixth day post implantation, in group A (control group) 6 ml of saline was injected intraperitoneally once a day for 3 days. In group B (single chemotherapy group) 6 ml of 5-Fu 75 mg/kg was injected intraperitoneally once a day for 3 days. In group C (combination of treatment group) both 5-Fu (75 mg/kg) and verapamil (25 mg/kg) were administered simultaneously as in A and B. In group D (simple verapamil group) only 6 ml of verapamil (25 mg/kg) was administered as above.Results Compared with groups A, B and D, The volume of cancer and the contents of liver cancer DNA and protein were significantly reduced. The rates of inhibiting cancer (89.9% in group C and 35.4% in group B) were significantly increased in group C. Group C had significantly long survival time compared to groups A, B and D (P<0.05). By light microscopy, a number of focal necroses were found in cancer tissue in group C.Conclusion Calcium channel blockers can enhance the antineoplastic effect of 5-Fu intraperitoneal chemotherapy to liver cancer ; The use of verapamil can not increase the toxicity of 5-Fu.%目的 探讨钙拮抗剂与腹腔内化疗联合应用对荷肝癌大鼠的作用及 钙拮抗剂与细胞毒药物的相互作用。方法 采用肝被膜下植入法建立肝癌动物模型,将荷瘤大鼠分成四 组:A组(对照组),腹腔内注射6ml生理盐水,每天1次,连续3天;B组(单纯化疗组),腹腔内注射5Fu

  10. Calcium signalling and calcium channels: evolution and general principles.

    Science.gov (United States)

    Verkhratsky, Alexei; Parpura, Vladimir

    2014-09-15

    Calcium as a divalent cation was selected early in evolution as a signaling molecule to be used by both prokaryotes and eukaryotes. Its low cytosolic concentration likely reflects the initial concentration of this ion in the primordial soup/ocean as unicellular organisms were formed. As the concentration of calcium in the ocean subsequently increased, so did the diversity of homeostatic molecules handling calcium. This includes the plasma membrane channels that allowed the calcium entry, as well as extrusion mechanisms, i.e., exchangers and pumps. Further diversification occurred with the evolution of intracellular organelles, in particular the endoplasmic reticulum and mitochondria, which also contain channels, exchanger(s) and pumps to handle the homeostasis of calcium ions. Calcium signalling system, based around coordinated interactions of the above molecular entities, can be activated by the opening of voltage-gated channels, neurotransmitters, second messengers and/or mechanical stimulation, and as such is all-pervading pathway in physiology and pathophysiology of organisms.

  11. Disease causing mutations of calcium channels.

    Science.gov (United States)

    Lorenzon, Nancy M; Beam, Kurt G

    2008-01-01

    Calcium ions play an important role in the electrical excitability of nerve and muscle, as well as serving as a critical second messenger for diverse cellular functions. As a result, mutations of genes encoding calcium channels may have subtle affects on channel function yet strongly perturb cellular behavior. This review discusses the effects of calcium channel mutations on channel function, the pathological consequences for cellular physiology, and possible links between altered channel function and disease. Many cellular functions are directly or indirectly regulated by the free cytosolic calcium concentration. Thus, calcium levels must be very tightly regulated in time and space. Intracellular calcium ions are essential second messengers and play a role in many functions including, action potential generation, neurotransmitter and hormone release, muscle contraction, neurite outgrowth, synaptogenesis, calcium-dependent gene expression, synaptic plasticity and cell death. Calcium ions that control cell activity can be supplied to the cell cytosol from two major sources: the extracellular space or intracellular stores. Voltage-gated and ligand-gated channels are the primary way in which Ca(2+) ions enter from the extracellular space. The sarcoplasm reticulum (SR) in muscle and the endoplasmic reticulum in non-muscle cells are the main intracellular Ca(2+) stores: the ryanodine receptor (RyR) and inositol-triphosphate receptor channels are the major contributors of calcium release from internal stores.

  12. Functional Importance of L- and P/Q-Type Voltage-Gated Calcium Channels in Human Renal Vasculature

    DEFF Research Database (Denmark)

    Hansen, Pernille B; Poulsen, Christian B; Walter, Steen

    2011-01-01

    in kidney function. It was hypothesized that human renal vascular excitation-contraction coupling involves different subtypes of channels. In human renal artery and dissected intrarenal blood vessels from nephrectomies, PCR analysis showed expression of L-type (Ca(v) 1.2), P/Q-type (Ca(v) 2.1), and T-type......, and L- and P/Q-type channels are of functional importance for the depolarization-induced vasoconstriction. The contribution of P/Q-type channels to contraction in the human vasculature is a novel mechanism for the regulation of renal blood flow and suggests that clinical treatment with calcium blockers......Calcium channel blockers are widely used for treatment of hypertension, because they decrease peripheral vascular resistance through inhibition of voltage-gated calcium channels. Animal studies of renal vasculature have shown expression of several types of calcium channels that are involved...

  13. Calcium channel as a potential anticancer agent.

    Science.gov (United States)

    Kriazhev, L

    2009-11-01

    Anticancer treatment in modern clinical practices includes chemotherapy and radiation therapy with or without surgical interventions. Efficiency of both methods varies greatly depending on cancer types and stages. Besides, chemo- and radiotherapy are toxic and damaging that causes serious side effects. This fact prompts the search for alternative methods of antitumor therapy. It is well known that prolonged or high increase of intracellular calcium concentration inevitably leads to the cell death via apoptosis or necrosis. However, stimulation of cell calcium level by chemical agents is hardly achievable because cells have very sophisticated machinery for maintaining intracellular calcium in physiological ranges. This obstacle can be overridden, nevertheless. It was found that calcium channels in so called calcium cells in land snails are directly regulated by extracellular calcium concentration. The higher the concentration the higher the calcium intake is through the channels. Bearing in mind that extracellular/intracellular calcium concentration ratio in human beings is 10,000-12,000 fold the insertion of the channel into cancer cells would lead to fast and uncontrollable by the cells calcium intake and cell death. Proteins composing the channel may be extracted from plasma membrane of calcium cells and sequenced by mass-spectrometry or N-terminal sequencing. Either proteins or corresponding genes could be used for targeted delivery into cancer cells.

  14. Anion-Channel Blockers Inhibit S-Type Anion Channels and Abscisic Acid Responses in Guard Cells.

    Science.gov (United States)

    Schwartz, A.; Ilan, N.; Schwarz, M.; Scheaffer, J.; Assmann, S. M.; Schroeder, J. I.

    1995-10-01

    The effects of anion-channel blockers on light-mediated stomatal opening, on the potassium dependence of stomatal opening, on stomatal responses to abscisic acid (ABA), and on current through slow anion channels in the plasma membrane of guard cells were investigated. The anion-channel blockers anthracene-9-carboxylic acid (9-AC) and niflumic acid blocked current through slow anion channels of Vicia faba L. guard cells. Both 9-AC and niflumic acid reversed ABA inhibition of stomatal opening in V. faba L. and Commelina communis L. The anion-channel blocker probenecid also abolished ABA inhibition of stomatal opening in both species. Additional tests of 9-AC effects on stomatal aperture in Commelina revealed that application of this anion-channel blocker allowed wide stomatal opening under low (1 mM) KCI conditions and increased the rate of stomatal opening under both low and high (100 mM) KCI conditions. These results indicate that anion channels can function as a negative regulator of stomatal opening, presumably by allowing anion efflux and depolarization, which prohibits ion up-take in guard cells. Furthermore, 9-AC prevented ABA induction of stomatal closure. A model in which ABA activation of anion channels contributes a rate-limiting mechanism during ABA-induced stomatal closure and inhibition of stomatal opening is discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-02-28

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

  16. Voltage-Gated Calcium Channels in Nociception

    Science.gov (United States)

    Yasuda, Takahiro; Adams, David J.

    Voltage-gated calcium channels (VGCCs) are a large and functionally diverse group of membrane ion channels ubiquitously expressed throughout the central and peripheral nervous systems. VGCCs contribute to various physiological processes and transduce electrical activity into other cellular functions. This chapter provides an overview of biophysical properties of VGCCs, including regulation by auxiliary subunits, and their physiological role in neuronal functions. Subsequently, then we focus on N-type calcium (Cav2.2) channels, in particular their diversity and specific antagonists. We also discuss the role of N-type calcium channels in nociception and pain transmission through primary sensory dorsal root ganglion neurons (nociceptors). It has been shown that these channels are expressed predominantly in nerve terminals of the nociceptors and that they control neurotransmitter release. To date, important roles of N-type calcium channels in pain sensation have been elucidated genetically and pharmacologically, indicating that specific N-type calcium channel antagonists or modulators are particularly useful as therapeutic drugs targeting chronic and neuropathic pain.

  17. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  18. David J. Triggle: Medicinal chemistry, to pharmacology, calcium channels, and beyond.

    Science.gov (United States)

    Walker, Michael J A

    2015-11-15

    David Triggle's scientific career began as a chemist, went through medicinal chemistry into pharmacology, and finally on to somewhat more philosophical interests in later years. It was a career marked by many contributions to all of those aspects of science. Chief amongst his many contributions, in addition to those in medicinal chemistry, was his work on the drugs known as calcium ion channel blockers or (calcium antagonists). In the calcium ion channel field he was a particularly instrumental figure in sorting out the mechanisms, actions and roles of the class of calcium channel blockers, known chemical and pharmacologically as the dihydropyridines (DHPs) in particular, as well as other calcium blockers of diverse structures. During the course of a long career, and extensive journeys into medicinal chemistry and pharmacology, he published voluminously in terms of papers, reviews, conference proceedings and books. Notably, many of his papers often had limited authorship where, as senior author it reflected his deep involvement in all aspects of the reported work. His work always helped clarify the field while his incisive reviews, together with his role in coordinating and running scientific meetings, were a great help in clarifying and organizing various fields of study. He has had a long and illustrious career, and is wellknown in the world of biomedical science; his contributions are appreciated, and well recognized everywhere. The following article attempts to chart a path through his work and contributions to medicinal chemistry, pharmacology, science, academia and students.

  19. Chronic use of the calcium channel blocker nifedipine effected on bone metabolism in elder with coronary heart disease%老年冠心病患者长期应用硝苯地平对骨代谢及功能的影响

    Institute of Scientific and Technical Information of China (English)

    陈斌

    2013-01-01

    目的:硝苯地平(NIF)临床广泛用于调节心率,本文主要研究年冠心病患者长期应用NIF对骨代谢及功能的影响。探讨NIF应用1年后对碱性磷酸酶(ALP)活性、骨钙蛋白(OCN)和钙离子水平的影响,为治疗骨代谢性疾病提供理论性的依据。方法:本研究筛选160名老年冠心病患者,均参加NIF治疗临床跟踪随访1年,观测并评价NIF的疗效及对骨代谢及功能。结果:本研究所有病例用药前与用药后,男性和女性体内的钙离子水平均显著升高(P0.05)。结论:对于长期使用NIF的老年患者,应当及时监测骨骼代谢水平以及骨骼发育状况评价指标,提前预防骨质疏松。%Calcium channel blockers have been reported to have such diverse effects as reduction in protein synthesis, diminished incorporation of proline into new col agen, and decreased hormone release in vitro. The study screened 160 elderly patients with coronary heart disease, are members of nifedipine treatment of clinical fol ow-up 1 year, observation and evaluation of nifedipine and its effect on bone metabolism and function. Results: In this study, al cases before treatment and after treatment, the average male and female body calcium ion water was significantly higher (P 0.05). Conclusion: In patients with long-term use of nifedipine should be timely monitoring of bone metabolism and bone development status evaluation, prevention of osteoporosis in advance. In summary, chronic nifedipine use in males is associated with adverse effect on bone metabolism in elder with coronary heart disease.

  20. Magnesium: Effect on ocular health as a calcium channel antagonist

    Directory of Open Access Journals (Sweden)

    Şafak Korkmaz

    2013-06-01

    Full Text Available Magnesium is the physiologic calcium channel blocker,involving in many different metabolic processes by maintainingcell membrane function, modulating smooth musclecontraction and influencing enzymatic activities. Magnesiumhas been shown to increase blood flow to tissuesby modifying endothelial function via endothelin-1 (ET-1and nitric Oxide (NO pathways. Magnesium also exhibitsneuroprotective role by blocking N-methyl-D-aspartate(NMDA receptor related calcium influx and by inhibitingthe release of glutamate, hence protects the cell againstoxidative stress and apoptosis. Both increase in bloodflow and its neuroprotective effect make magnesium agood candidate for glaucoma studies. Magnesium hasbeen shown to decrease oxidative stress and apoptosisin retinal tissue and to have retinal ganglion cell sparingeffect. A series of studies has been conducted aboutmagnesium could decrease insulin resistance in diabeticpatients, ease glycemia control and prevent diabetic retinopathy.Magnesium is found to be critically important inmaintaining normal ionic homeostasis of lens. Magnesiumdeficiency has been shown to cause increased lenticularoxidative stress and ionic imbalance in the lens so triggercataractogenesis. J Clin Exp Invest 2013; 4 (2: 244-251Key words: Magnesium, calcium channel blockage,glaucoma, neuroprotection, diabetic retinopathy, cataract

  1. Docking Studies of Phthalimide Pharmacophore as a Sodium Channel Blocker

    Directory of Open Access Journals (Sweden)

    Maryam Iman

    2013-09-01

    Full Text Available   Objective(s: Recently, phthalimide derivatives were designed based on ameltolide and thalidomide as they possess a similar degree of anticonvulsant potency due to their phenytoin-like profile. The ability of phthalimide pharmacophore to interact with neuronal voltage-dependent sodium channels was studied in the batrachotoxin affinity assay. Therefore, in the present study, a series of 19 compounds of phthalimide pharmacophore possessing a variety of substituents (NO2, NH2 , Me, Cl, COOH, MeO at 2-, 3-, and 4- position of the N-phenyl ring and N-(3-amino-2-methylphenyl succinimide, were subjected to docking studies in order to inhibit voltage-gated sodium channels.   Materials and Methods : Chemical structures of all compounds were designed using HYPERCHEM program and Conformational studies were performed through semi-empirical molecular orbital calculations method followed by PM3 force field. Total energy gradient calculated as a root mean square (RMS value, until the RMS gradient was 0.01 kcal mol-1. Among all energy minima conformers, the global minimum of compounds was used in docking calculations. Using a model of the open pore of Na channels, docking study was performed by AUTODOCK4.2 program. Results : Docking studies have revealed that these types of ligands interacted mainly with II-S6 residues of NaV1.2 through making hydrogen bonds and have additional hydrophobic interactions with domain I, II, III and IV in the channel's inner pore. Conclusion   : These computational studies have displayed that these compounds are capable of inhibiting Na channel, efficiently.

  2. Differential effects of K(+) channel blockers on frequency-dependent action potential broadening in supraoptic neurons.

    Science.gov (United States)

    Hlubek, M D; Cobbett, P

    2000-09-15

    Recordings were made from magnocellular neuroendocrine cells dissociated from the supraoptic nucleus of the adult guinea pig to determine the role of voltage gated K(+) channels in controlling the duration of action potentials and in mediating frequency-dependent action potential broadening exhibited by these neurons. The K(+) channel blockers charybdotoxin (ChTx), tetraethylammonium (TEA), and 4-aminopyridine (4-AP) increased the duration of individual action potentials indicating that multiple types of K(+) channel are important in controlling action potential duration. The effect of these K(+) channel blockers was almost completely reversed by simultaneous blockade of voltage gated Ca(2+) channels with Cd(2+). Frequency-dependent action potential broadening was exhibited by these neurons during trains of action potentials elicited by membrane depolarizing current pulses presented at 10 Hz but not at 1 Hz. 4-AP but not ChTx or TEA inhibited frequency-dependent action potential broadening indicating that frequency-dependent action potential broadening is dependent on increasing steady-state inactivation of A-type K(+) channels (which are blocked by 4-AP). A model of differential contributions of voltage gated K(+) channels and voltage gated Ca(2+) channels to frequency-dependent action potential broadening, in which an increase of Ca(2+) current during each successive action potential is permitted as a result of the increasing steady-state inactivation of A-type K(+) channels, is presented.

  3. Effect of propionyl-L-carnitine on L-type calcium channels in human heart sarcolemma

    Energy Technology Data Exchange (ETDEWEB)

    Bevilacqua, M.; Vago, T.; Norbiato, G. (Servizio di Endocrinologia, Milano, (Italy))

    1991-02-01

    Propionyl-L-carnitine (PC) protects perfused rat hearts against damage by ischemia-reperfusion. Activation of L-type calcium channel play a role on ischemia-reperfusion damage. Therefore, we studied the effect of PC on some properties of L-type calcium channels in an in vitro preparation from human myocardium sarcolemma (from patients with idiopathic dilated cardiomyopathy). Binding of the L-type calcium channel blockers isradipine ({sup 3}H)-PN 200-110 (PN) to plasma membrane preparations revealed a single population of binding sites (total number: Bmax = 213 +/- 34 fM/mg protein and affinity: Kd = 152 +/- 19 nM; n = 6). The characteristics of these binding sites were evaluated in the presence and in the absence of Ca{sup 2}{sup +} and of calcium blockers (D-888, a verapamillike drug, and diltiazem). Incubation in a Ca{sup 2}{sup +}-containing buffer increased the affinity of PN binding sites. Binding sites for PN were modulated by organic calcium channel blockers; in competition isotherms at 37{degree}C, D-888 (desmethoxyverapamil) decreased the PN binding, whereas diltiazem increased it. These results strongly suggest that the site labelled by PN is the voltage-operated calcium channel of the human myocardium. The addition of PC (1 mM) to plasma membranes labelled with PN at 37{degree}C decreased the affinity of the binding; this effect was counteracted by the addition of Ca{sup 2}{sup +} to the medium. This result was consistent with a competition between Ca{sup 2}{sup +} and PC. The effect of PC incubation at 4{degree}C was the opposite; at this temperature PC increased the affinity of the binding sites and the effect was obscured by Ca{sup 2}{sup +}.

  4. The role of L-type calcium channels in the development and expression of behavioral sensitization to ethanol.

    Science.gov (United States)

    Broadbent, Julie

    2013-10-11

    Behavioral sensitization is thought to play a significant role in drug addiction. L-type calcium channels have been implicated in sensitization to stimulant and opiate drugs but it is unclear if these channels also contribute to sensitization to ethanol. The effects of three L-type calcium channel blockers, nifedipine (1-7.5 mg/kg), diltiazem (12.5-50 mg/kg), and verapamil (12.5 and 25 mg/kg), on sensitization to ethanol (2 g/kg) were examined in DBA/2J mice. All three blockers reduced but did not prevent expression of sensitization. Only nifedipine blocked acquisition of sensitization. Nifedipine and verapamil decreased blood ethanol levels. The current findings suggest L-type calcium channels do not play a substantial role in sensitization to ethanol and that the neural mechanisms underlying sensitization to ethanol are distinct from those mediating sensitization to stimulants and opiates.

  5. Cystic fibrosis transmembrane conductance regulator chloride channel blockers: Pharmacological, biophysical and physiological relevance

    Institute of Scientific and Technical Information of China (English)

    Paul; Linsdell

    2014-01-01

    Dysfunction of the cystic fibrosis transmembrane con-ductance regulator(CFTR) chloride channel causes cys-tic fibrosis, while inappropriate activity of this channeloccurs in secretory diarrhea and polycystic kidney dis-ease. Drugs that interact directly with CFTR are there-fore of interest in the treatment of a number of diseasestates. This review focuses on one class of small mol-ecules that interacts directly with CFTR, namely inhibi-tors that act by directly blocking chloride movementthrough the open channel pore. In theory such com-pounds could be of use in the treatment of diarrheaand polycystic kidney disease, however in practice allknown substances acting by this mechanism to inhibitCFTR function lack either the potency or specificity forin vivo use. Nevertheless, this theoretical pharmaco-logical usefulness set the scene for the developmentof more potent, specific CFTR inhibitors. Biophysically,open channel blockers have proven most useful as ex-perimental probes of the structure and function of theCFTR chloride channel pore. Most importantly, the useof these blockers has been fundamental in developing afunctional model of the pore that includes a wide innervestibule that uses positively charged amino acid sidechains to attract both permeant and blocking anionsfrom the cell cytoplasm. CFTR channels are also subjectto this kind of blocking action by endogenous anionspresent in the cell cytoplasm, and recently this blocking effect has been suggested to play a role in the physio-logical control of CFTR channel function, in particular as a novel mechanism linking CFTR function dynamically to the composition of epithelial cell secretions. It has also been suggested that future drugs could target this same pathway as a way of pharmacologically increasing CFTR activity in cystic fibrosis. Studying open channel blockers and their mechanisms of action has resulted in significant advances in our understanding of CFTR as a pharmacological target in disease states, of

  6. Tryptophan hydroxylase is modulated by L-type calcium channels in the rat pineal gland.

    Science.gov (United States)

    Barbosa, Roseli; Scialfa, Julieta Helena; Terra, Ilza Mingarini; Cipolla-Neto, José; Simonneaux, Valérie; Afeche, Solange Castro

    2008-02-27

    Calcium is an important second messenger in the rat pineal gland, as well as cAMP. They both contribute to melatonin synthesis mediated by the three main enzymes of the melatonin synthesis pathway: tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase. The cytosolic calcium is elevated in pinealocytes following alpha(1)-adrenergic stimulation, through IP(3)-and membrane calcium channels activation. Nifedipine, an L-type calcium channel blocker, reduces melatonin synthesis in rat pineal glands in vitro. With the purpose of investigating the mechanisms involved in melatonin synthesis regulation by the L-type calcium channel, we studied the effects of nifedipine on noradrenergic stimulated cultured rat pineal glands. Tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase activities were quantified by radiometric assays and 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin contents were quantified by HPLC with electrochemical detection. The data showed that calcium influx blockaded by nifedipine caused a decrease in tryptophan hydroxylase activity, but did not change either arylalkylamine N-acetyltransferase or hydroxyindole-O-methyltransferase activities. Moreover, there was a reduction of 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin intracellular content, as well as a reduction of serotonin and melatonin secretion. Thus, it seems that the calcium influx through L-type high voltage-activated calcium channels is essential for the full activation of tryptophan hydroxylase leading to melatonin synthesis in the pineal gland.

  7. In Silico Predictions of hERG Channel Blockers in Drug Discovery

    DEFF Research Database (Denmark)

    Taboureau, Olivier; Sørensen, Flemming Steen

    2011-01-01

    drugs with different therapeutic indications and recognized as hERG blockers were recently withdrawn due to the risk of QT prolongation, arrhythmia and Torsade de Pointes.In silico techniques can provide a priori knowledge of hERG blockers, thus reducing the costs associated with screening assays......The risk for cardiotoxic side effects represents a major problem in clinical studies of drug candidates and regulatory agencies have explicitly recommended that all new drug candidates should be tested for blockage of the human Ether-a-go-go Related-Gene (hERG) potassium channel. Indeed, several....... Significant progress has been made in structure-based and ligand-based drug design and a number of models have been developed to predict hERG blockage.Although approaches such as homology modeling in combination with docking and molecular dynamics bring us closer to understand the drug-channel interactions...

  8. In silico predictions of hERG channel blockers in drug discovery

    DEFF Research Database (Denmark)

    Taboureau, Olivier; Jørgensen, Flemming Steen

    2011-01-01

    drugs with different therapeutic indications and recognized as hERG blockers were recently withdrawn due to the risk of QT prolongation, arrhythmia and Torsade de Pointes. In silico techniques can provide a priori knowledge of hERG blockers, thus reducing the costs associated with screening assays......The risk for cardiotoxic side effects represents a major problem in clinical studies of drug candidates and regulatory agencies have explicitly recommended that all new drug candidates should be tested for blockage of the human Ether-a-go-go Related-Gene (hERG) potassium channel. Indeed, several....... Significant progress has been made in structure-based and ligand-based drug design and a number of models have been developed to predict hERG blockage. Although approaches such as homology modeling in combination with docking and molecular dynamics bring us closer to understand the drug-channel interactions...

  9. I(Kur)/Kv1.5 channel blockers for the treatment of atrial fibrillation.

    Science.gov (United States)

    Tamargo, Juan; Caballero, Ricardo; Gómez, Ricardo; Delpón, Eva

    2009-04-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia. Anti-arrhythmic drugs remain the mainstay of therapy, but the available class I and III anti-arrhythmic drugs are only moderately effective in long-term restoring/maintaining sinus rhythm (SR) and can produce potentially fatal ventricular pro-arrhythmia. In an attempt to identify safer and more effective anti-arrhythmic drugs, drug discovery efforts have focused on 'atrial selective drugs' that target cardiac ion channel(s) that are exclusively or predominantly expressed in the atria. The ultra-rapid activating delayed rectifier K(+) current (I(Kur)), carried by Kv1.5 channels, is a major repolarizing current in human atria, but seems to play no role in the ventricle. This finding offers the possibility of developing selective I(Kur) blockers to restore and maintain SR without a risk of ventricular pro-arrhythmia. Several I(Kur) blockers are now being developed but clinical data are still limited, so the precise role of these agents in the treatment of AF remains to be defined. In this review we analyze the possible advantages and disadvantages of the developmental I(Kur) blockers as they represent the first step for the development of potential atrial selective drugs for a more effective and safer treatment and prevention of AF.

  10. Role of low voltage activated calcium channels in neuritogenesis and active migration of embryonic neural progenitor cells.

    Science.gov (United States)

    Louhivuori, Lauri M; Louhivuori, Verna; Wigren, Henna-Kaisa; Hakala, Elina; Jansson, Linda C; Nordström, Tommy; Castrén, Maija L; Akerman, Karl E

    2013-04-15

    The central role of calcium influx and electrical activity in embryonic development raises important questions about the role and regulation of voltage-dependent calcium influx. Using cultured neural progenitor cell (NPC) preparations, we recorded barium currents through voltage-activated channels using the whole-cell configuration of the patch-clamp technique and monitored intracellular free calcium concentrations with Fura-2 digital imaging. We found that NPCs as well as expressing high-voltage-activated (HVA) calcium channels express functional low-threshold voltage-dependent calcium channels in the very early stages of differentiation (5 h to 1 day). The size of the currents recorded at -50 versus -20 mV after 1 day in differentiation was dependent on the nature of the charge carrier. Peak currents measured at -20 mV in the presence 10 mM Ca2+ instead of 10 mM Ba2+ had a tendency to be smaller, whereas the nature of the divalent species did not influence the amplitude measured at -50 mV. The T-type channel blockers mibefradil and NNC 55-0396 significantly reduced the calcium responses elicited by depolarizing with extracellular potassium, while the overall effect of the HVA calcium channel blockers was small at differentiation day 1. At differentiation day 20, the calcium responses were effectively blocked by nifedipine. Time-lapse imaging of differentiating neurospheres cultured in the presence of low-voltage-activated (LVA) blockers showed a significant decrease in the number of active migrating neuron-like cells and neurite extensions. Together, these data provide evidence that LVA calcium channels are involved in the physiology of differentiating and migrating NPCs.

  11. Iron overload and apoptosis of HL-1 cardiomyocytes: effects of calcium channel blockade.

    Directory of Open Access Journals (Sweden)

    Mei-pian Chen

    Full Text Available Iron overload cardiomyopathy that prevails in some forms of hemosiderosis is caused by excessive deposition of iron into the heart tissue and ensuing damage caused by a raise in labile cell iron. The underlying mechanisms of iron uptake into cardiomyocytes in iron overload condition are still under investigation. Both L-type calcium channels (LTCC and T-type calcium channels (TTCC have been proposed to be the main portals of non-transferrinic iron into heart cells, but controversies remain. Here, we investigated the roles of LTCC and TTCC as mediators of cardiac iron overload and cellular damage by using specific Calcium channel blockers as potential suppressors of labile Fe(II and Fe(III ingress in cultured cardiomyocytes and ensuing apoptosis.Fe(II and Fe(III uptake was assessed by exposing HL-1 cardiomyocytes to iron sources and quantitative real-time fluorescence imaging of cytosolic labile iron with the fluorescent iron sensor calcein while iron-induced apoptosis was quantitatively measured by flow cytometry analysis with Annexin V. The role of calcium channels as routes of iron uptake was assessed by cell pretreatment with specific blockers of LTCC and TTCC.Iron entered HL-1 cardiomyocytes in a time- and dose-dependent manner and induced cardiac apoptosis via mitochondria-mediated caspase-3 dependent pathways. Blockade of LTCC but not of TTCC demonstrably inhibited the uptake of ferric but not of ferrous iron. However, neither channel blocker conferred cardiomyocytes with protection from iron-induced apoptosis.Our study implicates LTCC as major mediators of Fe(III uptake into cardiomyocytes exposed to ferric salts but not necessarily as contributors to ensuing apoptosis. Thus, to the extent that apoptosis can be considered a biological indicator of damage, the etiopathology of cardiosiderotic damage that accompanies some forms of hemosiderosis would seem to be unrelated to LTCC or TTCC, but rather to other routes of iron ingress present in

  12. Synthesis, QSAR and calcium channel modulator activity of new hexahydroquinoline derivatives containing nitroimidazole.

    Science.gov (United States)

    Miri, Ramin; Javidnia, Katayoun; Mirkhani, Hossein; Hemmateenejad, Bahram; Sepeher, Zahra; Zalpour, Masomeh; Behzad, Taherh; Khoshneviszadeh, Mehdi; Edraki, Najmeh; Mehdipour, Ahmad R

    2007-10-01

    The discovery that 1,4-dihydropyridine class of calcium channel antagonists inhibit Ca2+ influx represented a major therapeutic advance in the treatment of cardiovascular disease. In contrast to the effects of known calcium channel blockers of the Nifedipine-type, the so-called calcium channel agonists, such as Bay K8644 and CGP 28392, increase calcium influx by binding at the same receptor regions. Our goal was to discover a dual cardioselective Ca2+-channel agonist/vascular selective smooth muscle Ca2+ channel antagonist third-generation 1,4-dihydropyridine drug which would have a suitable therapeutic profile for treating congestive heart failure (CHF) patients. A series of unsymmetrical alkyl, cycloalkyl and aryl ester analogues of 2-methyl-4-(1-methyl)-5-nitro-2-imidazolyl-5-oxo-1,4,5,6,7, 8-hexahydroquinolin-3-arboxylate were synthesized using modified Hantzsch reaction. All compounds show calcium antagonist activity on guinea-pig ileum longitudinal smooth muscle and some of them show agonist effect activity on guinea-pig auricle. Effect of structural parameters on the Ca2+ channel agonist/antagonist was evaluated by quantitative structure-activity relationship analysis. These compounds could be considered as a synthon for developing a suitable drug for treating CHF patients.

  13. Acrolein-mediated conduction loss is partially restored by K⁺ channel blockers.

    Science.gov (United States)

    Yan, Rui; Page, Jessica C; Shi, Riyi

    2016-02-01

    Acrolein-mediated myelin damage is thought to be a critical mechanism leading to conduction failure following neurotrauma and neurodegenerative diseases. The exposure and activation of juxtaparanodal voltage-gated K(+) channels due to myelin damage leads to conduction block, and K(+) channel blockers have long been studied as a means for restoring axonal conduction in spinal cord injury (SCI) and multiple sclerosis (MS). In this study, we have found that 100 μM K(+) channel blockers 4-aminopyridine-3-methanol (4-AP-3-MeOH), and to a lesser degree 4-aminopyridine (4-AP), can significantly restore compound action potential (CAP) conduction in spinal cord tissue following acrolein-mediated myelin damage using a well-established ex vivo SCI model. In addition, 4-AP-3-MeOH can effectively restore CAP conduction in acrolein-damaged axons with a range of concentrations from 0.1 to 100 μM. We have also shown that while both compounds at 100 μM showed no preference of small- and large-caliber axons when restoring CAP conduction, 4-AP-3-MeOH, unlike 4-AP, is able to augment CAP amplitude while causing little change in axonal responsiveness measured in refractory periods and response to repetitive stimuli. In a prior study, we show that 4-AP-3-MeOH was able to functionally rescue mechanically injured axons. In this investigation, we conclude that 4-AP-3-MeOH is an effective K(+) channel blocker in restoring axonal conduction following both primary (physical) and secondary (chemical) insults. These findings also suggest that 4-AP-3-MeOH is a viable alternative of 4-AP for treating myelin damage and improving function following central nervous system trauma and neurodegenerative diseases.

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

    Directory of Open Access Journals (Sweden)

    Rimantas Treinys

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

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

    Science.gov (United States)

    Contreras, E; Tamayo, L; Amigo, M

    1988-04-13

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

  16. State-dependent blocker interactions with the CFTR chloride channel: implications for gating the pore.

    Science.gov (United States)

    Linsdell, Paul

    2014-12-01

    Chloride permeation through the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel is subject to voltage-dependent open-channel block by a diverse range of cytoplasmic anions. However, in most cases the ability of these blocking substances to influence the pore opening and closing process has not been reported. In the present work, patch clamp recording was used to investigate the state-dependent block of CFTR by cytoplasmic Pt(NO2)4(2-) ions. Two major effects of Pt(NO2)4(2-) were identified. First, this anion caused fast, voltage-dependent block of open channels, leading to an apparent decrease in single-channel current amplitude. Secondly, Pt(NO2)4(2-) also decreased channel open probability due to an increase in interburst closed times. Interestingly, mutations in the pore that weakened (K95Q) or strengthened (I344K, V345K) interactions with Pt(NO2)4(2-) altered blocker effects both on Cl(-) permeation and on channel gating, suggesting that both these effects are a consequence of Pt(NO2)4(2-) interaction with a single site within the pore. Experiments at reduced extracellular Cl(-) concentration hinted that Pt(NO2)4(2-) may have a third effect, possibly increasing channel activity by interfering with channel closure. These results suggest that Pt(NO2)4(2-) can enter from the cytoplasm into the pore inner vestibule of both open and closed CFTR channels, and that Pt(NO2)4(2-) bound in the inner vestibule blocks Cl(-) permeation as well as interfering with channel opening and, perhaps, channel closure. Implications for the location of the channel gate in the pore, and the operation of this gate, are discussed.

  17. Positive symptoms in multiple sclerosis: their treatment with sodium channel blockers, lidocaine and mexiletine.

    Science.gov (United States)

    Sakurai, M; Kanazawa, I

    1999-01-15

    Patients with multiple sclerosis (MS) often show positive symptoms of painful tonic seizure and dysesthesia as well as negative symptoms of paralysis and hypesthesia. Positive manifestation is paroxysmal and/or persistent. These are considered to be mediated by ectopic impulses generated at the site of demyelination, whereas negative symptoms are caused by conduction block. Conduction block at a demyelinated segment should reduce positive symptoms, but worsen negative ones. As reported previously, lidocaine, an Na channel blocker unmasks silent negative symptoms presumably by further reducing the action current in demyelinated portions and blocking conduction. Furthermore, because it blocks Na channels in a voltage- and frequency dependent manner, fibers that mediate positive symptoms are preferentially blocked. We administered lidocaine to 30 MS patients with positive symptoms. Lidocaine (mean plasma level, 2.4 pg/ml) almost completely abolished the paroxysmal manifestation of painful tonic seizures, neuralgic attacks, paroxysmal itching, and Lhermitte's sign. It also markedly alleviated persistent symptoms, but less so than paroxysmal symptoms. Similar effects were obtained with orally-administered mexiletine (300-400 mg/day), a derivative of lidocaine, but to a lesser extent. Na channel blockers have a dual effect on symptoms in MS, depending on whether symptoms are positive or negative. The mechanism that produces positive symptoms and the effects of the drugs on these symptoms are discussed.

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

    Science.gov (United States)

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

    2012-11-01

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

  19. Human beta-defensin 1, a new animal toxin-like blocker of potassium channel.

    Science.gov (United States)

    Feng, Jing; Xie, Zili; Yang, Weishan; Zhao, Yonghui; Xiang, Fang; Cao, Zhijian; Li, Wenxin; Chen, Zongyun; Wu, Yingliang

    2016-04-01

    The discovery of human β-defensin 2 (hBD2), as a Kv1.3 channel inhibitor with the unique molecular mechanism and novel immune modulatory function, suggests that human β-defensins are a novel class of channel ligands. Here, the function and mechanism of the human β-defensin 1 (hBD1) binding to potassium channels was investigated. Based on the structural similarity between hBD1 and Kv1.3 channel-sensitive hBD2, hBD1 was found to selectively inhibit human and mouse Kv1.3 channels with IC50 values of 11.8 ± 3.1 μM and 13.2 ± 4.0 μM, respectively. Different from hBD2 modifying Kv1.3 channel activation and increasing activation time constant, hBD1 did not affect the activation feature of both human and mouse Kv1.3 channels. In comparison with hBD2 simultaneously interacting with the extracellular S1-S2 linker and pore region of Kv1.3 channel, the chimeric channel and mutagenesis experiments showed that hBD1 only bound to the extracellular pore region of Kv1.3 channel instead of extracellular S1-S2 linker or S3-S4 linker. Together, these findings enhance knowledge of hBD1 as a new immune-related Kv1.3 channel blocker and highlight the major functional differences between hBD1 and hBD2 to explore in future research.

  20. Effect of magnesium sulfate combined with calcium channel blockers on cystatin C,uric acid, alpha fetal protein and urinary transferrin levels in patients with hypertension pregnancy%硫酸镁联合钙离子通道拮抗剂对妊娠期高血压患者血清胱抑素C、尿酸、甲胎蛋白及尿转铁蛋白水平的影响

    Institute of Scientific and Technical Information of China (English)

    蔡安利; 宋飞銮; 秦洁; 戴洁; 潘倩若; 吕杰强

    2015-01-01

    目的:探讨硫酸镁联合钙离子通道拮抗剂对妊娠期高血压患者血清胱抑素C( cystatin C)、尿酸、甲胎蛋白( alpha fetal protein,AFP)及尿转铁蛋白( transferrin,TRF)水平的影响及意义。方法选取温州医科大学附属第三医院2013年1月~2014年10月产科收治的75例妊娠期高血压患者,随机分为2组,对照组37例行临床常规治疗;实验组38例,在对照组基础上加用硫酸镁和钙离子通道拮抗剂治疗。检测2组患者血清胱抑素C、尿酸、甲胎蛋白及尿转铁蛋白水平变化,比较2组临床疗效。结果与对照组比较,实验组Cys C、尿酸水平较低(P<0.05),血清AFP水平、尿TRF水平较低(P<0.05),血清血细胞比容、血液粘度及红细胞聚集指数较低(P<0.05),总有效率明显高于对照组(P<0.05)。结论硫酸镁联合钙离子通道拮抗剂对妊娠期高血压疾病患者治疗有较好的临床疗效,能有效改善血液粘度,降低血清Cys C、尿酸、AFP和尿TRF水平。%Objective To explore the effect of magnesium sulfate combined with calcium channel blockers on cystatin C, uric acid, alpha fetal protein and urinary transferrin in patients with hypertension pregnancy.Methods 75 cases with hypertension of pregnancy were selected and divided into two groups, control group(n=37) were treated with conventional therapy, experiment group(n=38) were treated with magnesium sulfate combined with calcium channel blockers on the basis of control group.Cystatin C, uric acid, alpha fetal protein and urinary transferrin were compared after treatment between two groups.Results Compared with control group, Cys C, uric acid, serum AFP l, urinary TRF levels were all lower in experiment group( P<0.05), serum hematocrit, whole blood viscosity and erythrocyte aggregation index were all lower in experiment group(P<0.05).The total efficiency of experiment group was significantly higher than

  1. P-type calcium channels are blocked by the alkaloid daurisoline.

    Science.gov (United States)

    Lu, Y M; Fröstl, W; Dreessen, J; Knöpfel, T

    1994-07-21

    IN looking for a structurally defined non-peptide P-channel blocker we have tested the alkaloid daurisoline which has been isolated from traditional Chinese medicinal herb (Menispermum dauricum) used for the treatment of epilepsy, hypertension and asthma. We have found that daurisoline is an inhibitor of omega-Aga-IVA sensitive barium currents in cerebellar Purkinje cells and of excitatory postsynaptic potentials evoked in Purkinje cells by stimulating parallel fibres in acutely prepared cerebellar slices. Daurisoline did not significantly affect omega-Aga-IVA-insensitive barium currents recorded from granule cells freshly isolated from rat cerebellum. Daurisoline passes the blood-brain barrier and will, therefore, facilitate the functional characterization of brain calcium channels as well as the exploration of P-type calcium channels as possible drug targets.

  2. Designing a C84 fullerene as a specific voltage-gated sodium channel blocker

    Science.gov (United States)

    Hilder, Tamsyn A.; Chung, Shin-Ho

    2013-07-01

    Fullerene derivatives demonstrate considerable potential for numerous biological applications, such as the effective inhibition of HIV protease. Recently, they were identified for their ability to indiscriminately block biological ion channels. A fullerene derivative which specifically blocks a particular ion channel could lead to a new set of drug leads for the treatment of various ion channel-related diseases. Here, we demonstrate their extraordinary potential by designing a fullerene which mimics some of the functions of μ-conotoxin, a peptide derived from cone snail venom which potently binds to the bacterial voltage-gated sodium channel (NavAb). We show, using molecular dynamics simulations, that the C84 fullerene with six lysine derivatives uniformly attached to its surface is selective to NavAb over a voltage-gated potassium channel (Kv1.3). The side chain of one of the lysine residues protrudes into the selectivity filter of the channel, while the methionine residues located just outside of the channel form hydrophobic contacts with the carbon atoms of the fullerene. The modified C84 fullerene strongly binds to the NavAb channel with an affinity of 46 nM but binds weakly to Kv1.3 with an affinity of 3 mM. This potent blocker of NavAb may serve as a structural template from which potent compounds can be designed for the targeting of mammalian Nav channels. There is a genuine need to target mammalian Nav channels as a form of treatment of various diseases which have been linked to their malfunction, such as epilepsy and chronic pain.

  3. Voltage-dependent calcium channels from brain incorporated into planar lipid bilayers

    Science.gov (United States)

    Nelson, Mark T.; French, Robert J.; Krueger, Bruce K.

    1984-03-01

    Many important physiological processes, including neurotransmitter release and muscle contraction1-3, are regulated by the concentration of Ca2+ ions in the cell. Levels of cytoplasmic Ca2+ can be elevated by the entry of Ca2+ ions through voltage-dependent channels which are selective for Ca2+, Ba2+ and Sr2+ ions4-14. We have measured currents through single, voltage-dependent calcium channels from rat brain that have been incorporated into planar lipid bilayers. Channel gating was voltage-dependent: membrane depolarization increased the channel open times and decreased the closed times. The channels were selective for divalent cations over monovalent ions. The well-known calcium channel blockers, lanthanum and cadmium, produced a concentration-dependent reduction of the apparent single-channel conductance. Contrary to expectations14, the nature of the divalent cation carrying current through the channel affected not only the single-channel conductance, but also the channel open times, with mean open times being shortest for barium.

  4. On the top of ARB N/L type Ca channel blocker leads to less elevation of aldosterone

    Science.gov (United States)

    Konoshita, Tadashi; Kaeriyama, Saori; Urabe, Machi; Nakaya, Takahiro; Yamada, Mika; Ichikawa, Mai; Yamamoto, Katsushi; Sato, Satsuki; Imagawa, Michiko; Fujii, Miki; Makino, Yasukazu; Zenimaru, Yasuo; Wakahara, Shigeyuki; Suzuki, Jinya; Ishizuka, Tamotsu; Nakamura, Hiroyuki

    2016-01-01

    The activation of the renin–angiotensin system (RAS) is one of the unfavourable characteristics of calcium channel blocker (CCB). N type calcium channel is thought to be involved in renin gene transcription and adrenal aldosterone release. Accordingly, N/L type CCB has a possibility of less elevation of plasma aldosterone concentrations (PAC) among CCBs. In a monotherapy study, we had already demonstrated that N/L type CCB leads to less activation of the RAS compared with L type CCB. The objective of this study is to substantiate the hypothesis that at the condition of additive administration on the top of an angiotensin receptor blocker (ARB), still N/L type CCB leads to less elevation of PAC compared with L type one. Subjects were 60 hypertensives administered with valsartan. As an open label study, amlodipine (L type) or cilnidipine (N/L type) were administered on the top of valsartan (ARB) in a cross-over manner. Results were as follows (valsartan+amlodipine compared with valsartan+cilnidipine): systolic blood pressure (SBP)/diastolic blood pressure (DBP) (mmHg): 132±10/76±10 compared with 131±10/77±9, P=0.95/0.48, plasma renin activity (PRA) (ng/ml·h): 2.41±2.67 compared with 2.00±1.50 P=0.20, PAC (pg/ml): 77.3±31.0 compared with 67.4±24.8, P<0.05, urinary albumin excretion (UAE) (mg/gCr): 105.9±216.1 compared with 73.9±122.2, P<0.05. Thus, PAC at cilnidipine was significantly lower than those at amlodipine in spite of the comparable BP reductions. Besides, UAE was significantly lower at cilnidipine. In conclusion, on the top of the ARB, it is suggested that cilnidipine administration might lead to less elevation of PAC and reduction in UAE compared with amlodipine. PMID:27515419

  5. CHARACTERIZING CALCIUM INFLUX VIA VOLTAGE- AND LIGAND-GATED CALCIUM CHANNELS IN EMBRYONIC ALLIGATOR NEURONS IN CULTURE

    Science.gov (United States)

    Ju, Weina; Wu, Jiang; Pritz, Michael B.; Khanna, Rajesh

    2013-01-01

    Vertebrate brains share many features in common. Early in development, both the hindbrain and diencephalon are built similarly. Only later in time do differences in morphology occur. Factors that could potentially influence such changes include certain physiological properties of neurons. As an initial step to investigate this problem, embryonic Alligator brain neurons were cultured and calcium responses were characterized. The present report is the first to document culture of Alligator brain neurons in artificial cerebrospinal fluid (ACSF) as well as in standard mammalian tissue culture medium supplemented with growth factors. Alligator brain neuron cultures were viable for at least 1 week with unipolar neurites emerging by 24 hours. Employing Fura-2 AM, robust depolarization-induced calcium influx, was observed in these neurons. Using selective blockers of the voltage-gated calcium channels, the contributions of N-, P/Q-, R-, T-, and L-type channels in these neurons were assessed and their presence documented. Lastly, Alligator brain neurons were challenged with an excitotoxic stimulus (glutamate + glycine) where delayed calcium deregulation could be prevented by a classical NMDA receptor antagonist. PMID:24260711

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

    Science.gov (United States)

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

    2004-01-01

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

  7. 钙通道阻滞剂改善内质网应激抑制压力过负荷高血压大鼠的心肌重构%Protective effect of calcium channel blocker on hypertensive rat myocardial remodeling of pressure overload induced by endoplasmic reticulum stress

    Institute of Scientific and Technical Information of China (English)

    槐勇; 赵连友; 李炜; 郑强荪; 刘静; 郭丽; 丁璐

    2012-01-01

    目的:研究在压力过负荷应激状态下钙通道阻滞剂拉西地平对内质网应激(endoplasmic reticulum stress,ERS)分子钙网蛋白(calreticulin,CRT)和细胞凋亡效应分子-12(caspase-12)在大鼠心肌组织中的表达及对心肌重构的影响.方法:将30只雄性Sprague-Dawly(SD)大鼠随机分为3组,即假手术组(Sham组)、腹主动脉缩窄组(TAC组)及TAC+拉西地平干预组(简称拉西地平组),每组10只.通过颈动脉插管测定各组大鼠的血流动力学,心脏超声心动图检查左心室的形态结构.采用免疫组化染色法检测大鼠心肌中CRT及caspase-12蛋白的表达水平,TUNEL荧光染色法检测心肌细胞的凋亡率.结果:与Sham组相比较,TAC组大鼠的平均动脉压(MAP)、室间隔厚度(IVST)、左室后壁厚度(LVPWT)、左室质量指数(LVWI)、CRT和caspase-12蛋白表达水平及心肌细胞的凋亡率比较,均有显著升高(P<0.01).拉西地平组大鼠MAP、IVST、LVPWT、LVWI、CRT和caspase-12蛋白的表达水平及心肌细胞的凋亡率较TAC组明显下降(P<0.05).结论:内质网应激可能参与了压力过负荷高血压大鼠心肌重构的过程.钙通道阻滞剂拉西地平可能通过降低CRT及caspase-12的表达及减少心肌细胞的凋亡干预ERS介导的压力负荷所致高血压大鼠心肌肥厚的信号通路,从而通过改善内质网应激发挥对心脏的保护作用.%AIM: To investigate the influence of calcium channel blocker lacidipine on the expression of calreticulin (CRT) and caspase-12 in rat cardiac myocytes and the effects of lacidipine against myocardium remodeling under pressure overload conditions. METHODS: Thirty male Sprague Dawley rats were randomly divided into TAC group (transverse aortic constriction) , control group ( sham group) and TAC + lacidipine group with ten rats in each group. Invasive hemodynamics were measured through carotid cannulation and left ventricular morphology was monitored by echocardiography

  8. P/Q-type and T-type voltage-gated calcium channels are involved in the contraction of mammary and brain blood vessels from hypertensive patients

    DEFF Research Database (Denmark)

    Thuesen, A D; Lyngsø, K S; Rasmussen, L

    2017-01-01

    AIM: Calcium channel blockers are widely used in cardiovascular diseases. Besides L-type channels, T- and P/Q-type calcium channels are involved in the contraction of human renal blood vessels. It was hypothesized that T- and P/Q-type channels are involved in the contraction of human brain...... and mammary blood vessels. METHODS: Internal mammary arteries from bypass surgery patients and cerebral arterioles from patients with brain tumours with and without hypertension were tested in a myograph and perfusion set-up. PCR and immunohistochemistry were performed on isolated blood vessels. RESULTS......: The P/Q-type antagonist ω-agatoxin IVA (10(-8) mol L(-1) ) and the T-type calcium blocker mibefradil (10(-7) mol L(-1) ) inhibited KCl depolarization-induced contraction in mammary arteries from hypertensive patients with no effect on blood vessels from normotensive patients. ω-Agatoxin IVA decreased...

  9. BETA-BLOCKERS IN THE TREATMENT OF ARTERIAL HYPERTENSION: EVIDENCE BASED DATA AND REAL PRACTICE

    Directory of Open Access Journals (Sweden)

    M. V. Leonova

    2012-01-01

    Full Text Available Data of the largest meta-analyzes of beta-blockers use in arterial hypertension is presented. The role of beta-blockers among other basic groups of antihypertensive drugs (thiazide diuretics, calcium channel blockers, ACE inhibitors is evaluated. Special considerations of beta-blockers use in hypertensive patients with diabetes mellitus and chronic heart failure are discussed. Special attention is paid to bisoprolol.

  10. BETA-BLOCKERS IN THE TREATMENT OF ARTERIAL HYPERTENSION: EVIDENCE BASED DATA AND REAL PRACTICE

    Directory of Open Access Journals (Sweden)

    M. V. Leonova

    2015-12-01

    Full Text Available Data of the largest meta-analyzes of beta-blockers use in arterial hypertension is presented. The role of beta-blockers among other basic groups of antihypertensive drugs (thiazide diuretics, calcium channel blockers, ACE inhibitors is evaluated. Special considerations of beta-blockers use in hypertensive patients with diabetes mellitus and chronic heart failure are discussed. Special attention is paid to bisoprolol.

  11. Calcium influx through L-type channels attenuates skeletal muscle contraction via inhibition of adenylyl cyclases.

    Science.gov (United States)

    Menezes-Rodrigues, Francisco Sandro; Pires-Oliveira, Marcelo; Duarte, Thiago; Paredes-Gamero, Edgar Julian; Chiavegatti, Tiago; Godinho, Rosely Oliveira

    2013-11-15

    Skeletal muscle contraction is triggered by acetylcholine induced release of Ca(2+) from sarcoplasmic reticulum. Although this signaling pathway is independent of extracellular Ca(2+), L-type voltage-gated calcium channel (Cav) blockers have inotropic effects on frog skeletal muscles which occur by an unknown mechanism. Taking into account that skeletal muscle fiber expresses Ca(+2)-sensitive adenylyl cyclase (AC) isoforms and that cAMP is able to increase skeletal muscle contraction force, we investigated the role of Ca(2+) influx on mouse skeletal muscle contraction and the putative crosstalk between extracellular Ca(2+) and intracellular cAMP signaling pathways. The effects of Cav blockers (verapamil and nifedipine) and extracellular Ca(2+) chelator EGTA were evaluated on isometric contractility of mouse diaphragm muscle under direct electrical stimulus (supramaximal voltage, 2 ms, 0.1 Hz). Production of cAMP was evaluated by radiometric assay while Ca(2+) transients were assessed by confocal microscopy using L6 cells loaded with fluo-4/AM. Ca(2+) channel blockers verapamil and nifedipine had positive inotropic effect, which was mimicked by removal of extracellular Ca(+2) with EGTA or Ca(2+)-free Tyrode. While phosphodiesterase inhibitor IBMX potentiates verapamil positive inotropic effect, it was abolished by AC inhibitors SQ22536 and NYK80. Finally, the inotropic effect of verapamil was associated with increased intracellular cAMP content and mobilization of intracellular Ca(2+), indicating that positive inotropic effects of Ca(2+) blockers depend on cAMP formation. Together, our results show that extracellular Ca(2+) modulates skeletal muscle contraction, through inhibition of Ca(2+)-sensitive AC. The cross-talk between extracellular calcium and cAMP-dependent signaling pathways appears to regulate the extent of skeletal muscle contraction responses.

  12. Analytical models of calcium binding in a calcium channel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinn-Liang [Department of Applied Mathematics, National Hsinchu University of Education, Hsinchu 300, Taiwan (China); Eisenberg, Bob [Department of Molecular Biophysics and Physiology, Rush University, Chicago, Illinois 60612 (United States)

    2014-08-21

    The anomalous mole fraction effect of L-type calcium channels is analyzed using a Fermi like distribution with the experimental data of Almers and McCleskey [J. Physiol. 353, 585 (1984)] and the atomic resolution model of Lipkind and Fozzard [Biochemistry 40, 6786 (2001)] of the selectivity filter of the channel. Much of the analysis is algebraic, independent of differential equations. The Fermi distribution is derived from the configuration entropy of ions and water molecules with different sizes, different valences, and interstitial voids between particles. It allows us to calculate potentials and distances (between the binding ion and the oxygen ions of the glutamate side chains) directly from the experimental data using algebraic formulas. The spatial resolution of these results is comparable with those of molecular models, but of course the accuracy is no better than that implied by the experimental data. The glutamate side chains in our model are flexible enough to accommodate different types of binding ions in different bath conditions. The binding curves of Na{sup +} and Ca{sup 2+} for [CaCl{sub 2}] ranging from 10{sup −8} to 10{sup −2} M with a fixed 32 mM background [NaCl] are shown to agree with published Monte Carlo simulations. The Poisson-Fermi differential equation—that includes both steric and correlation effects—is then used to obtain the spatial profiles of energy, concentration, and dielectric coefficient from the solvent region to the filter. The energy profiles of ions are shown to depend sensitively on the steric energy that is not taken into account in the classical rate theory. We improve the rate theory by introducing a steric energy that lumps the effects of excluded volumes of all ions and water molecules and empty spaces between particles created by Lennard-Jones type and electrostatic forces. We show that the energy landscape varies significantly with bath concentrations. The energy landscape is not constant.

  13. Voltage-gated Calcium Channels and Autism Spectrum Disorders.

    Science.gov (United States)

    Breitenkamp, Alexandra F; Matthes, Jan; Herzig, Stefan

    2015-01-01

    Autism spectrum disorder is a complex-genetic disease and its etiology is unknown for the majority of cases. So far, more than one hundred different susceptibility genes were detected. Voltage-gated calcium channels are among the candidates linked to autism spectrum disorder by results of genetic studies. Mutations of nearly all pore-forming and some auxiliary subunits of voltage gated calcium channels have been revealed from investigations of autism spectrum disorder patients and populations. Though there are only few electrophysiological characterizations of voltage-gated calcium channel mutations found in autistic patients these studies suggest their functional relevance. In summary, both genetic and functional data suggest a potential role of voltage-gated calcium channels in autism spectrum disorder. Future studies require refinement of the clinical and systems biological concepts of autism spectrum disorder and an appropriate holistic approach at the molecular level, e.g. regarding all facets of calcium channel functions.

  14. Calcium channels, neuromuscular synaptic transmission and neurological diseases.

    Science.gov (United States)

    Urbano, Francisco J; Pagani, Mario R; Uchitel, Osvaldo D

    2008-09-15

    Voltage-dependent calcium channels are essential in neuronal signaling and synaptic transmission, and their functional alterations underlie numerous human disorders whether monogenic (e.g., ataxia, migraine, etc.) or autoimmune. We review recent work on Ca(V)2.1 or P/Q channelopathies, mostly using neuromuscular junction preparations, and focus specially on the functional hierarchy among the calcium channels recruited to mediate neurotransmitter release when Ca(V)2.1 channels are mutated or depleted. In either case, synaptic transmission is greatly compromised; evidently, none of the reported functional replacements with other calcium channels compensates fully.

  15. Abeta ion channels. Prospects for treating Alzheimer's disease with Abeta channel blockers.

    Science.gov (United States)

    Arispe, Nelson; Diaz, Juan C; Simakova, Olga

    2007-08-01

    The main pathological features in the Alzheimer's brain are progressive depositions of amyloid protein plaques among nerve cells, and neurofibrillary tangles within the nerve cells. The major components of plaques are Abeta peptides. Numerous reports have provided evidence that Abeta peptides are cytotoxic and may play a role in the pathogenesis of AD. An increasing number of research reports support the concept that the Abeta-membrane interaction event may be followed by the insertion of Abeta into the membrane in a structural configuration which forms an ion channel. This review summarizes experimental procedures which have been designed to test the hypothesis that the interaction of Abeta with a variety of membranes, both artificial and natural, results in the subsequent formation of Abeta ion channels We describe experiments, by ourselves and others, that support the view that Abeta is cytotoxic largely due to the action of Abeta channels in the cell membrane. The interaction of Abeta with the surface of the cell membrane may results in the activation of a chain of processes that, when large enough, become cytotoxic and induce cell death by apoptosis. Remarkably, the blockage of Abeta ion channels at the surface of the cell absolutely prevents the activation of these processes at different intracellular levels, thereby preserving the life of the cells. As a prospect for therapy for Alzheimer's disease, our findings at cellular level may be testable on AD animal models to elucidate the potential role and the magnitude of the contribution of the Abeta channels for induction of the disease.

  16. STIM and calcium channel complexes in cancer.

    Science.gov (United States)

    Jardin, Isaac; Rosado, Juan A

    2016-06-01

    The ion Ca(2+) is a ubiquitous second messenger that mediates a variety of cellular functions. Dysfunction of the mechanisms involved in Ca(2+) homeostasis underlies a number of pathological processes, including cancer. Store-operated Ca(2+) entry (SOCE) is a major mechanism for Ca(2+) entry modulated by the intracellular Ca(2+) stores. The Ca(2+)-selective store-operated current (ICRAC) is mediated by the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and the store-operated Ca(2+) (SOC) channel Orai1, while other non-selective cation currents (ISOC) involves the participation of members of the canonical transient receptor potential (TRPC) channel family, including TRPC1. Distinct isoforms of the key components of SOCE have been described in mammalian cells, STIM1 and 2, Orai1-3 and TRPC1-7. In cancer cells, SOCE has been reported to play an important role in cell cycle progression and proliferation, migration, metastasis and evasion of apoptosis. Changes in the expression of the key elements of SOCE and Ca(2+) homeostasis remodeling have been account to play important roles in the phenotypic changes observed in transformed cells. Despite there are differences in the expression level of the molecular components of SOCE, as well as in the relevance of the STIM, Orai and TRPC isoforms in SOCE and tumorigenesis among cancer cell types, there is a body of evidence supporting an important role for SOCE underlying the phenotypic modifications of cancer cells that propose STIM and the SOC channels as suitable candidate targets for future prognostic or therapeutic strategies. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen.

  17. Drosophila mushroom body Kenyon cells generate spontaneous calcium transients mediated by PLTX-sensitive calcium channels.

    Science.gov (United States)

    Jiang, Shaojuan Amy; Campusano, Jorge M; Su, Hailing; O'Dowd, Diane K

    2005-07-01

    Spontaneous calcium oscillations in mushroom bodies of late stage pupal and adult Drosophila brains have been implicated in memory consolidation during olfactory associative learning. This study explores the cellular mechanisms regulating calcium dynamics in Kenyon cells, principal neurons in mushroom bodies. Fura-2 imaging shows that Kenyon cells cultured from late stage Drosophila pupae generate spontaneous calcium transients in a cell autonomous fashion, at a frequency similar to calcium oscillations in vivo (10-20/h). The expression of calcium transients is up regulated during pupal development. Although the ability to generate transients is a property intrinsic to Kenyon cells, transients can be modulated by bath application of nicotine and GABA. Calcium transients are blocked, and baseline calcium levels reduced, by removal of external calcium, addition of cobalt, or addition of Plectreurys toxin (PLTX), an insect-specific calcium channel antagonist. Transients do not require calcium release from intracellular stores. Whole cell recordings reveal that the majority of voltage-gated calcium channels in Kenyon cells are PLTX-sensitive. Together these data show that influx of calcium through PLTX-sensitive voltage-gated calcium channels mediates spontaneous calcium transients and regulates basal calcium levels in cultured Kenyon cells. The data also suggest that these calcium transients represent cellular events underlying calcium oscillations in the intact mushroom bodies. However, spontaneous calcium transients are not unique to Kenyon cells as they are present in approximately 60% of all cultured central brain neurons. This suggests the calcium transients play a more general role in maturation or function of adult brain neurons.

  18. Microdamage induced calcium efflux from bone matrix activates intracellular calcium signaling in osteoblasts via L-type and T-type voltage-gated calcium channels.

    Science.gov (United States)

    Jung, Hyungjin; Best, Makenzie; Akkus, Ozan

    2015-07-01

    Mechanisms by which bone microdamage triggers repair response are not completely understood. It has been shown that calcium efflux ([Ca(2+)]E) occurs from regions of bone undergoing microdamage. Such efflux has also been shown to trigger intracellular calcium signaling ([Ca(2+)]I) in MC3T3-E1 cells local to damaged regions. Voltage-gated calcium channels (VGCCs) are implicated in the entry of [Ca(2+)]E to the cytoplasm. We investigated the involvement of VGCC in the extracellular calcium induced intracellular calcium response (ECIICR). MC3T3-E1 cells were subjected to one dimensional calcium efflux from their basal aspect which results in an increase in [Ca(2+)]I. This increase was concomitant with membrane depolarization and it was significantly reduced in the presence of Bepridil, a non-selective VGCC inhibitor. To identify specific type(s) of VGCC in ECIICR, the cells were treated with selective inhibitors for different types of VGCC. Significant changes in the peak intensity and the number of [Ca(2+)]I oscillations were observed when L-type and T-type specific VGCC inhibitors (Verapamil and NNC55-0396, respectively) were used. So as to confirm the involvement of L- and T-type VGCC in the context of microdamage, cells were seeded on devitalized notched bone specimen, which were loaded to induce microdamage in the presence and absence of Verapamil and NNC55-0396. The results showed significant decrease in [Ca(2+)]I activity of cells in the microdamaged regions of bone when L- and T-type blockers were applied. This study demonstrated that extracellular calcium increase in association with damage depolarizes the cell membrane and the calcium ions enter the cell cytoplasm by L- and T-type VGCCs.

  19. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels.

    Directory of Open Access Journals (Sweden)

    Adriano Senatore

    Full Text Available NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single gene compared to the calcium and sodium channels which diversified into twenty genes in humans. The single NALCN gene has alternatively-spliced exons at exons 15 or exon 31 that splices in novel selectivity filter residues that resemble calcium channels (EEEE or sodium channels (EKEE or EEKE. NALCN channels with alternative calcium, (EEEE and sodium, (EKEE or EEKE -selective pores are conserved in simple bilaterally symmetrical animals like flatworms to non-chordate deuterostomes. The single NALCN gene is limited as a sodium channel with a lysine (K-containing pore in vertebrates, but originally NALCN was a calcium-like channel, and evolved to operate as both a calcium channel and sodium channel for different roles in many invertebrates. Expression patterns of NALCN-EKEE in pond snail, Lymnaea stagnalis suggest roles for NALCN in secretion, with an abundant expression in brain, and an up-regulation in secretory organs of sexually-mature adults such as albumen gland and prostate. NALCN-EEEE is equally abundant as NALCN-EKEE in snails, but is greater expressed in heart and other muscle tissue, and 50% less expressed in the brain than NALCN-EKEE. Transfected snail NALCN-EEEE and NALCN-EKEE channel isoforms express in HEK-293T cells. We were not able to distinguish potential NALCN currents from background, non-selective leak conductances in HEK293T cells. Native leak currents without expressing NALCN genes in HEK-293T cells are NMDG(+ impermeant and blockable with 10 µM Gd(3+ ions and are indistinguishable from the hallmark currents ascribed to mammalian NALCN currents expressed in vitro by Lu et al. in Cell. 2007 Apr 20;129(2:371-83.

  20. 43. Calmodulin regulating calcium sensitivity of Na channels

    Directory of Open Access Journals (Sweden)

    R. Vegiraju

    2016-07-01

    Full Text Available By extrapolating information from existing research and observing previous assumptions regarding the structure of the Na Channel, this experiment was conducted under the hypothesis that the Na Channel is in part regulated by the calmodulin protein, as a result proving calcium sensitivity of the Na Channel. Furthermore, we assume that there is a one to one stoichiometry between the Na Channel and the Calmodulin. There has been extensive research into the functionality and structure of sodium ion channels (Na channels, as several diseases are associated with the lack of regulation of sodium ions, that is caused by the disfunction of these Na channels. However, one highly controversial matter in the field is the importance of the protein calmodulin (CaM and calcium in Na channel function. Calmodulin is a protein that is well known for its role as a calcium binding messenger protein, and that association is believed to play an indirect role in regulating the Na channel through the Na channel’s supposed calcium sensitivity. While there are proponents for both sides, there has been relatively little research that provides strong evidence for either case. In this experiment, the effect of calmodulin on NaV 1.5 is tested by preparing a set of cardiac cells (of the human specie with the NaV 1.5 C-Termini and CaM protein, which were then to be placed in solutions with varying concentrations of calcium. We took special care to test multiple concentrations of calcium, as previous studies have tested very low concentrations, with Manu Ben-Johny’s team from the John Hopkins laboratory in particular testing up to a meager 50 micromolar, despite producing a well-respected paper (By comparison, the average Na channel can naturally sustain a concentration of almost 1-2 millimolar and on some occasions, reaching even higher concentrations. After using light scattering and observing the signals given off by the calcium interacting with these Nav1.5/Ca

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

    OpenAIRE

    2008-01-01

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

  2. Recombinant expression of margatoxin and agitoxin-2 in Pichia pastoris: an efficient method for production of KV1.3 channel blockers.

    Directory of Open Access Journals (Sweden)

    Raveendra Anangi

    Full Text Available The K(v1.3 voltage-gated potassium channel regulates membrane potential and calcium signaling in human effector memory T cells that are key mediators of autoimmune diseases such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. Thus, subtype-specific K(v1.3 blockers have potential for treatment of autoimmune diseases. Several K(v1.3 channel blockers have been characterized from scorpion venom, all of which have an α/β scaffold stabilized by 3-4 intramolecular disulfide bridges. Chemical synthesis is commonly used for producing these disulfide-rich peptides but this approach is time consuming and not cost effective for production of mutants, fusion proteins, fluorescently tagged toxins, or isotopically labelled peptides for NMR studies. Recombinant production of K(v1.3 blockers in the cytoplasm of E. coli generally necessitates oxidative refolding of the peptides in order to form their native disulfide architecture. An alternative approach that avoids the need for refolding is expression of peptides in the periplasm of E. coli but this often produces low yields. Thus, we developed an efficient Pichia pastoris expression system for production of K(v1.3 blockers using margatoxin (MgTx and agitoxin-2 (AgTx2 as prototypic examples. The Pichia system enabled these toxins to be obtained in high yield (12-18 mg/L. NMR experiments revealed that the recombinant toxins adopt their native fold without the need for refolding, and electrophysiological recordings demonstrated that they are almost equipotent with the native toxins in blocking K(V1.3 (IC(50 values of 201±39 pM and 97 ± 3 pM for recombinant AgTx2 and MgTx, respectively. Furthermore, both recombinant toxins inhibited T-lymphocyte proliferation. A MgTx mutant in which the key pharmacophore residue K28 was mutated to alanine was ineffective at blocking K(V1.3 and it failed to inhibit T-lymphocyte proliferation. Thus, the approach described here provides an efficient method of

  3. Osteoblasts detect pericellular calcium concentration increase via neomycin-sensitive voltage gated calcium channels.

    Science.gov (United States)

    Sun, Xuanhao; Kishore, Vipuil; Fites, Kateri; Akkus, Ozan

    2012-11-01

    The mechanisms underlying the detection of critically loaded or micro-damaged regions of bone by bone cells are still a matter of debate. Our previous studies showed that calcium efflux originates from pre-failure regions of bone matrix and MC3T3-E1 osteoblasts respond to such efflux by an increase in the intracellular calcium concentration. The mechanisms by which the intracellular calcium concentration increases in response to an increase in the pericellular calcium concentration are unknown. Elevation of the intracellular calcium may occur via release from the internal calcium stores of the cell and/or via the membrane bound channels. The current study applied a wide range of pharmaceutical inhibitors to identify the calcium entry pathways involved in the process: internal calcium release from endoplasmic reticulum (ER, inhibited by thapsigargin and TMB-8), calcium receptor (CaSR, inhibited by calhex), stretch-activated calcium channel (SACC, inhibited by gadolinium), voltage-gated calcium channels (VGCC, inhibited by nifedipine, verapamil, neomycin, and ω-conotoxin), and calcium-induced-calcium-release channel (CICRC, inhibited by ryanodine and dantrolene). These inhibitors were screened for their effectiveness to block intracellular calcium increase by using a concentration gradient induced calcium efflux model which mimics calcium diffusion from the basal aspect of cells. The inhibitor(s) which reduced the intracellular calcium response was further tested on osteoblasts seeded on mechanically loaded notched cortical bone wafers undergoing damage. The results showed that only neomycin reduced the intracellular calcium response in osteoblasts, by 27%, upon extracellular calcium stimulus induced by concentration gradient. The inhibitory effect of neomycin was more pronounced (75% reduction in maximum fluorescence) for osteoblasts seeded on notched cortical bone wafers loaded mechanically to damaging load levels. These results imply that the increase in

  4. Neuroprotection in the treatment of glaucoma--A focus on connexin43 gap junction channel blockers.

    Science.gov (United States)

    Chen, Ying-Shan; Green, Colin R; Danesh-Meyer, Helen V; Rupenthal, Ilva D

    2015-09-01

    Glaucoma is a form of optic neuropathy and a common cause of blindness, affecting over 60 million people worldwide with an expected rise to 80 million by 2020. Successful treatment is challenging due to the various causes of glaucoma, undetectable symptoms at an early stage and inefficient delivery of drugs to the back of the eye. Conventional glaucoma treatments focus on the reduction of elevated intraocular pressure (IOP) using topical eye drops. However, their efficacy is limited to patients who suffer from high IOP glaucoma and do not address the underlying susceptibility of retinal ganglion cells (RGC) to degeneration. Glaucoma is known as a neurodegenerative disease which starts with RGC death and eventually results in damage of the optic nerve. Neuroprotective strategies therefore offer a novel treatment option for glaucoma by not only preventing neuronal loss but also disease progression. This review firstly gives an overview of the pathophysiology of glaucoma as well as current treatment options including conventional and novel delivery strategies. It then summarizes the rational for neuroprotection as a novel therapy for glaucomatous neuropathies and reviews current potential neuroprotective strategies to preserve RGC, with a focus on connexin43 (Cx43) gap junction channel blockers.

  5. Straightforward approach to produce recombinant scorpion toxins-Pore blockers of potassium channels.

    Science.gov (United States)

    Nekrasova, Oksana; Kudryashova, Ksenia; Fradkov, Arkadiy; Yakimov, Sergey; Savelieva, Maria; Kirpichnikov, Mikhail; Feofanov, Alexey

    2017-01-10

    Scorpion venom peptide blockers (KTx) of potassium channels are a valuable tool for structure-functional studies and prospective candidates for medical applications. Low yields of recombinant KTx hamper their wide application. We developed convenient and efficient bioengineering approach to a large-scale KTx production that meets increasing demands for such peptides. Maltose-binding protein was used as a carrier for cytoplasmic expression of folded disulfide-rich KTx in E. coli. TEV protease was applied for in vitro cleavage of the target peptide from the carrier. To produce KTx with retained native N-terminal sequence, the last residue of TEV protease cleavage site (CSTEV) was occupied by the native N-terminal residue of a target peptide. It was shown that decreased efficiency of hydrolysis of fusion proteins with non-canonical CSTEV can be overcome without by-product formation. Disulfide formation and folding of a target peptide occurred in cytoplasm eliminating the need for renaturation procedure in vitro. Advantages of this approach were demonstrated by producing six peptides with three disulfide bonds related to four KTx sub-families and achieving peptide yields of 12-22mg per liter of culture. The developed approach can be of general use for low-cost production of various KTx, as well as other disulfide-rich peptides and proteins.

  6. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

    Directory of Open Access Journals (Sweden)

    Yan Xu

    Full Text Available Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.

  7. Meroterpenoid Chrodrimanins Are Selective and Potent Blockers of Insect GABA-Gated Chloride Channels.

    Science.gov (United States)

    Xu, Yan; Furutani, Shogo; Ihara, Makoto; Ling, Yun; Yang, Xinling; Kai, Kenji; Hayashi, Hideo; Matsuda, Kazuhiko

    2015-01-01

    Meroterpenoid chrodrimanins, produced from Talaromyces sp. YO-2, are known to paralyze silkworm (Bombyx mori) larvae, but their target is unknown. We have investigated the actions of chrodrimanin B on ligand-gated ion channels of silkworm larval neurons using patch-clamp electrophysiology. Chrodrimanin B had no effect on membrane currents when tested alone at 1 μM. However, it completely blocked the γ-aminobutyric acid (GABA)-induced current and showed less pronounced actions on acetylcholine- and L-glutamate-induced currents, when delivered at 1 μM for 1 min prior to co-application with transmitter GABA. Thus, chrodrimanins were also tested on a wild-type isoform of the B. mori GABA receptor (GABAR) RDL using two-electrode voltage-clamp electrophysiology. Chrodrimanin B attenuated the peak current amplitude of the GABA response of RDL with an IC50 of 1.66 nM. The order of the GABAR-blocking potency of chrodrimanins B > D > A was in accordance with their reported insecticidal potency. Chrodrimanin B had no open channel blocking action when tested at 3 nM on the GABA response of RDL. Co-application with 3 nM chrodrimanin B shifted the GABA concentration response curve to a higher concentration and further increase of chrodrimanin B concentration to 10 nM; it reduced maximum current amplitude of the GABA response, pointing to a high-affinity competitive action and a lower affinity non-competitive action. The A282S;T286V double mutation of RDL, which impairs the actions of fipronil, hardly affected the blocking action of chrodrimanin B, indicating a binding site of chrodrimanin B distinct from that of fipronil. Chrodrimanin B showed approximately 1,000-fold lower blocking action on human α1β2γ2 GABAR compared to RDL and thus is a selective blocker of insect GABARs.

  8. Localization of large conductance calcium-activated potassium channels and their effect on calcitonin gene-related peptide release in the rat trigemino-neuronal pathway

    DEFF Research Database (Denmark)

    Wulf-Johansson, H.; Amrutkar, D.V.; Hay-Schmidt, Anders;

    2010-01-01

    pathophysiology. Here we study the expression and localization of BK(Ca) channels and CGRP in the rat trigeminal ganglion (TG) and the trigeminal nucleus caudalis (TNC) as these structures are involved in migraine pain. Also the effect of the BK(Ca) channel blocker iberiotoxin and the BK(Ca) channel opener NS......Large conductance calcium-activated potassium (BK(Ca)) channels are membrane proteins contributing to electrical propagation through neurons. Calcitonin gene-related peptide (CGRP) is a neuropeptide found in the trigeminovascular system (TGVS). Both BK(Ca) channels and CGRP are involved in migraine...

  9. Effect of beta-adrenoceptor blockers on human ether-a-go-go-related gene (HERG) potassium channels

    DEFF Research Database (Denmark)

    Dupuis, Delphine S; Klaerke, Dan A; Olesen, Søren-Peter

    2005-01-01

    Patients with congenital long QT syndrome may develop arrhythmias under conditions of increased sympathetic tone. We have addressed whether some of the beta-adrenoceptor blockers commonly used to prevent the development of these arrhythmias could per se block the cardiac HERG (Human Ether....... These data showed that HERG blockade by beta-adrenoceptor blockers occurred only at high micromolar concentrations, which are significantly above the recently established safe margin of 100 (Redfern et al., 2003).......-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride) blocked the HERG channel with similar affinity, whereas the beta1-receptor antagonists metoprolol and atenolol showed weak effects. Further, the four compounds blocked HERG channels expressed in a mammalian HEK293 cell line...

  10. Comparison of the Tocolytic Effects of Ritodrine and Ca++ Channel Blockers on Serum Oestradiol and Progesterone Levels

    OpenAIRE

    2003-01-01

    Experimental pregnancy was induced with gonadal steroids in in vivo ovariectomized rats. Conditions for premature delivery were established by giving a salt-rich diet and administering oxytocin to induce high-risk pregnancy. In order to avoid early delivery, a betamimetic ritodrine and the Ca++ channel blockers nitrendipine and nicardipine were administered to three separate groups. The effects of these three tocolytic agents were examined by determining serum oestradiol and progesterone ...

  11. A specific two-pore domain potassium channel blocker defines the structure of the TASK-1 open pore.

    Science.gov (United States)

    Streit, Anne K; Netter, Michael F; Kempf, Franca; Walecki, Magdalena; Rinné, Susanne; Bollepalli, Murali K; Preisig-Müller, Regina; Renigunta, Vijay; Daut, Jürgen; Baukrowitz, Thomas; Sansom, Mark S P; Stansfeld, Phillip J; Decher, Niels

    2011-04-22

    Two-pore domain potassium (K(2P)) channels play a key role in setting the membrane potential of excitable cells. Despite their role as putative targets for drugs and general anesthetics, little is known about the structure and the drug binding site of K(2P) channels. We describe A1899 as a potent and highly selective blocker of the K(2P) channel TASK-1. As A1899 acts as an open-channel blocker and binds to residues forming the wall of the central cavity, the drug was used to further our understanding of the channel pore. Using alanine mutagenesis screens, we have identified residues in both pore loops, the M2 and M4 segments, and the halothane response element to form the drug binding site of TASK-1. Our experimental data were used to validate a K(2P) open-pore homology model of TASK-1, providing structural insights for future rational design of drugs targeting K(2P) channels.

  12. Calcium Channel Blockade and Peroxisome Proliferator Activated Receptor γ Agonism Diminish Cognitive Loss and Preserve Endothelial Function During Diabetes Mellitus.

    Science.gov (United States)

    Jain, Swati; Sharma, B M; Sharma, Bhupesh

    2016-01-01

    Diabetes mellitus is considered as a main risk factor for vascular dementia. In the past, we have reported the induction of vascular dementia (VaD) by experimental diabetes. This study investigates the efficacy of a nifedipine, a calcium channel blocker and pioglitazone in the pharmacological interdiction of pancreatectomy diabetes (PaD) induced vascular endothelial dysfunction and subsequent VaD in rats. Attentional set shifting (ASST) and Morris water-maze (MWM) test were used for assessment of learning and memory. Vascular endothelial function, blood brain barrier permeability, serum glucose, serum nitrite/nitrate, oxidative stress (viz. aortic superoxide anion, brain thiobarbituric acid reactive species and brain glutathione), brain calcium and inflammation (myeloperoxidase) were also estimated. PaD rats have shown impairment of endothelial function, blood brain barrier permeability, learning and memory along with an increase in brain inflammation, oxidative stress and calcium. Administration of nifedipine and pioglitazone significantly attenuated PaD induced impairment of learning, memory, blood brain barrier permeability, endothelial function and biochemical parameters. It may be concluded that nifedipine, a calcium channel blocker may be considered as a potent pharmacological agent for the management of PaD induced endothelial dysfunction and subsequent VaD.

  13. Neuroprotective effects of volume-regulated anion channel blocker DCPIB on neonatal hypoxic-ischemic injury

    Institute of Scientific and Technical Information of China (English)

    Ammar ALIBRAHIM; Li-yan ZHAO; Christine You-jin BAE; Andrew BARSZCZYK; Christopher LF SUN; Guan-lei WANG; Hong-shuo SUN

    2013-01-01

    Aim:To evaluate the role of swelling-induced activation of volume-regulated anion channels (VRACs) in a neonatal hypoxic-ischemic injury model using the selective VRAC blocker 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on5-yl) oxobutyric acid (DCPIB).Methods:Cerebral hypoxic-ischemic injury was induced in 7-day-old mouse pups with Rice-Vannucci method.Prior to the onset of ischemia,the animals were ip administered DCPIB (10 mg/kg).The animals were sacrificed 24 h afterwards,coronal sections of the brains were cut and the areas of infarct were examined using TTC staining and an image-analysis system.Cultured PC12 cells were subjected to oxygen-glucose deprivation (OGD) for 4 h.The cellular viability was assessed using Cell Counting Kit 8.Intracellular chloride concentration [Clˉ]i was measured using 6-methoxy-N-ethylquinolinium iodide.Results:DCPIB-treated mice showed a significant reduction in hemispheric corrected infarct volume (26.65%+2.23%) compared to that in vehicle-treated mice (45.52%+1.45%,P<O.O01).DCPIB-treated mice also showed better functional recovery as they were more active than vehicle-treated mice at 4 and 24 h post injury.In cultured PC12 cells,DCPIB (10 μmol/L) significantly reduced OGD-induced cell death.Moreover,DCPIB (20 μmol/L) blocked hypotonic-induced decrease in [Clˉ]i in PC12 cells of both control and OGD groups.Conclusion:The results further support the pathophysiological role of VRACs in ischemic brain injury,and suggest DCPIB as a potential,easily administrable agent targeting VRACs in the context of perinatal and neonatal hypoxic-ischemic brain injury.

  14. Loop diuretics are open-channel blockers of the cystic fibrosis transmembrane conductance regulator with distinct kinetics

    Science.gov (United States)

    Ju, Min; Scott-Ward, Toby S; Liu, Jia; Khuituan, Pissared; Li, Hongyu; Cai, Zhiwei; Husbands, Stephen M; Sheppard, David N

    2014-01-01

    BACKGROUND AND PURPOSE Loop diuretics are widely used to inhibit the Na+, K+, 2Cl− co-transporter, but they also inhibit the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. Here, we investigated the mechanism of CFTR inhibition by loop diuretics and explored the effects of chemical structure on channel blockade. EXPERIMENTAL APPROACH Using the patch-clamp technique, we tested the effects of bumetanide, furosemide, piretanide and xipamide on recombinant wild-type human CFTR. KEY RESULTS When added to the intracellular solution, loop diuretics inhibited CFTR Cl− currents with potency approaching that of glibenclamide, a widely used CFTR blocker with some structural similarity to loop diuretics. To begin to study the kinetics of channel blockade, we examined the time dependence of macroscopic current inhibition following a hyperpolarizing voltage step. Like glibenclamide, piretanide blockade of CFTR was time and voltage dependent. By contrast, furosemide blockade was voltage dependent, but time independent. Consistent with these data, furosemide blocked individual CFTR Cl− channels with ‘very fast’ speed and drug-induced blocking events overlapped brief channel closures, whereas piretanide inhibited individual channels with ‘intermediate’ speed and drug-induced blocking events were distinct from channel closures. CONCLUSIONS AND IMPLICATIONS Structure–activity analysis of the loop diuretics suggests that the phenoxy group present in bumetanide and piretanide, but absent in furosemide and xipamide, might account for the different kinetics of channel block by locking loop diuretics within the intracellular vestibule of the CFTR pore. We conclude that loop diuretics are open-channel blockers of CFTR with distinct kinetics, affected by molecular dimensions and lipophilicity. PMID:24117047

  15. Potential L-Type Voltage-Operated Calcium Channel Blocking Effect of Drotaverine on Functional Models.

    Science.gov (United States)

    Patai, Zoltán; Guttman, András; Mikus, Endre G

    2016-12-01

    Drotaverine is considered an inhibitor of cyclic-3',5'-nucleotide-phophodiesterase (PDE) enzymes; however, published receptor binding data also support the potential L-type voltage- operated calcium channel (L-VOCC) blocking effect of drotaverine. Hence, in this work, we focus on the potential L-VOCC blocking effect of drotaverine by using L-VOCC-associated functional in vitro models. Accordingly, drotaverine and reference agents were tested on KCl-induced guinea pig tracheal contraction. Drotaverine, like the L-VOCC blockers nifedipine or diltiazem, inhibited the KCl-induced inward Ca(2+)- induced contraction in a concentration- dependent fashion. The PDE inhibitor theophylline had no effect on the KCl-evoked contractions, indicating its lack of inhibition on inward Ca(2+) flow. Drotaverine was also tested on the L-VOCC-mediated resting Ca(2+) refill model. In this model, the extracellular Ca(2+) enters the cells to replenish the emptied intracellular Ca(2+) stores. Drotaverine and L-VOCC blocker reference molecules inhibited Ca(2+) replenishment of Ca(2+)-depleted preparations detected by agonist-induced contractions in post-Ca(2+) replenishment Ca(2+)-free medium. Theophylline did not modify the Ca(2+) store replenishment after contraction. It seems that drotaverine, but not theophylline, inhibits inward Ca(2+) flux. The addition of CaCl2 to Ca(2+)-free medium containing the agonist induced inward Ca(2+) flow and subsequent contraction of Ca(2+)-depleted tracheal preparations. Drotaverine, similar to the L-VOCC blockers, inhibited inward Ca(2+) flow and blunted the slope of CaCl2-induced contraction in agonist containing Ca(2+)-free medium with Ca(2+)-depleted tracheal preparations. These results show that drotaverine behaves like L-VOCC blockers but, unlike PDE inhibitors using L-VOCC associated in vitro experimental models.

  16. T-type calcium channel: a privileged gate for calcium entry and control of adrenal steroidogenesis

    Directory of Open Access Journals (Sweden)

    Michel Florian Rossier

    2016-05-01

    Full Text Available Intracellular calcium plays a crucial role in modulating a variety of functions such as muscle contraction, hormone secretion, gene expression or cell growth. Calcium signaling has been however shown to be more complex than initially thought. Indeed, it is confined within cell microdomains and different calcium channels are associated with different functions, as shown by various channelopathies.Sporadic mutations on voltage-operated L-type calcium channels in adrenal glomerulosa cells have been shown recently to be the second most prevalent genetic abnormalities present in human aldosterone-producing adenoma. The observed modification of the threshold of activation of the mutated channels not only provides an explanation for this gain of function but reminds us on the importance of maintaining adequate electrophysiological characteristics to make channels able to exert specific cellular functions. Indeed, the contribution to steroid production of the various calcium channels expressed in adrenocortical cells is not equal and the reason has been investigated for a long time. Given the very negative resting potential of these cells, and the small membrane depolarization induced by their physiological agonists, low threshold T-type calcium channels are particularly well suited for responding under these conditions and conveying calcium into the cell, at the right place for controlling steroidogenesis. In contrast, high threshold L-type channels are normally activated by much stronger cell depolarizations. The fact that dihydropyridine calcium antagonists, specific for L-type channels, are poorly efficient for reducing aldosterone secretion either in vivo or in vitro, strongly supports the view that these two types of channels differently affect steroid biosynthesis.Whether a similar analysis is transposable to fasciculata cells and cortisol secretion is one of the questions addressed in the present review. No similar mutations on L-type or T

  17. Calcium-activated chloride channel TMEM16A modulates mucin secretion and airway smooth muscle contraction

    Science.gov (United States)

    Huang, Fen; Zhang, Hongkang; Wu, Meng; Yang, Huanghe; Kudo, Makoto; Peters, Christian J.; Woodruff, Prescott G.; Solberg, Owen D.; Donne, Matthew L.; Huang, Xiaozhu; Sheppard, Dean; Fahy, John V.; Wolters, Paul J.; Hogan, Brigid L. M.; Finkbeiner, Walter E.; Li, Min; Jan, Yuh-Nung; Jan, Lily Yeh; Rock, Jason R.

    2012-01-01

    Mucous cell hyperplasia and airway smooth muscle (ASM) hyperresponsiveness are hallmark features of inflammatory airway diseases, including asthma. Here, we show that the recently identified calcium-activated chloride channel (CaCC) TMEM16A is expressed in the adult airway surface epithelium and ASM. The epithelial expression is increased in asthmatics, particularly in secretory cells. Based on this and the proposed functions of CaCC, we hypothesized that TMEM16A inhibitors would negatively regulate both epithelial mucin secretion and ASM contraction. We used a high-throughput screen to identify small-molecule blockers of TMEM16A-CaCC channels. We show that inhibition of TMEM16A-CaCC significantly impairs mucus secretion in primary human airway surface epithelial cells. Furthermore, inhibition of TMEM16A-CaCC significantly reduces mouse and human ASM contraction in response to cholinergic agonists. TMEM16A-CaCC blockers, including those identified here, may positively impact multiple causes of asthma symptoms. PMID:22988107

  18. The molecular choreography of a store-operated calcium channel.

    Science.gov (United States)

    Lewis, Richard S

    2007-03-15

    Store-operated calcium channels (SOCs) serve essential functions from secretion and motility to gene expression and cell growth. A fundamental mystery is how the depletion of Ca2+ from the endoplasmic reticulum (ER) activates Ca2+ entry through SOCs in the plasma membrane. Recent studies using genetic approaches have identified genes encoding the ER Ca2+ sensor and a prototypic SOC, the Ca2+-release-activated Ca2+ (CRAC) channel. New findings reveal a unique mechanism for channel activation, in which the CRAC channel and its sensor migrate independently to closely apposed sites of interaction in the ER and the plasma membrane.

  19. Store-operated calcium channels and pro-inflammatory signals

    Institute of Scientific and Technical Information of China (English)

    Wei-chiao CHANG

    2006-01-01

    In non-excitable cells such as T lymphocytes,hepatocytes,mast cells,endothelia and epithelia,the major pathway for calcium(Ca2+)entry is through store-operated Ca2+ channels in the plasma membrane.These channels are activated by the emptying of intracellular Ca2+ stores,however,neither the gating mechanism nor the downstream targets of these channels has been clear established.Here,I review some of the proposed gating mechanisms of store-operated Ca2+ channels and the functional implications in regulating pro-inflammatory signals.

  20. CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

    Science.gov (United States)

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-09-01

    A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p ACM (p ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

  1. Regulation of voltage gated calcium channels by GPCRs and post-translational modification.

    Science.gov (United States)

    Huang, Junting; Zamponi, Gerald W

    2016-10-18

    Calcium entry via voltage gated calcium channels mediates a wide range of physiological functions, whereas calcium channel dysregulation has been associated with numerous pathophysiological conditions. There are myriad cell signaling pathways that act on voltage gated calcium channels to fine tune their activities and to regulate their cell surface expression. These regulatory mechanisms include the activation of G protein-coupled receptors and downstream phosphorylation events, and their control over calcium channel trafficking through direct physical interactions. Calcium channels also undergo post-translational modifications that alter both function and density of the channels in the plasma membrane. Here we focus on select aspects of these regulatory mechanisms and highlight recent developments.

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

    Science.gov (United States)

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

    2015-01-01

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

  3. Inhibition of N-Type Calcium Channels by Fluorophenoxyanilide Derivatives

    Directory of Open Access Journals (Sweden)

    Ellen C. Gleeson

    2015-04-01

    Full Text Available A set of fluorophenoxyanilides, designed to be simplified analogues of previously reported ω-conotoxin GVIA mimetics, were prepared and tested for N-type calcium channel inhibition in a SH-SY5Y neuroblastoma FLIPR assay. N-type or Cav2.2 channel is a validated target for the treatment of refractory chronic pain. Despite being significantly less complex than the originally designed mimetics, up to a seven-fold improvement in activity was observed.

  4. The Cl− channel blocker niflumic acid releases Ca2+ from an intracellular store in rat pulmonary artery smooth muscle cells

    Science.gov (United States)

    Cruickshank, Stuart F; Baxter, Lynne M; Drummond, Robert M

    2003-01-01

    The effect of the Cl− channel blockers niflumic acid (NFA), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), and anthracene-9-carboxylic acid (A-9-C), on Ca2+ signalling in rat pulmonary artery smooth muscle cells was examined. Intracellular Ca2+ concentration ([Ca2+]i) was monitored with either fura-2 or fluo-4, and caffeine was used to activate the ryanodine receptor, thereby releasing Ca2+ from the sarcoplasmic reticulum (SR). NFA and NPPB significantly increased basal [Ca2+]i and attenuated the caffeine-induced increase in [Ca2+]i. These Cl− channel blockers also increased the half-time (t1/2) to peak for the caffeine-induced [Ca2+]i transient, and slowed the removal of Ca2+ from the cytosol following application of caffeine. Since DIDS and A-9-C were found to adversely affect fura-2 fluorescence, fluo-4 was used to monitor intracellular Ca2+ in studies involving these Cl− channel blockers. Both DIDS and A-9-C increased basal fluo-4 fluorescence, indicating an increase in intracellular Ca2+, and while DIDS had no significant effect on the t1/2 to peak for the caffeine-induced Ca2+ transient, it was significantly increased by A-9-C. In the absence of extracellular Ca2+, NFA significantly increased basal [Ca2+]i, suggesting that the release of Ca2+ from an intracellular store was responsible for the observed effect. Depleting the SR with the combination of caffeine and cyclopiazonic acid prevented the increase in basal [Ca2+]i induced by NFA. Additionally, incubating the cells with ryanodine also prevented the increase in basal [Ca2+]i induced by NFA. These data show that Cl− channel blockers have marked effects on Ca2+ signalling in pulmonary artery smooth muscle cells. Furthermore, examination of the NFA-induced increase in [Ca2+]i indicates that it is likely due to Ca2+ release from an intracellular store, most probably the SR. PMID:14623766

  5. The Cl(-) channel blocker niflumic acid releases Ca(2+) from an intracellular store in rat pulmonary artery smooth muscle cells.

    Science.gov (United States)

    Cruickshank, Stuart F; Baxter, Lynne M; Drummond, Robert M

    2003-12-01

    The effect of the Cl- channel blockers niflumic acid (NFA), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), and anthracene-9-carboxylic acid (A-9-C), on Ca2+ signalling in rat pulmonary artery smooth muscle cells was examined. Intracellular Ca2+ concentration ([Ca2+]i) was monitored with either fura-2 or fluo-4, and caffeine was used to activate the ryanodine receptor, thereby releasing Ca2+ from the sarcoplasmic reticulum (SR). NFA and NPPB significantly increased basal [Ca2+]i and attenuated the caffeine-induced increase in [Ca2+]i. These Cl- channel blockers also increased the half-time (t1/2) to peak for the caffeine-induced [Ca2+]i transient, and slowed the removal of Ca2+ from the cytosol following application of caffeine. Since DIDS and A-9-C were found to adversely affect fura-2 fluorescence, fluo-4 was used to monitor intracellular Ca2+ in studies involving these Cl- channel blockers. Both DIDS and A-9-C increased basal fluo-4 fluorescence, indicating an increase in intracellular Ca2+, and while DIDS had no significant effect on the t1/2 to peak for the caffeine-induced Ca2+ transient, it was significantly increased by A-9-C. In the absence of extracellular Ca2+, NFA significantly increased basal [Ca2+]i, suggesting that the release of Ca2+ from an intracellular store was responsible for the observed effect. Depleting the SR with the combination of caffeine and cyclopiazonic acid prevented the increase in basal [Ca2+]i induced by NFA. Additionally, incubating the cells with ryanodine also prevented the increase in basal [Ca2+]i induced by NFA. These data show that Cl- channel blockers have marked effects on Ca2+ signalling in pulmonary artery smooth muscle cells. Furthermore, examination of the NFA-induced increase in [Ca2+]i indicates that it is likely due to Ca2+ release from an intracellular store, most probably the SR.

  6. Ion Channel Blockers as Antimicrobial Agents, Efflux Inhibitors, and Enhancers of Macrophage Killing Activity against Drug Resistant Mycobacterium tuberculosis.

    Directory of Open Access Journals (Sweden)

    Diana Machado

    Full Text Available Given the ability of M. tuberculosis to survive as an intracellular pathogen and its propensity to develop resistance to the existing antituberculosis drugs, its treatment requires new approaches. Here the antimycobacterial properties of verapamil, thioridazine, chlorpromazine, flupenthixol and haloperidol were investigated against a panel of drug resistant M. tuberculosis strains, both in vitro and on human-infected macrophages. These compounds are efflux inhibitors that share among them the characteristic of being ion channel blockers. In vitro, all compounds exhibited synergistic inhibitory activities when combined with isoniazid and rifampicin, and were able to inhibit active efflux, demonstrating their role as efflux inhibitors. Gene expression analysis showed that M. tuberculosis efflux genes were overexpressed in response to antibiotic exposure, in vitro and within macrophages, irrespective of their resistance pattern. These compounds displayed a rapid and high killing activity against M. tuberculosis, associated with a decrease in intracellular ATP levels demonstrating that the bactericidal action of the ion channel blockers against M. tuberculosis clinical strains is associated with their interference with energy metabolism. The compounds led to a decrease in the intracellular mycobacterial load by increasing phagosome acidification and activating lysosomal hydrolases. The results presented in this study enable us to propose the following mechanism of action for these compounds: a in the bacteria, the compounds generate a cascade of events involving the inhibition of the respiratory chain complexes and energy production for efflux activity. Indirectly, this reduce the resistance level to antituberculosis drugs potentiating their activity; b on the host cell, the treatment with the ion channel blockers increases phagosome acidification and induces the expression of phagosomal hydrolases, leading to bacterial growth restriction

  7. Diltiazem and verapamil preferentially block inactivated cardiac calcium channels.

    Science.gov (United States)

    Kanaya, S; Arlock, P; Katzung, B G; Hondeghem, L M

    1983-02-01

    Diltiazem has been proposed to act by blocking calcium channels of cardiac and smooth muscle since it has pharmacological [12-14] and clinical [10] effects that resemble those of verapamil, an agent that has been shown to block these channels [3]. However, block of the slow inward current by diltiazem has not been directly demonstrated. In fact, it has been suggested that diltiazem has an entirely different mechanism of action [7]. We therefore studied the blocking effects of diltiazem and verapamil on cardiac calcium channels by measuring the slow inward current in voltage-clamped ferret myocardium. Both drugs blocked the slow inward current in a use-dependent fashion, i.e. the block was enhanced by increased frequency of activating clamps and by more positive holding potentials. However, we found that short single activating clamps resulted in minimal block, whereas prolonging the clamp step progressively enhanced the blockade. Thus, a single long clamp caused as much blockade as a train of shorter pulses. These results demonstrate that diltiazem and verapamil block the slow inward current by binding to calcium channels in a state-dependent fashion, i.e. inactivated channels have a high affinity for the drugs, while rested and open channels have a lower affinity.

  8. Oxidative Stress and Maxi Calcium-Activated Potassium (BK Channels

    Directory of Open Access Journals (Sweden)

    Anton Hermann

    2015-08-01

    Full Text Available All cells contain ion channels in their outer (plasma and inner (organelle membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells, alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences.

  9. Effects and mechanisms of store-operated calcium channel blockade on hepatic ischemia-reperfusion injury in rats

    Institute of Scientific and Technical Information of China (English)

    Li-Jie Pan; Zi-Chao Zhang; Zhen-Ya Zhang; Wen-Jun Wang; Yue Xu; Zong-Ming Zhang

    2012-01-01

    AIM: To further investigate the important role of storeoperated calcium channels (SOCs) in rat hepatocytes and to explore the effects of SOC blockers on hepatic ischemia-reperfusion injury (HIRI). METHODS: Using freshly isolated hepatocytes from a rat model of HIRI (and controls), we measured cytosolic free Ca2+ concentration (by calcium imaging), net Ca2+ fluxes (by a non-invasive micro-test technique), the SOC current (ISOC; by whole-cell patch-clamp recording), and taurocholate secretion [by high-performance liquid chromatography and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays]. RESULTS: Ca2+ oscillations and net Ca2+ fluxes mediated by Ca2+ entry via SOCs were observed in rat hepatocytes. ISOC was significantly higher in HIRI groups than in controls (57.0 ± 7.5 pA vs 31.6 ± 2.7 pA, P <0.05) and was inhibited by La3+. Taurocholate secretion by hepatocytes into culture supernatant was distinctly lower in HIRI hepatocytes than in controls, an effect reversed by SOC blockers. CONCLUSION: SOCs are pivotal in HIRI. SOC blockers protected against HIRI and assisted the recovery of secretory function in hepatocytes. Thus, they are likely to become a novel class of effective drugs for prevention or therapy of HIRI patients in the future.

  10. Mechanism underlying blockade of voltage-gated calcium channels by agmatine in cultured rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Jian-quan ZHENG; Xie-chuan WENG; Xiao-dan GAI; Jin LI; Wen-bin XIAO

    2004-01-01

    AIM: To investigate whether agmatine could selectively block a given type of the voltage-gated calcium channels (VGCC) and whether related receptors are involved in the blocking effect of agmatine on VGCC. METHODS: The whole-cell patch recording technique was performed to record VGCC currents in the cultured neonatal rat hippocampal neurons. RESULTS: Verapamil (100 μmol/L), a selective blocker of L-type calcium channel, significantly inhibited VGCC current by 80 %± 7 %. Agmatine (100 μmol/L) could further depress the remained currents by 25 %±6 %. The α2-adrenoceptor antagonist yohimbine (10 μmol/L) and the I2 imidazoline receptor antagonist idazoxon (10 and 40 μmol/L) had no significant effect on VGCC currents when used respectively. When the mixture of yohimbine and agmatine was applied, VGCC currents were still depressed remarkably. However, the blocking effect of agmatine was decreased by 29 %± 8 % in the presence of idazoxon (10 μmol/L). The effect of idazoxon did not increase at a higher concentration (40 μmol/L). CONCLUSION: Agmatine could block the L- and other types of VGCC currents in the cultured rat hippocampal neurons. Blocking effect of agmatine on VGCC was partially related to I2 imidazoline receptor and had no relationship with α2-adrenoceptors.

  11. A novel high-throughput screening assay for HCN channel blocker using membrane potential-sensitive dye and FLIPR.

    Science.gov (United States)

    Vasilyev, Dmitry V; Shan, Qin J; Lee, Yan T; Soloveva, Veronica; Nawoschik, Stanley P; Kaftan, Edward J; Dunlop, John; Mayer, Scott C; Bowlby, Mark R

    2009-10-01

    Hyperpolarization-activated cation nonselective (HCN) channels represent an interesting group of targets for drug development. In this study, the authors report the development of a novel membrane potential-sensitive dye (MPSD) assay for HCN channel modulators that has been miniaturized into 384-well fluorescent imaging plate reader (FLIPR) high-throughput screening (HTS) format. When optimized (by cell plating density, plate type, cell recovery from cryopreservation), the well-to-well signal variability was low, with a Z' = 0.73 and coefficient of variation = 6.4%, whereas the MPSD fluorescence signal amplitude was -23,700 +/- 1500 FLIPR(3) relative fluorescence units (a linear relationship was found between HCN1 MPSD fluorescence signal and the cell plating density) and was completely blocked by 30 microM ZD7288. The assay tolerated up to 1% DMSO, inclusion of which did not significantly change the signal kinetics or amplitude. A single-concentration screening of an ion channel-focused library composed of 4855 compounds resulted in 89 HCN1 blocker hits, 51 of which were subsequently analyzed with an 8-point concentration-response analysis on the IonWorks HT electrophysiology platform. The correlation between MPSD and the electrophysiology assay was moderate, as shown by the linear regression analysis (r(2) = 0.56) between the respective IC(50)s obtained using these 2 assays. The reported HTS-compatible HCN channel blocker assay can serve as a tool in drug discovery in the pursuit of HCN channel isoform-selective small molecules that could be used in the development of clinically relevant compounds.

  12. Kv1.5 blockers preferentially inhibit TASK-1 channels: TASK-1 as a target against atrial fibrillation and obstructive sleep apnea?

    Science.gov (United States)

    Kiper, Aytug K; Rinné, Susanne; Rolfes, Caroline; Ramírez, David; Seebohm, Guiscard; Netter, Michael F; González, Wendy; Decher, Niels

    2015-05-01

    Atrial fibrillation and obstructive sleep apnea are responsible for significant morbidity and mortality in the industrialized world. There is a high medical need for novel drugs against both diseases, and here, Kv1.5 channels have emerged as promising drug targets. In humans, TASK-1 has an atrium-specific expression and TASK-1 is also abundantly expressed in the hypoglossal motor nucleus. We asked whether known Kv1.5 channel blockers, effective against atrial fibrillation and/or obstructive sleep apnea, modulate TASK-1 channels. Therefore, we tested Kv1.5 blockers with different chemical structures for their TASK-1 affinity, utilizing two-electrode voltage clamp (TEVC) recordings in Xenopus oocytes. Despite the low structural conservation of Kv1.5 and TASK-1 channels, we found all Kv1.5 blockers analyzed to be even more effective on TASK-1 than on Kv1.5. For instance, the half-maximal inhibitory concentration (IC50) values of AVE0118 and AVE1231 (A293) were 10- and 43-fold lower on TASK-1. Also for MSD-D, ICAGEN-4, S20951 (A1899), and S9947, the IC50 values were 1.4- to 70-fold lower than for Kv1.5. To describe this phenomenon on a molecular level, we used in silico models and identified unexpected structural similarities between the two drug binding sites. Kv1.5 blockers, like AVE0118 and AVE1231, which are promising drugs against atrial fibrillation or obstructive sleep apnea, are in fact potent TASK-1 blockers. Accordingly, block of TASK-1 channels by these compounds might contribute to the clinical effectiveness of these drugs. The higher affinity of these blockers for TASK-1 channels suggests that TASK-1 might be an unrecognized molecular target of Kv1.5 blockers effective in atrial fibrillation or obstructive sleep apnea.

  13. Characterization of a new Kv1.3 channel-specific blocker, J123, from the scorpion Buthus martensii Karsch.

    Science.gov (United States)

    Shijin, Yin; Hong, Yi; Yibao, Ma; Zongyun, Chen; Han, Song; Yingliang, Wu; Zhijian, Cao; Wenxin, Li

    2008-09-01

    The potassium channel Kv1.3 is an attractive pharmacological target for T-cell-mediated autoimmune diseases, and specific and selective peptidic blockers of Kv1.3 channels have served as valuable therapeutic leads for treating these diseases. Here, we found a new peptide toxin, J123, with 43 amino acids including six cysteine residues by screening the venomous cDNA library of scorpion Buthus martensii Karsch, which has been used as traditional medicine in China for more than 2000 years. The sequence analysis suggested that peptide J123 constituted a new member of the alpha-KTx toxins. The electrophysiological experiments further indicated that peptide J123 has a novel pharmacological profiles: it blocked Kv1.3 channel with high potency (IC50=0.79 nM), and exhibited good selectivity on Kv1.3 over Kv1.1 (>1000-fold) and Kv1.2 (about 30-fold), respectively. Furthermore, peptide J123 had no activity on SKCa2 and SKCa3 channels at micromolar concentration level. Based on the pharmacological activities, the possible channel-interacting surface of peptide J123 was also predicted by molecular modeling and docking. All these data not only enrich the knowledge of the structure-function relationship of the new Kv1.3-speicific peptide but also present a potential drug candidate for selectively targeting Kv1.3 channels.

  14. Identification of a new specific Kv1.3 channel blocker, Ctri9577, from the scorpion Chaerilus tricostatus.

    Science.gov (United States)

    Xie, Shujun; Feng, Jing; Yu, Congya; Li, Zhi; Wu, Yingliang; Cao, Zhijian; Li, Wenxin; He, Xiaohua; Xiang, Ming; Han, Song

    2012-07-01

    Scorpion toxins are valuable resources for discovering new ion channel modulators and drug candidates. Potassium channel Kv1.3 is an important pharmacological target of T cell-mediated autoimmune diseases, which are encouraging the screening and design of the specific peptide blockers for Kv1.3 channel. Ctri9577, the first neurotoxin gene of Chaerilidae family was cloned from the venom of the scorpion Chaerilus tricostatus through the constructing its cDNA library. The sequence analysis showed that the mature peptide of Ctri9577 contained 39 amino acid residues including six conserved cysteines, whose low sequence similarity indicated that it was a new member of α-KTx15 subfamily. By using expression and purification technology, the recombinant peptide was obtained. Subsequently, the electrophysiological experiments indicated that the Ctri9577 peptide selectively inhibited Kv1.3 channel current with an IC(50) of 0.49±0.45 nM without effectively blocking potassium channels Kv1.1, Kv1.2, hERG and SK3. All these findings not only enrich the knowledge of toxins from the Chaerilidae family, but also present a novel potential drug candidate targeting Kv1.3 channels for the therapy of autoimmune diseases.

  15. Actin Dynamics Regulates Voltage-Dependent Calcium-Permeable Channels of the Vicia faba Guard Cell Plasma Membrane

    Institute of Scientific and Technical Information of China (English)

    Wei Zhang; Liu-Min Fan

    2009-01-01

    Free cytosolic Ca~(2+) ([Ca~(2+)]_(cyt)) is an ubiquitous second messenger in plant cell signaling, and [Ca~(2+)]_(cyt) elevation is associated with Ca~(2+)-permeable channels in the plasma membrane and endomembranes regulated by a wide range of stimuli. However, knowledge regarding Ca~(2+) channels and their regulation remains limited in planta. A type of voltage-dependent Ca~(2+)-permeable channel was identified and characterized for the Vicia faba L. guard cell plasma membrane by using patch-clamp techniques. These channels are permeable to both Ba~(2+) and Ca~(2+), and their activities can be inhibited by micromolar Gd~(3+). The unitary conductance and the reversal potential of the channels depend on the Ca~(2+) or Ba~(2+) gradients across the plasma membrane. The inward whole-cell Ca~(2+) (Ba~(2+)) current, as well as the unitary current amplitude and NP. of the single Ca~(2+) channel, increase along with the membrane hyperpolarization. Pharmacological experiments suggest that actin dynamics may serve as an upstream regulator of this type of calcium channel of the guard cell plasma membrane. Cytochalasin D, an actin polymerization blocker, activated the NP_o of these channels at the single channel level and increased the current amplitude at the whole-cell level. But these channel activations and current increments could be restrained by pretreatment with an F-actin stabilizer, phalloidin. The potential physiological significance of this regulatory mechanism is also discussed.

  16. Heterogeneity of Calcium Channel/cAMP-Dependent Transcriptional Activation.

    Science.gov (United States)

    Kobrinsky, Evgeny

    2015-01-01

    The major function of the voltage-gated calcium channels is to provide the Ca(2+) flux into the cell. L-type voltage-gated calcium channels (Cav1) serve as voltage sensors that couple membrane depolarization to many intracellular processes. Electrical activity in excitable cells affects gene expression through signaling pathways involved in the excitation-transcription (E-T) coupling. E-T coupling starts with activation of the Cav1 channel and results in initiation of the cAMP-response element binding protein (CREB)-dependent transcription. In this review we discuss the new quantitative approaches to measuring E-T signaling events. We describe the use of wavelet transform to detect heterogeneity of transcriptional activation in nuclei. Furthermore, we discuss the properties of discovered microdomains of nuclear signaling associated with the E-T coupling and the basis of the frequency-dependent transcriptional regulation.

  17. The beta-adrenergic blocker carvedilol restores L-type calcium current in a myocardial infarction model of rabbit

    Institute of Scientific and Technical Information of China (English)

    LI Xia; HUANG Cong-xin; JIANG Hong; CAO Feng; WANG Teng

    2005-01-01

    Background Carvedilol, an antagonist of α1- and β-adrenergic receptors, has shown efficacy in reducing all-cause death and arrhythmia death for ischemic heart disease and congestive heart failure in several large-scale trials. It has been found to prevent ventricular remodeling, and recently was reported to reverse down-regulation of Na+ channel in a chronic heart failure model. This study was conducted to investigate whether carvedilol could reverse the ion remodeling in a myocardial infarction model of rabbit.Methods After the procedure of coronary ligation, animals were randomized to placebo or carvedilol treatment (5 mg/kg). Action potentials, L-type calcium current (Ica L) and the effect of isoproterenol stimulation on Ica L were measured using whole-cell patch method. Evaluation of the expression of calcium channel subunits was carried out by RT-PCR and Western blot. Results The results indicate that mean peak Ica L densities (pA/pF) at +10 mV was reduced in postinfarction myocytes (5.33±0.45, n=25) compared to sham myocytes (6.52±0.21, n=20). Treatment of myocardial infarction rabbits with carvedilol could restore it partially (5.91±0.39, n=20, P<0.05). However, steady-state activation parameters were similar in three groups. With stimulation by isoproterenol (1 μmol/L) Ica L increased in all three groups, but the increase was smaller in postinfarction myocytes. mRNA levels of calcium channel subunit CaA1 gene was decreased but CaB2a, CaB2b and CaB3 mRNA levels did not change after MI. Corresponding change in CaA1 protein was also observed. Conclusions The results demonstrate that carvedilol restores Ica L density and reverse the downregulation of CaA1 postinfarction.

  18. ZD7288, a selective hyperpolarization-activated cyclic nucleotide-gated channel blocker, inhibits hippocampal synaptic plasticity

    Institute of Scientific and Technical Information of China (English)

    Xiao-xue Zhang; Xiao-chun Min; Xu-lin Xu; Min Zheng; Lian-jun Guo

    2016-01-01

    The selective hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker 4-(N-ethyl-N-phenylamino)-1,2-dimeth-yl-6-(methylamino) pyrimidinium chloride (ZD7288) blocks the induction of long-term potentiation in the perforant path–CA3 region in rat hippocampusin vivo. To explore the mechanisms underlying the action of ZD7288, we recorded excitatory postsynaptic potentials in perforant path–CA3 synapses in male Sprague-Dawley rats. We measured glutamate content in the hippocampus and in cultured hip-pocampal neurons using high performance liquid chromatography, and determined intracellular Ca2+ concentration ([Ca2+]i) using Fura-2. ZD7288 inhibited the induction and maintenance of long-term potentiation, and these effects were mirrored by the nonspeciifc HCN channel blocker cesium. ZD7288 also decreased glutamate release in hippocampal tissue and in cultured hippocampal neurons. Further-more, ZD7288 attenuated glutamate-induced rises in [Ca2+]i in a concentration-dependent manner and reversed 8-Br-cAMP-mediated facilitation of these glutamate-induced [Ca2+]i rises. Our results suggest that ZD7288 inhibits hippocampal synaptic plasticity both gluta-mate release and resultant [Ca2+]i increases in rat hippocampal neurons.

  19. Mechanisms of atrial fibrillation termination by rapidly unbinding Na+ channel blockers: insights from mathematical models and experimental correlates.

    Science.gov (United States)

    Comtois, Philippe; Sakabe, Masao; Vigmond, Edward J; Munoz, Mauricio; Texier, Anne; Shiroshita-Takeshita, Akiko; Nattel, Stanley

    2008-10-01

    Atrial fibrillation (AF) is the most common sustained clinical arrhythmia and is a problem of growing proportions. Recent studies have increased interest in fast-unbinding Na(+) channel blockers like vernakalant (RSD1235) and ranolazine for AF therapy, but the mechanism of efficacy is poorly understood. To study how fast-unbinding I(Na) blockers affect AF, we developed realistic mathematical models of state-dependent Na(+) channel block, using a lidocaine model as a prototype, and studied the effects on simulated cholinergic AF in two- and three-dimensional atrial substrates. We then compared the results with in vivo effects of lidocaine on vagotonic AF in dogs. Lidocaine action was modeled with the Hondeghem-Katzung modulated-receptor theory and maximum affinity for activated Na(+) channels. Lidocaine produced frequency-dependent Na(+) channel blocking and conduction slowing effects and terminated AF in both two- and three-dimensional models with concentration-dependent efficacy (maximum approximately 89% at 60 microM). AF termination was not related to increases in wavelength, which tended to decrease with the drug, but rather to decreased source Na(+) current in the face of large ACh-sensitive K(+) current-related sinks, leading to the destabilization of primary generator rotors and a great reduction in wavebreak, which caused primary rotor annihilations in the absence of secondary rotors to resume generator activity. Lidocaine also reduced the variability and maximum values of the dominant frequency distribution during AF. Qualitatively similar results were obtained in vivo for lidocaine effects on vagal AF in dogs, with an efficacy of 86% at 2 mg/kg iv, as well as with simulations using the guarded-receptor model of lidocaine action. These results provide new insights into the mechanisms by which rapidly unbinding class I antiarrhythmic agents, a class including several novel compounds of considerable promise, terminate AF.

  20. Formaldehyde increases intracellular calcium concentration in primary cultured hippocampal neurons partly through NMDA receptors and T-type calcium channels

    Institute of Scientific and Technical Information of China (English)

    Ye-Nan Chi; Xu Zhang; Jie Cai; Feng-Yu Liu; Guo-Gang Xing; You Wan

    2012-01-01

    Objective Formaldehyde at high concentrations is a contributor to air pollution.It is also an endogenous metabolic product in cells,and when beyond physiological concentrations,has pathological effects on neurons.Formaldehyde induces mis-folding and aggregation of neuronal tau protein,hippocampal neuronal apoptosis,cognitive impairment and loss of memory functions,as well as excitation of peripheral nociceptive neurons in cancer pain models.Intracellular calcium ([Ca2+]i) is an important intracellular messenger,and plays a key role in many pathological processes.The present study aimed to investigate the effect of formaldehyde on [Ca2+]i and the possible involvement of N-methyl-D-aspartate receptors (NMDARs) and T-type Ca2+ channels on the cell membrane.Methods Using primary cultured hippocampal neurons as a model,changes of [Ca2+]i in the presence of formaldehyde at a low concentration were detected by confocal laser scanning microscopy.Results Formaldehyde at 1 mmol/L approximately doubled [Ca2+]i.(2R)-amino-5-phosphonopentanoate (AP5,25 μtmol/L,an NMDAR antagonist) and mibefradil (MIB,1 μtmol/L,a T-type Ca2+ channel blocker),given 5 min after formaldehyde perfusion,each partly inhibited the formaldehyde-induced increase of [Ca2+]i,and this inhibitory effect was reinforced by combined application of AP5 and MIB.When applied 3 min before formaldehyde perfusion,AP5 (even at 50 μmol/L) did not inhibit the formaldehyde-induced increase of [Ca2+]i,but MIB (1 μmol/L) significantly inhibited this increase by 70%.Conclusion These results suggest that formaldehyde at a low concentration increases [Ca2+]i in cultured hippocampal neurons; NMDARs and T-type Ca2+ channels may be involved in this process.

  1. A novel SCN9A mutation responsible for primary erythromelalgia and is resistant to the treatment of sodium channel blockers.

    Science.gov (United States)

    Wu, Min-Tzu; Huang, Po-Yuan; Yen, Chen-Tung; Chen, Chih-Cheng; Lee, Ming-Jen

    2013-01-01

    Primary erythromelalgia (PE) is an autosomal dominant neurological disorder characterized by severe burning pain and erythema in the extremities upon heat stimuli or exercise. Mutations in human SCN9A gene, encoding the α-subunit of the voltage-gated sodium channel, Na(v)1.7, were found to be responsible for PE. Three missense mutations of SCN9A gene have recently been identified in Taiwanese patients including a familial (I136V) and two sporadic mutations (I848T, V1316A). V1316A is a novel mutation and has not been characterized yet. Topologically, I136V is located in DI/S1 segment and both I848T and V1316A are located in S4-S5 linker region of DII and DIII domains, respectively. To characterize the elelctrophysiological manifestations, the channel conductance with whole-cell patch clamp was recorded on the over-expressed Chinese hamster overy cells. As compared with wild type, the mutant channels showed a significant hyperpolarizing shift in voltage dependent activation and a depolarizing shift in steady-state fast inactivation. The recovery time from channel inactivation is faster in the mutant than in the wild type channels. Since warmth can trigger and exacerbate symptoms, we then examine the influence of tempearture on the sodium channel conduction. At 35°C, I136V and V1316A mutant channels exhibit a further hyperpolarizing shift at activation as compared with wild type channel, even though wild type channel also produced a significant hyperpolarizing shift compared to that of 25°C. High temperature caused a significant depolarizing shift in steady-state fast inactivation in all three mutant channels. These findings may confer to the hyperexcitability of sensory neurons, especially at high temperature. In order to identifying an effective treatment, we tested the IC₅₀ values of selective sodium channel blockers, lidocaine and mexiletine. The IC₅₀ for mexiletine is lower for I848T mutant channel as compared to that of the wild type and other two

  2. A novel SCN9A mutation responsible for primary erythromelalgia and is resistant to the treatment of sodium channel blockers.

    Directory of Open Access Journals (Sweden)

    Min-Tzu Wu

    Full Text Available Primary erythromelalgia (PE is an autosomal dominant neurological disorder characterized by severe burning pain and erythema in the extremities upon heat stimuli or exercise. Mutations in human SCN9A gene, encoding the α-subunit of the voltage-gated sodium channel, Na(v1.7, were found to be responsible for PE. Three missense mutations of SCN9A gene have recently been identified in Taiwanese patients including a familial (I136V and two sporadic mutations (I848T, V1316A. V1316A is a novel mutation and has not been characterized yet. Topologically, I136V is located in DI/S1 segment and both I848T and V1316A are located in S4-S5 linker region of DII and DIII domains, respectively. To characterize the elelctrophysiological manifestations, the channel conductance with whole-cell patch clamp was recorded on the over-expressed Chinese hamster overy cells. As compared with wild type, the mutant channels showed a significant hyperpolarizing shift in voltage dependent activation and a depolarizing shift in steady-state fast inactivation. The recovery time from channel inactivation is faster in the mutant than in the wild type channels. Since warmth can trigger and exacerbate symptoms, we then examine the influence of tempearture on the sodium channel conduction. At 35°C, I136V and V1316A mutant channels exhibit a further hyperpolarizing shift at activation as compared with wild type channel, even though wild type channel also produced a significant hyperpolarizing shift compared to that of 25°C. High temperature caused a significant depolarizing shift in steady-state fast inactivation in all three mutant channels. These findings may confer to the hyperexcitability of sensory neurons, especially at high temperature. In order to identifying an effective treatment, we tested the IC₅₀ values of selective sodium channel blockers, lidocaine and mexiletine. The IC₅₀ for mexiletine is lower for I848T mutant channel as compared to that of the wild type

  3. Effects of acute and chronic nicotine on elevated plus maze in mice: involvement of calcium channels.

    Science.gov (United States)

    Biala, Grazyna; Budzynska, Barbara

    2006-05-30

    The current experiments examined the anxiety-related effects of acute and repeated nicotine administration using the elevated plus maze test in mice. Nicotine (0.1 mg/kg s.c., 5 and 30 min after injection; 0.5 mg/kg, s.c., 5 min after injection) had an anxiogenic effect, shown by specific decreases in the percentage of time spent on the open arms and in the percentage of open arm entries. Tolerance developed to this anxiogenic action after 6 days of daily nicotine administration (0.1 mg/kg, s.c.). Five minutes after the seventh injection, an anxiolytic effect was observed, i.e., specific increases in the percentage of time spent on the open arms and in the percentage of open arm entries. L-type voltage-dependent calcium channel antagonists nimodipine (5 and 10 mg/kg, i.p.), flunarizine (5 and 10 mg/kg, i.p.), verapamil (5, 10, 20 mg/kg) and diltiazem (5, 10, 20 mg/kg, i.p.) were also injected prior to an acute low dose of nicotine or to each injection of chronic nicotine. Our results revealed that calcium channel blockers dose-dependently attenuated both an anxiogenic effect of nicotine as well as the development of tolerance to this effect. Our results suggest that neural calcium-dependent mechanisms are involved in the anxiety-related responses to acute and chronic nicotine injection that may ultimately lead to addiction and smoking relapse in human smokers.

  4. A calcium channel mutant mouse model of hypokalemic periodic paralysis

    OpenAIRE

    Wu, Fenfen; Mi, Wentao; Hernández-Ochoa, Erick O.; Burns, Dennis K.; Fu, Yu; Gray, Hillery F; Struyk, Arie F.; Martin F Schneider; Cannon, Stephen C.

    2012-01-01

    Hypokalemic periodic paralysis (HypoPP) is a familial skeletal muscle disorder that presents with recurrent episodes of severe weakness lasting hours to days associated with reduced serum potassium (K+). HypoPP is genetically heterogeneous, with missense mutations of a calcium channel (CaV1.1) or a sodium channel (NaV1.4) accounting for 60% and 20% of cases, respectively. The mechanistic link between CaV1.1 mutations and the ictal loss of muscle excitability during an attack of weakness in Hy...

  5. Calcium-permeable ion channels in the kidney.

    Science.gov (United States)

    Zhou, Yiming; Greka, Anna

    2016-06-01

    Calcium ions (Ca(2+)) are crucial for a variety of cellular functions. The extracellular and intracellular Ca(2+) concentrations are thus tightly regulated to maintain Ca(2+) homeostasis. The kidney, one of the major organs of the excretory system, regulates Ca(2+) homeostasis by filtration and reabsorption. Approximately 60% of the Ca(2+) in plasma is filtered, and 99% of that is reabsorbed by the kidney tubules. Ca(2+) is also a critical signaling molecule in kidney development, in all kidney cellular functions, and in the emergence of kidney diseases. Recently, studies using genetic and molecular biological approaches have identified several Ca(2+)-permeable ion channel families as important regulators of Ca(2+) homeostasis in kidney. These ion channel families include transient receptor potential channels (TRP), voltage-gated calcium channels, and others. In this review, we provide a brief and systematic summary of the expression, function, and pathological contribution for each of these Ca(2+)-permeable ion channels. Moreover, we discuss their potential as future therapeutic targets.

  6. Characterization of the first K⁺ channel blockers from the venom of the Moroccan scorpion Buthus occitanus Paris.

    Science.gov (United States)

    Martin-Eauclaire, Marie-France; Céard, Brigitte; Belghazi, Maya; Lebrun, Régine; Bougis, Pierre E

    2013-12-01

    The availability of a large variety of specific blockers, which inhibit different K(+) currents, would help to elucidate their differences in physiological function. Short peptide toxins isolated from scorpion venoms are able to block voltage-dependent or Ca(2+)-activated K(+) channels. Here, we have studied the venom of the Moroccan scorpion Buthus occitanus Paris (BoP) in order to find new peptides, which could enlarge our structure-function relationship knowledge on the Kv1.3 blocker Kaliotoxin (KTX) that belongs to the α-KTx3.1 family. Indeed and since more a decade, KTX is widely used by international investigators because it exhibits a quite sharp specificity and a high-affinity for the Kv1.3 channel, which is not only a neuronal channel but also a therapeutic target for diverse autoimmune diseases such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. The BoP venom was first investigated using HPLC and MALDI-TOF/MS. Further, the HPLC fractions were screened by ELISA with antibodies raised against KTX. These antibodies recognized at least three components toxic in mice by intracerebroventricular injection. They were further pharmacologically characterized by competition using (125)I-KTX bound to its specific binding sites on rat brain synaptosomes. A single component (4161 Da) inhibited totally the (125)I-KTX binding and with high-affinity (IC50 = 0.1 nM), while the two other components poorly competed with (IC50 > 100 nM). These toxins were sequenced in full by Edman's degradation. The high-affinity ligand (BoPKTX) shares 86% sequence identity with KTX and was classified as toxin α-KTx3.17. The two others peptides (BoP1 and BoP2, 4093 Da and 4121 Da, respectively) only differ by a Lys/Arg mutation. Their amino acid sequences were related to Martentoxin, which has been characterized from the Chinese scorpion Buthus martenzi Karch and described as both a BKCa and Kv1.3 blocker. Accordingly, they belong to the α-KTx16 family.

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

    Science.gov (United States)

    Hansen, Pernille B L

    2015-02-15

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

  8. Dissection of the Mechanical Impedance Components of the Outer Hair Cell Using a Chloride-Channel Blocker

    Science.gov (United States)

    Harasztosi, Csaba; Gummer, Anthony W.

    2011-11-01

    The voltage-dependent chloride-channel blocker anthracene-9-carboxylic acid (9AC) has been found to reduce the imaginary but not the real part of the mechanical impedance of the organ of Corti, suggesting that the effective stiffness of outer hair cells (OHCs) is reduced by 9AC. To examine whether 9AC interacts directly with the motor protein prestin to reduce the membrane component of the impedance, the patch-clamp technique in whole-cell configuration was used to measure the nonlinear capacitance (NLC) of isolated OHCs and, as control, prestin-transfected human embryonic kidney 293 (HEK293) cells. Extracellular application of 9AC significantly reduced the NLC of both OHCs and HEK293 cells. Intracellular 9AC did not influence the blocking effect of the extracellular applied drug. These results suggest that 9AC interacts directly with prestin, reducing the effective stiffness of the motor, and that the interaction is extracellular.

  9. Hippocampal long-term potentiation is not accompanied by presynaptic spike broadening, unlike synaptic potentiation by K+ channel blockers.

    Science.gov (United States)

    Laerum, H; Storm, J F

    1994-02-21

    The expression of hippocampal long-term potentiation (LTP) is thought to be at least partly due to increased transmitter release. To test whether this increase is due to a broadening of the presynaptic action potential, we have compared the presynaptic fibre volley before and after LTP induction, or application of K+ channel blockers, in CA1 of rat hippocampal slices. Tetraethylammonium (TEA; 1 mM) induced a parallel increase in the fibre volley duration of the slope of the field EPSP, indicating that a presynaptic spike broadening underlying synaptic potentiation can be detected. In contrast, induction of LTP did not produce any measurable change in the fibre volley, although the average increase in the EPSP slope was larger than with TEA. These results indicate that LTP expression is not primarily due to a presynaptic spike broadening.

  10. Presynaptic Localization and Possible Function of Calcium-Activated Chloride Channel Anoctamin 1 in the Mammalian Retina.

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    Ji Hyun Jeon

    Full Text Available Calcium (Ca(2+-activated chloride (Cl(- channels (CaCCs play a role in the modulation of action potentials and synaptic responses in the somatodendritic regions of central neurons. In the vertebrate retina, large Ca(2+-activated Cl(- currents (ICl(Ca regulate synaptic transmission at photoreceptor terminals; however, the molecular identity of CaCCs that mediate ICl(Ca remains unclear. The transmembrane protein, TMEM16A, also called anoctamin 1 (ANO1, has been recently validated as a CaCC and is widely expressed in various secretory epithelia and nervous tissues. Despite the fact that tmem16a was first cloned in the retina, there is little information on its cellular localization and function in the mammalian retina. In this study, we found that ANO1 was abundantly expressed as puncta in 2 synaptic layers. More specifically, ANO1 immunoreactivity was observed in the presynaptic terminals of various retinal neurons, including photoreceptors. ICl(Ca was first detected in dissociated rod bipolar cells expressing ANO1. ICl(Ca was abolished by treatment with the Ca(2+ channel blocker Co(2+, the L-type Ca(2+ channel blocker nifedipine, and the Cl(- channel blockers 5-nitro-2-(3-phenylpropylamino benzoic acid (NPPB and niflumic acid (NFA. More specifically, a recently discovered ANO1-selective inhibitor, T16Ainh-A01, and a neutralizing antibody against ANO1 inhibited ICl(Ca in rod bipolar cells. Under a current-clamping mode, the suppression of ICl(Ca by using NPPB and T16Ainh-A01 caused a prolonged Ca(2+ spike-like depolarization evoked by current injection in dissociated rod bipolar cells. These results suggest that ANO1 confers ICl(Ca in retinal neurons and acts as an intrinsic regulator of the presynaptic membrane potential during synaptic transmission.

  11. TRPC1 regulates calcium-activated chloride channels in salivary gland cells.

    Science.gov (United States)

    Sun, Yuyang; Birnbaumer, Lutz; Singh, Brij B

    2015-11-01

    Calcium-activated chloride channel (CaCC) plays an important role in modulating epithelial secretion. It has been suggested that in salivary tissues, sustained fluid secretion is dependent on Ca(2+) influx that activates ion channels such as CaCC to initiate Cl(-) efflux. However direct evidence as well as the molecular identity of the Ca(2+) channel responsible for activating CaCC in salivary tissues is not yet identified. Here we provide evidence that in human salivary cells, an outward rectifying Cl(-) current was activated by increasing [Ca(2+)]i, which was inhibited by the addition of pharmacological agents niflumic acid (NFA), an antagonist of CaCC, or T16Ainh-A01, a specific TMEM16a inhibitor. Addition of thapsigargin (Tg), that induces store-depletion and activates TRPC1-mediated Ca(2+) entry, potentiated the Cl(-) current, which was inhibited by the addition of a non-specific TRPC channel blocker SKF96365 or removal of external Ca(2+). Stimulation with Tg also increased plasma membrane expression of TMEM16a protein, which was also dependent on Ca(2+) entry. Importantly, in salivary cells, TRPC1 silencing, but not that of TRPC3, inhibited CaCC especially upon store depletion. Moreover, primary acinar cells isolated from submandibular gland also showed outward rectifying Cl(-) currents upon increasing [Ca(2+)]i. These Cl(-) currents were again potentiated with the addition of Tg, but inhibited in the presence of T16Ainh-A01. Finally, acinar cells isolated from the submandibular glands of TRPC1 knockout mice showed significant inhibition of the outward Cl(-) currents without decreasing TMEM16a expression. Together the data suggests that Ca(2+) entry via the TRPC1 channels is essential for the activation of CaCC.

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

    Science.gov (United States)

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

    2015-03-01

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

  13. Effect of calcium channel blocker on gap junctional connexin 43 in infarcted myocardium in rats%钙通道阻滞剂对梗死心肌中不同部位心肌连接蛋白43表达的影响

    Institute of Scientific and Technical Information of China (English)

    杨永健; 速晓华; 唐兵; 李德; 杨大春

    2011-01-01

    目的:研究L和L/T型钙通道阻制剂对梗死心脏不同部位(坏死区域、肥厚区域等)心肌组织中连接蛋白43(Cx43)的影响.方法:随机将大鼠48只分为假手术组、心肌梗死(MI)组、阿莫地平(L型钙通道阻滞剂)组和米贝拉地尔(L/T型钙通道阻滞剂)组(每组n=12只).通过结扎大鼠左冠状动脉建立MI模型,术前7 d,上述4个组分别用安慰剂、L型钙通道阻滞剂阿莫地平4 mg/(kg·d)和L/T型钙通道阻滞剂米贝拉地尔10 mg/(kg·d).术后1、3、7 d,分别检测左心室游离壁(LVFW,梗死区)、心室间隔(IS,肥厚区)和右心室壁(Rv),正常心肌组织中Cx43蛋白的表达.术后7 d显微直视下测LVFW处MI病灶的大小、IS的厚度及左心室的大小.结果:IS中Cx43蛋白表达于术后1、3、7 d呈逐渐增加的趋势;LVFW中Cx43蛋白的表达于术后1、3、7 d时均处于低水平,与对照组相比差异显著(P<0.05).RV中Cx43蛋白的表达于术后1、3、7 d无显著差异,与对照组相比也无显著性差异.米贝拉地尔能明显地抑制LVFW心肌组织中Cx43表达的下调,缩小MI病灶;阿莫地平则抑制肥厚心肌中Cx43蛋白的表达,明显抑制IS的肥厚.结论:MI病理过程中,梗死病灶内Cx43的表达下调,肥厚组织中Cx43的表达上调.L和L/T型钙通道阻滞剂均能减轻心肌重构与选择性地调节心肌组织中Cx43的表达有关.%AIM: To investigate the effect of cardiac L- and L/T-type Ca2+ channels on gap junctional connexin 43 ( Cx43 ) in myocardium infarcted heart remodeling of rats. METHODS: Rat myocardium infarction model was established by permanent ligation of the left coronary artery. Infarcted rats were treated with oral placebo, amlodipine [ L-channel blockade, 4 mg/( kg · day) ] or mibefradil [ L/T-channel blockade, 10 mg/(kg·day] beginning 7 days before induction of myocardial infarction (MI). Protein levels of Cx43 were measured 1, 3 and 7 days postcoronary occlusion in the noninfarcted and

  14. Physiology and Regulation of Calcium Channels in Stomatal Guard Cells

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Julian I.

    2007-05-02

    Stomatal pores in the epidermis of leaves regulate the diffusion of CO2 into leaves for photosynthetic carbon fixation and control water loss of plants during drought periods. Guard cells sense CO2, water status, light and other environmental conditions to regulate stomatal apertures for optimization of CO2 intake and plant growth under drought stress. The cytosolic second messenger calcium contributes to stomatal movements by transducing signals and regulating ion channels in guard cells. Studies suggest that both plasma membrane Ca2+ influx channels and vacuolar/organellar Ca2+ release channels contribute to ABA-induced Ca2+ elevations in guard cells. Recent research in the P.I.'s laboratory has led to identification of a novel major cation-selective Ca2+-permeable influx channel (Ica) in the plasma membrane of Arabidopsis guard cells. These advances will allow detailed characterization of Ica plasma membrane Ca2+ influx channels in guard cells. The long term goal of this research project is to gain a first detailed characterization of these novel plasma membrane Ca2+-permeable channel currents in Arabidopsis guard cells. The proposed research will investigate the hypothesis that Ica represents an important Ca2+ influx pathway for ABA and CO2 signal transduction in Arabidopsis guard cells. These studies will lead to elucidation of key signal transduction mechanisms by which plants balance CO2 influx into leaves and transpirational water loss and may contribute to future strategies for manipulating gas exchange for improved growth of crop plants and for biomass production.

  15. TRPM8 and Nav1.8 sodium channels are required for transthyretin-induced calcium influx in growth cones of small-diameter TrkA-positive sensory neurons

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    Vincent Adele J

    2011-03-01

    Full Text Available Abstract Background Familial amyloidotic polyneuropathy (FAP is a peripheral neuropathy caused by the extracellular accumulation and deposition of insoluble transthyretin (TTR aggregates. However the molecular mechanism that underlies TTR toxicity in peripheral nerves is unclear. Previous studies have suggested that amyloidogenic proteins can aggregate into oligomers which disrupt intracellular calcium homeostasis by increasing the permeability of the plasma membrane to extracellular calcium. The aim of the present study was to examine the effect of TTR on calcium influx in dorsal root ganglion neurons. Results Levels of intracellular cytosolic calcium were monitored in dorsal root ganglion (DRG neurons isolated from embryonic rats using the calcium-sensitive fluorescent indicator Fluo4. An amyloidogenic mutant form of TTR, L55P, induced calcium influx into the growth cones of DRG neurons, whereas wild-type TTR had no significant effect. Atomic force microscopy and dynamic light scattering studies confirmed that the L55P TTR contained oligomeric species of TTR. The effect of L55P TTR was decreased by blockers of voltage-gated calcium channels (VGCC, as well as by blockers of Nav1.8 voltage-gated sodium channels and transient receptor potential M8 (TRPM8 channels. siRNA knockdown of TRPM8 channels using three different TRPM8 siRNAs strongly inhibited calcium influx in DRG growth cones. Conclusions These data suggest that activation of TRPM8 channels triggers the activation of Nav1.8 channels which leads to calcium influx through VGCC. We suggest that TTR-induced calcium influx into DRG neurons may contribute to the pathophysiology of FAP. Furthermore, we speculate that similar mechanisms may mediate the toxic effects of other amyloidogenic proteins such as the β-amyloid protein of Alzheimer's disease.

  16. Variability of Potassium Channel Blockers in Mesobuthus eupeus Scorpion Venom with Focus on Kv1.1

    Science.gov (United States)

    Kuzmenkov, Alexey I.; Vassilevski, Alexander A.; Kudryashova, Kseniya S.; Nekrasova, Oksana V.; Peigneur, Steve; Tytgat, Jan; Feofanov, Alexey V.; Kirpichnikov, Mikhail P.; Grishin, Eugene V.

    2015-01-01

    The lesser Asian scorpion Mesobuthus eupeus (Buthidae) is one of the most widely spread and dispersed species of the Mesobuthus genus, and its venom is actively studied. Nevertheless, a considerable amount of active compounds is still under-investigated due to the high complexity of this venom. Here, we report a comprehensive analysis of putative potassium channel toxins (KTxs) from the cDNA library of M. eupeus venom glands, and we compare the deduced KTx structures with peptides purified from the venom. For the transcriptome analysis, we used conventional tools as well as a search for structural motifs characteristic of scorpion venom components in the form of regular expressions. We found 59 candidate KTxs distributed in 30 subfamilies and presenting the cysteine-stabilized α/β and inhibitor cystine knot types of fold. M. eupeus venom was then separated to individual components by multistage chromatography. A facile fluorescent system based on the expression of the KcsA-Kv1.1 hybrid channels in Escherichia coli and utilization of a labeled scorpion toxin was elaborated and applied to follow Kv1.1 pore binding activity during venom separation. As a result, eight high affinity Kv1.1 channel blockers were identified, including five novel peptides, which extend the panel of potential pharmacologically important Kv1 ligands. Activity of the new peptides against rat Kv1.1 channel was confirmed (IC50 in the range of 1–780 nm) by the two-electrode voltage clamp technique using a standard Xenopus oocyte system. Our integrated approach is of general utility and efficiency to mine natural venoms for KTxs. PMID:25792741

  17. Molecular modeling and structural analysis of two-pore domain potassium channels TASK1 interactions with the blocker A1899

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    David Mauricio Ramirez

    2015-03-01

    Full Text Available A1899 is a potent and highly selective blocker of the Two-pore domain potassium (K2P channel TASK-1, it acts as an antagonist blocking the K+ flux and binds to TASK-1 in the inner cavity and shows an activity in nanomolar order. This drug travels through the central cavity and finally binds in the bottom of the selectivity filter with some threonines and waters molecules forming a H-bond network and several hydrophobic interactions. Using alanine mutagenesis screens the binding site was identify involving residues in the P1 and P2 pore loops, the M2 and M4 transmembrane segments, and the halothane response element; mutations were introduced in the human TASK-1 (KCNK3, NM_002246 expressed in Oocytes from anesthetized Xenopus laevis frogs. Based in molecular modeling and structural analysis as such as molecular docking and binding free energy calculations a pose was suggested using a TASK-1 homology models. Recently, various K2P crystal structures have been obtained. We want redefined – from a structural point of view – the binding mode of A1899 in TASK-1 homology models using as a template the K2P crystal structures. By computational structural analysis we describe the molecular basis of the A1899 binding mode, how A1899 travel to its binding site and suggest an interacting pose (Figure 1. after 100 ns of molecular dynamics simulation (MDs we found an intra H-Bond (80% of the total MDs, a H-Bond whit Thr93 (42% of the total MDs, a pi-pi stacking interaction between a ring and Phe125 (88% of the total MDs and several water bridges. Our experimental and computational results allow the molecular understanding of the structural binding mechanism of the selective blocker A1899 to TASK-1 channels. We identified the structural common and divergent features of TASK-1 channel through our theoretical and experimental studies of A1899 drug action.

  18. Intermediate-Conductance-Ca2-Activated K Channel Intermediate-Conductance Calcium-Activated Potassium Channel (IKCa1) is Upregulated and Promotes Cell Proliferation in Cervical Cancer

    Science.gov (United States)

    Liu, Ling; Zhan, Ping; Nie, Dan; Fan, Lingye; Lin, Hairui; Gao, Lanyang; Mao, Xiguang

    2017-01-01

    Background Accumulating data point to intermediate-conductance calcium-activated potassium channel (IKCa1) as a key player in controlling cell cycle progression and proliferation of human cancer cells. However, the role that IKCa1 plays in the growth of human cervical cancer cells is largely unexplored. Material/Methods In this study, Western blot analysis, immunohistochemical staining, and RT-PCR were first used for IKCa1protein and gene expression assays in cervical cancer tissues and HeLa cells. Then, IKCa1 channel blocker and siRNA were employed to inhibit the functionality of IKCa1 and downregulate gene expression in HeLa cells, respectively. After these treatments, we examined the level of cell proliferation by MTT method and measured IKCa1 currents by conventional whole-cell patch clamp technique. Cell apoptosis was assessed using the Annexin V-FITC/Propidium Iodide (PI) double-staining apoptosis detection kit. Results We demonstrated that IKCa1 mRNA and protein are preferentially expressed in cervical cancer tissues and HeLa cells. We also showed that the IKCa1 channel blocker, clotrimazole, and IKCa1 channel siRNA can be used to suppress cervical cancer cell proliferation and decrease IKCa1 channel current. IKCa1 downregulation by specific siRNAs induced a significant increase in the proportion of apoptotic cells in HeLa cells. Conclusions IKCa1 is overexpressed in cervical cancer tissues, and IKCa1 upregulation in cervical cancer cell linea enhances cell proliferation, partly by reducing the proportion of apoptotic cells. PMID:28280257

  19. Diphenytoin, riluzole and lidocaine: three sodium channel blockers, with different mechanisms of action, decrease hippocampal epileptiform activity.

    Science.gov (United States)

    Diao, Lihong; Hellier, Jennifer L; Uskert-Newsom, Jessica; Williams, Philip A; Staley, Kevin J; Yee, Audrey S

    2013-10-01

    Epilepsy is a condition affecting 1-2% of the population, characterized by the presence of spontaneous, recurrent seizures. The most common type of acquired epilepsy is temporal lobe epilepsy (TLE). Up to 30% of patients with TLE are refractory to currently available compounds, and there is an urgent need to identify novel targets for therapy. Here, we utilized the in-vitro CA3 burst preparation to examine alterations in network excitability, characterized by changes in interburst interval. Specifically, we show that bath application of three different sodium channel blockers-diphenytoin, riluzole, and lidocaine-slow spontaneous CA3 bursts. This in turn, decreased the epileptiform activity. These compounds work at different sites on voltage-gated sodium channels, but produce a similar network phenotype of decreased excitability. In the case of diphenytoin and riluzole, the change in network activity (i.e., increased interburst intervals) was persistent following drug washout. Lidocaine application, however, only increased the CA3 interburst interval when it was in the bath solution. Thus, its action was not permanent and resulted in returning CA3 bursting to baseline levels. These data demonstrate that the CA3 burst preparation provides a relatively easy and quick platform for identifying compounds that can decrease network excitability, providing the initial screen for further and more complex in-vivo, freely-behaving animal studies.

  20. Support for calcium channel gene defects in autism spectrum disorders

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    Lu Ake Tzu-Hui

    2012-12-01

    Full Text Available Abstract Background Alternation of synaptic homeostasis is a biological process whose disruption might predispose children to autism spectrum disorders (ASD. Calcium channel genes (CCG contribute to modulating neuronal function and evidence implicating CCG in ASD has been accumulating. We conducted a targeted association analysis of CCG using existing genome-wide association study (GWAS data and imputation methods in a combined sample of parent/affected child trios from two ASD family collections to explore this hypothesis. Methods A total of 2,176 single-nucleotide polymorphisms (SNP (703 genotyped and 1,473 imputed covering the genes that encode the α1 subunit proteins of 10 calcium channels were tested for association with ASD in a combined sample of 2,781 parent/affected child trios from 543 multiplex Caucasian ASD families from the Autism Genetics Resource Exchange (AGRE and 1,651 multiplex and simplex Caucasian ASD families from the Autism Genome Project (AGP. SNP imputation using IMPUTE2 and a combined reference panel from the HapMap3 and the 1,000 Genomes Project increased coverage density of the CCG. Family-based association was tested using the FBAT software which controls for population stratification and accounts for the non-independence of siblings within multiplex families. The level of significance for association was set at 2.3E-05, providing a Bonferroni correction for this targeted 10-gene panel. Results Four SNPs in three CCGs were associated with ASD. One, rs10848653, is located in CACNA1C, a gene in which rare de novo mutations are responsible for Timothy syndrome, a Mendelian disorder that features ASD. Two others, rs198538 and rs198545, located in CACN1G, and a fourth, rs5750860, located in CACNA1I, are in CCGs that encode T-type calcium channels, genes with previous ASD associations. Conclusions These associations support a role for common CCG SNPs in ASD.

  1. Stimulation of protein kinase C recruits covert calcium channels in Aplysia bag cell neurons.

    Science.gov (United States)

    Strong, J A; Fox, A P; Tsien, R W; Kaczmarek, L K

    The modulation of voltage-activated calcium currents by protein kinases provides excitable cells with a mechanism for regulating their electrical behaviour. At the single channel level, modulation of calcium current has, to date, been characterized only in cardiac muscle, where beta-adrenergic agonists, acting through cyclic AMP-dependent protein kinase, enhance the calcium current by increasing channel availability and opening. We now report that enhancement of calcium current in the peptidergic bag cell neurons of Aplysia by protein kinase C occurs through a different mechanism, the recruitment of a previously covert class of calcium channel. Under control conditions, bag cell neurons contain only one class of voltage-activated calcium channel with a conductance of approximately 12 pS. After exposure to agents that activate protein kinase C, these neurons also express a second class of calcium channel with a different unitary conductance (approximately 24 pS) that is never seen in untreated cells.

  2. Effects of in vitro and in vivo lead exposure on voltage-dependent calcium channels in central neurons of Lymnaea stagnalis.

    Science.gov (United States)

    Audesirk, G

    1987-01-01

    Currents through calcium channels of members of an identified cluster of neurons (B cells) in the pond snail Lymnaea stagnalis were studied under voltage clamp. The normal physiological saline was modified to maximize the visibility of voltage-dependent calcium currents and minimize contamination by other currents. Barium was used as the charge carrier for the calcium channels. Depolarizing voltage steps induce an inward current, the magnitude of which varies with the barium concentration. In brains taken from animals not exposed in vivo to lead, in vitro addition of lead acetate to the recording medium (0.25 to 14 microM) inhibits the barium current by 59 +/- 14% (mean +/- s.d.), in a manner that is independent of the lead concentration. The magnitude of the residual current still varies with the barium concentration. The voltage dependence of the current appears to be unaffected by lead. In contrast to some other calcium-channel blockers, such as cobalt, the inhibition of barium currents by in vitro lead exposure is irreversible, at least in short-term experiments. Contrary to expectations based on these in vitro results, barium currents in B cells of animals exposed to 5 microM lead for 6 to 12 weeks in vivo were approximately twice as large as barium currents in B cells from unexposed controls, when both were recorded in lead-free saline. It is possible that chronic in vivo lead exposure causes an increase in the number of calcium channels in these neurons.

  3. NERVE EXCITABILITY CHANGES AFTER NA(V)1.8 CHANNEL BLOCKER TREATMENT IN MICE DEFICIENT OF MYELIN PROTEIN P-0

    DEFF Research Database (Denmark)

    Moldovan, M.; Rosberg, M. R.; Alvarez Herrero, Susana;

    2016-01-01

    -gated Na + channel isoforms with ectopic expression of NaV1.8 on motor axons. This raised the hypothesis that treatments with NaV1.8 blockers could be used in treatment strategies to improve the motor function in these models. We investigated the effect of the NaV1.8 subtype selective blocker A-803467...... and of the novel blocker Compound 31 (C31, Bioorg Med Chem Lett 2010, 20, 6812; AbbVie Inc.) which can be orally administered. Double P0 and NaV1.8 knockouts were used as controls. Multiple measures of tibial nerve excitability by “threshold-tracking” were used to monitor the acute changes in motor axon membrane...

  4. Complexes of Peptide Blockers with Kv1.6 Pore Domain: Molecular Modeling and Studies with KcsA-Kv1.6 Channel.

    Science.gov (United States)

    Nekrasova, O V; Volyntseva, A D; Kudryashova, K S; Novoseletsky, V N; Lyapina, E A; Illarionova, A V; Yakimov, S A; Korolkova, Yu V; Shaitan, K V; Kirpichnikov, M P; Feofanov, A V

    2016-09-17

    Potassium voltage-gated Kv1.6 channel, which is distributed primarily in neurons of central and peripheral nervous systems, is of significant physiological importance. To date, several high-affinity Kv1.6-channel blockers are known, but the lack of selective ones among them hampers the studies of tissue localization and functioning of Kv1.6 channels. Here we present an approach to advanced understanding of interactions of peptide toxin blockers with a Kv1.6 pore. It combines molecular modeling studies and an application of a new bioengineering system based on a KcsA-Kv1.6 hybrid channel for the quantitative fluorescent analysis of blocker-channel interactions. Using this system we demonstrate that peptide toxins agitoxin 2, kaliotoxin1 and OSK1 have similar high affinity to the extracellular vestibule of the K(+)-conducting pore of Kv1.6, hetlaxin is a low-affinity ligand, whereas margatoxin and scyllatoxin do not bind to Kv1.6 pore. Binding of toxins to Kv1.6 pore has considerable inverse dependence on the ionic strength. Model structures of KcsA-Kv1.6 and Kv1.6 complexes with agitoxin 2, kaliotoxin 1 and OSK1 were obtained using homology modeling and molecular dynamics simulation. Interaction interfaces, which are formed by 15-19 toxin residues and 10 channel residues, are described and compared. Specific sites of Kv1.6 pore recognition are identified for targeting of peptide blockers. Analysis of interactions between agitoxin 2 derivatives with point mutations (S7K, S11G, L19S, R31G) and KcsA-Kv1.6 confirms reliability of the calculated complex structure.

  5. Voltage-Gated Calcium Channel Antagonists and Traumatic Brain Injury

    Directory of Open Access Journals (Sweden)

    Bruce Lyeth

    2013-06-01

    Full Text Available Traumatic brain injury (TBI is a leading cause of death and disability in the United States. Despite more than 30 years of research, no pharmacological agents have been identified that improve neurological function following TBI. However, several lines of research described in this review provide support for further development of voltage gated calcium channel (VGCC antagonists as potential therapeutic agents. Following TBI, neurons and astrocytes experience a rapid and sometimes enduring increase in intracellular calcium ([Ca2+]i. These fluxes in [Ca2+]i drive not only apoptotic and necrotic cell death, but also can lead to long-term cell dysfunction in surviving cells. In a limited number of in vitro experiments, both L-type and N-type VGCC antagonists successfully reduced calcium loads as well as neuronal and astrocytic cell death following mechanical injury. In rodent models of TBI, administration of VGCC antagonists reduced cell death and improved cognitive function. It is clear that there is a critical need to find effective therapeutics and rational drug delivery strategies for the management and treatment of TBI, and we believe that further investigation of VGCC antagonists should be pursued before ruling out the possibility of successful translation to the clinic.

  6. Newer calcium channel antagonists and the treatment of hypertension.

    Science.gov (United States)

    Cummins, D F

    1999-07-01

    Calcium channel antagonists have become popular medications for the management of hypertension. These agents belong to the diphenylalkylamine, benzothiazepine, dihydropyridine, or tetralol chemical classes. Although the medications share a common pharmacological mechanism in reducing peripheral vascular resistance, clinical differences between the sub-classes can be linked to structural profiles. This heterogeneity is manifested by differences in vascular selectivity, effects on cardiac conduction and adverse events. The lack of differentiation between calcium channel antagonists in clinical trials has contributed to uncertainty associated with their impact on morbidity and mortality. Data from more recent studies in specific patient populations underscores the importance of investigating these antihypertensives as individual agents. A proposed therapeutic classification system suggests that newer agents should share the slow onset and long-acting antihypertensive effect of amlodipine. Additionally, a favourable trough-to-peak ratio has been recommended as an objective measurement of efficacy. The newer drugs, barnidipine and lacidipine, have a therapeutic profile similar to amlodipine, but trough-to-peak ratios are not substantially greater than the recommended minimum of 0.50. Aranidipine, cilnidipine and efonidipine have unique pharmacological properties that distinguish them from traditional dihydropyridines. Although clinical significance is unconfirmed, these newer options may be beneficial for patients with co-morbid conditions that preclude use of older antagonists.

  7. Hypericum perforatum modulates apoptosis and calcium mobilization through voltage-gated and TRPM2 calcium channels in neutrophil of patients with Behcet's disease.

    Science.gov (United States)

    Nazıroğlu, Mustafa; Sahin, Mehmet; Ciğ, Bilal; Aykur, Mehmet; Erturan, Ijlal; Ugan, Yunus

    2014-03-01

    Behcet's disease (BD) is a chronic, inflammatory, and multisystemic condition although its pathogenesis is uncertain. Main component of St. John's wort (Hypericum perforatum, HP) is hyperforin and induces antiinflammatory and antioxidant properties. We aimed to investigate effects of HP on oxidative stress, apoptosis, and cytosolic-free Ca²⁺ [Ca²⁺](i) concentration in neutrophil of BD patients. Nine new-diagnosed active patients with BD and nine control subjects were included in the study. Disease activity was considered by clinical findings. Neutrophil samples were obtained from the patients and controls. The neutrophils from patients were divided into three subgroups and were incubated with HP, voltage-gated calcium channel (VGCC) blockers, (verapamil+dilitiazem) and non-specific TRPM2 channel blocker (2-aminoethyl diphenylborinate, 2-APB), respectively. The neutrophils were stimulated by fMLP as a Ca²⁺-concentration agonist and oxidative stress former. Caspase-3, caspase-9, apoptosis, lipid peroxidation, and [Ca²⁺](i) values were high in the patient groups, although cell viability, glutathione (GSH), and glutathione peroxidase (GSH-Px) values were low in patient group. However, the [Ca²⁺](i), caspase-3, and caspase-9 values decreased markedly in patient+HP group although GSH and GSH-Px values increased in the group. The [Ca²⁺](i) concentration was also decreased in the patient group by V+D, 2-APB, and HP incubations. In conclusion, we observed the importance of neutrophil Ca²⁺ entry, apoptosis, and oxidative stress through gating VGCC and TRPM2 channels in the neutrophils in the pathogenesis and activation of the patients with BD. HP induced protective effects on oxidative stress by modulating Ca²⁺ influx in BD patients.

  8. MDIMP, a novel cardiac Ca(2+) channel blocker with atrial selectivity.

    Science.gov (United States)

    Santamaria-Herrera, Mireille Aline; Ríos-Pérez, Erick Benjamín; de la Rosa, Juan Antonio Manuel; García-Castañeda, Maricela; Osornio-Garduño, Diana Stephanie; Ramos-Mondragón, Roberto; Mancilla-Percino, Teresa; Avila, Guillermo

    2016-06-15

    In cardiac muscle cells both T-and L-type Ca(2+) channels (TTCCs and LTCCs, respectively) are expressed, and the latter are relevant to a process known as excitation-contraction coupling (ECC). Evidence obtained from docking studies suggests that isoindolines derived from α-amino acids bind to the LTCC CaV1.2. In the present study, we investigated whether methyl (S)-2-(1,3-dihydroisoindol-2-yl)-4-methylpentanoate (MDIMP), which is derived from L-leucine, modulates both Ca(2+) channels and ECC. To this end, mechanical properties, as well as Ca(2+) transients and currents, were all investigated in isolated cardiac myocytes. The effects of MDIMP on CaV1.2 (transiently expressed in 293T/17 cells) were also studied. In this system, evidence was found for an inhibitory action that develops and recovers in min, with an IC50 of 450µM. With respect to myocytes: atrial-TTCCs, atrial-LTCCs, and ventricular-LTCCs were also inhibited, in that order of potency. Accordingly, Ca(2+) transients, contractions, and window currents of LTCCs were all reduced more strongly in atrial cells. Interestingly, while the modulation of LTCCs was state-independent in these cells, it was state-dependent, and dual, on the ventricular ones. Furthermore, practically all of the ventricular LTCCs were closed at resting membrane potentials. This could explain their resistance to MDIMP, as they were affected in only open or inactivated states. All these features in turn explain the preferential down-regulation of the atrial ECC. Thus, our results support the view that isoindolines bind to Ca(2+) channels, improve our knowledge of the corresponding structure-function relationship, and may be relevant for conditions where decreased atrial activity is desired.

  9. Effects of calcium channel blocker, nifedipine, on antidepressant activity of fluvoxamine, venlafaxine and tianeptine in mice

    Directory of Open Access Journals (Sweden)

    Ashok K. Sharma

    2015-02-01

    Conclusions: Nifedipine, fluvoxamine, venlafaxine and tianeptine possess antidepressant activity and nifedipine exhibits synergistic antidepressant activity with fluvoxamine, venlafaxine and tianeptine. [Int J Basic Clin Pharmacol 2015; 4(1.000: 82-88

  10. Novel tacrine derivatives that block neuronal calcium channels.

    Science.gov (United States)

    de los Ríos, Cristóbal; Marco, José L; Carreiras, María D C; Chinchón, P M; García, Antonio G; Villarroya, Mercedes

    2002-06-01

    A new series of tacrine (9-amino-1,2,3,4-tetrahydroacridine) derivatives were synthesized and their effects on 45Ca(2+) entry into bovine adrenal chromaffin cells stimulated with dimethylphenylpiperazinium (DMPP) or K(+), studied. At 3 microM, compound 1 did not affect (45)Ca(2+) uptake evoked by DMPP. Compounds 14, 15 and 17 inhibited the effects of DMPP by 30%. Compounds 3, 9 and tacrine blocked the DMPP signal by about 50%. Compounds 5 and 12 were the most potent blockers of DMPP-stimulated 45Ca(2+) entry (90%); the rest of the compounds inhibited the effects of DMPP by 70-80%. Compounds 1, 3, 4, 8, 10, 11, 13, 16, 17 and tacrine inhibited 45Ca(2+) uptake induced by K(+) about 20%. Compounds 6, 14 and 15 inhibited the K(+) effects by 10% or less. Compounds 7, 9, 12 and 18 blocked the K(+) signal by 30% and, finally, compounds 2 and 5 inhibited the K(+)-induced 45Ca(2+) entry by 50%. None of the new compounds was as effective as diltiazem (IC(50)=0.03 microM) in causing relaxation of the rat aorta precontracted with 35 mM K(+); the most potent was compound 7 (IC(50)=0.3 microM). Compounds 5, 6, 8, 9, 10 and 13 had IC(50)s around 10 microM and compounds 3, 4, 11 and 12 around 20 microM. Blockade of Ca(2+) entry through neuronal voltage-dependent Ca(2+) channels, without concomitant blockade of vascular Ca(2+) channels, suggests that some of these compounds might exhibit neuroprotectant effects but not undesirable hemodynamic effects.

  11. Effect of potassium channel blocker Tetraethylammonium pretreatment on prevention of the 6-OHDA-induced chronic Parkinson's disease in rats

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    H. Haghdoost-Yazdi

    2016-06-01

    Full Text Available Background: Nuclease and caspase activities that promote death signals and cause apoptosis are dependent to potassium ion. Objective: The aim of this study was to investigate the effect of potassium channel blocker tetraethylammonium (TEA on prevention of Parkinson's disease in rats. Methods: This experimental study was conducted on 33 male rats in Qazvin University of Medical Sciences, 2014. 6-hydroxydopamine (6-OHDA was injected into the striatum of the brain. The rats received different doses of TEA twice daily the day before the 6-OHDA injection till 15 days after the injection. The severity of Parkinsonism was assessed by the apomorphine-induced rotational behavior, the elevated body swing test (EBST, and the rotarod test. Data were analyzed using Kruskal Wallis and Mann Whitney U tests. Findings: Pretreatment with 5 mg/kg TEA significantly reduced the severity of rotations compared to the saline group. TEA did not reduce the swings in the EBST. In the rotarod test, TEA caused significant improvement in the motor performance of the rats. Conclusion: With regards to the results, it seems that pretreatment with TEA can partly reduce the severity of behavioral symptoms in the 6-OHDA-induced chronic Parkinson's disease. The higher the TEA dose, the more significant the reduction in the severity of symptoms.

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

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    Leila eChaieb

    2015-04-01

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

  13. Myocardial perfusion abnormality and effects of Ca channel blockers on myocardial ischemia in patients with hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Yoko [Kyoto Prefectural Univ. of Medicine (Japan)

    1997-03-01

    The purpose of this study was to investigate the frequency of myocardial ischemia and characteristic regions of myocardial hypoperfusion during stress in patients with hypertrophic cardiomyopathy. Furthermore, the effects of Ca channel blocker (verapamil, diltiazem) on myocardial ischemia were studied. One hundred patients with hypertrophic cardiomyopathy underwent exercise {sup 201}Tl SPECT. Sixty-eight patients had one or more {sup 201}Tl abnormalities. Of the 68 patients with {sup 201}Tl abnormalities, 56 had reversible {sup 201}Tl abnormalities and 12 had fixed defect. {sup 201}Tl abnormalities were frequently distributed in the anterior and posterior areas of junction between the ventricular septum and the free wall and the apex. Of the 56 patients with reversible {sup 201}Tl abnormalities, 40 patients underwent one more exercise {sup 201}Tl SPECT after 8 weeks of oral administration of verapamil or diltiazem. The {sup 201}Tl defect was visually scored as the defect score. Transient dilation index was calculated as an index of subendocardial ischemia. The mean defect score decreased significantly from 9.80{+-}4.35 to 5.50{+-}4.63 after verapamil and from 9.90{+-}5.17 to 5.50{+-}4.89 after diltiazem. Mean transient dilation index decreased from 1.20{+-}0.12 to 1.08{+-}0.09 after treatment with verapamil and from 1.16{+-}0.10 to 1.02{+-}0.09 after treatment with diltiazem. (K.H.)

  14. Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus.

    Science.gov (United States)

    Chameau, Pascal; Qin, Yongjun; Spijker, Sabine; Smit, August Benjamin; Smit, Guus; Joëls, Marian

    2007-01-01

    Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover, we addressed the putative gene targets that eventually lead to the enhanced calcium currents. Electrophysiological recordings were performed in nucleated patches that allow excellent voltage control. Calcium currents in these patches almost exclusively involve N- and L-type channels. We found that L- but not N-type calcium currents were largely enhanced after treatment with a high dose of corticosterone sufficient to activate glucocorticoid receptors. Voltage dependency and kinetic properties of the currents were unaffected by the hormone. Nonstationary noise analysis suggests that the increased current is not caused by a larger unitary conductance, but rather to a doubling of the number of functional channels. Quantitative real-time PCR revealed that transcripts of the Ca(v)1 subunits encoding for the N- or L-type calcium channels are not upregulated in the mouse CA1 area; instead, a strong, direct, and consistent upregulation of the beta4 subunit was observed. This indicates that the corticosteroid-induced increase in number of L-type calcium channels is not caused by a simple transcriptional regulation of the pore-forming subunit of the channels.

  15. Structural Dynamics of the Potassium Channel Blocker ShK: SRLS Analysis of (15)N Relaxation.

    Science.gov (United States)

    Meirovitch, Eva; Tchaicheeyan, Oren; Sher, Inbal; Norton, Raymond S; Chill, Jordan H

    2015-12-10

    The 35-residue ShK peptide binds with high affinity to voltage-gated potassium channels. The dynamics of the binding surface was studied recently with (microsecond to millisecond) (15)N relaxation dispersion and (picosecond to nanosecond) (15)N spin relaxation of the N-H bonds. Relaxation dispersion revealed microsecond conformational-exchange-mediated exposure of the functionally important Y23 side chain to the peptide surface. The spin relaxation parameters acquired at 14.1 and 16.45 T have been subjected to model-free (MF) analysis, which yielded a squared generalized order parameter, S(2), of approximately 0.85 for virtually all of the N-H bonds. Only a "rigid backbone" evaluation could be inferred. We ascribe this limited information to the simplicity of MF in the context of challenging data. To improve the analysis, we apply the slowly relaxing local structure (SRLS) approach, which is a generalization of MF. SRLS describes N-H bond dynamics in ShK in terms of a local potential, u, ranging from 10 to 18.5 kBT, and a local diffusion rate, D2, ranging from 4.2 × 10(8) to 2.4 × 10(10) s(-1). This analysis shows that u is outstandingly strong for Y23 and relatively weak for K22, whereas D2 is slow for Y23 and fast for K22. These observations are relevant functionally because of the key role of the K22-Y23 dyad in ShK binding to potassium channels. The disulfide-bond network exhibits a medium-strength potential and an alternating wave-like D2 pattern. This is indicative of moderate structural restraints and motional plasticity, in support of, although not directly correlated with, the microsecond binding-related conformational exchange process detected previously. Thus, new information on functionally important residues in ShK and its overall conformational stability emerged from the SRLS analysis, as compared with the previous MF-based estimate of backbone dynamics as backbone rigidity.

  16. Differential calcium signaling mediated by voltage-gated calcium channels in rat retinal ganglion cells and their unmyelinated axons.

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    Allison Sargoy

    Full Text Available Aberrant calcium regulation has been implicated as a causative factor in the degeneration of retinal ganglion cells (RGCs in numerous injury models of optic neuropathy. Since calcium has dual roles in maintaining homeostasis and triggering apoptotic pathways in healthy and injured cells, respectively, investigation of voltage-gated Ca channel (VGCC regulation as a potential strategy to reduce the loss of RGCs is warranted. The accessibility and structure of the retina provide advantages for the investigation of the mechanisms of calcium signalling in both the somata of ganglion cells as well as their unmyelinated axons. The goal of the present study was to determine the distribution of VGCC subtypes in the cell bodies and axons of ganglion cells in the normal retina and to define their contribution to calcium signals in these cellular compartments. We report L-type Ca channel α1C and α1D subunit immunoreactivity in rat RGC somata and axons. The N-type Ca channel α1B subunit was in RGC somata and axons, while the P/Q-type Ca channel α1A subunit was only in the RGC somata. We patch clamped isolated ganglion cells and biophysically identified T-type Ca channels. Calcium imaging studies of RGCs in wholemounted retinas showed that selective Ca channel antagonists reduced depolarization-evoked calcium signals mediated by L-, N-, P/Q- and T-type Ca channels in the cell bodies but only by L-type Ca channels in the axons. This differential contribution of VGCC subtypes to calcium signals in RGC somata and their axons may provide insight into the development of target-specific strategies to spare the loss of RGCs and their axons following injury.

  17. CaV1.2 calcium channels: just cut out to be regulated?

    Science.gov (United States)

    Groth, Rachel D; Tirko, Natasha N; Tsien, Richard W

    2014-06-04

    Tight regulation of calcium entry through the L-type calcium channel CaV1.2 ensures optimal excitation-response coupling. In this issue of Neuron, Michailidis et al. (2014) demonstrate that CaV1.2 activity triggers negative feedback regulation through proteolytic cleavage of the channel within the core of the pore-forming subunit.

  18. Mouse sperm patch-clamp recordings reveal single Cl- channels sensitive to niflumic acid, a blocker of the sperm acrosome reaction.

    Science.gov (United States)

    Espinosa, F; de la Vega-Beltrán, J L; López-González, I; Delgado, R; Labarca, P; Darszon, A

    1998-04-10

    Ion channels lie at the heart of gamete signaling. Understanding their regulation will improve our knowledge of sperm physiology, and may lead to novel contraceptive strategies. Sperm are tiny (approximately 3 microm diameter) and, until now, direct evidence of ion channel activity in these cells was lacking. Using patch-clamp recording we document here, for the first time, the presence of cationic and anionic channels in mouse sperm. Anion selective channels were blocked by niflumic acid (NA) (IC50 = 11 microM). The blocker was effective also in inhibiting the acrosome reaction induced by the zona pellucida, GABA or progesterone. These observations suggest that Cl- channels participate in the sperm acrosome reaction in mammals.

  19. Calcium channel structural determinants of synaptic transmission between identified invertebrate neurons.

    Science.gov (United States)

    Spafford, J David; Munno, David W; Van Nierop, Pim; Feng, Zhong-Ping; Jarvis, Scott E; Gallin, Warren J; Smit, August B; Zamponi, Gerald W; Syed, Naweed I

    2003-02-01

    We report here that unlike what was suggested for many vertebrate neurons, synaptic transmission in Lymnaea stagnalis occurs independent of a physical interaction between presynaptic calcium channels and a functional complement of SNARE proteins. Instead, synaptic transmission in Lymnaea requires the expression of a C-terminal splice variant of the Lymnaea homolog to mammalian N- and P/Q-type calcium channels. We show that the alternately spliced region physically interacts with the scaffolding proteins Mint1 and CASK, and that synaptic transmission is abolished following RNA interference knockdown of CASK or after the injection of peptide sequences designed to disrupt the calcium channel-Mint1 interactions. Our data suggest that Mint1 and CASK may serve to localize the non-L-type channels at the active zone and that synaptic transmission in invertebrate neurons utilizes a mechanism for optimizing calcium entry, which occurs independently of a physical association between calcium channels and SNARE proteins.

  20. Effects of calcium channel antagonists on the motivational effects of nicotine and morphine in conditioned place aversion paradigm.

    Science.gov (United States)

    Budzynska, Barbara; Polak, Piotr; Biala, Grazyna

    2012-03-01

    The motivational component of drug withdrawal may contribute to drug seeking and relapse through the negative reinforcement-related process; thus, it is important to understand the mechanisms that mediate affective withdrawal behaviors. The present study was undertaken to examine the calcium-dependent mechanism of negative motivational symptoms of nicotine and morphine withdrawal using the conditioned place aversion (CPA) paradigm. Rats were chronically treated with nicotine (1.168 mg/kg, free base, s.c., 11 days, three times daily) or morphine (10 mg/kg,s.c., 11 days, twice daily). Then, during conditioning, rats pre-treated with nicotine or morphine received a nicotinic receptor antagonist mecamylamine (3.5 mg/kg) or an opioid receptor antagonist naloxone (1 mg/kg) to precipitate withdrawal in their initially preferred compartment, or saline in their non-preferred compartment. Our results demonstrated that after three conditioning sessions, mecamylamine induced a clear place aversion in rats that had previously received nicotine injections, and naloxone induced a significant place aversion in rats that had previously received morphine injections. Further, the major findings showed that calcium channel antagonists, i.e., nimodipine, verapamil and flunarizine (5 and 10 mg/kg, i.p.), injected before the administration of mecamylamine or naloxone, attenuated nicotine or morphine place aversion. As an outcome, these findings support the hypothesis that similar calcium-dependent mechanisms are involved in aversive motivational component associated with nicotine a morphine withdrawal. We can suggest that calcium channel blockers have potential for alleviating nicotine and morphine addiction by selectively decreasing the incentive motivational properties of both drugs, and may be beneficial as smoking cessation or opioid dependence pharmacotherapies.

  1. The cardiac L-type calcium channel distal carboxy terminus autoinhibition is regulated by calcium.

    Science.gov (United States)

    Crump, Shawn M; Andres, Douglas A; Sievert, Gail; Satin, Jonathan

    2013-02-01

    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.

  2. Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels in cultured rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Zhi-ying LIN; Li-min CHEN; Jing ZHANG; Xiao-dong PAN; Yuan-gui ZHU; Qin-yong YE; Hua-pin HUANG; Xiao-chun CHEN

    2012-01-01

    Aim:To investigate the effect of ginsenoside Rb1 on voltage-gated calcium currents in cultured rat hippocampal neurons and the modulatory mechanism.Methods:Cultured hippocampal neurons were prepared from Sprague Dawley rat embryos.Whole-cell configuration of the patchclamp technique was used to record the voltage-gated calcium currents (VGCCs)from the hippocampal neurons,and the effect of Rb1 was examined.Results:Rb1 (2-100 μmol/L)inhibited VGCCs in a concentration-dependent manner,and the current was mostly recovered upon wash-out.The specific L-type Ca2+ channel inhibitor nifedipine (10 μmol/L)occluded Rb1-induced inhibition on VGCCs.Neither the selective N-type Ca2+ channel blocker ω-conotoxin-GVlA (1 μmoVL),nor the selective P/Q-type Ca2+ channel blocker ωo-agatoxin IVA (30 nmol/L)diminished Rb1-sensitive VGCCs.Rb1 induced a leftward shift of the steady-state inactivation curve of Ica to a negative potential without affecting its activation kinetics or reversal potential in the I-V curve.The inhibitory effect of Rb1 was neither abolished by the adenylyl cyclase activator forskolin (10 μmol/L),nor by the PKA inhibitor H-89 (10 μmol/L).Conclusion:Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels,without affecting the N-type or P/Q-type Ca2+ channels in hippocampal neurons,cAMP-PKA signaling pathway is not involved in this effect.

  3. Effect of potassium channel blocker 4-aminopyridine pretreatment on the 6-OHDA-induced Parkinson's disease in rats

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    M. Sofiabadi

    2015-06-01

    Full Text Available Background: Nuclease and caspase enzymes activities which promote death signals and lead to apoptosis are dependent to potassium ions. Objective: The aim of this study was to determine the effect of 4-aminopyridine (4-AP potassium channel blocker on the animal model of Parkinson's disease. Methods: This experimental study was performed in Qazvin University of Medical Sciences, 2013. Male Rats were received different doses of 4-AP twice daily from half an hour before injection of 6-hydroxydopamine (6-OHDA to 7 or 15 days after that. 6-OHDA was injected into medial forebrain bundle (MFB in acute model groups and into striatum in chronic model groups. The severity of Parkinsonism was assessed by standard behavioral methods. Data were analyzed using Kruskal-Wallis and Mann Whitney U tests. Findings: In acute model groups, administration of 0.5 mg/kg 4-AP (n=9 had no remarkable effect on behavioral symptoms, but 1 mg/kg 4-AP (n=8 significantly reduced the severity of apomorphine-induced rotations and improved motor learning in rotarod test. In chronic model groups, although 1 mg/kg 4-AP (n=7 significantly reduced the severity of rotations and improved motor learning, but 0.5 mg/kg 4-AP (n=8 was more effective. Conclusion: Pretreatment with 4-AP can reduce 6-OHDA-induced dopaminergic neuron death. Since the chronic model of 6-OHDA is more similar to Parkinson's disease in human, the low dose of 4-AP is recommended for treatment of this disease.

  4. Cilnidipine, but not amlodipine, ameliorates osteoporosis in ovariectomized hypertensive rats through inhibition of the N-type calcium channel.

    Science.gov (United States)

    Shimizu, Hideo; Nakagami, Hironori; Yasumasa, Natsuki; Mariana, Osako Kiomy; Kyutoku, Mariko; Koriyama, Hiroshi; Nakagami, Futoshi; Shimamura, Munehisa; Rakugi, Hiromi; Morishita, Ryuichi

    2012-01-01

    Both osteoporosis and high blood pressure are major diseases in aging populations. Recent studies demonstrated that some antihypertensive drugs reduced the risk of bone fracture in elderly patients. Although calcium channel blockers (CCB) are widely used as first-line antihypertensive agents, there is no evidence that they prevent osteoporosis. In this study, we investigated the effects of two types of CCB on bone metabolism: cilnidipine (L-/N-type CCB), which suppresses norepinephrine release from the sympathetic nerve, and amlodipine (L-type CCB). In ovariectomized female spontaneous hypertensive rats, administration of cilnidipine, but not amlodipine, resulted in a significant increase in the ratio of alkaline phosphatase to tartrate-resistant acid phosphatase (TRAP) and a decrease in the number of osteoclasts, as assessed by TRAP staining in the proximal tibia. Bone mineral density, moreover, was significantly higher in the cilnidipine group as compared with the amlodipine group and was associated with a significant decrease in a urinary collagen degradation product (deoxypyridinoline). The degree of prevention of osteoporosis by cilnidipine was similar to that of carvedilol (a β-blocker) because β-blockers reduce fracture risks though the inhibition of osteoclast activation. Interestingly, these effects cannot be attributed to the reduction of blood pressure because all three drugs significantly decreased blood pressure. In contrast, both cilnidipine and carvedilol, but not amlodipine, significantly decreased heart rate, indicating that both cilnidipine and carvedilol suppressed sympathetic nervous activity. Overall, our present data showed that cilnidipine (L-/N-type CCB) ameliorated osteoporosis in ovariectomized hypertensive rats. These pleiotropic effects of antihypertensive drugs such as cilnidipine and carvedilol might provide additional benefits in the treatment of hypertensive postmenopausal women.

  5. SLO BK Potassium Channels Couple Gap Junctions to Inhibition of Calcium Signaling in Olfactory Neuron Diversification.

    Science.gov (United States)

    Alqadah, Amel; Hsieh, Yi-Wen; Schumacher, Jennifer A; Wang, Xiaohong; Merrill, Sean A; Millington, Grethel; Bayne, Brittany; Jorgensen, Erik M; Chuang, Chiou-Fen

    2016-01-01

    The C. elegans AWC olfactory neuron pair communicates to specify asymmetric subtypes AWCOFF and AWCON in a stochastic manner. Intercellular communication between AWC and other neurons in a transient NSY-5 gap junction network antagonizes voltage-activated calcium channels, UNC-2 (CaV2) and EGL-19 (CaV1), in the AWCON cell, but how calcium signaling is downregulated by NSY-5 is only partly understood. Here, we show that voltage- and calcium-activated SLO BK potassium channels mediate gap junction signaling to inhibit calcium pathways for asymmetric AWC differentiation. Activation of vertebrate SLO-1 channels causes transient membrane hyperpolarization, which makes it an important negative feedback system for calcium entry through voltage-activated calcium channels. Consistent with the physiological roles of SLO-1, our genetic results suggest that slo-1 BK channels act downstream of NSY-5 gap junctions to inhibit calcium channel-mediated signaling in the specification of AWCON. We also show for the first time that slo-2 BK channels are important for AWC asymmetry and act redundantly with slo-1 to inhibit calcium signaling. In addition, nsy-5-dependent asymmetric expression of slo-1 and slo-2 in the AWCON neuron is necessary and sufficient for AWC asymmetry. SLO-1 and SLO-2 localize close to UNC-2 and EGL-19 in AWC, suggesting a role of possible functional coupling between SLO BK channels and voltage-activated calcium channels in AWC asymmetry. Furthermore, slo-1 and slo-2 regulate the localization of synaptic markers, UNC-2 and RAB-3, in AWC neurons to control AWC asymmetry. We also identify the requirement of bkip-1, which encodes a previously identified auxiliary subunit of SLO-1, for slo-1 and slo-2 function in AWC asymmetry. Together, these results provide an unprecedented molecular link between gap junctions and calcium pathways for terminal differentiation of olfactory neurons.

  6. Different effects of calcium antagonist and beta-blocker therapy on left-ventricular diastolic function in ischemic heart disease. A direct comparison of the impact of mibefradil and atenolol

    DEFF Research Database (Denmark)

    Hassager, C; Thygesen, K; Grande, P

    2001-01-01

    OBJECTIVE: To compare the effect of a calcium antagonist and a beta-blocker on left-ventricular diastolic function in patients with ischemic heart disease. METHODS: 138 patients with chronic stable angina pectoris were randomized in a multicenter, double-blind trial to treatment with either...

  7. Reversible block of the calcium release channel/ryanodine receptor by protamine, a heparin antidote.

    Science.gov (United States)

    Koulen, P; Ehrlich, B E

    2000-07-01

    Channel activity of the calcium release channel from skeletal muscle, ryanodine receptor type 1, was measured in the presence and absence of protamine sulfate on the cytoplasmic side of the channel. Single-channel activity was measured after incorporating channels into planar lipid bilayers. Optimally and suboptimally calcium-activated calcium release channels were inactivated by the application of protamine to the cytoplasmic side of the channel. Recovery of channel activity was not observed while protamine was present. The addition of protamine bound to agarose beads did not change channel activity, implying that the mechanism of action involves an interaction with the ryanodine receptor rather than changes in the bulk calcium concentration of the medium. The block of channel activity by protamine could be reversed either by removal by perfusion with buffer or by the addition of heparin to the cytoplasmic side of the channel. Microinjection of protamine into differentiated C(2)C(12) mouse muscle cells prevented caffeine-induced intracellular calcium release. The results suggest that protamine acts on the ryanodine receptor in a similar but opposite manner from heparin and that protamine can be used as a potent, reversible inhibitor of ryanodine receptor activity.

  8. GABAA increases calcium in subventricular zone astrocyte-like cells through L- and T-type voltage-gated calcium channels

    Directory of Open Access Journals (Sweden)

    Stephanie Z Young

    2010-04-01

    Full Text Available In the adult neurogenic subventricular zone (SVZ, the behavior of astrocyte-like cells and some of their functions depend on changes in intracellular Ca2+ levels and tonic GABAA receptor activation. However, it is unknown whether, and if so how, GABAA receptor activity regulates intracellular Ca2+ dynamics in SVZ astrocytes. To monitor Ca2+ activity selectively in astrocyte-like cells, we used two lines of transgenic mice expressing either GFP fused to a Gq-coupled receptor or DsRed under the human glial fibrillary acidic protein (hGFAP promoter. GABAA receptor activation induced Ca2+ increases in 40-50% of SVZ astrocytes. GABAA-induced Ca2+ increases were prevented with nifedipine and mibefradil, blockers of L- and T-type voltage-gated calcium channels (VGCC. The L-type Ca2+ channel activator BayK 8644 increased the percentage of GABAA-responding astrocyte-like cells to 75%, suggesting that the majority of SVZ astrocytes express functional VGCCs. SVZ astrocytes also displayed spontaneous Ca2+ activity, the frequency of which was regulated by tonic GABAA receptor activation. These data support a role for ambient GABA in tonically regulating intracellular Ca2+ dynamics through GABAA receptors and VGCC in a subpopulation of astrocyte-like cells in the postnatal SVZ.

  9. Large-conductance calcium-activated potassium channels facilitate transmitter release in salamander rod synapse.

    Science.gov (United States)

    Xu, Jian Wei; Slaughter, Malcolm M

    2005-08-17

    Large-conductance calcium-activated potassium (BK) channels are colocalized with calcium channels at sites of exocytosis at the presynaptic terminals throughout the nervous system. It is expected that their activation would provide negative feedback to transmitter release, but the opposite is sometimes observed. Attempts to resolve this apparent paradox based on alterations in action potential waveform have been ambiguous. In an alternative approach, we investigated the influence of this channel on neurotransmitter release in a nonspiking neuron, the salamander rod photoreceptors. Surprisingly, the BK channel facilitates calcium-mediated transmitter release from rods. The two presynaptic channels form a positive coupled loop. Calcium influx activates the BK channel current, leading to potassium efflux that increases the calcium current. The normal physiological voltage range of the rod is well matched to the dynamics of this positive loop. When the rod is further depolarized, then the hyperpolarizing BK channel current exceeds its facilitatory effect, causing truncation of transmitter release. Thus, the calcium channel-BK channel linkage performs two functions at the synapse: nonlinear potentiator and safety brake.

  10. Primary erythromelalgia in a 12-year-old boy: positive response to sodium channel blockers despite negative SCN9A mutations.

    Science.gov (United States)

    Jakob, A; Creutzfeldt, R; Staszewski, O; Winterpacht, A; Berner, R; Hufnagel, M

    2012-09-01

    Erythromelalgia is a rare disorder characterized by recurrent pain attacks, swelling and redness in the distal extremities. The primary forms of the disorder are caused by mutations in voltage-gated sodium channels. Treatment is difficult and controlled therapeutic studies offer little to no guidance. We report on a 12-year-old boy and his first occurrence of primary erythromelalgia. Genetic findings for mutations in the SCN9A gene, which encodes for the α-subunit of sodium channel NaV1.7, were negative. Although initial treatment with sodium nitroprusside was ineffective, subsequent medication with lidocaine and mexiletine, in combination with gabapentin, was successful. Despite negative findings for mutations in the sodium channels, the use of sodium channel blockers should be considered in these patients.

  11. Fetal calcium regulates branching morphogenesis in the developing human and mouse lung: involvement of voltage-gated calcium channels.

    Science.gov (United States)

    Brennan, Sarah C; Finney, Brenda A; Lazarou, Maria; Rosser, Anne E; Scherf, Caroline; Adriaensen, Dirk; Kemp, Paul J; Riccardi, Daniela

    2013-01-01

    Airway branching morphogenesis in utero is essential for optimal postnatal lung function. In the fetus, branching morphogenesis occurs during the pseudoglandular stage (weeks 9-17 of human gestation, embryonic days (E)11.5-16.5 in mouse) in a hypercalcaemic environment (~1.7 in the fetus vs. ~1.1-1.3 mM for an adult). Previously we have shown that fetal hypercalcemia exerts an inhibitory brake on branching morphogenesis via the calcium-sensing receptor. In addition, earlier studies have shown that nifedipine, a selective blocker of L-type voltage-gated Ca(2+) channels (VGCC), inhibits fetal lung growth, suggesting a role for VGCC in lung development. The aim of this work was to investigate the expression of VGCC in the pseudoglandular human and mouse lung, and their role in branching morphogenesis. Expression of L-type (CaV1.2 and CaV1.3), P/Q type (CaV2.1), N-type (CaV2.2), R-type (CaV2.3), and T-type (CaV3.2 and CaV3.3) VGCC was investigated in paraffin sections from week 9 human fetal lungs and E12.5 mouse embryos. Here we show, for the first time, that Cav1.2 and Cav1.3 are expressed in both the smooth muscle and epithelium of the developing human and mouse lung. Additionally, Cav2.3 was expressed in the lung epithelium of both species. Incubating E12.5 mouse lung rudiments in the presence of nifedipine doubled the amount of branching, an effect which was partly mimicked by the Cav2.3 inhibitor, SNX-482. Direct measurements of changes in epithelial cell membrane potential, using the voltage-sensitive fluorescent dye DiSBAC2(3), demonstrated that cyclic depolarisations occur within the developing epithelium and coincide with rhythmic occlusions of the lumen, driven by the naturally occurring airway peristalsis. We conclude that VGCC are expressed and functional in the fetal human and mouse lung, where they play a role in branching morphogenesis. Furthermore, rhythmic epithelial depolarisations evoked by airway peristalsis would allow for branching to match

  12. 5,6-EET potently inhibits T-type calcium channels

    DEFF Research Database (Denmark)

    Cazade, M.; Bidaud, I.; Hansen, Pernille B. Lærkegaard;

    2014-01-01

    T-type calcium channels (T-channels) are important actors in neuronal pacemaking, in heart rhythm, and in the control of the vascular tone. T-channels are regulated by several endogenous lipids including the primary eicosanoid arachidonic acid (AA), which display an important role in vasodilation...

  13. Immunolocalization and expression of small-conductance calcium-activated potassium channels in human myometrium

    DEFF Research Database (Denmark)

    Rosenbaum, Sofia T; Svalø, Julie; Nielsen, Karsten;

    2012-01-01

    Small-conductance calcium-activated potassium (SK3) channels have been detected in human myometrium and we have previously shown a functional role of SK channels in human myometrium in vitro. The aims of this study were to identify the precise localization of SK3 channels and to quantify SK3 mRNA...

  14. New Role of P/Q-type Voltage-gated Calcium Channels

    DEFF Research Database (Denmark)

    Hansen, Pernille B L

    2015-01-01

    Voltage-gated calcium channels are important for the depolarization-evoked contraction of vascular smooth muscle cells (SMCs), with L-type channels being the classical channel involved in this mechanism. However, it has been demonstrated that the CaV2.1 subunit, which encodes a neuronal isoform o...

  15. Signal processing by T-type calcium channel interactions in the cerebellum

    Science.gov (United States)

    Engbers, Jordan D. T.; Anderson, Dustin; Zamponi, Gerald W.; Turner, Ray W.

    2013-01-01

    T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa) channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs). In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (IT) and hyperpolarization-activated cation current (IH) are activated during trains of inhibitory postsynaptic potentials. These currents have distinct, and yet synergistic, roles in the subthreshold domain with IT generating a rebound burst and IH controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing IH to increase the efficacy of IT and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect

  16. Signal processing by T-type calcium channel interactions in the cerebellum

    Directory of Open Access Journals (Sweden)

    Jordan D.T. Engbers

    2013-11-01

    Full Text Available T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs. In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (IT and hyperpolarization-activated cation current (IH are activated during trains of IPSPs. These currents have distinct, and yet synergistic, roles in the subthreshold domain with IT generating a rebound burst and IH controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing IH to increase the efficacy of IT, and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect effects on

  17. Signal processing by T-type calcium channel interactions in the cerebellum.

    Science.gov (United States)

    Engbers, Jordan D T; Anderson, Dustin; Zamponi, Gerald W; Turner, Ray W

    2013-11-27

    T-type calcium channels of the Cav3 family are unique among voltage-gated calcium channels due to their low activation voltage, rapid inactivation, and small single channel conductance. These special properties allow Cav3 calcium channels to regulate neuronal processing in the subthreshold voltage range. Here, we review two different subthreshold ion channel interactions involving Cav3 channels and explore the ability of these interactions to expand the functional roles of Cav3 channels. In cerebellar Purkinje cells, Cav3 and intermediate conductance calcium-activated potassium (IKCa) channels form a novel complex which creates a low voltage-activated, transient outward current capable of suppressing temporal summation of excitatory postsynaptic potentials (EPSPs). In large diameter neurons of the deep cerebellar nuclei, Cav3-mediated calcium current (I T) and hyperpolarization-activated cation current (I H) are activated during trains of inhibitory postsynaptic potentials. These currents have distinct, and yet synergistic, roles in the subthreshold domain with I T generating a rebound burst and I H controlling first spike latency and rebound spike precision. However, by shortening the membrane time constant the membrane returns towards resting value at a faster rate, allowing I H to increase the efficacy of I T and increase the range of burst frequencies that can be generated. The net effect of Cav3 channels thus depends on the channels with which they are paired. When expressed in a complex with a KCa channel, Cav3 channels reduce excitability when processing excitatory inputs. If functionally coupled with an HCN channel, the depolarizing effect of Cav3 channels is accentuated, allowing for efficient inversion of inhibitory inputs to generate a rebound burst output. Therefore, signal processing relies not only on the activity of individual subtypes of channels but also on complex interactions between ion channels whether based on a physical complex or by indirect

  18. T-type calcium channel Cav3.2 deficient mice show elevated anxiety, impaired memory and reduced sensitivity to psychostimulants.

    Directory of Open Access Journals (Sweden)

    Giuseppe eGangarossa

    2014-03-01

    Full Text Available The fine-tuning of neuronal excitability relies on a tight control of Ca2+ homeostasis. The low voltage-activated T-type calcium channels (Cav3.1, Cav3.2 and Cav3.3 isoforms play a critical role in regulating these processes. Despite their wide expression throughout the central nervous system, the implication of T-type Cav3.2 isoform in brain functions is still poorly characterized. Here we investigate the effect of genetic ablation of this isoform in affective disorders, including anxiety, cognitive functions as well as sensitivity to drugs of abuse. Using a wide range of behavioral assays we show that genetic ablation of the cacna1h gene results in an anxiety-like phenotype, whereas novelty-induced locomotor activity is unaffected. Deletion of the T-type channel Cav3.2 also triggers impairment of hippocampus-dependent recognition memories. Acute and sensitized hyperlocomotion induced by d-amphetamine and cocaine are dramatically reduced in T-type Cav3.2 deficient mice. In addition, the administration of the T-type blocker TTA-A2 prevented the expression of locomotor sensitization observed in wildtype mice. In conclusion, our data reveal that physiological activity of this specific Ca2+ channel is required for affective and cognitive behaviors. Moreover, our work highlights the interest of T-type channel blockers as therapeutic strategies to reverse drug-associated alterations.

  19. The facilitating effect of systemic administration of Kv7/M channel blocker XE991 on LTP induction in the hippocampal CA1 area independent of muscarinic activation.

    Science.gov (United States)

    Song, Ming-Ke; Cui, Yong-Yao; Zhang, Wei-Wei; Zhu, Liang; Lu, Yang; Chen, Hong-Zhuan

    2009-09-11

    A large amount of in vitro studies demonstrate suppression of M-current in hippocampal neurons by Kv7/M channel blocker results in depolarization of membrane potential and release of neurotransmitters, such as acetylcholine and glutamate, suggesting that Kv7/M channel may play important roles in regulating synaptic plasticity. In the present study, we examined the in vivo effect of Kv7/M channel inhibition on the long-term potentiation (LTP) induction at basal dendrites in hippocampal CA1 area of urethane-anaesthetized rats. The Kv7/M channel was inhibited by intraperitoneal injection of XE991 (10mg/kg) and the LTP of field excitatory postsynaptic potential (fEPSP) was induced by supra-threshold high frequency stimulation (S1 HFS). A weak protocol which was just below the threshold for evoking LTP was used as sub-threshold high frequency stimulation (S2 HFS). XE991 did not significantly alter the slope of fEPSP and the magnitude of LTP induced by S1 HFS, suggesting that Kv7/M channel inhibition had little or no effect on glutamatergic transmission under basal conditions. However, XE991 could make S2 HFS evoke LTP even after the application of the muscarinic cholinergic (mACh) receptor antagonist scopolamine, suggesting that Kv7/M channel inhibition lowered the threshold for LTP induction and the effect was independent of muscarinic activation. Based on the above findings, we concluded that the facilitating effect of XE991 on LTP induction is not mediated by its ability to enhance the release of acetylcholine; therefore, Kv7/M channel blockers may provide a therapeutic benefit to cholinergic deficiency-related cognitive impairment, e.g., Alzheimer's disease.

  20. Calcium-permeable ion channels in control of autophagy and cancer.

    Science.gov (United States)

    Kondratskyi, Artem; Yassine, Maya; Kondratska, Kateryna; Skryma, Roman; Slomianny, Christian; Prevarskaya, Natalia

    2013-01-01

    Autophagy, or cellular self-eating, is a tightly regulated cellular pathway the main purpose of which is lysosomal degradation and subsequent recycling of cytoplasmic material to maintain normal cellular homeostasis. Defects in autophagy are linked to a variety of pathological states, including cancer. Cancer is the disease associated with abnormal tissue growth following an alteration in such fundamental cellular processes as apoptosis, proliferation, differentiation, migration and autophagy. The role of autophagy in cancer is complex, as it can promote both tumor prevention and survival/treatment resistance. It's now clear that modulation of autophagy has a great potential in cancer diagnosis and treatment. Recent findings identified intracellular calcium as an important regulator of both basal and induced autophagy. Calcium is a ubiquitous secondary messenger which regulates plethora of physiological and pathological processes such as aging, neurodegeneration and cancer. The role of calcium and calcium-permeable channels in cancer is well-established, whereas the information about molecular nature of channels regulating autophagy and the mechanisms of this regulation is still limited. Here we review existing mechanisms of autophagy regulation by calcium and calcium-permeable ion channels. Furthermore, we will also discuss some calcium-permeable channels as the potential new candidates for autophagy regulation. Finally we will propose the possible link between calcium permeable channels, autophagy and cancer progression and therapeutic response.

  1. NIFLUMIC ACID BLOCKS NATIVE AND RECOMBINANT T-TYPE CHANNELS

    OpenAIRE

    Balderas, E; Arteaga-Tlecuitl, R; Rivera, M; Gomora, JC; Darszon, A.

    2012-01-01

    Voltage-dependent calcium channels are widely distributed in animal cells, including spermatozoa. Calcium is fundamental in many sperm functions such as: motility, capacitation and the acrosome reaction, all essential for fertilization. Pharmacological evidence has suggested T-type calcium channels participate in the acrosome reaction. Niflumic acid (NA), a non-steroidal anti-inflammatory drug commonly used as chloride channel blocker, blocks T-currents in mouse spermatogenic cells and Cl− ch...

  2. Emerging roles of L-type voltage gated and other calcium channels in T lymphocytes.

    Directory of Open Access Journals (Sweden)

    Abdallah eBadou

    2013-08-01

    Full Text Available In T lymphocytes, calcium ion controls a variety of biological processes including development, survival, proliferation, and effector functions. These distinct and specific roles are regulated by different calcium signals, which are generated by various plasma membrane calcium channels. The repertoire of calcium-conducting proteins in T lymphocytes includes store-operated CRAC channels, transient receptor potential (TRP channels, P2X channels, and L-type voltage-gated calcium (Cav1 channels. In this paper, we will focus mainly on the role of the Cav1 channels found expressed by T lymphocytes, where these channels appear to operate in a TCR stimulation-dependent and voltage-sensor independent manner. We will review their expression profile at various differentiation stages of CD4 and CD8 T lymphocytes. Then, we will present crucial genetic evidence in favor of a role of these Cav1 channels and related regulatory proteins in both CD4 and CD8 T cell functions such as proliferation, survival, cytokine production and cytolysis. Finally, we will provide evidence and speculate on how these voltage-gated channels might function in the T lymphocyte, a non-excitable cell.

  3. Ryanodine Receptors Selectively Interact with L Type Calcium Channels in Mouse Taste Cells.

    Directory of Open Access Journals (Sweden)

    Michelle R Rebello

    Full Text Available WE REPORTED THAT RYANODINE RECEPTORS ARE EXPRESSED IN TWO DIFFERENT TYPES OF MAMMALIAN PERIPHERAL TASTE RECEPTOR CELLS: Type II and Type III cells. Type II cells lack voltage-gated calcium channels (VGCCs and chemical synapses. In these cells, ryanodine receptors contribute to the taste-evoked calcium signals that are initiated by opening inositol trisphosphate receptors located on internal calcium stores. In Type III cells that do have VGCCs and chemical synapses, ryanodine receptors contribute to the depolarization-dependent calcium influx.The goal of this study was to establish if there was selectivity in the type of VGCC that is associated with the ryanodine receptor in the Type III taste cells or if the ryanodine receptor opens irrespective of the calcium channels involved. We also wished to determine if the ryanodine receptors and VGCCs require a physical linkage to interact or are simply functionally associated with each other. Using calcium imaging and pharmacological inhibitors, we found that ryanodine receptors are selectively associated with L type VGCCs but likely not through a physical linkage.Taste cells are able to undergo calcium induced calcium release through ryanodine receptors to increase the initial calcium influx signal and provide a larger calcium response than would otherwise occur when L type channels are activated in Type III taste cells.

  4. The metabolic impact of β-hydroxybutyrate on neurotransmission: Reduced glycolysis mediates changes in calcium responses and KATP channel receptor sensitivity

    DEFF Research Database (Denmark)

    Lund, Trine Meldgaard; Ploug, K.B.; Iversen, Anne

    2015-01-01

    -hydroxybutyrate might change neuronal function as there is a known coupling between metabolism and neurotransmission. The purpose of this study was to shed light on the effects of the ketone body β-hydroxybutyrate on glycolysis and neurotransmission in cultured murine glutamatergic neurons. Previous studies have shown...... an effect of β-hydroxybutyrate on glucose metabolism, and the present study further specified this by showing attenuation of glycolysis when β-hydroxybutyrate was present in these neurons. In addition, the NMDA receptor-induced calcium responses in the neurons were diminished in the presence of β...... to a combination of glucose and R-β-hydroxybutyrate in cultured neurons. Using the latter combination, glycolysis was diminished, NMDA receptor-induced calcium responses were lower, and the KATP channel blocker glibenclamide caused a higher transmitter release....

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

    Science.gov (United States)

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

    2007-01-19

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

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

    Science.gov (United States)

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

    2016-04-01

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

  7. T-type voltage-gated calcium channels regulate the tone of mouse efferent arterioles

    DEFF Research Database (Denmark)

    Poulsen, Christian B; Al-Mashhadi, Rozh H; Cribbs, Leanne L;

    2011-01-01

    Voltage-gated calcium channels are important for the regulation of renal blood flow and the glomerular filtration rate. Excitation-contraction coupling in afferent arterioles is known to require activation of these channels and we studied their role in the regulation of cortical efferent arteriolar...... tone. We used microdissected perfused mouse efferent arterioles and found a transient vasoconstriction in response to depolarization with potassium; an effect abolished by removal of extracellular calcium. The T-type voltage-gated calcium channel antagonists mibefradil and nickel blocked this potassium....... Low concentrations of nickel, an agent that blocks Ca(v)3.2, had a similar effect. Thus, T-type voltage-gated calcium channels are functionally important for depolarization-induced vasoconstriction and subsequent dilatation in mouse cortical efferent arterioles.Kidney International advance online...

  8. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    Science.gov (United States)

    Jorgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne; Civitelli, Roberto; Sorensen, Ole Helmer; Steinberg, Thomas H.

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium.

  9. T-type calcium channel expression in cultured human neuroblastoma cells

    Institute of Scientific and Technical Information of China (English)

    Xianjie Wen; Shiyuan Xu; Lingling Wang; Hua Liang; Chengxiang Yang; Hanbing Wang; Hongzhen Liu

    2011-01-01

    Human neuroblastoma cells (SH-SY5Y) have similar structures and functions as neural cells and have been frequently used for cell culture studies of neural cell functions. Previous studies have revealed Land N-type calcium channels in SH-SY5Y cells. However, the distribution of the low -voltage activated calcium channel (namely called T-type calcium channel, including Cav3.1, Cav3.2, and Cav3.3) in SH-SY5Y cells remains poorly understood. The present study detected mRNA and protein expression of the T-type calcium channel (Cav3.1, Cav3.2, and Cav3.3) in cultured SH-SY5Y cells using real-time polymerase chain reaction (PCR) and western blot analysis. Results revealed mRNA and protein expression from all three T-type calcium channel subtypes in SH-SY5Y cells. Moreover,Cav3.1 was the predominant T-type calcium channel subtype in SH-SY5Y cells.

  10. Osteoclast cytosolic calcium, regulated by voltage-gated calcium channels and extracellular calcium, controls podosome assembly and bone resorption

    Science.gov (United States)

    Miyauchi, A.; Hruska, K. A.; Greenfield, E. M.; Duncan, R.; Alvarez, J.; Barattolo, R.; Colucci, S.; Zambonin-Zallone, A.; Teitelbaum, S. L.; Teti, A.

    1990-01-01

    The mechanisms of Ca2+ entry and their effects on cell function were investigated in cultured chicken osteoclasts and putative osteoclasts produced by fusion of mononuclear cell precursors. Voltage-gated Ca2+ channels (VGCC) were detected by the effects of membrane depolarization with K+, BAY K 8644, and dihydropyridine antagonists. K+ produced dose-dependent increases of cytosolic calcium ([Ca2+]i) in osteoclasts on glass coverslips. Half-maximal effects were achieved at 70 mM K+. The effects of K+ were completely inhibited by dihydropyridine derivative Ca2+ channel blocking agents. BAY K 8644 (5 X 10(-6) M), a VGCC agonist, stimulated Ca2+ entry which was inhibited by nicardipine. VGCCs were inactivated by the attachment of osteoclasts to bone, indicating a rapid phenotypic change in Ca2+ entry mechanisms associated with adhesion of osteoclasts to their resorption substrate. Increasing extracellular Ca2+ ([Ca2+]e) induced Ca2+ release from intracellular stores and Ca2+ influx. The Ca2+ release was blocked by dantrolene (10(-5) M), and the influx by La3+. The effects of [Ca2+]e on [Ca2+]i suggests the presence of a Ca2+ receptor on the osteoclast cell membrane that could be coupled to mechanisms regulating cell function. Expression of the [Ca2+]e effect on [Ca2+]i was similar in the presence or absence of bone matrix substrate. Each of the mechanisms producing increases in [Ca2+]i, (membrane depolarization, BAY K 8644, and [Ca2+]e) reduced expression of the osteoclast-specific adhesion structure, the podosome. The decrease in podosome expression was mirrored by a 50% decrease in bone resorptive activity. Thus, stimulated increases of osteoclast [Ca2+]i lead to cytoskeletal changes affecting cell adhesion and decreasing bone resorptive activity.

  11. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting...... in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal...... of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx...

  12. Ca(2+)-activated K(+) channel-3.1 blocker TRAM-34 attenuates airway remodeling and eosinophilia in a murine asthma model

    NARCIS (Netherlands)

    Girodet, P.O.; Ozier, A.; Carvalho, G.; Ilina, O.; Ousova, O.; Gadeau, A.P.; Begueret, H.; Wulff, H.; Marthan, R.; Bradding, P.; Berger, P.

    2013-01-01

    Key features of asthma include bronchial hyperresponsiveness (BHR), eosinophilic airway inflammation, and bronchial remodeling, characterized by subepithelial collagen deposition, airway fibrosis, and increased bronchial smooth muscle (BSM) mass. The calcium-activated K(+) channel K(Ca)3.1 is expres

  13. A selective blocker of Kv1.2 and Kv1.3 potassium channels from the venom of the scorpion Centruroides suffusus suffusus.

    Science.gov (United States)

    Corzo, Gerardo; Papp, Ferenc; Varga, Zoltan; Barraza, Omar; Espino-Solis, Pavel G; Rodríguez de la Vega, Ricardo C; Gaspar, Rezso; Panyi, Gyorgy; Possani, Lourival D

    2008-10-30

    A novel potassium channel blocker peptide was purified from the venom of the scorpion Centruroides suffusus suffusus by high-performance liquid chromatography and its amino acid sequence was completed by Edman degradation and mass spectrometry analysis. It contains 38 amino acid residues with a molecular weight of 4000.3Da, tightly folded by three disulfide bridges. This peptide, named Css20, was shown to block preferentially the currents of the voltage-dependent K+-channels Kv1.2 and Kv1.3. It did not affect several other ion channels tested at 10 nM concentration. Concentration-response curves of Css20 yielded an IC50 of 1.3 and 7.2 nM for Kv1.2- and Kv1.3-channels, respectively. Interestingly, despite the similar affinities for the two channels the association and dissociation rates of the toxin were much slower for Kv1.2, implying that different interactions may be involved in binding to the two channel types; an implication further supported by in silico docking analyses. Based on the primary structure of Css20, the systematic nomenclature proposed for this toxin is alpha-KTx 2.13.

  14. Differential CaMKII regulation by voltage-gated calcium channels in the striatum.

    Science.gov (United States)

    Pasek, Johanna G; Wang, Xiaohan; Colbran, Roger J

    2015-09-01

    Calcium signaling regulates synaptic plasticity and many other functions in striatal medium spiny neurons to modulate basal ganglia function. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a major calcium-dependent signaling protein that couples calcium entry to diverse cellular changes. CaMKII activation results in autophosphorylation at Thr286 and sustained calcium-independent CaMKII activity after calcium signals dissipate. However, little is known about the mechanisms regulating striatal CaMKII. To address this, mouse brain slices were treated with pharmacological modulators of calcium channels and punches of dorsal striatum were immunoblotted for CaMKII Thr286 autophosphorylation as an index of CaMKII activation. KCl depolarization increased levels of CaMKII autophosphorylation ~2-fold; this increase was blocked by an LTCC antagonist and was mimicked by treatment with pharmacological LTCC activators. The chelation of extracellular calcium robustly decreased basal CaMKII autophosphorylation within 5min and increased levels of total CaMKII in cytosolic fractions, in addition to decreasing the phosphorylation of CaMKII sites in the GluN2B subunit of NMDA receptors and the GluA1 subunit of AMPA receptors. We also found that the maintenance of basal levels of CaMKII autophosphorylation requires low-voltage gated T-type calcium channels, but not LTCCs or R-type calcium channels. Our findings indicate that CaMKII activity is dynamically regulated by multiple calcium channels in the striatum thus coupling calcium entry to key downstream substrates.

  15. Voltage-gated calcium channels and their auxiliary subunits: physiology and pathophysiology and pharmacology.

    Science.gov (United States)

    Dolphin, Annette C

    2016-10-01

    Voltage-gated calcium channels are essential players in many physiological processes in excitable cells. There are three main subdivisions of calcium channel, defined by the pore-forming α1 subunit, the CaV 1, CaV 2 and CaV 3 channels. For all the subtypes of voltage-gated calcium channel, their gating properties are key for the precise control of neurotransmitter release, muscle contraction and cell excitability, among many other processes. For the CaV 1 and CaV 2 channels, their ability to reach their required destinations in the cell membrane, their activation and the fine tuning of their biophysical properties are all dramatically influenced by the auxiliary subunits that associate with them. Furthermore, there are many diseases, both genetic and acquired, involving voltage-gated calcium channels. This review will provide a general introduction and then concentrate particularly on the role of auxiliary α2 δ subunits in both physiological and pathological processes involving calcium channels, and as a therapeutic target.

  16. Multi-ion conduction bands in a simple model of calcium ion channels

    CERN Document Server

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

    2012-01-01

    We report self-consistent Brownian dynamics simulations of a simple electrostatic model of the selectivity filters (SF) of calcium ion channels. They reveal regular structure in the conductance and selectivity as functions of the fixed negative charge Qf at the SF. This structure comprises distinct regions of high conductance (conduction bands) M0, M1, M2 separated by regions of zero-conductance (stop-bands). Two of these conduction bands, M1 and M2, demonstrate high calcium selectivity and prominent anomalous mole fraction effects and can be identified with the L-type and RyR calcium channels.

  17. Localization of large conductance calcium-activated potassium channels and their effect on calcitonin gene-related peptide release in the rat trigemino-neuronal pathway.

    Science.gov (United States)

    Wulf-Johansson, H; Amrutkar, D V; Hay-Schmidt, A; Poulsen, A N; Klaerke, D A; Olesen, J; Jansen-Olesen, I

    2010-06-02

    Large conductance calcium-activated potassium (BK(Ca)) channels are membrane proteins contributing to electrical propagation through neurons. Calcitonin gene-related peptide (CGRP) is a neuropeptide found in the trigeminovascular system (TGVS). Both BK(Ca) channels and CGRP are involved in migraine pathophysiology. Here we study the expression and localization of BK(Ca) channels and CGRP in the rat trigeminal ganglion (TG) and the trigeminal nucleus caudalis (TNC) as these structures are involved in migraine pain. Also the effect of the BK(Ca) channel blocker iberiotoxin and the BK(Ca) channel opener NS11021 on CGRP release from isolated TG and TNC was investigated. By RT-PCR, BK(Ca) channel mRNA was detected in the TG and the TNC. A significant difference in BK(Ca) channel mRNA transcript levels were found using qPCR between the TNC as compared to the TG. The BK(Ca) channel protein was more expressed in the TNC as compared to the TG shown by western blotting. Immunohistochemistry identified BK(Ca) channels in the nerve cell bodies of the TG and the TNC. The beta2- and beta4-subunit proteins were found in the TG and the TNC. They were both more expressed in the TNC as compared to TG shown by western blotting. In isolated TNC, the BK(Ca) channel blocker iberiotoxin induced a concentration-dependent release of CGRP that was attenuated by the BK(Ca) channel opener NS11021. No effect on basal CGRP release was found by NS11021 in isolated TG or TNC or by iberiotoxin in TG. In conclusion, we found both BK(Ca) channel mRNA and protein expression in the TG and the TNC. The BK(Ca) channel protein and the modulatory beta2- and beta4-subunt proteins were more expressed in the TNC than in the TG. Iberiotoxin induced an increase in CGRP release from the TNC that was attenuated by NS11021. Thus, BK(Ca) channels might have a role in trigeminovascular pain transmission.

  18. The antibody targeting the E314 peptide of human Kv1.3 pore region serves as a novel, potent and specific channel blocker.

    Directory of Open Access Journals (Sweden)

    Xiao-Fang Yang

    Full Text Available Selective blockade of Kv1.3 channels in effector memory T (T(EM cells was validated to ameliorate autoimmune or autoimmune-associated diseases. We generated the antibody directed against one peptide of human Kv1.3 (hKv1.3 extracellular loop as a novel and possible Kv1.3 blocker. One peptide of hKv1.3 extracellular loop E3 containing 14 amino acids (E314 was chosen as an antigenic determinant to generate the E314 antibody. The E314 antibody specifically recognized 63.8KD protein stably expressed in hKv1.3-HEK 293 cell lines, whereas it did not recognize or cross-react to human Kv1.1(hKv1.1, Kv1.2(hKv1.2, Kv1.4(hKv1.4, Kv1.5(hKv1.5, KCa3.1(hKCa3.1, HERG, hKCNQ1/hKCNE1, Nav1.5 and Cav1.2 proteins stably expressed in HEK 293 cell lines or in human atrial or ventricular myocytes by Western blotting analysis and immunostaining detection. By the technique of whole-cell patch clamp, the E314 antibody was shown to have a directly inhibitory effect on hKv1.3 currents expressed in HEK 293 or Jurkat T cells and the inhibition showed a concentration-dependence. However, it exerted no significant difference on hKv1.1, hKv1.2, hKv1.4, hKv1.5, hKCa3.1, HERG, hKCNQ1/hKCNE1, L-type Ca(2+ or voltage-gated Na(+ currents. The present study demonstrates that the antibody targeting the E314 peptide of hKv1.3 pore region could be a novel, potent and specific hKv1.3 blocker without affecting a variety of closely related K(v1 channels, KCa3.1 channels and functional cardiac ion channels underlying central nervous system (CNS disorders or drug-acquired arrhythmias, which is required as a safe clinic-promising channel blocker.

  19. Chronic fluoxetine treatment increases NO bioavailability and calcium-sensitive potassium channels activation in rat mesenteric resistance arteries.

    Science.gov (United States)

    Pereira, Camila A; Ferreira, Nathanne S; Mestriner, Fabiola L; Antunes-Rodrigues, José; Evora, Paulo R B; Resstel, Leonardo B M; Carneiro, Fernando S; Tostes, Rita C

    2015-10-15

    Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), has effects beyond its antidepressant properties, altering, e.g., mechanisms involved in blood pressure and vasomotor tone control. Although many studies have addressed the acute impact of fluoxetine on the cardiovascular system, there is a paucity of information on the chronic vascular effects of this SSRI. We tested the hypothesis that chronic fluoxetine treatment enhances the vascular reactivity to vasodilator stimuli by increasing nitric oxide (NO) signaling and activation of potassium (K+) channels. Wistar rats were divided into two groups: (I) vehicle (water for 21 days) or (II) chronic fluoxetine (10 mg/kg/day in the drinking water for 21 days). Fluoxetine treatment increased endothelium-dependent and independent vasorelaxation (analyzed by mesenteric resistance arteries reactivity) as well as constitutive NO synthase (NOS) activity, phosphorylation of eNOS at Serine1177 and NO production, determined by western blot and fluorescence. On the other hand, fluoxetine treatment did not alter vascular expression of neuronal and inducible NOS or guanylyl cyclase (GC). Arteries from fluoxetine-treated rats exhibited increased relaxation to pinacidil. Increased acetylcholine vasorelaxation was abolished by a calcium-activated K+ channel (KCa) blocker, but not by an inhibitor of KATP channels. On the other hand, vascular responses to Bay 41-2272 and 8-bromo-cGMP were similar between the groups. In conclusion, chronic fluoxetine treatment increases endothelium-dependent and independent relaxation of mesenteric resistance arteries by mechanisms that involve increased eNOS activity, NO generation, and KCa channels activation. These effects may contribute to the cardiovascular effects associated with chronic fluoxetine treatment.

  20. Activation of endothelial and epithelial KCa2.3 calcium-activated potassium channels by NS309 relaxes human small pulmonary arteries and bronchioles

    DEFF Research Database (Denmark)

    Kroigaard, Christel; Dalsgaard, Thomas; Nielsen, Gorm;

    2012-01-01

    -dependent relaxations. NS309 was equally potent in relaxing pulmonary arteries, but less potent in bronchioles, than salbutamol. NS309 relaxations were blocked by the KCa2 channel blocker apamin, while the KCa3.1 channel blocker, charybdotoxin failed to reduce relaxation to NS309 (0.011 mu M). CONCLUSIONS...

  1. INVESTIGATION OF SEIZURE ACTIVITY AFTER CYCLIC NUCLEOTIDE PHOSPHODIESTERASE INHIBITION WITH SECOND MESSENGER AND CALCIUM ION CHANNEL INHIBITION IN MICE

    Directory of Open Access Journals (Sweden)

    J Nandhakumar

    2012-03-01

    Full Text Available The role of PDE-4 inhibitor etazolate, was evaluated in the presence of PDE-7 inhibitor, BRL-50481, in animal models of epilepsy. Seizures were induced in the animals by subjecting them to injection of chemical convulsants, Pilocarpine, Kainic acid (KA and maximal electroshock (MES. The combination of etazolate and BRL50481 treated mice showed a significant (P<0.001 quick onset of action, jerky movements and convulsion when compared to gabapentin. The combination of etazolate and sGC inhibitor, methylene blue (MB treated mice showed a significant (P<0.001 delay in onset of action, jerky movements and convulsion when compare to gabapentin as well as against the combination of etazolate with BRL 50481.The present study mainly highlights the individual effects of etazolate and combination with BRL-50481 potentiates (P<0.001 the onset of seizure activity against all models of convulsion. The study mainly comprises the onset of seizures, mortality/recovery, percentage of prevention of seizures (anticonvulsant and total duration of convulsive time. The total convulsive time was prolonged significantly (P<0.05 and P<0.01 in combination of methylene blue with etazolate treated (28.59% and 35.15 % groups, compared to DMSO received group (100% in the MES model. In the same way, the combination of calcium channel modulator (CCM and calcium channel blocker (CCB amiodarone and nifedipine respectively, with etazolate showed a significant (P<0.001 delay in onset of seizures, compared to DMSO and etazolate treated groups in all models of epilepsy. This confirms that both CCM and CCB possess anticonvulsant activity. Finally, the study reveals that identification of new cAMP mediated phosphodiesterases family members offers a potential new therapy for epilepsy management in future.

  2. Activation of a cGMP-sensitive calcium-dependent chloride channel may cause transition from calcium waves to whole cell oscillations in smooth muscle cells

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian Brings; Aalkjær, Christian; Nilsson, Holger;

    2007-01-01

    waves sweeping through the cytoplasm when the sarcoplasmic reticulum (SR) is stimulated to release calcium. A rise in cGMP leads to the experimentally observed transition from waves to whole cell calcium oscillations. At the same time, membrane potential starts to oscillate and the frequency...... approximately doubles. In this transition, the simulated results point to a key role for a recently discovered cGMP-sensitive calcium-dependent chloride channel. This channel depolarizes the membrane in response to calcium released from the SR. In turn, depolarization causes a uniform opening of L-type calcium...

  3. The effects of inorganic lead on voltage-sensitive calcium channels differ among cell types and among channel subtypes.

    Science.gov (United States)

    Audesirk, G; Audesirk, T

    1993-01-01

    The whole-cell version of patch clamping was used to compare the effects of acute in vitro exposure to inorganic lead (Pb2+) on voltage-sensitive calcium channels in cultured N1E-115 mouse neuroblastoma cells and E18 rat hippocampal neurons. Free Pb2+ concentrations in salines with a high lead-buffering capacity were measured with a calibrated Pb(2+)-selective electrode. Previously, we found that N1E-115 neurons contain low voltage activated, rapidly inactivating (T) channels and high voltage activated, slowly inactivating (L) channels. Pb2+ inhibits both channel subtypes in N1E-115 cells, with some selectivity against L-type channels (IC50 approximately 700 nM free Pb2+ for L-type channels, 1300 nM free Pb2+ for T-type channels; Audesirk and Audesirk, 1991). In addition to T-type and L-type channels, cultured E18 rat hippocampal neurons have been reported to contain high voltage-activated, rapidly inactivating (N) channels. In our experiments with 5 to 20 day old cultures, almost all neurons showed substantial L-type current, approximately half showed significant N-type current, and fewer than 5% showed significant T-type current. We found that Pb2+ is somewhat selective against L-type channels (IC50 approximately 30 nM free Pb2+ in 10 mM Ba2+ as the charge carrier, 55 nM in 50 mM Ba2+) compared to N-channels (IC50 approximately 80 nM free Pb2+ in 10 mM Ba2+, 200 nM in 50 mM Ba2+). These results suggest that the effects of Pb2+ on calcium channels of vertebrate neurons vary both among cell types and among channel subtypes.

  4. Combining other antihypertensive drugs with β-blockers in hypertension: a focus on safety and tolerability.

    Science.gov (United States)

    Richards, Tiffany R; Tobe, Sheldon W

    2014-05-01

    Combining multiple classes of antihypertensive drugs together is one of the most important factors for achieving blood pressure control in most hypertensive patients. The benefits of combination therapy in comparison with monotherapy include: a synergistic enhancement of each drug's hypertensive effects and a potential reduction of side effects if each drug is used at a lower dose. Although long-acting dihydropyridine calcium channel blockers and β-blockers are a good fit for combination therapy, because of the risk of atrioventricular block and bradycardia, the combination of verapamil and β-blockers is not advised. In addition, the combination of higher-dose diltiazem and β-blockers is also not advised. β-blockers and diuretic agents as initial lone combination therapy are not the preferred combination to be used in uncomplicated hypertension. Using an angiotensin-converting enzyme inhibitor as initial combination therapy with most β-blockers is not recommended because of a lack of antihypertensive efficacy. Nebivolol, however, appears different in this regard and might provide an opportunity for combining these 2 classes of agents with proven cardiovascular benefits for better blood pressure control. Adding an α-blocker to a β-blocker is an effective combination.

  5. State-dependent FRET reports calcium- and voltage-dependent gating-ring motions in BK channels

    OpenAIRE

    Miranda, Pablo; Contreras, Jorge E.; Plested, Andrew J. R.; Sigworth, Fred J.; Holmgren, Miguel; Giraldez, Teresa

    2013-01-01

    Large-conductance voltage- and calcium-dependent potassium channels (BK, “Big K+”) are important controllers of cell excitability. In the BK channel, a large C-terminal intracellular region containing a “gating-ring” structure has been proposed to transduce Ca2+ binding into channel opening. Using patch-clamp fluorometry, we have investigated the calcium and voltage dependence of conformational changes of the gating-ring region of BK channels, while simultaneously monitoring channel conductan...

  6. Brain death provokes very acute alteration in myocardial morphology detected by echocardiography: preventive effect of beta-blockers.

    Science.gov (United States)

    Ferrera, René; Hadour, Guylaine; Tamion, Fabienne; Henry, Jean-Paul; Mulder, Paul; Richard, Vincent; Thuillez, Christian; Ovize, Michel; Derumeaux, Geneviève

    2011-03-01

    Our objective was to evaluate immediate acute changes in myocardial function during the autonomic storm of brain death (BD). Wistar rats were divided into four groups (n = 8/group): controls without any treatment, β-blocker (Esmolol®, 10 mg/kg), calcium channel blocker (Diltiazem®, 10 mg/kg), or alpha-blocker (Prazosin®, 0.3 mg/kg). Treatments were administered intravenously 5 min before BD induction. Echocardiography (ATL-5000, 8 MHz) was performed to measure left ventricular (LV) dimensions and fractional shortening at baseline, during BD induction and 5 min and 15 min after BD. In controls, BD was immediately associated with an increase in wall thickness and a decrease in LV cavity dimension. This myocardial wall hypertrophy was completely prevented by β-blockers, but not with calcium- and alpha-blockers. Extensive myocardial interstitial edema was found in all groups, except in the β-blocker group. Myocardial wall hypertrophy was also prevented during a longer follow-up of 180 min after BD in β-blocker group as opposed to controls. In conclusion, BD is associated with an immediate and severe myocardial damage related to an important interstitial edema which is prevented by β-blockers.

  7. Voltage gated calcium channels negatively regulate protective immunity to Mycobacterium tuberculosis.

    Directory of Open Access Journals (Sweden)

    Shashank Gupta

    Full Text Available Mycobacterium tuberculosis modulates levels and activity of key intracellular second messengers to evade protective immune responses. Calcium release from voltage gated calcium channels (VGCC regulates immune responses to pathogens. In this study, we investigated the roles of VGCC in regulating protective immunity to mycobacteria in vitro and in vivo. Inhibiting L-type or R-type VGCC in dendritic cells (DCs either using antibodies or by siRNA increased calcium influx in an inositol 1,4,5-phosphate and calcium release calcium activated channel dependent mechanism that resulted in increased expression of genes favoring pro-inflammatory responses. Further, VGCC-blocked DCs activated T cells that in turn mediated killing of M. tuberculosis inside macrophages. Likewise, inhibiting VGCC in infected macrophages and PBMCs induced calcium influx, upregulated the expression of pro-inflammatory genes and resulted in enhanced killing of intracellular M. tuberculosis. Importantly, compared to healthy controls, PBMCs of tuberculosis patients expressed higher levels of both VGCC, which were significantly reduced following chemotherapy. Finally, blocking VGCC in vivo in M. tuberculosis infected mice using specific antibodies increased intracellular calcium and significantly reduced bacterial loads. These results indicate that L-type and R-type VGCC play a negative role in M. tuberculosis infection by regulating calcium mobilization in cells that determine protective immunity.

  8. A genetic screen for dihydropyridine (DHP-resistant worms reveals new residues required for DHP-blockage of mammalian calcium channels.

    Directory of Open Access Journals (Sweden)

    Trevor C Y Kwok

    2008-05-01

    Full Text Available Dihydropyridines (DHPs are L-type calcium channel (Ca(v1 blockers prescribed to treat several diseases including hypertension. Ca(v1 channels normally exist in three states: a resting closed state, an open state that is triggered by membrane depolarization, followed by a non-conducting inactivated state that is triggered by the influx of calcium ions, and a rapid change in voltage. DHP binding is thought to alter the conformation of the channel, possibly by engaging a mechanism similar to voltage dependent inactivation, and locking a calcium ion in the pore, thereby blocking channel conductance. As a Ca(v1 channel crystal structure is lacking, the current model of DHP action has largely been achieved by investigating the role of candidate Ca(v1 residues in mediating DHP-sensitivity. To better understand DHP-block and identify additional Ca(v1 residues important for DHP-sensitivity, we screened 440,000 randomly mutated Caenorhabditis elegans genomes for worms resistant to DHP-induced growth defects. We identified 30 missense mutations in the worm Ca(v1 pore-forming (alpha(1 subunit, including eleven in conserved residues known to be necessary for DHP-binding. The remaining polymorphisms are in eight conserved residues not previously associated with DHP-sensitivity. Intriguingly, all of the worm mutants that we analyzed phenotypically exhibited increased channel activity. We also created orthologous mutations in the rat alpha(1C subunit and examined the DHP-block of current through the mutant channels in culture. Six of the seven mutant channels examined either decreased the DHP-sensitivity of the channel and/or exhibited significant residual current at DHP concentrations sufficient to block wild-type channels. Our results further support the idea that DHP-block is intimately associated with voltage dependent inactivation and underscores the utility of C. elegans as a screening tool to identify residues important for DHP interaction with mammalian

  9. Calcium-Activated Potassium Channels in Ischemia Reperfusion: A Brief Update

    Directory of Open Access Journals (Sweden)

    Jean-Yves eTano

    2014-10-01

    Full Text Available Ischemia and reperfusion (IR injury constitutes one of the major causes of cardiovascular morbidity and mortality. The discovery of new therapies to block/mediate the effects of IR is therefore an important goal in the biomedical sciences. Dysfunction associated with IR involves modification of calcium-activated potassium channels (KCa through different mechanisms, which are still under study. Respectively, the KCa family, major contributors to plasma membrane calcium influx in cells and essential players in the regulation of the vascular tone are interesting candidates. This family is divided into two groups including the large conductance (BKCa and the small/intermediate conductance (SKCa/IKCa K+ channels. In the heart and brain, these channels have been described to offer protection against IR injury. BKCa and SKCa channels deserve special attention since new data demonstrate that these channels are also expressed in mitochondria. More studies are however needed to fully determine their potential use as therapeutic targets.

  10. Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels.

    Directory of Open Access Journals (Sweden)

    Tamas Szikra

    Full Text Available Calcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolarized by light. We have used optical imaging and whole-cell voltage clamp to measure the contribution of store-operated Ca(2+ entry (SOCE to Ca(2+ homeostasis and its role in regulation of neurotransmission at cone synapses. Mn(2+ quenching of Fura-2 revealed sustained divalent cation entry in hyperpolarized cones. Ca(2+ influx into cone inner segments was potentiated by hyperpolarization, facilitated by depletion of intracellular Ca(2+ stores, unaffected by pharmacological manipulation of voltage-operated or cyclic nucleotide-gated Ca(2+ channels and suppressed by lanthanides, 2-APB, MRS 1845 and SKF 96365. However, cation influx through store-operated channels crossed the threshold for activation of voltage-operated Ca(2+ entry in a subset of cones, indicating that the operating range of inner segment signals is set by interactions between store- and voltage-operated Ca(2+ channels. Exposure to MRS 1845 resulted in approximately 40% reduction of light-evoked postsynaptic currents in photopic horizontal cells without affecting the light responses or voltage-operated Ca(2+ currents in simultaneously recorded cones. The spatial pattern of store-operated calcium entry in cones matched immunolocalization of the store-operated sensor STIM1. These findings show that store-operated channels regulate spatial and temporal properties of Ca(2+ homeostasis in vertebrate cones and demonstrate their role in generation of sustained excitatory signals across the first retinal synapse.

  11. The role of calcium in growth induced by indole-3-acetic acid and gravity in the leaf-sheath pulvinus of oat (Avena sativa)

    Science.gov (United States)

    Brock, T. G.; Burg, J.; Ghosheh, N. S.; Kaufman, P. B.

    1992-01-01

    Leaf-sheath pulvini of excised segments from oat (Avena sativa L.) were induced to grow by treatment with 10 micromoles indole-3-acetic acid (IAA), gravistimulation, or both, and the effects of calcium, EGTA, and calcium channel blockers on growth were evaluated. Unilaterally applied calcium (10 mM CaCl2) significantly inhibited IAA-induced growth in upright pulvini but had no effect on growth induced by either gravity or gravity plus IAA. Calcium alone had no effect on upright pulvini. The calcium chelator EGTA alone (10 mM) stimulated growth in upright pulvini. However, EGTA had no effect on either IAA- or gravity-induced growth but slightly diminished growth in IAA-treated gravistimulated pulvini. The calcium channel blockers lanthanum chloride (25 mM), verapamil (2.5 mM), and nifedipine (2.5 mM) greatly inhibited growth as induced by IAA (> or = 50% inhibition) or IAA plus gravity (20% inhibition) but had no effect on gravistimulated pulvini. Combinations of channel blockers were similar in effect on IAA action as individual blockers. Since neither calcium ions nor EGTA significantly affected the graviresponse of pulvini, we conclude that apoplastic calcium is unimportant in leaf-sheath pulvinus gravitropism. The observation that calcium ions and calcium channel blockers inhibit IAA-induced growth, but have no effect on gravistimulated pulvini, further supports previous observations that gravistimulation alters the responsiveness of pulvini to IAA.

  12. T Cell Receptor Mediated Calcium Entry Requires Alternatively Spliced Cav1.1 Channels.

    Directory of Open Access Journals (Sweden)

    Didi Matza

    Full Text Available The process of calcium entry in T cells is a multichannel and multi-step process. We have studied the requirement for L-type calcium channels (Cav1.1 α1S subunits during calcium entry after TCR stimulation. High expression levels of Cav1.1 channels were detected in activated T cells. Sequencing and cloning of Cav1.1 channel cDNA from T cells revealed that a single splice variant is expressed. This variant lacks exon 29, which encodes the linker region adjacent to the voltage sensor, but contains five new N-terminal exons that substitute for exons 1 and 2, which are found in the Cav1.1 muscle counterpart. Overexpression studies using cloned T cell Cav1.1 in 293HEK cells (that lack TCR suggest that the gating of these channels was altered. Knockdown of Cav1.1 channels in T cells abrogated calcium entry after TCR stimulation, suggesting that Cav1.1 channels are controlled by TCR signaling.

  13. Comparative pharmacodynamics of eight calcium channel blocking agents in Japanese essential hypertensive patients.

    Science.gov (United States)

    Shimada, S; Nakajima, Y; Yamamoto, K; Sawada, Y; Iga, T

    1996-03-01

    The relationships between plasma drug concentration and antihypertensive effect of eight calcium channel antagonists (nicardipine, nifedipine, nilvadipine, benidipine, manidipine, barnidipine, nitrendipine and efonidipine) in Japanese essential hypertensive patients were analyzed. Based on the effect compartment model, we could explain the long duration of the pharmacological effect, and there was significant correlation (r = 0.876, p < 0.05) between estimated EC50 values and the dissociation constants (Kd) obtained from in vitro binding studies. We also developed the ion-channel binding model to understand the pharmacodynamics of long acting calcium antagonists. The model was also well fitted to antihypertensive effect data. A significant correlation between the apparent in vivo dissociation constants and in vitro Kd values was observed with a slope of 1.45 (r = 0.913), suggesting that the mechanism of long-lasting antihypertensive effect of newer developed calcium antagonists is due to their high binding affinity at ion-channel sites.

  14. Activation of a cGMP-sensitive calcium-dependent chloride channel may cause transition from calcium waves to whole-cell oscillations in smooth muscle cells

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian; Aalkjær, Christian; Nilsson, Holger;

    2007-01-01

    waves sweeping through the cytoplasm when the SR is stimulated to release calcium. A rise in cyclic guanosine monophosphate (cGMP) leads to the experimentally observed transition from waves to whole-cell calcium oscillations. At the same time membrane potential starts to oscillate and the frequency...... approximately doubles. In this transition, the simulated results point to a key role for a recently discovered cGMP-sensitive calcium-dependent chloride channel. This channel depolarizes the membrane in response to calcium released from the SR. In turn, depolarization causes uniform opening of L-type calcium...... onset of oscillations in membrane potential within the individual cell may underlie sudden intercellular synchronization and the appearance of vasomotion. Key words: Vasomotion, Chloride channel, cGMP, Mathematical model, Calcium waves....

  15. Dual pathways of calcium entry in spike and plateau phases of luteinizing hormone release from chicken pituitary cells: sequential activation of receptor-operated and voltage-sensitive calcium channels by gonadotropin-releasing hormone

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, J.S.; Wakefield, I.K.; King, J.A.; Mulligan, G.P.; Millar, R.P.

    1988-04-01

    It has previously been shown that, in pituitary gonadotrope cells, the initial rise in cytosolic Ca2+ induced by GnRH is due to a Ca2+ mobilization from intracellular stores. This raises the possibility that the initial transient spike phase of LH release might be fully or partially independent of extracellular Ca2+. We have therefore characterized the extracellular Ca2+ requirements, and the sensitivity to Ca2+ channel blockers, of the spike and plateau phases of secretion separately. In the absence of extracellular Ca2+ the spike and plateau phases were inhibited by 65 +/- 4% and 106 +/- 3%, respectively. Both phases exhibited a similar dependence on concentration of extracellular Ca2+. However, voltage-sensitive Ca2+ channel blockers D600 and nifedipine had a negligible effect on the spike phase, while inhibiting the plateau phase by approximately 50%. In contrast, ruthenium red, Gd3+ ions, and Co2+ ions inhibited both spike and plateau phases to a similar extent as removal of extracellular Ca2+. A fraction (35 +/- 4%) of spike phase release was resistant to removal of extracellular Ca2+. This fraction was abolished after calcium depletion of the cells by preincubation with EGTA in the presence of calcium ionophore A23187, indicating that it depends on intracellular Ca2+ stores. Neither absence of extracellular Ca2+, nor the presence of ruthenium red or Gd3+ prevented mobilization of 45Ca2+ from intracellular stores by GnRH. We conclude that mobilization of intracellular stored Ca2+ is insufficient by itself to account for full spike phase LH release.

  16. External bioenergy-induced increases in intracellular free calcium concentrations are mediated by Na+/Ca2+ exchanger and L-type calcium channel.

    Science.gov (United States)

    Kiang, Juliann G; Ives, John A; Jonas, Wayne B

    2005-03-01

    External bioenergy (EBE, energy emitted from a human body) has been shown to increase intracellular calcium concentration ([Ca2+]i, an important factor in signal transduction) and regulate the cellular response to heat stress in cultured human lymphoid Jurkat T cells. In this study, we wanted to elucidate the underlying mechanisms. A bioenergy specialist emitted bioenergy sequentially toward tubes of cultured Jurkat T cells for one 15-minute period in buffers containing different ion compositions or different concentrations of inhibitors. [Ca2+], was measured spectrofluorometrically using the fluorescent probe fura-2. The resting [Ca2+]i in Jurkat T cells was 70 +/- 3 nM (n = 130) in the normal buffer. Removal of external calcium decreased the resting [Ca2+]i to 52 +/- 2 nM (n = 23), indicating that Ca2+ entry from the external source is important for maintaining the basal level of [Ca2+]i. Treatment of Jurkat T cells with EBE for 15 min increased [Ca2+]i by 30 +/- 5% (P EBE did not attenuate [Ca2+]i responsiveness to EBE. Removal of external Ca2+ or Na+, but not Mg2+, inhibited the EBE-induced increase in [Ca2+]i. Dichlorobenzamil, an inhibitor of Na+/Ca2+ exchangers, also inhibited the EBE-induced increase in [Ca2+]i in a concentration-dependent manner with an IC50 of 0.11 +/- 0.02 nM. When external [K+] was increased from 4.5 mM to 25 mM, EBE decreased [Ca2+]i. The EBE-induced increase was also blocked by verapamil, an L-type voltage-gated Ca2+ channel blocker. These results suggest that the EBE-induced [Ca2+]i increase may serve as an objective means for assessing and validating bioenergy effects and those specialists claiming bioenergy capability. The increase in [Ca2+]i is mediated by activation of Na+/Ca2+ exchangers and opening of L-type voltage-gated Ca2+ channels.

  17. Therapeutic potential of RQ-00311651, a novel T-type Ca2+ channel blocker, in distinct rodent models for neuropathic and visceral pain.

    Science.gov (United States)

    Sekiguchi, Fumiko; Kawara, Yuma; Tsubota, Maho; Kawakami, Eri; Ozaki, Tomoka; Kawaishi, Yudai; Tomita, Shiori; Kanaoka, Daiki; Yoshida, Shigeru; Ohkubo, Tsuyako; Kawabata, Atsufumi

    2016-08-01

    T-type Ca channels (T channels), particularly Cav3.2 among the 3 isoforms, play a role in neuropathic and visceral pain. We thus characterized the effects of RQ-00311651 (RQ), a novel T-channel blocker, in HEK293 cells transfected with human Cav3.1 or Cav3.2 by electrophysiological and fluorescent Ca signaling assays, and also evaluated the antiallodynic/antihyperalgesic activity of RQ in somatic, visceral, and neuropathic pain models in rodents. RQ-00311651 strongly suppressed T currents when tested at holding potentials of -65 ∼ -60 mV, but not -80 mV, in the Cav3.1- or Cav3.2-expressing cells. RQ-00311651 also inhibited high K-induced Ca signaling in those cells. In mice, RQ, administered intraperitoneally (i.p.) at 5 to 20 mg/kg or orally at 20 to 40 mg/kg, significantly suppressed the somatic hyperalgesia and visceral pain-like nociceptive behavior/referred hyperalgesia caused by intraplantar and intracolonic administration of NaHS or Na2S, H2S donors, respectively, which involve the enhanced activity of Cav3.2 channels. RQ-00311651, given i.p. at 5 to 20 mg/kg, exhibited antiallodynic or antihyperalgesic activity in rats with spinal nerve injury-induced neuropathy or in rats and mice with paclitaxel-induced neuropathy. Oral and i.p. RQ at 10 to 20 mg/kg also suppressed the visceral nociceptive behavior and/or referred hyperalgesia accompanying cerulein-induced acute pancreatitis and cyclophosphamide-induced cystitis in mice. The analgesic and antihyperalgesic/antiallodynic doses of oral and i.p. RQ did not significantly affect the locomotor activity and motor coordination. Together, RQ is considered a state-dependent blocker of Cav3.1/Cav3.2 T channels and may serve as an orally available analgesic for treatment of neuropathic and inflammatory pain including distinct visceral pain with minimum central side effects.

  18. Electrophysiological and antiarrhythmic effects of the novel I(Kur) channel blockers, S9947 and S20951, on left vs. right pig atrium in vivo in comparison with the I(Kr) blockers dofetilide, azimilide, d,l-sotalol and ibutilide.

    Science.gov (United States)

    Knobloch, Karsten; Brendel, Joachim; Peukert, Stefan; Rosenstein, Björn; Busch, Andreas E; Wirth, Klaus J

    2002-11-01

    Inhibition of the cardiac Kv1.5 channel, the molecular base for the human cardiac ultrarapid delayed rectifier potassium current (I(Kur)), is considered a new promising atrial selective antiarrhythmic concept since this channel is presumed to contribute to atrial but not ventricular repolarization in the human heart. In a previous study in pigs we found clear baseline differences in refractoriness between left and right atrium with shorter effective refractory periods (ERPs) of the left atrium associated with a high left atrial vulnerability for tachyarrhythmias. In this newly established model we compared atrial and ventricular effects of two novel I(Kur) blockers, S9947 and S20951, with the I(Kr) blockers dofetilide, azimilide, ibutilide and d,l-sotalol. In pentobarbital anesthetized pigs (n=45) we determined ERPs in the free walls of both atria with the S1-S2-stimulus method at three basic cycle lengths (BCL 240/300/400 ms) and QTc-intervals. The incidence of atrial tachyarrhythmias triggered by the S2-extrastimulus of the left atrium was evaluated (referred to as left atrial vulnerability). In contrast to I(Kr) blockade, I(Kur) blockade had no effect on the QT-interval, but prolonged the atrial ERP. The I(Kur) blockers were significantly stronger on left atrial ERP, I(Kr) blockers on right atrial ERP (PKur) blocker S20951, 3 mg/kg, prolonged left vs. right atrial ERP by 28+/-5 ms vs. 12+/-3 ms and S9947, 3 mg/kg, by 45+/-7 ms vs. 19+/-6 ms. By contrast the effect of dofetilide, 10 microg/kg, was stronger on the right than left atrium (47+/-6 ms vs. 25+/-2 ms), a profile also found with azimilide (5 mg/kg, 43+/-3 ms vs. 17+/-3 ms), ibutilide (15 microg/kg, 70+/-10 ms vs. 29+/-4 ms) and d,l-sotalol (1.5 mg/kg, 57+/-6 ms vs. 36+/-4 ms). The I(Kur) blockers, S20951and S9947, significantly decreased left atrial vulnerability (-82% and -100%, respectively, PKur) and I(Kr) blockers showed substantial differences in their atrial and ventricular actions in pigs. I

  19. Disruption of learned timing in P/Q calcium channel mutants.

    Directory of Open Access Journals (Sweden)

    Akira Katoh

    Full Text Available To optimize motor performance, both the amplitude and temporal properties of movements should be modifiable by motor learning. Here we report that the modification of movement timing is highly dependent on signaling through P/Q-type voltage-dependent calcium channels. Two lines of mutant mice heterozygous for P/Q-type voltage-dependent calcium channels exhibited impaired plasticity of eye movement timing, but relatively intact plasticity of movement amplitude during motor learning in the vestibulo-ocular reflex. The results thus demonstrate a distinction between the molecular signaling pathways regulating the timing versus amplitude of movements.

  20. Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein

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    Masahiro Kawahara

    2011-01-01

    Full Text Available Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP play crucial roles in the pathogenesis of Alzheimer's disease (AD. Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”, and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.

  1. Shaker-type Kv1 channel blockers increase the peristaltic activity of guinea-pig ileum by stimulating acetylcholine and tachykinins release by the enteric nervous system.

    Science.gov (United States)

    Vianna-Jorge, Rosane; Oliveira, Cyntia F; Garcia, Maria L; Kaczorowski, Gregory J; Suarez-Kurtz, Guilherme

    2003-01-01

    1 A constant intraluminal pressure system was used to evaluate the effects of Kv1 channel blockers on the peristaltic activity of guinea-pig ileum. 2 The nortriterpene correolide, a non-selective inhibitor of all Kv1 sub-types, causes progressive and sustained reduction of the pressure threshold for eliciting peristaltic contractions. 3 Margatoxin (MgTX), alpha-dendrotoxin (alpha-DTX) and dendrotoxin-K (DTX-K), highly selective peptidyl inhibitors of certain Kv1 sub-types, cause immediate reduction of the pressure threshold. This effect subsides with time, irrespective of the peptides' concentration in the bath. In preparations pretreated with saturating concentrations of MgTX, correolide further stimulates the peristaltic activity. 4 Iberiotoxin (IbTX), a selective inhibitor of the high-conductance Ca(2+)-activated K(+) (BK) channels, and charybdotoxin (ChTX), which inhibits Kv1.2 and Kv1.3 as well as BK channels, fail to stimulate the peristaltic activity. 5 Blockade of muscarinic receptors by atropine reduces, and occasionally suppresses the peristaltic activity of guinea-pig ileum. In atropine-treated preparations, correolide and MgTX retain their abilities to reduce the pressure threshold and are able to restore the peristaltic reflex in the preparations where this reflex was suppressed by atropine. 6 The stimulatory effect of correolide and MgTX in atropine-treated preparations is abolished by subsequent addition of selective antagonists of both NK1 and NK2 receptors. 7 In conclusion, blockade of Kv1, particularly Kv1.1 channels, increases the peristaltic activity of guinea-pig ileum by enhancing the release of neurotransmitters at the enteric nervous system. In contrast, stimulation of the myogenic motility by blockade of BK channels does not affect the threshold for the peristaltic reflex.

  2. Pharmacological Characterization of the Native Store-Operated Calcium Channels of Cortical Neurons from Embryonic Mouse Brain

    Science.gov (United States)

    Chauvet, Sylvain; Jarvis, Louis; Chevallet, Mireille; Shrestha, Niroj; Groschner, Klaus; Bouron, Alexandre

    2016-01-01

    In the murine brain, the first post-mitotic cortical neurons formed during embryogenesis express store-operated channels (SOCs) sensitive to Pyr3, initially proposed as a blocker of the transient receptor potential channel of C type 3 (TRPC3 channel). However, Pyr3 does not discriminate between Orai and TRPC3 channels, questioning the contribution of TRPC3 in SOCs. This study was undertaken to clarify the molecular identity and the pharmacological profile of native SOCs from E13 cortical neurons. The mRNA expression of STIM1-2 and Orai1-3 was assessed by quantitative reverse transcription polymerase chain reaction. E13 cortical neurons expressed STIM1-2 mRNAs, with STIM2 being the predominant isoform. Only transcripts of Orai2 were found but no Orai1 and Orai3 mRNAs. Blockers of Orai and TRPC channels (Pyr6, Pyr10, EVP4593, SAR7334, and GSK-7975A) were used to further characterize the endogenous SOCs. Their activity was recorded using the fluorescent Ca2+ probe Fluo-4. Cortical SOCs were sensitive to the Orai blockers Pyr6 and GSK-7975A, as well as to EVP4593, zinc, copper, and gadolinium ions, the latter one being the most potent SOCs blocker tested (IC50 ∼10 nM). SOCs were insensitive to the TRPC channel blockers Pyr10 and SAR7334. In addition, preventing mitochondrial Ca2+ uptake inhibited SOCs which were unaffected by inhibitors of the Ca2+-independent phospholipase A2. Altogether, Orai2 channels are present at the beginning of the embryonic murine cortico-genesis and form the core component of native SOCs in the immature cortex. This Ca2+ route is likely to play a role in the formation of the brain cortex. PMID:28018223

  3. The effect of verapamil and diltiazem on cardiac stimulant effect of adrenaline and calcium chloride on isolated frog heart

    Directory of Open Access Journals (Sweden)

    Lakhavat Sudhakar, Naveen Kumar T, Tadvi NA, Venkata Rao Y

    2013-04-01

    Full Text Available Background: Calcium channel blockers block voltage dependent L-type of calcium channel and thus reduce the frequency of opening of these channels in response to depolarization. The result is a marked decrease in transmembrane calcium current associated with long lasting relaxation of vascular smooth muscle, reduction in contractility in cardiac muscle, decrease in pacemaker activity in the SA node and decrease in conduction velocity in the AV node. Among Calcium channel blockers verapamil, is cardio selective, nifedipine is vascular smooth muscle selective, while diltiazem exhibits intermediate selectivity. Methods: In the present study, the effect of two Ca++ channel blocker, Verapamil and Diltiazem were compared on the isolated frog heart by using adrenaline & calcium chloride as standard on frog heart contractility. Results and conclusion: Adrenaline and calcium chloride increased the amplitude of contraction of isolated perfused frog heart. The L- type of Ca2+ channel blockers verapamil and diltiazem produced dose dependent (2mg, 4mg, 8mg, and 16mg reduction in the amplitude of contraction produced by calcium chloride in isolated perfused frog heart. There was no statistical significant difference (p > 0.05 between the inhibitory effect of diltiazem and verapamil on calcium chloride induced contraction of isolated frog heart.

  4. Electromagnetic fields act via activation of voltage-gated calcium channels to produce beneficial or adverse effects.

    Science.gov (United States)

    Pall, Martin L

    2013-08-01

    The direct targets of extremely low and microwave frequency range electromagnetic fields (EMFs) in producing non-thermal effects have not been clearly established. However, studies in the literature, reviewed here, provide substantial support for such direct targets. Twenty-three studies have shown that voltage-gated calcium channels (VGCCs) produce these and other EMF effects, such that the L-type or other VGCC blockers block or greatly lower diverse EMF effects. Furthermore, the voltage-gated properties of these channels may provide biophysically plausible mechanisms for EMF biological effects. Downstream responses of such EMF exposures may be mediated through Ca(2+) /calmodulin stimulation of nitric oxide synthesis. Potentially, physiological/therapeutic responses may be largely as a result of nitric oxide-cGMP-protein kinase G pathway stimulation. A well-studied example of such an apparent therapeutic response, EMF stimulation of bone growth, appears to work along this pathway. However, pathophysiological responses to EMFs may be as a result of nitric oxide-peroxynitrite-oxidative stress pathway of action. A single such well-documented example, EMF induction of DNA single-strand breaks in cells, as measured by alkaline comet assays, is reviewed here. Such single-strand breaks are known to be produced through the action of this pathway. Data on the mechanism of EMF induction of such breaks are limited; what data are available support this proposed mechanism. Other Ca(2+) -mediated regulatory changes, independent of nitric oxide, may also have roles. This article reviews, then, a substantially supported set of targets, VGCCs, whose stimulation produces non-thermal EMF responses by humans/higher animals with downstream effects involving Ca(2+) /calmodulin-dependent nitric oxide increases, which may explain therapeutic and pathophysiological effects.

  5. Calcium-dependent potassium channels play a critical role for burst termination in the locomotor network in lamprey.

    Science.gov (United States)

    el Manira, A; Tegnér, J; Grillner, S

    1994-10-01

    1. The possible involvement of calcium-dependent potassium channels (KCa) in the termination of locomotor bursts was investigated by administration of a specific blocker, apamin, in the lamprey spinal cord in vitro. The effects were examined by recording the efferent activity in ventral roots and by intracellular recording from interneurons and motoneurons. During fictive locomotion induced by N-methyl-D-aspartate (NMDA), apamin was found to affect both the frequency of bursting and the regularity of the locomotor pattern. 2. At the single cell level, NMDA can induce pacemaker-like membrane potential oscillations in individual neurons after administration of tetrodotoxin. Apamin (2.5 microM) produced a marked increase of the duration of the depolarizing plateau phase occurring during these NMDA-induced oscillations; this shows that the repolarization of the plateau is initiated by a progressive activation of apamin-sensitive KCa-channels. 3. The action potential is followed by an afterhyperpolarization (AHP) with a fast and a slow phase (sAHP). The latter is known to be caused by apamin-sensitive KCa-channels. During repetitive firing, the interspike interval is dependent on the amplitude and the duration of the sAHP. Apamin caused a reduction of the spike frequency adaptation with a concomitant increase in the firing frequency. In some cells, apamin in addition reduced the threshold for the action potential. Apamin-sensitive KCa-channels thus will be involved in controlling both the onset and the duration of neuronal firing in the lamprey spinal cord. 4. During fictive locomotion induced by NMDA (40-200 microM), a blockade of KCa-channels by apamin produced an increase of the coefficient of variation (mean = 167%, n = 26), which was statistically significant in 21 out of 26 experiments. At 40-150 microM NMDA, an average increase in cycle duration was 77% and statistically significant in 15 out of 20 preparations. At 200 microM NMDA (corresponding to higher burst

  6. Variability of Potassium Channel Blockers in Mesobuthus eupeus Scorpion Venom with Focus on Kv1.1: AN INTEGRATED TRANSCRIPTOMIC AND PROTEOMIC STUDY.

    Science.gov (United States)

    Kuzmenkov, Alexey I; Vassilevski, Alexander A; Kudryashova, Kseniya S; Nekrasova, Oksana V; Peigneur, Steve; Tytgat, Jan; Feofanov, Alexey V; Kirpichnikov, Mikhail P; Grishin, Eugene V

    2015-05-08

    The lesser Asian scorpion Mesobuthus eupeus (Buthidae) is one of the most widely spread and dispersed species of the Mesobuthus genus, and its venom is actively studied. Nevertheless, a considerable amount of active compounds is still under-investigated due to the high complexity of this venom. Here, we report a comprehensive analysis of putative potassium channel toxins (KTxs) from the cDNA library of M. eupeus venom glands, and we compare the deduced KTx structures with peptides purified from the venom. For the transcriptome analysis, we used conventional tools as well as a search for structural motifs characteristic of scorpion venom components in the form of regular expressions. We found 59 candidate KTxs distributed in 30 subfamilies and presenting the cysteine-stabilized α/β and inhibitor cystine knot types of fold. M. eupeus venom was then separated to individual components by multistage chromatography. A facile fluorescent system based on the expression of the KcsA-Kv1.1 hybrid channels in Escherichia coli and utilization of a labeled scorpion toxin was elaborated and applied to follow Kv1.1 pore binding activity during venom separation. As a result, eight high affinity Kv1.1 channel blockers were identified, including five novel peptides, which extend the panel of potential pharmacologically important Kv1 ligands. Activity of the new peptides against rat Kv1.1 channel was confirmed (IC50 in the range of 1-780 nm) by the two-electrode voltage clamp technique using a standard Xenopus oocyte system. Our integrated approach is of general utility and efficiency to mine natural venoms for KTxs.

  7. [Discovering L-type calcium channels inhibitors of antihypertensive drugs based on drug repositioning].

    Science.gov (United States)

    Liang, Ying-xi; He, Yu-su; Jiang, Lu-di; Yue, Qiao-xin; Cui, Shuai; Bin, Li; Ye, Xiao-tong; Zhang, Xiao-hua; Zhang, Yang-ling

    2015-09-01

    This study was amid to construct the pharmacophore model of L-type calcium channel antagonist in the application of screening Drugbank and TCMD. This paper repositions the approved drugs resulting from virtual screening and discusses the relocation-based drug discovery methods, screening antihypertensive drugs with L-type calcium channel function from TCMD. Qualitative hypotheses wre generated by HipHop separately on the basis of 12 compounds with antagonistic action on L-type calcium channel expressed in rabbit cardiac muscle. Datebase searching method was used to evaluate the generated hypotheses. The optimum hypothesis was used to search Drugbank and TCMD. This paper repositions the approved drugs and evaluates the antihypertensive effect of the chemical constituent of traditional Chinese medicine resulting from virtual screening by the matching score and literature. The results showed that optimum qualitative hypothesis is with six features, which were two hydrogen-bond acceptors, four hydrophobic groups, and the CAI value of 2.78. Screening Drugbank achieves 93 approved drugs. Screening TCMD achieves 285 chemical constituents of traditional Chinese medicine. It was concluded that the hypothesis is reliable and can be used to screen datebase. The approved drugs resulting from virtual screening, such as pravastatin, are potentially L-type calcium channels inhibitors. The chemical constituents of traditional Chinese medicine, such as Arctigenin III and Arctigenin are potentially antihypertensive drugs. It indicates that Drug Repositioning based on hypothesis is possible.

  8. L-type Voltage-Gated Calcium Channels in Conditioned Fear: A Genetic and Pharmacological Analysis

    Science.gov (United States)

    McKinney, Brandon C.; Sze, Wilson; White, Jessica A.; Murphy, Geoffrey G.

    2008-01-01

    Using pharmacological approaches, others have suggested that L-type voltage-gated calcium channels (L-VGCCs) mediate both consolidation and extinction of conditioned fear. In the absence of L-VGCC isoform-specific antagonists, we have begun to investigate the subtype-specific role of LVGCCs in consolidation and extinction of conditioned fear…

  9. A potent and selective peptide blocker of the Kv1.3 channel: prediction from free-energy simulations and experimental confirmation.

    Directory of Open Access Journals (Sweden)

    M Harunur Rashid

    Full Text Available The voltage-gated potassium channel Kv1.3 is a well-established target for treatment of autoimmune diseases. ShK peptide from a sea anemone is one of the most potent blockers of Kv1.3 but its application as a therapeutic agent for autoimmune diseases is limited by its lack of selectivity against other Kv channels, in particular Kv1.1. Accurate models of Kv1.x-ShK complexes suggest that specific charge mutations on ShK could considerably enhance its specificity for Kv1.3. Here we evaluate the K18A mutation on ShK, and calculate the change in binding free energy associated with this mutation using the path-independent free energy perturbation and thermodynamic integration methods, with a novel implementation that avoids convergence problems. To check the accuracy of the results, the binding free energy differences were also determined from path-dependent potential of mean force calculations. The two methods yield consistent results for the K18A mutation in ShK and predict a 2 kcal/mol gain in Kv1.3/Kv1.1 selectivity free energy relative to wild-type peptide. Functional assays confirm the predicted selectivity gain for ShK[K18A] and suggest that it will be a valuable lead in the development of therapeutics for autoimmune diseases.

  10. Activity-dependent regulation of T-type calcium channels by submembrane calcium ions.

    Science.gov (United States)

    Cazade, Magali; Bidaud, Isabelle; Lory, Philippe; Chemin, Jean

    2017-01-21

    Voltage-gated Ca(2+) channels are involved in numerous physiological functions and various mechanisms finely tune their activity, including the Ca(2+) ion itself. This is well exemplified by the Ca(2+)-dependent inactivation of L-type Ca(2+) channels, whose alteration contributes to the dramatic disease Timothy Syndrome. For T-type Ca(2+) channels, a long-held view is that they are not regulated by intracellular Ca(2+). Here we challenge this notion by using dedicated electrophysiological protocols on both native and expressed T-type Ca(2+) channels. We demonstrate that a rise in submembrane Ca(2+) induces a large decrease in T-type current amplitude due to a hyperpolarizing shift in the steady-state inactivation. Activation of most representative Ca(2+)-permeable ionotropic receptors similarly regulate T-type current properties. Altogether, our data clearly establish that Ca(2+) entry exerts a feedback control on T-type channel activity, by modulating the channel availability, a mechanism that critically links cellular properties of T-type Ca(2+) channels to their physiological roles.

  11. Solid-Phase Synthesis of New Trp(Nps-Containing Dipeptide Derivatives as TRPV1 Channel Blockers

    Directory of Open Access Journals (Sweden)

    Rosario González-Muñiz

    2010-07-01

    Full Text Available Trp(Nps-Lys-NH2 derivatives, bearing alkyl or guanidine groups either at the N–terminus or on the Lys side-chain or at both positions were conveniently prepared on solid-phase and evaluated as TRPV1 channel antagonists.

  12. Calcium Channel Expression and Applicability as Targeted Therapies in Melanoma

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    A. Macià

    2015-01-01

    Full Text Available The remodeling of Ca2+ signaling is a common finding in cancer pathophysiology serving the purpose of facilitating proliferation, migration, or survival of cancer cells subjected to stressful conditions. One particular facet of these adaptive changes is the alteration of Ca2+ fluxes through the plasma membrane, as described in several studies. In this review, we summarize the current knowledge about the expression of different Ca2+ channels in the plasma membrane of melanoma cells and its impact on oncogenic Ca2+ signaling. In the last few years, new molecular components of Ca2+ influx pathways have been identified in melanoma cells. In addition, new links between Ca2+ homeostasis and specific cell processes important in melanoma tumor progression have been unveiled. Thus, not only do Ca2+ channels appear to have a potential as prognostic markers, but their pharmacological blockade or gene silencing is hinted as interesting therapeutic approaches.

  13. EFFECT OF ELECTROACUPUNCTURE AND CALCIUM-CHANNEL INHIBITORS ON CYTOPLASMIC FREE CALCIUM CONCENTRATION OF MOUSE BRAIN CELLS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-mei; XIE Ji-min; CHEN Min; ZHANG Yan

    2005-01-01

    Objective: To study the effect of electroacupuncture (EA) and Verapamil and Nifedipine (calcium channel inhibitors) on free calcium concentrations of cells and intrasynaptosomes in hypothalamus (HT), periaqueductual grey matter (PAG) and hippocampus (HIP) of mice. Methods: The female ICR mice were randomly divided into control, EA, CaCl2 and CaCl2+EA groups (n=8 in each group). Pain threshold was detected by using radiation-heat irradiation-induced tail flick method. EA (8 Hz, a suitable stimulating strength, dense-sparse waves and duration of 30 min) was applied to"Shuigou" (水沟 GV 26) and "Chengjiang" (承浆CV 24). CaCl2 (10 μL, 0.2 μmol/L) was injected into the lateral cerebral ventricle of mice after EA. The concentrations of cytosolic free calcium ([Ca2+]i) in HIP, PAG, HT cell suspension specimen and hippocampal intrasynaptosome suspension of mice were determined by the fluorescent calcium indicator Fura-2-AM and a spectrofluorometer. Results: During EA analgesia, the intracellular free [Ca2+]i in HT and PAG specimens and intrsynaptosomal [Ca2+]i of the 3 cerebral regions decreased considerably (P<0.05~0.01), but that in hippocampal cell suspension increased significantly (P<0.01) in comparison with control group. The concentrations of hippocampal intrasynaptosomal free [Ca2+]i decreased significantly after adding Verapamil and Nifedipine to the extracted hippocampal intrasynaptosomal specimen. Microinjection of CaCl2 into lateral ventricle had no apparent influence on degree of analgesia (DA)% and intracellular and intrasynapsotomal [Ca2+]i, but significantly lower DA% and reduce changes of cytosolic and intrasynaptosomal [Ca2+]i induced by EA stimulation. Conclusion: Calcium ion in the neurons and intrasynaptosome of HT, PAG and HIP is involved in electroacupuncture analgesia.

  14. New 1,4-dihydropyridines endowed with NO-donor and calcium channel agonist properties.

    Science.gov (United States)

    Visentin, Sonja; Rolando, Barbara; Di Stilo, Antonella; Fruttero, Roberta; Novara, Monica; Carbone, Emilio; Roussel, Christian; Vanthuyne, Nicolas; Gasco, Alberto

    2004-05-06

    A new series of calcium channel agonists structurally related to Bay K8644, containing NO donor furoxans and the related furazans unable to release NO, is described. The racemic mixtures were studied for their action on L-type Ca(2+) channels expressed in cultured rat insulinoma RINm5F cells. All the products proved to be potent calcium channel agonists. All the racemic mixtures, with the only exception of the carbamoyl derivatives 9, 12 endowed with scanty solubility, were separated by chiral chromatography into the corresponding enantiomers; the (+) enantiomers were found to be potent agonists while the (-) ones were feeble antagonists. The racemic mixtures were also assessed for their positive inotropic activity on electrically stimulated rat papillary muscle and for their ability to increase Ca(2+) entry into the vascular smooth muscle of rat aorta strips. The cyanofuroxan 8 proved to be an interesting product with dual Ca(2+)-dependent positive inotropic and NO-dependent vasodilating activity.

  15. Simultaneous determination of a novel calcium entry blocker, monatepil maleate, and its metabolites in rat plasma by means of solid-phase extraction and reversed-phase liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Kurono, M; Suzuki, K; Yoshida, K; Naruto, S

    1997-02-21

    A reversed-phase LC method with electrochemical detection is described for the simultaneous determination of monatepil maleate (AJ-2615, AJ), a novel calcium entry blocker, and its three S-oxidized metabolites in plasma. These compounds were extracted from plasma by solid-phase extraction and injected onto an ODS column. The determination limit in plasma (0.5 ml) was 10 ng/ml for AJ and 5 ng/ml for the three metabolites. The method was applied to the determination of AJ and the metabolites in rat plasma samples.

  16. Different effects of calcium antagonist and beta-blocker therapy on left-ventricular diastolic function in ischemic heart disease. A direct comparison of the impact of mibefradil and atenolol

    DEFF Research Database (Denmark)

    Hassager, C; Thygesen, K; Grande, P;

    2001-01-01

    OBJECTIVE: To compare the effect of a calcium antagonist and a beta-blocker on left-ventricular diastolic function in patients with ischemic heart disease. METHODS: 138 patients with chronic stable angina pectoris were randomized in a multicenter, double-blind trial to treatment with either...... mibefradil or atenolol for 6 weeks (50 mg once daily for 2 weeks followed by 100 mg once daily for 4 weeks). The ratio between early (E) and late (A) diastolic mitral flow velocities (E/A), the E wave deceleration time (DT) and the left ventricular isovolumetric relaxation time (IRT) were measured by Doppler...

  17. Significant natriuretic and antihypertensive action of the epithelial sodium channel blocker amiloride in diabetic patients with and without nephropathy

    DEFF Research Database (Denmark)

    Andersen, Henrik; Hansen, Pernille B L; Bistrup, Claus;

    2016-01-01

    OBJECTIVE: Diabetic nephropathy is associated with aberrant glomerular filtration of serine proteases. The study was designed to test the hypothesis that the epithelial sodium channel is activated proteolytically by urine plasmin in diabetic nephropathy and mediates renal sodium retention. METHODS......: In an open-label intervention study on type 1 diabetes patients on standardized NaCl intake (200 mmol/day) with (n = 15) and without diabetic nephropathy (control, n = 12), urinary Na excretion in response to oral amiloride (20 or 40 mg/day for 2 days) was compared. RESULTS: A total of 27 patients completed...... renal Na excretion, reduced blood pressure, albuminuria, and total and active plasmin in urine. It is concluded that epithelial sodium channel is an attractive target to attain blood pressure control in long-term type I diabetes with no enhanced activity associated with nephropathy....

  18. [Persistence in drug therapy of hypertension among different treatment groups and comparison between fixed-dose combinations of ara II + calcium channel blockers vs ace inhibitors + calcium channel blockers].

    Science.gov (United States)

    Waisman, Gabriel Dario; Garfi, Leonardo Guillermo; Izbizky, Gustavo Hernan; Tortella, Juan Jose

    2012-01-01

    La hipertensión arterial (HTA) es una enfermedad crónica, y prevalente, que requiere un tratamiento sostenido en el tiempo donde existen medidas farmacológicas y no farmacológicas para su control. La “persistencia” es la continuidad de los tratamientos farmacológicos. Conocer cual es la persistencia de los diferentes grupos terapéuticos antihipertensivos podría ayudar a priorizar aquellos con mejores resultados. El objetivo es describir la persistencia al tratamiento antihipertensivo en una cohorte de pacientes utilizando diferentes métodos y comparar la persistencia en los diferentes grupos farmacológicos utilizados para el tratamiento de la HTA. Materiales y Métodos: Estudio observacional, de cohorte retrospectiva utilizando bases de datos secundarias obtenidas durante la dispensación de medicamentos y de los registros hospitalarios electrónicos del Hospital Italiano de Buenos Aires. Población adulta con diagnóstico de HTA y seguimiento por 2 años. Resultados: Los diuréticos, betabloqueantes de primera generación e inhibidores de la enzima convertidora de angiotensina son los grupos con la caída más importante en la persistencia. Los antagonistas de la angiotensina en monoterapia o junto con diurético y los betabloqueantes de segunda generación demostraron los mejores resultados de persistencia. La persistencia nunca llegó al 60% de los pacientes tratados a los 2 años. Conclusión: Pese a haber realizado la medición de la persistencia a través de distintos métodos los resultados fueron similares y demostraron una baja persistencia al tratamiento antihipertensivo. No encontramos variables extra farmacológicas que pudieran explicar la diferente persistencia en los diferentes grupos terapéuticos.

  19. Putative calcium-binding domains of the Caenorhabditis elegans BK channel are dispensable for intoxication and ethanol activation.

    Science.gov (United States)

    Davis, S J; Scott, L L; Ordemann, G; Philpo, A; Cohn, J; Pierce-Shimomura, J T

    2015-07-01

    Alcohol modulates the highly conserved, voltage- and calcium-activated potassium (BK) channel, which contributes to alcohol-mediated behaviors in species from worms to humans. Previous studies have shown that the calcium-sensitive domains, RCK1 and the Ca(2+) bowl, are required for ethanol activation of the mammalian BK channel in vitro. In the nematode Caenorhabditis elegans, ethanol activates the BK channel in vivo, and deletion of the worm BK channel, SLO-1, confers strong resistance to intoxication. To determine if the conserved RCK1 and calcium bowl domains were also critical for intoxication and basal BK channel-dependent behaviors in C. elegans, we generated transgenic worms that express mutated SLO-1 channels predicted to have the RCK1, Ca(2+) bowl or both domains rendered insensitive to calcium. As expected, mutating these domains inhibited basal function of SLO-1 in vivo as neck and body curvature of these mutants mimicked that of the BK null mutant. Unexpectedly, however, mutating these domains singly or together in SLO-1 had no effect on intoxication in C. elegans. Consistent with these behavioral results, we found that ethanol activated the SLO-1 channel in vitro with or without these domains. By contrast, in agreement with previous in vitro findings, C. elegans harboring a human BK channel with mutated calcium-sensing domains displayed resistance to intoxication. Thus, for the worm SLO-1 channel, the putative calcium-sensitive domains are critical for basal in vivo function but unnecessary for in vivo ethanol action.

  20. Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli.

    Science.gov (United States)

    Ilatovskaya, Daria V; Palygin, Oleg; Levchenko, Vladislav; Staruschenko, Alexander

    2015-06-27

    Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells in the pathogenesis of various renal diseases has been established since podocyte injury leads to proteinuria and foot process effacement. It was previously reported that various endogenous agents may cause a dramatic overload in intracellular Ca(2+) concentration in podocytes, presumably leading to albuminuria, and this likely occurs via calcium-conducting ion channels. Therefore, it appeared important to study calcium handling in the podocytes both under normal conditions and in various pathological states. However, available experimental approaches have remained somewhat limited to cultured and transfected cells. Although they represent a good basic model for such studies, they are essentially extracted from the native environment of the glomerulus. Here we describe the methodology of studying podocytes as a part of the freshly isolated whole glomerulus. This preparation retains the functional potential of the podocytes, which are still attached to the capillaries; therefore, podocytes remain in the environment that conserves the major parts of the glomeruli filtration apparatus. The present manuscript elaborates on two experimental approaches that allow 1) real-time detection of calcium concentration changes with the help of ratiometric confocal fluorescence microscopy, and 2) the recording of the single ion channels activity in the podocytes of the freshly isolated glomeruli. These methodologies utilize the advantages of the native environment of the glomerulus that enable researchers to resolve acute changes in the intracellular calcium handling in response to applications of various agents, measure basal concentration of calcium within the cells (for instance, to evaluate disease progression), and assess and manipulate calcium conductance at the level of single ion channels.

  1. Enhanced currents through L-type calcium channels in cardiomyocytes disturb the electrophysiology of the dystrophic heart.

    Science.gov (United States)

    Koenig, Xaver; Rubi, Lena; Obermair, Gerald J; Cervenka, Rene; Dang, Xuan B; Lukacs, Peter; Kummer, Stefan; Bittner, Reginald E; Kubista, Helmut; Todt, Hannes; Hilber, Karlheinz

    2014-02-15

    Duchenne muscular dystrophy (DMD), induced by mutations in the gene encoding for the cytoskeletal protein dystrophin, is an inherited disease characterized by progressive muscle weakness. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with cardiac complications. These include cardiomyopathy development and cardiac arrhythmias. The current understanding of the pathomechanisms in the heart is very limited, but recent research indicates that dysfunctional ion channels in dystrophic cardiomyocytes play a role. The aim of the present study was to characterize abnormalities in L-type calcium channel function in adult dystrophic ventricular cardiomyocytes. By using the whole cell patch-clamp technique, the properties of currents through calcium channels in ventricular cardiomyocytes isolated from the hearts of normal and dystrophic adult mice were compared. Besides the commonly used dystrophin-deficient mdx mouse model for human DMD, we also used mdx-utr mice, which are both dystrophin- and utrophin-deficient. We found that calcium channel currents were significantly increased, and channel inactivation was reduced in dystrophic cardiomyocytes. Both effects enhance the calcium influx during an action potential (AP). Whereas the AP in dystrophic mouse cardiomyocytes was nearly normal, implementation of the enhanced dystrophic calcium conductance in a computer model of a human ventricular cardiomyocyte considerably prolonged the AP. Finally, the described dystrophic calcium channel abnormalities entailed alterations in the electrocardiograms of dystrophic mice. We conclude that gain of function in cardiac L-type calcium channels may disturb the electrophysiology of the dystrophic heart and thereby cause arrhythmias.

  2. Characterisation of marrubenol, a diterpene extracted from Marrubium vulgare, as an L-type calcium channel blocker

    OpenAIRE

    El-Bardai, Sanae; Wibo, Maurice; Hamaide, Marie-Christine; Lyoussi, Badiaa; Quetin-Leclercq, Joëlle; Morel, Nicole

    2003-01-01

    1. The objective of the present study was to investigate the mechanism of the relaxant activity of marrubenol, a diterpenoid extracted from Marrubium vulgare. In rat aorta, marrubenol was a more potent inhibitor of the contraction evoked by 100 mM KCl (IC50: 11.8+/-0.3 microM, maximum relaxation: 93+/-0.6%) than of the contraction evoked by noradrenaline (maximum relaxation: 30+/-1.5%). 2. In fura-2-loaded aorta, marrubenol simultaneously inhibited the Ca2+ signal and the contraction evoked b...

  3. Potentiation of anticonvulsant activity of phenytoin by calcium channel blockers (verapamil and amlodipine against maximal electroshock seizures in rats

    Directory of Open Access Journals (Sweden)

    Monika Sharma

    2014-08-01

    Conclusions: From the present investigation, it may be concluded that the dose of DPH may be reduced in an antiepileptic individual who is on verapamil and amlodipine therapy. [Int J Basic Clin Pharmacol 2014; 3(4.000: 608-610

  4. Role for voltage gated calcium channels in calcitonin gene-related peptide release in the rat trigeminovascular system

    DEFF Research Database (Denmark)

    Amrutkar, D V; Ploug, K B; Olesen, J

    2011-01-01

    Clinical and genetic studies have suggested a role for voltage gated calcium channels (VGCCs) in the pathogenesis of migraine. Release of calcitonin gene-related peptide (CGRP) from trigeminal neurons has also been implicated in migraine. The VGCCs are located presynaptically on neurons and are i...... releases CGRP, and the release is regulated by Ca2+ ions and voltage-gated calcium channels.......Clinical and genetic studies have suggested a role for voltage gated calcium channels (VGCCs) in the pathogenesis of migraine. Release of calcitonin gene-related peptide (CGRP) from trigeminal neurons has also been implicated in migraine. The VGCCs are located presynaptically on neurons...

  5. Treatment with a Ca(2+) channel blocker, barnidipine, reduces platelet-derived growth factor B-chain mRNA in glomeruli of spontaneously hypertensive rats.

    Science.gov (United States)

    Hashimoto, M; Yamauchi, T; Ogura, T; Oishi, T; Mimura, Y; Otsuka, F; Kashihara, N; Makino, H

    1999-01-01

    We investigated the effect of barnidipine hydrochloride, a Ca(2+) channel blocker, on the glomerular level of mRNA expression of platelet-derived growth factor (PDGF) B-chain and transforming growth factor (TGF)-beta(1) in spontaneously hypertensive rats (SHR) with reverse transcription and polymerase chain reaction. Thirteen-week-old SHR were provided with food containing barnidipine (0.6 mg/g of food, average dose during treatment: 53 mg/kg of body mass/day) for 3 weeks. A stable reduction in systolic blood pressure relative to that of age-matched control SHR was recorded after week 1 of therapy. Although no renal histological changes were observed after 3 weeks of treatment with barnidipine, the level of expression of PDGF B-chain mRNA in glomeruli was significantly reduced relative to that in control SHR. The glomerular level of TGF-beta(1) mRNA expression was not affected by the treatment. Treatment with barnidipine significantly reduced the excretion of urinary protein. Thus, the stable reduction in systemic blood pressure by barnidipine is associated with a reduction in PDGF B-chain mRNA expression in the glomerulus and reduction in urinary protein excretion in SHR.

  6. A role for L-type calcium channels in the maturation of parvalbumin-containing hippocampal interneurons.

    Science.gov (United States)

    Jiang, M; Swann, J W

    2005-01-01

    While inhibitory interneurons are well recognized to play critical roles in the brain, relatively little is know about the molecular events that regulate their growth and differentiation. Calcium ions are thought to be important in neuronal development and L-type voltage gated Ca(+2) channels have been implicated in activity-dependent mechanisms of early-life. However, few studies have examined the role of these channels in the maturation of interneurons. The studies reported here were conducted in hippocampal slice cultures and indicate that the L-type Ca(+2) channel agonists and antagonists accelerate and suppress respectively the growth of parvalbumin-containing interneurons. The effects of channel blockade were reversible suggesting they are not the result of interneuronal cell death. Results from immunoblotting showed that these drugs have similar effects on the expression of the GABA synthetic enzymes, glutamic acid decarboxylase65, glutamic acid decarboxylase67 and the vesicular GABA transporter. This suggests that L-type Ca(+2) channels regulate not only parvalbumin expression but also interneuron development. These effects are likely mediated by actions on the interneurons themselves since the alpha subunits of L-type channels, voltage-gated calcium channel subunit 1.2 and voltage-gated calcium channel subunit 1.3 were found to be highly expressed in neonatal mouse hippocampus and co-localized with parvalbumin in interneurons. Results also showed that while these interneurons can contain either subunit, voltage-gated calcium channel subunit 1.3 was more widely expressed. Taken together results suggest that an important subset of developing interneurons expresses L-type Ca(+2) channels alpha subunits, voltage-gated calcium channel subunit 1.2 and especially voltage-gated calcium channel subunit 1.3 and that these channels likely regulate the development of these interneurons in an activity-dependent manner.

  7. Calcium channel antagonists suppress cross-tolerance to the anxiogenic effects of D-amphetamine and nicotine in the mouse elevated plus maze test.

    Science.gov (United States)

    Biala, Grazyna; Kruk, Marta

    2008-01-01

    The purpose of the current experiments was to examine the anxiety-related effects of repeated amphetamine and nicotine administration using the mouse elevated plus maze (EPM). d-amphetamine was administered daily for 8 days (2 mg/kg, i.p.). On the 9th day, mice were challenged with amphetamine (2 mg/kg, i.p.) or nicotine (0.1 mg/kg, s.c.), and were tested 30 min after this last injection. Additionally, a distinct group of mice was pretreated with nicotine (0.1 mg/kg, s.c., 6 days). These mice were subjected to nicotine (0.1 mg/kg, s.c.) or amphetamine (2 mg/kg, i.p.) challenge on the seventh day to see if full crossover effects developed after the pretreatment of both psychostimulant drugs. Moreover, the L-type voltage-dependent calcium channel antagonists nimodipine (5 and 10 mg/kg, i.p.), flunarizine (5 and 10 mg/kg, i.p.), verapamil (5 and 10 mg/kg, i.p.) and diltiazem (5 and 10 mg/kg, i.p.) were injected prior to each injection of chronic d-amphetamine or nicotine. We observed cross-tolerance to the anxiogenic effects of d-amphetamine and nicotine that was blunted by a pretreatment with calcium channel blockers. Overall our findings imply that similar neural calcium-dependent mechanisms are involved in the anxiety-related responses to chronic amphetamine and nicotine injections. As anxiety seems to be an important factor for the development of psychostimulant dependence, the L-type VDCC antagonists can offer an interesting approach for the pharmacotherapy of addiction, including amphetamine and/or nicotine dependence.

  8. Influence of bupropion and calcium channel antagonists on the nicotine-induced memory-related response of mice in the elevated plus maze.

    Science.gov (United States)

    Biała, Grazyna; Kruk, Marta

    2009-01-01

    In this study, we investigated the effects of acute administration of nicotine on memory-related behavior in mice using the elevated plus maze test. In this test, the time necessary for mice to move from the open arm to the enclosed arm (i.e., transfer latency) was used as an index of memory. Our results revealed that nicotine (0.035 and 0.175 mg/kg, base, sc) shortened the transfer latency relative to the saline-treated group. Moreover, we investigated the effects of bupropion (10, 20 and 40 mg/kg, ip) and L-type voltage-dependent calcium channel antagonists (nimodipine, flunarizine, verapamil, diltiazem - 5, 10 and 20 mg/kg, ip) on memory-related behavior. At all tested doses, bupropion, did not significantly affect transfer latency. However, flunarizine and verapamil (both at 10 mg/kg) resulted in a slight decrease in transfer latency, whereas nimodipine (10 mg/kg) increased transfer latency. Interestingly, both bupropion (20 mg/kg) and calcium channel blockers (5 mg/kg) attenuated the improvement of memory induced by nicotine. Our findings indicate that the cholinergic nicotinic system may play an important role in memory consolidation, and that neural calcium-dependent mechanisms can be involved in the modulation of memory-related responses induced by nicotine. The results of these studies have revealed neuronal mechanisms that are important for nicotinic modulation of cognition and will be useful for the treatments of human disorders in which cholinergic pathways have been implicated, such as psychiatric disorders and addiction.

  9. Aluminium and hydrogen ions inhibit a mechanosensory calcium-selective cation channel

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    The tension-dependent activity of mechanosensory calcium-selective cation channels in excised plasmalemmal patches from onion bulb scale epidermis is modulated by pH in the physiologically meaningful range between 4.5 and 7.2. It is rapidly lowered by lowering pH and rapidly raised by raising pH. Channel activity is effectively inhibited by low levels of aluminium ions and activity can be partially restored by washing for a few minutes. We suggest that under normal conditions the sensitivity of the mechanosensory channels to pH of the wall free space plays important roles in regulation of plant activities such as growth. We further suggest that, when levels of acid and aluminium ions in the soil solution are high, they might inhibit similar sensory channels in cells of the root tip, thus contributing critically to the acid soil syndrome.

  10. The potential role of calcium antagonists in the management of congestive heart failure : Initial experience with lacidipine

    NARCIS (Netherlands)

    deVries, RJM; Dunselman, PHJM

    1995-01-01

    First-generation calcium antagonists have been used in patients with congestive heart failure with rather disappointing results. Therefore, second-generation dihydropyridine calcium-channel blockers, such as felodipine and lacidipine, have been developed that may be beneficial in congestive heart fa

  11. Role of Calcium Channels in the Protective Effect of Hydrogen Sulfide in Rat Cardiomyoblasts

    Directory of Open Access Journals (Sweden)

    Daniele Avanzato

    2014-04-01

    Full Text Available Background: Hydrogen sulfide contributes to the reduction of oxidative stress-related injury in cardiomyocytes but the underlying mechanism is still unclear. Aims: Here we investigated the role of voltage-operated calcium channels (VOCCs as mediators of the beneficial effect of H2S against oxidative stress in cultured rat cardiomyoblasts (H9c2. Methods: Intracellular calcium signals were measured by fluorimetric live cell imaging and cell viability by colorimetric assay. Results: Treatment with H2S donor (NaHS 10 µM or Nifedipine (10 µM decreased resting intracellular calcium concentration [Ca]i, suggesting that L-type VOCCs are negatively modulated by H2S. In the presence of Nifedipine H2S was still able to lower [Ca]i, while co-incubation with Nifedipine and Ni2+ 100 µM completely prevented H2S-dependent [Ca]i decrease, suggesting that both L-type and T-type VOCCs are inhibited by H2S. In addition, in the same experimental conditions, H2S triggered a slow increase of [Ca]i whose molecular nature remains to be clarified. Pretreatment of H9c2 with NaHS (10 µM significantly prevented cell death induced by H2O2. This effect was mimicked by pretreatment with L-Type calcium channel inhibitor Nifedipine (10 µM. Conclusions: The data provide the first evidence that H2S protects rat cardiomyoblasts against oxidative challenge through the inhibition of L-type calcium channels.

  12. Postcountershock myocardial damage after pretreatment with adrenergic and calcium channel antagonists in halothane-anesthetized dogs

    Energy Technology Data Exchange (ETDEWEB)

    Gaba, D.M.; Metz, S.; Maze, M.

    1985-05-01

    Transthoracic electric countershock can cause necrotic myocardial lesions in humans as well as experimental animals. The authors investigated the effect on postcountershock myocardial damage of pretreatment with prazosin, an alpha-1 antagonist; L-metoprolol, a beta-1 antagonist, and verapamil, a calcium channel-blocking agent. Twenty dogs were anesthetized with halothane and given two transthoracic countershocks of 295 delivered joules each after drug or vehicle treatment. Myocardial injury was quantitated 24 h following countershock by measuring the uptake of technetium-99m pyrophosphate in the myocardium. Elevated technetium-99m pyrophosphate uptake occurred in visible lesions in most dogs regardless of drug treatment. For each of four parameters of myocardial damage there was no statistically significant difference between control animals and those treated with prazosin, metoprolol, or verapamil. These data suggest that adrenergic or calcium channel-mediated mechanisms are not involved in the pathogenesis of postcountershock myocardial damage.

  13. Synaptic Ribbons Require Ribeye for Electron Density, Proper Synaptic Localization, and Recruitment of Calcium Channels

    Directory of Open Access Journals (Sweden)

    Caixia Lv

    2016-06-01

    Full Text Available Synaptic ribbons are structures made largely of the protein Ribeye that hold synaptic vesicles near release sites in non-spiking cells in some sensory systems. Here, we introduce frameshift mutations in the two zebrafish genes encoding for Ribeye and thus remove Ribeye protein from neuromast hair cells. Despite Ribeye depletion, vesicles collect around ribbon-like structures that lack electron density, which we term “ghost ribbons.” Ghost ribbons are smaller in size but possess a similar number of smaller vesicles and are poorly localized to synapses and calcium channels. These hair cells exhibit enhanced exocytosis, as measured by capacitance, and recordings from afferent neurons post-synaptic to hair cells show no significant difference in spike rates. Our results suggest that Ribeye makes up most of the synaptic ribbon density in neuromast hair cells and is necessary for proper localization of calcium channels and synaptic ribbons.

  14. Channel properties of the splicing isoforms of the olfactory calcium-activated chloride channel Anoctamin 2.

    Science.gov (United States)

    Ponissery Saidu, Samsudeen; Stephan, Aaron B; Talaga, Anna K; Zhao, Haiqing; Reisert, Johannes

    2013-06-01

    Anoctamin (ANO)2 (or TMEM16B) forms a cell membrane Ca(2+)-activated Cl(-) channel that is present in cilia of olfactory receptor neurons, vomeronasal microvilli, and photoreceptor synaptic terminals. Alternative splicing of Ano2 transcripts generates multiple variants with the olfactory variants skipping exon 14 and having alternative splicing of exon 4. In the present study, 5' rapid amplification of cDNA ends analysis was conducted to characterize the 5' end of olfactory Ano2 transcripts, which showed that the most abundant Ano2 transcripts in the olfactory epithelium contain a novel starting exon that encodes a translation initiation site, whereas transcripts of the publically available sequence variant, which has an alternative and longer 5' end, were present in lower abundance. With two alternative starting exons and alternative splicing of exon 4, four olfactory ANO2 isoforms are thus possible. Patch-clamp experiments in transfected HEK293T cells expressing these isoforms showed that N-terminal sequences affect Ca(2+) sensitivity and that the exon 4-encoded sequence is required to form functional channels. Coexpression of the two predominant isoforms, one with and one without the exon 4 sequence, as well as coexpression of the two rarer isoforms showed alterations in channel properties, indicating that different isoforms interact with each other. Furthermore, channel properties observed from the coexpression of the predominant isoforms better recapitulated the native channel properties, suggesting that the native channel may be composed of two or more splicing isoforms acting as subunits that together shape the channel properties.

  15. Direct recording and molecular identification of the calcium channel of primary cilia

    Science.gov (United States)

    Decaen, Paul G.; Delling, Markus; Vien, Thuy N.; Clapham, David E.

    2013-12-01

    A primary cilium is a solitary, slender, non-motile protuberance of structured microtubules (9+0) enclosed by plasma membrane. Housing components of the cell division apparatus between cell divisions, primary cilia also serve as specialized compartments for calcium signalling and hedgehog signalling pathways. Specialized sensory cilia such as retinal photoreceptors and olfactory cilia use diverse ion channels. An ion current has been measured from primary cilia of kidney cells, but the responsible genes have not been identified. The polycystin proteins (PC and PKD), identified in linkage studies of polycystic kidney disease, are candidate channels divided into two structural classes: 11-transmembrane proteins (PKD1, PKD1L1 and PKD1L2) remarkable for a large extracellular amino terminus of putative cell adhesion domains and a G-protein-coupled receptor proteolytic site, and the 6-transmembrane channel proteins (PKD2, PKD2L1 and PKD2L2; TRPPs). Evidence indicates that the PKD1 proteins associate with the PKD2 proteins via coiled-coil domains. Here we use a transgenic mouse in which only cilia express a fluorophore and use it to record directly from primary cilia, and demonstrate that PKD1L1 and PKD2L1 form ion channels at high densities in several cell types. In conjunction with an accompanying manuscript, we show that the PKD1L1-PKD2L1 heteromeric channel establishes the cilia as a unique calcium compartment within cells that modulates established hedgehog pathways.

  16. Allopregnanolone-induced rise in intracellular calcium in embryonic hippocampal neurons parallels their proliferative potential

    Directory of Open Access Journals (Sweden)

    Brinton Roberta

    2008-12-01

    Full Text Available Abstract Background Factors that regulate intracellular calcium concentration are known to play a critical role in brain function and neural development, including neural plasticity and neurogenesis. We previously demonstrated that the neurosteroid allopregnanolone (APα; 5α-pregnan-3α-ol-20-one promotes neural progenitor proliferation in vitro in cultures of rodent hippocampal and human cortical neural progenitors, and in vivo in triple transgenic Alzheimer's disease mice dentate gyrus. We also found that APα-induced proliferation of neural progenitors is abolished by a calcium channel blocker, nifedipine, indicating a calcium dependent mechanism for the proliferation. Methods In the present study, we investigated the effect of APα on the regulation of intracellular calcium concentration in E18 rat hippocampal neurons using ratiometric Fura2-AM imaging. Results Results indicate that APα rapidly increased intracellular calcium concentration in a dose-dependent and developmentally regulated manner, with an EC50 of 110 ± 15 nM and a maximal response occurring at three days in vitro. The stereoisomers 3β-hydroxy-5α-hydroxy-pregnan-20-one, and 3β-hydroxy-5β-hydroxy-pregnan-20-one, as well as progesterone, were without significant effect. APα-induced intracellular calcium concentration increase was not observed in calcium depleted medium and was blocked in the presence of the broad spectrum calcium channel blocker La3+, or the L-type calcium channel blocker nifedipine. Furthermore, the GABAA receptor blockers bicuculline and picrotoxin abolished APα-induced intracellular calcium concentration rise. Conclusion Collectively, these data indicate that APα promotes a rapid, dose-dependent, stereo-specific, and developmentally regulated increase of intracellular calcium concentration in rat embryonic hippocampal neurons via a mechanism that requires both the GABAA receptor and L-type calcium channel. These data suggest that AP

  17. Anti-Convulsant Activity of Boerhaavia diffusa: Plausible Role of Calcium Channel Antagonism

    OpenAIRE

    Mandeep Kaur; Rajesh Kumar Goel

    2011-01-01

    “Ethnopharmacological” use of roots of Boerhaavia diffusa (B. diffusa) in the treatment of epilepsy in Nigerian folk medicine and reports showing the presence of a calcium channel antagonistic compound “liriodendrin” in its roots, led us to undertake the present study. The study was designed to investigate the methanolic root extract of B. diffusa and its different fractions including liriodendrin-rich fraction for exploring the possible role of liriodendrin in its anti-convulsant activity. A...

  18. Lavender Oil-Potent Anxiolytic Properties via Modulating Voltage Dependent Calcium Channels

    OpenAIRE

    2013-01-01

    Recent clinical data support the clinical use of oral lavender oil in patients suffering from subsyndromal anxiety. We identified the molecular mechanism of action that will alter the perception of lavender oil as a nonspecific ingredient of aromatherapy to a potent anxiolytic inhibiting voltage dependent calcium channels (VOCCs) as highly selective drug target. In contrast to previous publications where exorbitant high concentrations were used, the effects of lavender oil in behavioral, bioc...

  19. Expression of the apoptotic calcium channel P2X7 in the glandular epithelium.

    Science.gov (United States)

    Slater, Michael; Danieletto, Suzanne; Barden, Julian A

    2005-03-01

    In the current study, expression of the apoptotic calcium channel receptor P2X(7) and prostate-specific antigen (PSA) levels were studied in biopsy cores from 174 patients as well as 20 radical prostatectomy cases. In clinical biopsies, we have previously demonstrated that P2X(1 )and P2X(2) calcium channel receptors are absent from normal prostate epithelium that does not progress to prostate cancer within 5 years. In cases that did progress to prostate cancer however, P2X(1 )and P2X(2) labeling was observed in a stage-specific manner first in the nucleus, then the cytoplasm and finally on the apical epithelium, as prostate cancer developed. These markers were present up to 5 years before cancer was detectable by the usual morphological criteria (Gleason grading) as determined by H and E staining. In the current study, the apoptotic calcium channel receptor P2X(7) yielded similar results to that of P2X(1) and P2X(2). Using radical prostatectomy tissue sections as well as biopsies, these changes in calcium channel metabolism were noted throughout the prostate, indicating a field effect. This finding suggests that the presence of a prostate tumor could be detected without the need for direct sampling of tumor tissue, leading to detection of false negative cases missed by H or E stain. The reliability of PSA levels as a prognostic indicator has been questioned in recent years. In the current study, PSA levels were correlated with the P2X(7) labeling results. All patients who exhibited no P2X(7) labeling had a prostatic serum antigen (PSA) level of 2. This finding suggests that increasing PSA may be an accurate indicator of cancer development.

  20. Deltamethrin Inhibits the Human T-type Voltage-Sensitive Calcium Channel (Cav3.2

    Directory of Open Access Journals (Sweden)

    Steven B. Symington

    2009-01-01

    Full Text Available The goal of this study was to determine the effect of deltamethrin, a pyrethroid insecticide, on CaV3.2, a human T-type voltage-sensitive calcium channel expressed in Xenopus laevis (X.laevis oocytes. Cav3.2 cDNA was transcribed into cRNA; the cRNA was then injected into X.laevis oocytes and electrophysiologically characterized using the two-electrode voltage clamp technique with Ba2+ as a charge carrier. Deltamethrin (10-7 M reduced peak current in a nonreversible manner compared to the untreated control, but had no effect on the voltagedependent activation and inactivation kinetics. These findings confirm that human CaV3.2 is a target for deltamethrin and quite possibly other pyrethroid insecticides. These studies provide insight into the molecular mechanisms of the effect that pyrethroids have on voltage-sensitive calcium channels in general. This information will allow a more complete understanding of the molecular and cellular nature of pyrethroid-induced toxicity and expand our knowledge of the structure-activity relationships of pyrethroids with regard to their action on voltage-sensitive calcium channels.

  1. Treatment of Na(v)1.7-mediated pain in inherited erythromelalgia using a novel sodium channel blocker.

    Science.gov (United States)

    Goldberg, Yigal Paul; Price, Nicola; Namdari, Rostam; Cohen, Charles Jay; Lamers, Mieke H; Winters, Conrad; Price, James; Young, Clint E; Verschoof, Henry; Sherrington, Robin; Pimstone, Simon Neil; Hayden, Michael Reuben

    2012-01-01

    Mutations in the SCN9A gene leading to deficiency of its protein product, Na(v)1.7, cause congenital indifference to pain (CIP). CIP is characterized by the absence of the ability to sense pain associated with noxious stimuli. In contrast, the opposite phenotype to CIP, inherited erythromelalgia (IEM), is a disorder of spontaneous pain caused by missense mutations resulting in gain-of-function in Na(v)1.7 that promote neuronal hyperexcitability. The primary aim of this study was to demonstrate that Na(v)1.7 antagonism could alleviate the pain of IEM, thereby demonstrating the utility of this opposite phenotype model as a tool for rapid proof-of-concept for novel analgesics. An exploratory, randomized, double-blind, 2-period crossover study was conducted in 4 SCN9A mutation-proven IEM patients. In each treatment period (2days), separated by a 2-day washout period, patients were orally administered XEN402 (400mg twice daily) or matching placebo. In 3 patients, pain was induced by heat or exercise during each treatment arm. A fourth patient, in constant severe pain, required no induction. Patient-reported outcomes of pain intensity and/or relief were recorded, and the time taken to induce pain was measured. The ability to induce pain in IEM patients was significantly attenuated by XEN402 compared with placebo. XEN402 increased the time to maximal pain induction and significantly reduced the amount of pain (42% less) after induction (P=.014). This pilot study showed that XEN402 blocks Na(v)1.7-mediated pain associated with IEM, thereby demonstrating target engagement in humans and underscoring the use of rare genetic disorders with mutant target channels as a novel approach to rapid proof-of-concept.

  2. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX....... Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon......)-sensitive fast Na(+) spike faithfully followed repetitive depolarizing pulses with little change in spike duration or amplitude, while a strong outward rectification dominated responses to long-lasting depolarizations. High-threshold calcium spikes were uncovered following addition of potassium channel blockers...

  3. 钾通道阻断剂4-氨基吡啶诱导海马CA1锥体神经元钙瞬变%Calcium transient of CA1 pyramidal neurons induced by potassium blocker 4-aminopyridine in acute hippocampal slices

    Institute of Scientific and Technical Information of China (English)

    苏涛; 丛文东; 廖卫平

    2011-01-01

    Objective To investigate the calcium transient of CA1 pyramidal neurons induced by potassium blocker 4-aminopyridine (4-AP) in acute hippocampal slices to explore the relation between potassium channel function and calcium transient, and their mechanism. Methods Fluorescent probe was employed to mark the hippocampai neurons in acute brain slices of rats; confocal microscopy was used to perform calcium imaging to observe the influences of different concentrations of 4-AP and perfusate with/without calcium on calcium transient of CA1 pyramidal neurons. Results The response of [Ca2+]I to lower concentration of 4-AP (<15 mmol/L) was in a dose-dependent manner (r2=0.910, P=0.000); the higher the concentration of 4-AP (20-80 mmol/L), the lower the peak level of calcium transient. The latency and amplitude of calcium transient induced by 4-AP were obviously reduced when the extracellular condition was switched to an absence of calcium, which was significantly different as compared with that with calcium (P<0.05). Conclusion Blockade of potassium channels with 4-AP can increase [Ca2+]I in the hippocampal pyramidal neurons of acute slices. The increase of [Ca2+]1 to 4-AP could be ascribe to calcium release from intracellular stores and calcium influx from extracellular matrix.%目的 研究4-氨基吡啶(4-AP)诱导的急性脑片海马CA1锥体神经元钙瞬变现象,探讨钾通道功能与钙瞬变的关系及可能机制.方法 荧光探针标记正常大鼠急性脑片海马神经元.共聚焦显微镜技术进行钙成像,观察不同浓度4-AP及细胞灌流液条件对神经元钙瞬变的影响.结果 低浓度(<15 mmol/L)4-AP诱导的钙瞬变峰值与剂量呈线性相关(r2=0.910,P=0.000),高浓度(20~80 mmol/L)4-AP诱导的钙瞬变峰值随浓度增高而下降.在无钙灌流液条件下,4-AP诱导的钙瞬变峰值水平下降,达峰时间延长,与含钙灌流液比较差异有统计学意义(P<0.05).结论 4-AP可诱导急性脑片海马CA1锥体神经

  4. Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells.

    Science.gov (United States)

    Cherkashin, Alexander P; Kolesnikova, Alisa S; Tarasov, Michail V; Romanov, Roman A; Rogachevskaja, Olga A; Bystrova, Marina F; Kolesnikov, Stanislav S

    2016-02-01

    Specialized Ca(2+)-dependent ion channels ubiquitously couple intracellular Ca(2+) signals to a change in cell polarization. The existing physiological evidence suggests that Ca(2+)-activated Cl(-) channels (CaCCs) are functional in taste cells. Because Ano1 and Ano2 encode channel proteins that form CaCCs in a variety of cells, we analyzed their expression in mouse taste cells. Transcripts for Ano1 and Ano2 were detected in circumvallate (CV) papillae, and their expression in taste cells was confirmed using immunohistochemistry. When dialyzed with CsCl, taste cells of the type III exhibited no ion currents dependent on cytosolic Ca(2+). Large Ca(2+)-gated currents mediated by TRPM5 were elicited in type II cells by Ca(2+) uncaging. When TRPM5 was inhibited by triphenylphosphine oxide (TPPO), ionomycin stimulated a small but resolvable inward current that was eliminated by anion channel blockers, including T16Ainh-A01 (T16), a specific Ano1 antagonist. This suggests that CaCCs, including Ano1-like channels, are functional in type II cells. In type I cells, CaCCs were prominently active, blockable with the CaCC antagonist CaCCinh-A01 but insensitive to T16. By profiling Ano1 and Ano2 expressions in individual taste cells, we revealed Ano1 transcripts in type II cells only, while Ano2 transcripts were detected in both type I and type II cells. P2Y agonists stimulated Ca(2+)-gated Cl(-) currents in type I cells. Thus, CaCCs, possibly formed by Ano2, serve as effectors downstream of P2Y receptors in type I cells. While the role for TRPM5 in taste transduction is well established, the physiological significance of expression of CaCCs in type II cells remains to be elucidated.

  5. In vivo impact of presynaptic calcium channel dysfunction on motor axons in episodic ataxia type 2.

    Science.gov (United States)

    Tomlinson, Susan E; Tan, S Veronica; Burke, David; Labrum, Robyn W; Haworth, Andrea; Gibbons, Vaneesha S; Sweeney, Mary G; Griggs, Robert C; Kullmann, Dimitri M; Bostock, Hugh; Hanna, Michael G

    2016-02-01

    Ion channel dysfunction causes a range of neurological disorders by altering transmembrane ion fluxes, neuronal or muscle excitability, and neurotransmitter release. Genetic neuronal channelopathies affecting peripheral axons provide a unique opportunity to examine the impact of dysfunction of a single channel subtype in detail in vivo. Episodic ataxia type 2 is caused by mutations in CACNA1A, which encodes the pore-forming subunit of the neuronal voltage-gated calcium channel Cav2.1. In peripheral motor axons, this channel is highly expressed at the presynaptic neuromuscular junction where it contributes to action potential-evoked neurotransmitter release, but it is not expressed mid-axon or thought to contribute to action potential generation. Eight patients from five families with genetically confirmed episodic ataxia type 2 underwent neurophysiological assessment to determine whether axonal excitability was normal and, if not, whether changes could be explained by Cav2.1 dysfunction. New mutations in the CACNA1A gene were identified in two families. Nerve conduction studies were normal, but increased jitter in single-fibre EMG studies indicated unstable neuromuscular transmission in two patients. Excitability properties of median motor axons were compared with those in 30 age-matched healthy control subjects. All patients had similar excitability abnormalities, including a high electrical threshold and increased responses to hyperpolarizing (P ataxia type 2 thus has unexpected effects on axon excitability, which may reflect an indirect effect of abnormal calcium current fluxes during development.

  6. The involvement of the Mid1/Cch1/Yvc1 calcium channels in Aspergillus fumigatus virulence.

    Directory of Open Access Journals (Sweden)

    Patrícia Alves de Castro

    Full Text Available Aspergillus fumigatus is a major opportunistic pathogen and allergen of mammals. Calcium homeostasis and signaling is essential for numerous biological processes and also influences A. fumigatus pathogenicity. The presented study characterized the function of the A. fumigatus homologues of three Saccharomyces cerevisiae calcium channels, voltage-gated Cch1, stretch-activated Mid1 and vacuolar Yvc1. The A. fumigatus calcium channels cchA, midA and yvcA were regulated at transcriptional level by increased calcium levels. The YvcA::GFP fusion protein localized to the vacuoles. Both ΔcchA and ΔmidA mutant strains showed reduced radial growth rate in nutrient-poor minimal media. Interestingly, this growth defect in the ΔcchA strain was rescued by the exogenous addition of CaCl2. The ΔcchA, ΔmidA, and ΔcchA ΔmidA strains were also sensitive to the oxidative stress inducer, paraquat. Restriction of external Ca(2+ through the addition of the Ca(2+-chelator EGTA impacted upon the growth of the ΔcchA and ΔmidA strains. All the A. fumigatus ΔcchA, ΔmidA, and ΔyvcA strains demonstrated attenuated virulence in a neutropenic murine model of invasive pulmonary aspergillosis. Infection with the parental strain resulted in a 100% mortality rate at 15 days post-infection, while the mortality rate of the ΔcchA, ΔmidA, and ΔyvcA strains after 15 days post-infection was only 25%. Collectively, this investigation strongly indicates that CchA, MidA, and YvcA play a role in A. fumigatus calcium homeostasis and virulence.

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

    Science.gov (United States)

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

    2014-02-05

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

  8. Alterations in expression of Cat-315 epitope of perineuronal nets during normal ageing, and its modulation by an open-channel NMDA receptor blocker, memantine.

    Science.gov (United States)

    Yamada, Jun; Ohgomori, Tomohiro; Jinno, Shozo

    2017-03-08

    The perineuronal net (PNN), a specialized aggregate of the extracellular matrix, is involved in neuroprotection against oxidative stress, which is now recognized as a major contributor to age-related decline in brain functions. In this study, we investigated the age-related molecular changes of PNNs using monoclonal antibody Cat-315, which recognizes human natural killer-1 (HNK-1) glycan on aggrecan-based PNNs. Western blot analysis showed that the expression levels of Cat-315 epitope in the hippocampus were higher in middle-aged (MA, 12-month-old) mice than in young adult (YA, 2-month-old) mice. Although there were no differences in the expression levels of Cat-315 epitope between old age (OA, 20-month-old) and MA mice, Cat-315 immunoreactivity was also detected in astrocytes of OA mice. To focus on Cat-315 epitope in PNNs, we used YA and MA mice in the following experiments. Optical disector analysis showed that there were no differences in the numbers of Cat-315-positive (Cat-315(+) ) PNNs between YA and MA mice. Fluorescence intensity analysis indicated that Cat-315 immunoreactivity in PNNs increased with age in the dorsal hippocampus, which is mainly involved in cognitive functions. Administration of an open-channel blocker of NMDA receptor, memantine, reduced the expression levels of Cat-315 epitope in the hippocampus. Furthermore, the numbers of glutamatergic and GABAergic terminals colocalized with Cat-315 epitope around parvalbumin-positive neurons were decreased by memantine. These findings provide novel insight into the involvement of PNNs in normal brain ageing, and suggest that memantine may counteract the age-related alterations in expression levels of Cat-315 epitope via regulation of its subcellular localization. This article is protected by copyright. All rights reserved.

  9. Eukaliuric diuresis and natriuresis in response to the KATP channel blocker U37883A: micropuncture studies on the tubular site of action.

    Science.gov (United States)

    Huang, D Y; Osswald, H; Vallon, V

    1999-08-01

    1. Systemic application of U37883A, a blocker of ATP sensitive potassium (KATP) channels, elicits diuresis and natriuresis without significantly altering urinary potassium excretion. 2. To elucidate tubular sites of action upstream to the distal nephron, micropuncture experiments were performed in nephrons with superficial glomeruli of anaesthetized Munich-Wistar-Frömter rats during systemic application of U37883A (1, 5 or 15 mg kg-1 i.v.). 3. The observed eukaliuric diuresis and natriuresis in response to U37883A at 15 mg kg-1 was accompanied by an increase in early distal tubular flow rate (VED) from 10 - 18 nl min(-1) reflecting a reduction in fractional reabsorption of fluid up to this site (FR-fluid) of 13%. The latter proposed an effect on water-permeable segments such as the proximal tubule which could fully account for the observed reduction in fractional reabsorption of Na+ up to the early distal tubule (FR-Na+) of 8% and the increase in early distal tubular Na+ concentration ([Na+]ED) from 35 - 51 mM whereas [K+]ED was left unaltered. 4. In comparison, furosemide (3 mg kg-1 i.v.), which acts in the water-impermeable thick ascending limb, elicited diuresis, natriuresis and kaliuresis which were associated with a fall in FR-Na+ of 10% with no change in FR-fluid, and a rise in [Na+]ED from 42 - 117 mM and [K+]ED from 1.2 - 5.7 mM with no change in VED. 5. Direct late proximal tubular fluid collections confirmed a significant inhibition of fluid reabsorption in proximal convoluted tubule in response to systemic application of U37883A. 6. These findings suggest that the diuretic and natriuretic effect upstream to the distal tubule in response to systemic application of U37883A involves actions on water-permeable segments such as the proximal convoluted tubule.

  10. Pharmacokinetics, metabolism and excretion of [(14)C]-lanicemine (AZD6765), a novel low-trapping N-methyl-d-aspartic acid receptor channel blocker, in healthy subjects.

    Science.gov (United States)

    Guo, Jian; Zhou, Diansong; Grimm, Scott W; Bui, Khanh H

    2015-03-01

    1.(1S)-1-phenyl-2-(pyridin-2-yl)ethanamine (lanicemine; AZD6765) is a low-trapping N-methyl-d-aspartate (NMDA) channel blocker that has been studied as an adjunctive treatment in major depressive disorder. The metabolism and disposition of lanicemine was determined in six healthy male subjects after a single intravenous infusion dose of 150 mg [(14)C]-lanicemine. 2.Blood, urine and feces were collected from all subjects. The ratios of Cmax and AUC(0-∞) of lanicemine to plasma total radioactivity were 84 and 66%, respectively, indicating that lanicemine was the major circulating component with T1/2 at 16 h. The plasma clearance of lanicemine was 8.3 L/h, revealing that lanicemine is a low-clearance compound. The mean recovery of radioactivity from urine was 93.8% of radioactive dose. 3.In urine samples, 10 metabolites of lanicemine were identified. Among which, an O-glucuronide conjugate (M1) was the most abundant metabolite (∼11% of the dose in excreta). In plasma, the circulatory metabolites were identified as a para-hydroxylated metabolite (M1), an O-glucuronide (M2), an N-carbamoyl glucuronide (M3) and an N-acetylated metabolite (M6). The average amount of each of metabolite was less than 4% of total radioactivity detected in plasma or urine. 4.In conclusion, lanicemine is a low-clearance compound. The unchanged drug and metabolites are predominantly eliminated via urinary excretion.

  11. Correlated ions in a calcium channel model: a Poisson-Fermi theory.

    Science.gov (United States)

    Liu, Jinn-Liang; Eisenberg, Bob

    2013-10-10

    We derive a continuum model, called the Poisson-Fermi equation, of biological calcium channels (of cardiac muscle, for example) designed to deal with crowded systems in which ionic species and side chains nearly fill space. The model is evaluated in three dimensions. It includes steric and correlation effects and is derived from classical hard-sphere lattice models of configurational entropy of finite size ions and solvent molecules. The maximum allowable close packing (saturation) condition is satisfied by all ionic species with different sizes and valences in a channel system, as shown theoretically and numerically. Unphysical overcrowding ("divergence") predicted by the Gouy-Chapman diffuse model (produced by a Boltzmann distribution of point charges with large potentials) does not occur with the Fermi-like distribution. Using probability theory, we also provide an analytical description of the implicit dielectric model of ionic solutions that gives rise to a global and a local formula for the chemical potential. In this primitive model, ions are treated as hard spheres and solvent molecules are described as a dielectric medium. The Poisson-Fermi equation is a local formula dealing with different correlations at different places. The correlation effects are apparent in our numerical results. Our results show variations of dielectric permittivity from bath to channel pore described by a new dielectric function derived as an output from the Poisson-Fermi analysis. The results are consistent with existing theoretical and experimental results. The binding curve of Poisson-Fermi is shown to match Monte Carlo data and illustrates the anomalous mole fraction effect of calcium channels, an effective blockage of permeation of sodium ions by a tiny concentration (or number) of calcium ions.

  12. Effects of Arecoline on Calcium Channel Currents and Caffeine-induced Calcium Release in Isolated Single Ventricular Myocyte of Guinea Pig

    Institute of Scientific and Technical Information of China (English)

    林先明; 李真; 胡本容; 夏国瑾; 姚伟星; 向继洲

    2002-01-01

    Summary: The effects of Arecoline (Are) on calcium mobilization were investigated. In isolatedsingle ventricular myocyte of guinea pig, patch clamp whole cell recording techniques were used torecord the current of L-type calcium channel and cytosolic Ca2+ level ([Ca2+]i) labeled with fluo-rescence probe Fluo-3/AM was measured under a laser scanning confocal microscope. Results re-vealed that Are (3-100 μmol/L) could inhibit L-type calcium current in a concentration-depen-dent manner and the value of IC50 was 33. 73μmol/L (n= 5). In the absence of extracellular calci-um, the resting levels of [Ca2+]i was not affected by Are (n=6, P>0. 05), but pretreatmentwith Are (30 μmol/L) could significantly inhibit the [Ca2+]i elevation induced by caffeine (10mmol/L, n = 6, P < 0. 01). It was concluded that Are could inhibit not only calcium influxthrough L-type calcium channel but also calcium release from sarcoplasmic reticulum.

  13. Long-Term Blocking of Calcium Channels in mdx Mice Results in Differential Effects on Heart and Skeletal Muscle

    DEFF Research Database (Denmark)

    Jørgensen, Louise Helskov; Blain, Alison; Greally, Elizabeth;

    2011-01-01

    calcium ions to enter the cell. The objective of this study was to investigate the effect of chronically blocking calcium channels with the aminoglycoside antibiotic streptomycin from onset of disease in the mdx mouse model of Duchenne muscular dystrophy (DMD). Treatment in utero onwards delayed onset...... in older mice. However, streptomycin treatment did not show positive effects in diaphragm or heart muscle, and heart pathology was worsened. Thus, blocking calcium channels even before disease onset does not prevent dystrophy, making this an unlikely treatment for DMD. These findings highlight...

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

    CERN Document Server

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

    2013-01-01

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

  15. Distinct regions that control ion selectivity and calcium-dependent activation in the bestrophin ion channel.

    Science.gov (United States)

    Vaisey, George; Miller, Alexandria N; Long, Stephen B

    2016-11-22

    Cytoplasmic calcium (Ca(2+)) activates the bestrophin anion channel, allowing chloride ions to flow down their electrochemical gradient. Mutations in bestrophin 1 (BEST1) cause macular degenerative disorders. Previously, we determined an X-ray structure of chicken BEST1 that revealed the architecture of the channel. Here, we present electrophysiological studies of purified wild-type and mutant BEST1 channels and an X-ray structure of a Ca(2+)-independent mutant. From these experiments, we identify regions of BEST1 responsible for Ca(2+) activation and ion selectivity. A "Ca(2+) clasp" within the channel's intracellular region acts as a sensor of cytoplasmic Ca(2+). Alanine substitutions within a hydrophobic "neck" of the pore, which widen it, cause the channel to be constitutively active, irrespective of Ca(2+). We conclude that the primary function of the neck is as a "gate" that controls chloride permeation in a Ca(2+)-dependent manner. In contrast to what others have proposed, we find that the neck is not a major contributor to the channel's ion selectivity. We find that mutation of a cytosolic "aperture" of the pore does not perturb the Ca(2+) dependence of the channel or its preference for anions over cations, but its mutation dramatically alters relative permeabilities among anions. The data suggest that the aperture functions as a size-selective filter that permits the passage of small entities such as partially dehydrated chloride ions while excluding larger molecules such as amino acids. Thus, unlike ion channels that have a single "selectivity filter," in bestrophin, distinct regions of the pore govern anion-vs.-cation selectivity and the relative permeabilities among anions.

  16. Follicle-stimulating hormone receptor-mediated uptake of sup 45 Ca sup 2+ by proteoliposomes and cultured rat sertoli cells: Evidence for involvement of voltage-activated and voltage-independent calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, P.; Reichert, L.E. Jr. (Albany Medical College, NY (USA))

    1989-12-01

    We have previously reported incorporation into liposomes of Triton X-100-solubilized FSH receptor-G-protein complexes derived from purified bovine calf testis membranes. In the present study we have used this model system to show that FSH induces flux of 45Ca2+ into such proteoliposomes in a hormone-specific concentration-dependent manner. FSH, inactivated by boiling, had no stimulatory effect on 45Ca2+ flux, nor did isolated alpha- or beta-subunits of FSH. Addition of GTP (or its analogs 5'-guanylylimidodiphosphate and guanosine-5'-O-(3-thiotriphosphate)) or sodium fluoride (in the presence or absence of GTP or its analogs) failed to induce 45Ca2+ flux into proteoliposomes, suggesting that the uptake of 45Ca2+ was receptor, and not G-protein, related. Voltage-independent (ruthenium red and gadolinium chloride) and voltage-activated (methyoxyverapamil and nifedipine) calcium channel-blocking agents reduced FSH-stimulated 45Ca2+ flux into proteoliposomes to control levels. FSH also induced uptake of 45Ca2+ by cultured rat Sertoli cells. Ruthenium red and gadolinium chloride had no effect on basal levels of 45Ca2+ uptake or estradiol secretion by cultured rat Sertoli cells, nor did methoxyverapamil or nifedipine. All four calcium channel blockers, however, were able to reduce FSH-induced 45Ca2+ uptake to basal levels and FSH-stimulated conversion of androstenedione to estradiol by up to 50%, indicating an involvement of Ca2+ in FSH-stimulated steroidogenesis. Our results suggest that the well documented changes in intracellular calcium levels consequent to FSH binding may be due, at least in part, to an influx of calcium through FSH receptor-regulated calcium channels.

  17. Nitric oxide regulates neuronal activity via calcium-activated potassium channels.

    Directory of Open Access Journals (Sweden)

    Lei Ray Zhong

    Full Text Available Nitric oxide (NO is an unconventional membrane-permeable messenger molecule that has been shown to play various roles in the nervous system. How NO modulates ion channels to affect neuronal functions is not well understood. In gastropods, NO has been implicated in regulating the feeding motor program. The buccal motoneuron, B19, of the freshwater pond snail Helisoma trivolvis is active during the hyper-retraction phase of the feeding motor program and is located in the vicinity of NO-producing neurons in the buccal ganglion. Here, we asked whether B19 neurons might serve as direct targets of NO signaling. Previous work established NO as a key regulator of growth cone motility and neuronal excitability in another buccal neuron involved in feeding, the B5 neuron. This raised the question whether NO might modulate the electrical activity and neuronal excitability of B19 neurons as well, and if so whether NO acted on the same or a different set of ion channels in both neurons. To study specific responses of NO on B19 neurons and to eliminate indirect effects contributed by other cells, the majority of experiments were performed on single cultured B19 neurons. Addition of NO donors caused a prolonged depolarization of the membrane potential and an increase in neuronal excitability. The effects of NO could mainly be attributed to the inhibition of two types of calcium-activated potassium channels, apamin-sensitive and iberiotoxin-sensitive potassium channels. NO was found to also cause a depolarization in B19 neurons in situ, but only after NO synthase activity in buccal ganglia had been blocked. The results suggest that NO acts as a critical modulator of neuronal excitability in B19 neurons, and that calcium-activated potassium channels may serve as a common target of NO in neurons.

  18. Responses of channel catfish (Ictalurus punctatus) swim-up fry to dietary calcium in soft and hard water.

    Science.gov (United States)

    Scarpa, J; Gatlin, D M

    1993-12-01

    1. Responses of channel catfish (Ictalurus punctatus) swim-up fry to dietary calcium in soft ( 100 mg/l as CaCO3) water were determined by feeding purified egg-white diets containing 0, 0.5, 1.0, or 2.0% calcium from CaCO3 for 8 weeks. 2. Catfish fry fed the basal diet (0.03% Ca) in hard and soft water had lower whole-body ash and whole-body calcium concentrations but higher weight gain and survival than those fed calcium-supplemented diets. 3. Fry in soft water generally had lower whole-body ash, whole-body calcium, and survival, as well as a higher incidence of spinal deformities than fry in hard water. 4. Feeding higher levels of calcium to fry reared in soft water did not increase whole-body calcium levels or decrease spinal deformities to the levels observed for fry reared in hard water and fed supplemental calcium. 5. These data indicate that calcium derived solely from dietary or environmental sources was not sufficient for optimum health of channel catfish fry.

  19. Antischistosomal activity of a calcium channel antagonist on schistosomula and adult Schistosoma mansoni worms

    Directory of Open Access Journals (Sweden)

    Vanessa Silva-Moraes

    2013-08-01

    Full Text Available Current schistosomiasis control strategies are largely based on chemotherapeutic agents and a limited number of drugs are available today. Praziquantel (PZQ is the only drug currently used in schistosomiasis control programs. Unfortunately, this drug shows poor efficacy in patients during the earliest infection phases. The effects of PZQ appear to operate on the voltage-operated Ca2+channels, which are located on the external Schistosoma mansoni membrane. Because some Ca2+channels have dihydropyridine drug class (a class that includes nifedipine sensitivity, an in vitro analysis using a calcium channel antagonist (clinically used for cardiovascular hypertension was performed to determine the antischistosomal effects of nifedipine on schistosomula and adult worm cultures. Nifedipine demonstrated antischistosomal activity against schistosomula and significantly reduced viability at all of the concentrations used alone or in combination with PZQ. In contrast, PZQ did not show significant efficacy when used alone. Adult worms were also affected by nifedipine after a 24 h incubation and exhibited impaired motility, several lesions on the tegument and intense contractility. These data support the idea of Ca2+channels subunits as drug targets and favour alternative therapeutic schemes when drug resistance has been reported. In this paper, strong arguments encouraging drug research are presented, with a focus on exploring schistosomal Ca2+channels.

  20. Control of spontaneous firing patterns by the selective coupling of calcium currents to calcium-activated potassium currents in striatal cholinergic interneurons.

    Science.gov (United States)

    Goldberg, Joshua A; Wilson, Charles J

    2005-11-02

    The spontaneous firing patterns of striatal cholinergic interneurons are sculpted by potassium currents that give rise to prominent afterhyperpolarizations (AHPs). Large-conductance calcium-activated potassium (BK) channel currents contribute to action potential (AP) repolarization; small-conductance calcium-activated potassium channel currents generate an apamin-sensitive medium AHP (mAHP) after each AP; and bursts of APs generate long-lasting slow AHPs (sAHPs) attributable to apamin-insensitive currents. Because all these currents are calcium dependent, we conducted voltage- and current-clamp whole-cell recordings while pharmacologically manipulating calcium channels of the plasma membrane and intracellular stores to determine what sources of calcium activate the currents underlying AP repolarization and the AHPs. The Cav2.2 (N-type) blocker omega-conotoxin GVIA (1 microM) was the only blocker that significantly reduced the mAHP, and it induced a transition to rhythmic bursting in one-third of the cells tested. Cav1 (L-type) blockers (10 microM dihydropyridines) were the only ones that significantly reduced the sAHP. When applied to cells induced to burst with apamin, dihydropyridines reduced the sAHPs and abolished bursting. Depletion of intracellular stores with 10 mM caffeine also significantly reduced the sAHP current and reversibly regularized firing. Application of 1 microM omega-conotoxin MVIIC (a Cav2.1/2.2 blocker) broadened APs but had a negligible effect on APs in cells in which BK channels were already blocked by submillimolar tetraethylammonium chloride, indicating that Cav2.1 (Q-type) channels provide the calcium to activate BK channels that repolarize the AP. Thus, calcium currents are selectively coupled to the calcium-dependent potassium currents underlying the AHPs, thereby creating mechanisms for control of the spontaneous firing patterns of these neurons.

  1. Transmembrane proteoglycans control stretch-activated channels to set cytosolic calcium levels

    DEFF Research Database (Denmark)

    Gopal, Sandeep; Søgaard, Pernille; Multhaupt, Hinke A B;

    2015-01-01

    show that syndecans regulate transient receptor potential canonical (TRPCs) channels to control cytosolic calcium equilibria and consequent cell behavior. In fibroblasts, ligand interactions with heparan sulfate of syndecan-4 recruit cytoplasmic protein kinase C to target serine714 of TRPC7...... with subsequent control of the cytoskeleton and the myofibroblast phenotype. In epidermal keratinocytes a syndecan-TRPC4 complex controls adhesion, adherens junction composition, and early differentiation in vivo and in vitro. In Caenorhabditis elegans, the TRPC orthologues TRP-1 and -2 genetically complement...

  2. Developmental mapping of small-conductance calcium-activated potassium channel expression in the rat nervous system.

    Science.gov (United States)

    Gymnopoulos, Marco; Cingolani, Lorenzo A; Pedarzani, Paola; Stocker, Martin

    2014-04-01

    Early electrical activity and calcium influx regulate crucial aspects of neuronal development. Small-conductance calcium-activated potassium (SK) channels regulate action potential firing and shape calcium influx through feedback regulation in mature neurons. These functions, observed in the adult nervous system, make them ideal candidates to regulate activity- and calcium-dependent processes in neurodevelopment. However, to date little is known about the onset of expression and regions expressing SK channel subunits in the embryonic and postnatal development of the central nervous system (CNS). To allow studies on the contribution of SK channels to different phases of development of single neurons and networks, we have performed a detailed in situ hybridization mapping study, providing comprehensive distribution profiles of all three SK subunits (SK1, SK2, and SK3) in the rat CNS during embryonic and postnatal development. SK channel transcripts are expressed at early stages of prenatal CNS development. The three SK channel subunits display different developmental expression gradients in distinct CNS regions, with time points of expression and up- or downregulation that can be associated with a range of diverse developmental events. Their early expression in embryonic development suggests an involvement of SK channels in the regulation of developmental processes. Additionally, this study shows how the postnatal ontogenetic patterns lead to the adult expression map for each SK channel subunit and how their coexpression in the same regions or neurons varies throughout development.

  3. Voltage and Calcium Dual Channel Optical Mapping of Cultured HL-1 Atrial Myocyte Monolayer

    Science.gov (United States)

    Zhao, Weiwei; Fast, Vladimir G.; Ye, Tong; Ai, Xun

    2015-01-01

    Optical mapping has proven to be a valuable technique to detect cardiac electrical activity on both intact ex vivo hearts and in cultured myocyte monolayers. HL-1 cells have been widely used as a 2-Dimensional cellular model for studying diverse aspects of cardiac physiology. However, it has been a great challenge to optically map calcium (Ca) transients and action potentials simultaneously from the same field of view in a cultured HL-1 atrial cell monolayer. This is because special handling and care is required to prepare healthy cells that can be electrically captured and optically mapped. Therefore, we have developed an optimal working protocol for dual channel optical mapping. In this manuscript, we have described in detail how to perform the dual channel optical mapping experiment. This protocol is a useful tool to enhance the understanding of action potential propagation and Ca kinetics in arrhythmia development. PMID:25867896

  4. L-type calcium channels and calcium/calmodulin-dependent kinase II differentially mediate behaviors associated with nicotine withdrawal in mice.

    Science.gov (United States)

    Jackson, K J; Damaj, M I

    2009-07-01

    Smoking is a widespread health problem. Because the nicotine withdrawal syndrome is a major contributor to continued smoking and relapse, it is important to understand the molecular and behavioral mechanisms of nicotine withdrawal to generate more effective smoking cessation therapies. Studies suggest a role for calcium-dependent mechanisms, such as L-type calcium channels and calcium/calmodulin-dependent protein kinase II (CaMKII), in the effects of nicotine dependence; however, the role of these mechanisms in nicotine-mediated behaviors is unclear. Thus, the goal of this study was to elucidate the role of L-type calcium channels and CaMKII in nicotine withdrawal behaviors. Using both pharmacological and genetic methods, our results show that L-type calcium channels are involved in physical, but not affective, nicotine withdrawal behaviors. Although our data do provide evidence of a role for CaMKII in nicotine withdrawal behaviors, our pharmacological and genetic assessments yielded different results concerning the specific role of the kinase. Pharmacological data suggest that CaMKII is involved in somatic signs and affective nicotine withdrawal, and activity level is decreased after nicotine withdrawal, whereas the genetic assessments yielded results suggesting that CaMKII is involved only in the anxiety-related response, yet the kinase activity may be increased after nicotine withdrawal; thus, future studies are necessary to clarify the precise behavioral specifics of the relevance of CaMKII in nicotine withdrawal behaviors. Overall, our data show that L-type calcium channels and CaMKII are relevant in nicotine withdrawal and differentially mediate nicotine withdrawal behaviors.

  5. T-type calcium channels consolidate tonic action potential output of thalamic neurons to neocortex.

    Science.gov (United States)

    Deleuze, Charlotte; David, François; Béhuret, Sébastien; Sadoc, Gérard; Shin, Hee-Sup; Uebele, Victor N; Renger, John J; Lambert, Régis C; Leresche, Nathalie; Bal, Thierry

    2012-08-29

    The thalamic output during different behavioral states is strictly controlled by the firing modes of thalamocortical neurons. During sleep, their hyperpolarized membrane potential allows activation of the T-type calcium channels, promoting rhythmic high-frequency burst firing that reduces sensory information transfer. In contrast, in the waking state thalamic neurons mostly exhibit action potentials at low frequency (i.e., tonic firing), enabling the reliable transfer of incoming sensory inputs to cortex. Because of their nearly complete inactivation at the depolarized potentials that are experienced during the wake state, T-channels are not believed to modulate tonic action potential discharges. Here, we demonstrate using mice brain slices that activation of T-channels in thalamocortical neurons maintained in the depolarized/wake-like state is critical for the reliable expression of tonic firing, securing their excitability over changes in membrane potential that occur in the depolarized state. Our results establish a novel mechanism for the integration of sensory information by thalamocortical neurons and point to an unexpected role for T-channels in the early stage of information processing.

  6. Molecular mechanism underlying β1 regulation in voltage- and calcium-activated potassium (BK) channels.

    Science.gov (United States)

    Castillo, Karen; Contreras, Gustavo F; Pupo, Amaury; Torres, Yolima P; Neely, Alan; González, Carlos; Latorre, Ramon

    2015-04-14

    Being activated by depolarizing voltages and increases in cytoplasmic Ca(2+), voltage- and calcium-activated potassium (BK) channels and their modulatory β-subunits are able to dampen or stop excitatory stimuli in a wide range of cellular types, including both neuronal and nonneuronal tissues. Minimal alterations in BK channel function may contribute to the pathophysiology of several diseases, including hypertension, asthma, cancer, epilepsy, and diabetes. Several gating processes, allosterically coupled to each other, control BK channel activity and are potential targets for regulation by auxiliary β-subunits that are expressed together with the α (BK)-subunit in almost every tissue type where they are found. By measuring gating currents in BK channels coexpressed with chimeras between β1 and β3 or β2 auxiliary subunits, we were able to identify that the cytoplasmic regions of β1 are responsible for the modulation of the voltage sensors. In addition, we narrowed down the structural determinants to the N terminus of β1, which contains two lysine residues (i.e., K3 and K4), which upon substitution virtually abolished the effects of β1 on charge movement. The mechanism by which K3 and K4 stabilize the voltage sensor is not electrostatic but specific, and the α (BK)-residues involved remain to be identified. This is the first report, to our knowledge, where the regulatory effects of the β1-subunit have been clearly assigned to a particular segment, with two pivotal amino acids being responsible for this modulation.

  7. Synergism of ochratoxin B and calcium-channel antagonist verapamil caused mitochondrial dysfunction.

    Science.gov (United States)

    Chatopadhyay, Pronobesh; Tariang, Banlumlang; Agnihotri, Amit; Veer, Vijay

    2014-09-01

    We examined the mechanism by which the ochratoxin B induced interaction with calcium-channel antagonist verapamil and mitochondrial dysfunction of the rat trachea in vitro experiment. The tracheas were cut into 2-3 mm wide rings and suspended in a tissue bath. Isometric tension was continuously measured with an isometric force transducer connected to a computer-based data acquisition system. Verapamil (1 × 10(-6) M) produced a concentration-dependent contraction response in rat's tracheal rings pre-contracted by acetylcholine. Incubation of rat's tracheal rings with the ochratoxin B significantly potentiated the contraction responses of verapamil. Verapamil and OTB accelerate the overloading of Ca(2+) in tracheal smooth muscle contributes the tissue toxicity as shown in electron microscopy and mitochondrial enzymes, through a mechanism that could involve perturbations of Ca(2+) homeostasis. These results proved that ochratoxin B is a potential vasoconstrictor mycotoxin with the presence of calcium-channel antagonist. In conclusion, disturbance of Ca(2+) homeostasis caused by OTA and plays a significant role in produces toxicity through mitochondrial enzyme inhibition.

  8. Calcium regulation of HCN channels supports persistent activity in a multiscale model of neocortex.

    Science.gov (United States)

    Neymotin, S A; McDougal, R A; Bulanova, A S; Zeki, M; Lakatos, P; Terman, D; Hines, M L; Lytton, W W

    2016-03-01

    Neuronal persistent activity has been primarily assessed in terms of electrical mechanisms, without attention to the complex array of molecular events that also control cell excitability. We developed a multiscale neocortical model proceeding from the molecular to the network level to assess the contributions of calcium (Ca(2+)) regulation of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in providing additional and complementary support of continuing activation in the network. The network contained 776 compartmental neurons arranged in the cortical layers, connected using synapses containing AMPA/NMDA/GABAA/GABAB receptors. Metabotropic glutamate receptors (mGluR) produced inositol triphosphate (IP3) which caused the release of Ca(2+) from endoplasmic reticulum (ER) stores, with reuptake by sarco/ER Ca(2+)-ATP-ase pumps (SERCA), and influence on HCN channels. Stimulus-induced depolarization led to Ca(2+) influx via NMDA and voltage-gated Ca(2+) channels (VGCCs). After a delay, mGluR activation led to ER Ca(2+) release via IP3 receptors. These factors increased HCN channel conductance and produced firing lasting for ∼1min. The model displayed inter-scale synergies among synaptic weights, excitation/inhibition balance, firing rates, membrane depolarization, Ca(2+) levels, regulation of HCN channels, and induction of persistent activity. The interaction between inhibition and Ca(2+) at the HCN channel nexus determined a limited range of inhibition strengths for which intracellular Ca(2+) could prepare population-specific persistent activity. Interactions between metabotropic and ionotropic inputs to the neuron demonstrated how multiple pathways could contribute in a complementary manner to persistent activity. Such redundancy and complementarity via multiple pathways is a critical feature of biological systems. Mediation of activation at different time scales, and through different pathways, would be expected to protect against disruption, in

  9. The effects of S4 segments on the voltage-dependence of inactivation for Cav3.1 calcium channels

    Institute of Scientific and Technical Information of China (English)

    LI JunYing

    2007-01-01

    T-type calcium channels exhibit fast voltage-dependent inactivation,for which the underlying structure-function relationship still remains unclear.To investigate the roles of S4 segments in voltage-dependent inactivation of T-type calcium channels,we created S4 replacement chimeras between Cav3.1 calcium channels(fast voltage-dependent inactivation)and Cav1.2 calcium channels(little oltage-dependent inactivation)by replacing S4s in Cav3.1 with the corresponding regions in Cav1.2.Wild type and chimeric channels were expressed in Xenopus oocytes and channel currents were recorded with two-electrode voltage-clamp.We showed that replacing S4 region in domain I shifted voltage-dependence for inactivation of Cav3.1 to the left,and the V0.5 inact and kinact value were significantly changed.However replacing S4s in domains Ⅱ-Ⅳ had no effects on the voltage-dependent inactivation properties.These results suggest that the roles of S4 segments in domains Ⅰ-Ⅳ are different,and S4 in domain I is likely to be involved in voltage-dependent Inactivation process.Its movement during membrane depolarization may trigger a conformational change in the inactivation gate.

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

    Institute of Scientific and Technical Information of China (English)

    陈立华; 于嘉; 刘丽旭; 曹美鸿

    2002-01-01

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

  11. Lavender oil-potent anxiolytic properties via modulating voltage dependent calcium channels.

    Science.gov (United States)

    Schuwald, Anita M; Nöldner, Michael; Wilmes, Thomas; Klugbauer, Norbert; Leuner, Kristina; Müller, Walter E

    2013-01-01

    Recent clinical data support the clinical use of oral lavender oil in patients suffering from subsyndromal anxiety. We identified the molecular mechanism of action that will alter the perception of lavender oil as a nonspecific ingredient of aromatherapy to a potent anxiolytic inhibiting voltage dependent calcium channels (VOCCs) as highly selective drug target. In contrast to previous publications where exorbitant high concentrations were used, the effects of lavender oil in behavioral, biochemical, and electrophysiological experiments were investigated in physiological concentrations in the nanomolar range, which correlate to a single dosage of 80 mg/d in humans that was used in clinical trials. We show for the first time that lavender oil bears some similarities with the established anxiolytic pregabalin. Lavender oil inhibits VOCCs in synaptosomes, primary hippocampal neurons and stably overexpressing cell lines in the same range such as pregabalin. Interestingly, Silexan does not primarily bind to P/Q type calcium channels such as pregabalin and does not interact with the binding site of pregabalin, the α2δ subunit of VOCCs. Lavender oil reduces non-selectively the calcium influx through several different types of VOCCs such as the N-type, P/Q-type and T-type VOCCs. In the hippocampus, one brain region important for anxiety disorders, we show that inhibition by lavender oil is mainly mediated via N-type and P/Q-type VOCCs. Taken together, we provide a pharmacological and molecular rationale for the clinical use of the oral application of lavender oil in patients suffering from anxiety.

  12. Lavender oil-potent anxiolytic properties via modulating voltage dependent calcium channels.

    Directory of Open Access Journals (Sweden)

    Anita M Schuwald

    Full Text Available Recent clinical data support the clinical use of oral lavender oil in patients suffering from subsyndromal anxiety. We identified the molecular mechanism of action that will alter the perception of lavender oil as a nonspecific ingredient of aromatherapy to a potent anxiolytic inhibiting voltage dependent calcium channels (VOCCs as highly selective drug target. In contrast to previous publications where exorbitant high concentrations were used, the effects of lavender oil in behavioral, biochemical, and electrophysiological experiments were investigated in physiological concentrations in the nanomolar range, which correlate to a single dosage of 80 mg/d in humans that was used in clinical trials. We show for the first time that lavender oil bears some similarities with the established anxiolytic pregabalin. Lavender oil inhibits VOCCs in synaptosomes, primary hippocampal neurons and stably overexpressing cell lines in the same range such as pregabalin. Interestingly, Silexan does not primarily bind to P/Q type calcium channels such as pregabalin and does not interact with the binding site of pregabalin, the α2δ subunit of VOCCs. Lavender oil reduces non-selectively the calcium influx through several different types of VOCCs such as the N-type, P/Q-type and T-type VOCCs. In the hippocampus, one brain region important for anxiety disorders, we show that inhibition by lavender oil is mainly mediated via N-type and P/Q-type VOCCs. Taken together, we provide a pharmacological and molecular rationale for the clinical use of the oral application of lavender oil in patients suffering from anxiety.

  13. Neuroprotective activity of stiripentol with a possible involvement of voltage-dependent calcium and sodium channels.

    Science.gov (United States)

    Verleye, Marc; Buttigieg, Dorothée; Steinschneider, Rémy

    2016-02-01

    A growing body of data has shown that recurrent epileptic seizures may be caused by an excessive release of the excitatory neurotransmitter glutamate in the brain. Glutamatergic overstimulation results in massive neuronal influxes of calcium and sodium through N-methyl-D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainic acid glutamate subtype receptors and also through voltage-gated calcium and sodium channels. These persistent and abnormal sodium and calcium entry points have deleterious consequences (neurotoxicity) for neuronal function. The therapeutic value of an antiepileptic drug would include not only control of seizure activity but also protection of neuronal tissue. The present study examines the in vitro neuroprotective effects of stiripentol, an antiepileptic compound with γ-aminobutyric acidergic properties, on neuronal-astroglial cultures from rat cerebral cortex exposed to oxygen-glucose deprivation (OGD) or to glutamate (40 µM for 20 min), two in vitro models of brain injury. In addition, the affinity of stiripentol for the different glutamate receptor subtypes and the interaction with the cell influx of Na(+) and of Ca(2+) enhanced by veratridine and NMDA, respectively, are assessed. Stiripentol (10-100 µM) included in the culture medium during OGD or with glutamate significantly increased the number of surviving neurons relative to controls. Stiripentol displayed no binding affinity for different subtypes of glutamate receptors (IC50  >100 µM) but significantly blocked the entry of Na(+) and Ca(2+) activated by veratridine and NMDA, respectively. These results suggest that Na(+) and Ca(2+) channels could contribute to the neuroprotective properties of sitiripentol.

  14. Yeast respond to hypotonic shock with a calcium pulse

    Science.gov (United States)

    Batiza, A. F.; Schulz, T.; Masson, P. H.

    1996-01-01

    We have used the transgenic AEQUORIN calcium reporter system to monitor the cytosolic calcium ([Ca2+]cyt) response of Saccharomyces cerevisiae to hypotonic shock. Such a shock generates an almost immediate and transient rise in [Ca2+]cyt which is eliminated by gadolinium, a blocker of stretch-activated channels. In addition, this transient rise in [Ca2+]cyt is initially insensitive to 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), an extracellular calcium chelator. However, BAPTA abruptly attenuates the maintenance of that transient rise. These data show that hypotonic shock generates a stretch-activated channel-dependent calcium pulse in yeast. They also suggest that the immediate calcium influx is primarily generated from intracellular stores, and that a sustained increase in [Ca2+]cyt depends upon extracellular calcium.

  15. Cav1.2, but not Cav1.3, L-type calcium channel subtype mediates nicotine-induced conditioned place preference in miceo.

    Science.gov (United States)

    Liu, Yudan; Harding, Meghan; Dore, Jules; Chen, Xihua

    2017-04-03

    Nicotine use is one of the most common forms of drug addiction. Although L-type calcium channels (LTCCs) are involved in nicotine addiction, the contribution of the two primary LTCC subtypes (Cav1.2 and 1.3) is unknown. This study aims to determine the contribution of these two LTCC subtypes to nicotine-induced conditioned place preference (CPP) responses by using transgenic mouse models that do not express Cav1.3 (Cav1.3(-/-)) or contain a mutation in the dihydropyridine (DHP) site of the Cav1.2 (Cav1.2DHP(-/-)). We found a hyperbolic dose dependent nicotine (0.1-1mg/kg; 0.5mg/kg optimum) effect on place preference in wild type (WT) mice, that could be prevented by the DHP LTCC blocker nifedipine pretreatment. Similarly, Cav1.3(-/-) mice showed nicotine-induced place preference which was antagonized by nifedipine. In contrast, nifedipine pretreatment of Cav1.2DHP(-/-) mice had no effect on nicotine-induced CPP responses, suggesting an involvement of Cav1.2 subtype in the nicotine-induced CPP response. Nifedipine alone failed to produce either conditioned place aversion or CPP in WT mice. These results collectively indicate Cav1.2, but not Cav1.3 LTCC subtype regulates, at least in part, the reinforcing effects of nicotine use.

  16. Impact of Na⁺ channel blockers on transmural dispersion of refractoriness and arrhythmic susceptibility in guinea-pig left ventricle.

    Science.gov (United States)

    Osadchii, Oleg E

    2012-09-15

    Clinically, class Ib antiarrhythmic agents (selective I(Na) blockers) are considered to be safe drugs, whereas class Ia and Ic agents (non-selective blockers of both I(Na) and I(Kr), the rapid component of the delayed rectifier) may evoke proarrhythmia. I hypothesized that this difference is accounted for by differential drug effects on transmural dispersion of refractoriness, in the presence of the reciprocal distribution profile of I(Na) and I(Kr) across ventricular wall, as determined in previous studies. Specifically, less epicardial than endocardial I(Na) reserve would likely contribute to a greater prolongation of the effective refractory period (ERP) at epicardium by the I(Na) blocker, thereby reducing epicardial-to-endocardial ERP dispersion, with resulting antiarrhythmic effect. In contrast, less endocardial than epicardial I(Kr) reserve would likely contribute to a greater prolongation of repolarization at the endocardium by the I(Kr) blocker, thereby amplifying transmural ERP dispersion and inducing arrhythmia. In perfused guinea-pig hearts, dofetilide, a specific I(Kr) blocker, as well as class Ia (quinidine, procainamide) and class Ic agents (flecainide), were found to prolong the QT interval and monophasic action potential duration, and elicited greater endocardial than epicardial ERP prolongation, thus markedly increasing transmural ERP dispersion. These changes were associated with episodes of monomorphic ventricular tachycardia in 30-40% of experiments. In contrast, class Ib agents (lidocaine, mexiletine) evoked greater epicardial than endocardial ERP lengthening, thereby decreasing transmural ERP dispersion, and produced no tachyarrhythmia. These findings suggest that transmural ERP dispersion is the electrophysiological determinant which may shape the profile of class I agent effects on arrhythmic susceptibility.

  17. Possible roles of exceptionally conserved residues around the selectivity filters of sodium and calcium channels.

    Science.gov (United States)

    Tikhonov, Denis B; Zhorov, Boris S

    2011-01-28

    In the absence of x-ray structures of sodium and calcium channels their homology models are used to rationalize experimental data and design new experiments. A challenge is to model the outer-pore region that folds differently from potassium channels. Here we report a new model of the outer-pore region of the NaV1.4 channel, which suggests roles of highly conserved residues around the selectivity filter. The model takes from our previous study (Tikhonov, D. B., and Zhorov, B. S. (2005) Biophys. J. 88, 184-197) the general disposition of the P-helices, selectivity filter residues, and the outer carboxylates, but proposes new intra- and inter-domain contacts that support structural stability of the outer pore. Glycine residues downstream from the selectivity filter are proposed to participate in knob-into-hole contacts with the P-helices and S6s. These contacts explain the adapted tetrodotoxin resistance of snakes that feed on toxic prey through valine substitution of isoleucine in the P-helix of repeat IV. Polar residues five positions upstream from the selectivity filter residues form H-bonds with the ascending-limb backbones. Exceptionally conserved tryptophans are engaged in inter-repeat H-bonds to form a ring whose π-electrons would facilitate passage of ions from the outer carboxylates to the selectivity filter. The outer-pore model of CaV1.2 derived from the NaV1.4 model is also stabilized by the ring of exceptionally conservative tryptophans and H-bonds between the P-helices and ascending limbs. In this model, the exceptionally conserved aspartate downstream from the selectivity-filter glutamate in repeat II facilitates passage of calcium ions to the selectivity-filter ring through the tryptophan ring. Available experimental data are discussed in view of the models.

  18. Pharmacology of the human red cell voltage-dependent cation channel Part I. Activation by clotrimazole and analogues

    DEFF Research Database (Denmark)

    Barksmann, Trine Lyberth; Kristensen, Berit I.; Christophersen, Palle.

    2004-01-01

    Human red cells, Nonselective voltage dependent cation channel, NSVDC channel, Gárdos channel blockers, NSVDC channel activators......Human red cells, Nonselective voltage dependent cation channel, NSVDC channel, Gárdos channel blockers, NSVDC channel activators...

  19. Differential regulation of voltage- and calcium-activated potassium channels in human B lymphocytes.

    Science.gov (United States)

    Partiseti, M; Choquet, D; Diu, A; Korn, H

    1992-06-01

    The expression and characteristics of K+ channels of human B lymphocytes were studied by using single and whole-cell patch-clamp recordings. They were gated by depolarization (voltage-gated potassium current, IKv, 11-20 pS) and by an increase in intracellular Ca2+ concentration (calcium-activated potassium current, IKCa, 26 pS), respectively. The level of expression of these channels was correlated with the activational status of the cell. Both conductances are blocked by tetraethylammonium, verapamil, and charybdotoxin, and are insensitive to apamin; 4-aminopyridine blocks IK, preferentially. We used a protein kinase C activator (PMA) or antibodies to membrane Ig (anti-mu) to activate resting splenocytes in culture. Although IKv was recorded in the majority of the resting lymphocytic population, less than 20% of the activated cells expressed this conductance. However, in this subset the magnitude of IKv was 20-fold larger than in resting cells. On the other hand, IKCa was detected in nearly one half of the resting cells, whereas all activated cells expressed this current. The magnitude of IKCa was, on average, 30 times larger in activated than in nonactivated cells. These results probably reflect that during the course of activation 1) the number of voltage-dependent K+ channels per cell decreases and increases in a small subset and 2) the number of Ca(2+)-dependent K+ channels per cell increases in all cells. We suggest that the expression of functional Ca(2+)- and voltage-activated K+ channels are under the control of different regulatory signals.

  20. The pre-synaptic blocker toosendanin does not inhibit secretion in exocrine cells

    Institute of Scientific and Technical Information of China (English)

    Zong-Jie Cui; Xue-Hui He

    2002-01-01

    AIM: Toosendanin is a pre-synaptic blocker at theneuromuscular junction and its inhibitory effect is dividedinto an initial facilitative/stimulatory phase followed by aprolonged inhibitory phase. The present study investigatedwhether the subsequent inhibitory phase was due toexhaustion of the secretory machinery as a result of extensivestimulation during the initial facilitative phase. Morespecifically, this paper examined whether toosendanin coulddirectly inhibit the secretory machinery in exocrine cells.METHODS: Rat pancreatic acinar cells were isolated bycollagenase digestion. Secretion was assessed by measuringthe amount of amylase released into the extracellular mediumas a percentage of the total present in the cells beforestimulation. Cholecystokinin (CCK)-induced increases inintracellular calcium in single cells were measured with fura-2 microfluorometry.RESULTS: Effects of toosendanin on CCK-induced amylasesecretion and calcium oscillations were investigated.Toosendanin of 87-870 tM had no effect on 10 pM-100 nMCCK-stimulated amylase secretion, nor did 8.7-870 μMtoosendanin inhibit 5 pM CCK-induced calcium oscillations.In contrast, 10 nM CCK1 receptor antagonist FK 480 completelyblocked 5 pM CCK-induced calcium oscillations.CONCLUSION: The pre-synaptic "blocker" toosendanin is aselective activator of the voltage-dependent calcium channels,but does not interfere with the secretory machinery itself.

  1. Effect of blockers of Kv and BKCa channels on muscle tension of rabbit oddi sphincter in vivo and th e regulatory effect of paeoniflorin%Kv 和 BK Ca通道阻断剂对家兔离体 Oddi括约肌肌环张力的作用及芍药甙的调控作用

    Institute of Scientific and Technical Information of China (English)

    雒建瑞; 王芳; 冯骅; 王长淼

    2014-01-01

    Objective It is to investigate the effect of blockers of voltage-gated potassium channels ( Kv) , large-conduct-ance calcium-activated potassium channel ( BKCa) on sphincter of Oddi ( sphincter of Oddi , SO) from rabbits muscle ten-sion rings, and to explore the regulatory effect of the active ingredients of traditional Chinese medicine paeoniflorin on them . Methods Isolated rabbit sphincter of Oddi muscle rings specimens were prepared and placed on the smooth muscle perfusion bath temperature to observe the contraction effect of Kv channel blocker 4-aminopyridine (4-AP), BKCa channel blocker tetraethylammonium chloride( TEA) on isolated rabbit SO muscle rings and the effects of paeoniflorin on the contraction effects induced by 4-AP and TEA.Resul ts 4-AP and TEA both could cause contraction of SO muscle rings , with the the concen-trations increased , the contraction degrees increased .The contraction effects induced by 4-AP and TEA could be inhibited by paeoniflorin .Conclusion In vitro condition , Kv channel and BKCa channel play a major role in the maintenance of sphincter of Oddi resting membrane potential of cells .Paeoniflorin may influence the relaxant responses of SO cells possibly through the regulation of Kv and BKCa channels .%目的:探讨电压依赖性钾通道( Kv)、大电导钙激活钾通道( BKCa )阻断剂对家兔离体Oddi 括约肌( SO)肌环张力的作用及中药芍药的有效成分芍药甙对其调控作用。方法制备离体兔Oddi 括约肌肌环标本,放置于平滑肌恒温灌流浴槽中,观察Kv通道阻断剂4-aminopyridine (4-AP)、BKCa通道阻断剂tetraethylammonium chloride ( TEA)对家兔离体SO肌环的收缩作用;观察芍药甙对4-AP和TEA引起的收缩作用的影响。结果4-AP、TEA均可以引起SO肌环收缩,且随4-AP、TEA浓度增加,收缩程度也在增强。4-AP和TEA对SO肌环的收缩作用可以被芍药甙抑制。结论在离体条件下,Kv通道和BKCa通道

  2. The large conductance calcium-activated K(+) channel interacts with the small GTPase Rab11b.

    Science.gov (United States)

    Sokolowski, Sophia; Harvey, Margaret; Sakai, Yoshihisa; Jordan, Amy; Sokolowski, Bernd

    2012-09-21

    The transduction of sound by the receptor or hair cells of the cochlea leads to the activation of ion channels found in the basal and lateral regions of these cells. Thus, the processing of these transduced signals to the central nervous system is tied to the regulation of baso-lateral ion channels. The large conductance calcium-activated potassium or BK channel was revealed to interact with the small GTPase, Rab11b, which is one of many Rabs found in various endosomal pathways. Immunoelectron microscopy showed the colocalization of these two proteins in receptor cells and auditory neurons. Using Chinese hamster ovary cells as a heterologous expression system, Rab11b increased or decreased BK expression, depending on the overexpression or RNAi knockdown of Rab, respectively. Additional mutation analyses, using a yeast two-hybrid assay, suggested that this GTPase moderately interacts within a region of BK exclusive of the N- or C-terminal tails. These data suggest that this small GTPase regulates BK in a slow recycling process through the endocytic compartment and to the plasmalemma.

  3. T Cell Subset and Stimulation Strength-Dependent Modulation of T Cell Activation by Kv1.3 Blockers

    Science.gov (United States)

    Fung-Leung, Wai-Ping; Edwards, Wilson; Liu, Yi; Ngo, Karen; Angsana, Julianty; Castro, Glenda; Wu, Nancy; Liu, Xuejun; Swanson, Ronald V.; Wickenden, Alan D.

    2017-01-01

    Kv1.3 is a voltage-gated potassium channel expressed on T cells that plays an important role in T cell activation. Previous studies have shown that blocking Kv1.3 channels in human T cells during activation results in reduced calcium entry, cytokine production, and proliferation. The aim of the present study was to further explore the effects of Kv1.3 blockers on the response of different human T cell subsets under various stimulation conditions. Our studies show that, unlike the immune suppressor cyclosporine A, the inhibitory effect of Kv1.3 blockers was partial and stimulation strength dependent, with reduced inhibitory efficacy on T cells under strengthened anti-CD3/CD28 stimulations. T cell responses to allergens including house dust mites and ragweed were partially reduced by Kv1.3 blockers. The effect of Kv1.3 inhibition was dependent on T cell subsets, with stronger effects on CCR7- effector memory compared to CCR7+ central memory CD4 T cells. Calcium entry studies also revealed a population of CD4 T cells resistant to Kv1.3 blockade. Activation of CD4 T cells was accompanied with an increase in Kv1.3 currents but Kv1.3 transcripts were found to be reduced, suggesting a posttranscriptional mechanism in the regulation of Kv1.3 activities. In summary, Kv1.3 blockers inhibit T cell activation in a manner that is highly dependent on the T cell identity and stimulation strength, These findings suggest that Kv1.3 blockers inhibit T cells in a unique, conditional manner, further refining our understanding of the therapeutic potential of Kv1.3 blockers. PMID:28107393

  4. Gynura procumbens Merr. decreases blood pressure in rats by vasodilatation via inhibition of calcium channels

    Directory of Open Access Journals (Sweden)

    See-Ziau Hoe

    2011-01-01

    Full Text Available INTRODUCTION: Gynura procumbens has been shown to decrease blood pressure via inhibition of the angiotensinconverting enzyme. However, other mechanisms that may contribute to the hypotensive effect have not been studied. OBJECTIVES: To investigate the cardiovascular effects of a butanolic fraction of Gynura procumbens in rats. METHODS: Anaesthetized rats were given intravenous bolus injections of butanolic fraction at doses of 2.5-20 mg/kg in vivo. The effect of butanolic fraction on vascular reactivity was recorded in isolated rat aortic rings in vitro. RESULTS: Intravenous administrations of butanolic fraction elicited significant (p<0.001 and dose-dependent decreases in the mean arterial pressure. However, a significant (p<0.05 decrease in the heart rate was observed only at the higher doses (10 and 20 mg/kg. In isolated preparations of rat aortic rings, phenylephrine (1×10-6 M- or potassium chloride (8×10-2 M-precontracted endothelium-intact and -denuded tissue; butanolic fraction (1×10-6-1×10-1 g/ml induced similar concentration-dependent relaxation of the vessels. In the presence of 2.5×10-3 and 5.0×10-3 g/ml butanolic fraction, the contractions induced by phenylephrine (1×10-9-3×10-5 M and potassium chloride (1×10-2-8×10-2 M were significantly antagonized. The calcium-induced vasocontractions (1×10-4-1×10-2 M were antagonized by butanolic fraction concentration-dependently in calcium-free and high potassium (6×10-2 M medium, as well as in calcium- and potassium-free medium containing 1×10-6 M phenylephrine. However, the contractions induced by noradrenaline (1×10-6 M and caffeine (4.5×10-2 M were not affected by butanolic fraction. CONCLUSION: Butanolic fraction contains putative hypotensive compounds that appear to inhibit calcium influx via receptor-operated and/or voltage-dependent calcium channels to cause vasodilation and a consequent fall in blood pressure.

  5. Exposure to extremely low-frequency electromagnetic fields inhibits T-type calcium channels via AA/LTE4 signaling pathway.

    Science.gov (United States)

    Cui, Yujie; Liu, Xiaoyu; Yang, Tingting; Mei, Yan-Ai; Hu, Changlong

    2014-01-01

    Extremely low-frequency electromagnetic fields (ELF-EMF) causes various biological effects through altering intracellular calcium homeostasis. The role of high voltage-gated (HVA) calcium channels in ELF-EMF induced effects has been extensively studied. However, the effect of ELF-EMF on low-voltage-gated (LVA) T-type calcium channels has not been reported. In this study, we test the effect of ELF-EMF (50Hz) on human T-type calcium channels transfected in HEK293 cells. Conversely to its stimulant effects on HVA channels, ELF-EMF exposure inhibited all T-type (Cav3.1, Cav3.2 and Cav3.3) channels. Neither the protein expression nor the steady-state activation and inactivation kinetics of Cav3.2 channels were altered by ELF-EMF (50Hz, 0.2mT) exposure. Exposure to ELF-EMF increased both arachidonic acid (AA) and leukotriene E4 (LTE4) levels in HEK293 cells. CAY10502 and bestatin, which block the increase of AA and LTE4 respectively, abrogated the ELF-EMF inhibitory effect on Cav3.2 channels. Exogenous LTE4 mimicked the ELF-EMF inhibition of T-type calcium channels. ELF-EMF (50Hz) inhibits native T-type calcium channels in primary cultured mouse cortical neurons via LTE4. We conclude that 50Hz ELF-EMF inhibits T-type calcium channels through AA/LTE4 signaling pathway.

  6. Glucocorticoids specifically enhance L-type calcium current amplitude and affect calcium channel subunit expression in the mouse hippocampus.

    NARCIS (Netherlands)

    Chameau, P.J.P.; Qin, Y.J.; Smit, G.; Joëls, M.

    2007-01-01

    Previous studies have shown that corticosterone enhances whole cell calcium currents in CA1 pyramidal neurons, through a pathway involving binding of glucocorticoid receptor homodimers to the DNA. We examined whether glucocorticoids show selectivity for L- over N-type of calcium currents. Moreover,

  7. Mechanism of Action of Novel Glibenclamide Derivatives on Potassium and Calcium Channels for Insulin Secretion.

    Science.gov (United States)

    Frederico, Marisa Jádson Silva; Castro, Allisson Jhonatan Gomes; Menegaz, Danusa; De Bernardis Murat, Cahuê; Mendes, Camila Pires; Mascarello, Alessandra; Nunes, Ricardo José; Silva, Fátima Regina Mena Barreto

    2016-06-14

    Glibenclamide is widely used and remains a cornerstone and an effective antihyperglycemic drug. After the casual discovery of its hypoglycemic potential, this compound was introduced for diabetes treatment. However, the long-term side effects reveal that glibenclamide should be replaced by new molecules able to maintain the health of β-cells, protecting them from hyperstimulation/hyperexcitability, hyperinsulinemia, functional failure and cell death. The aim of this review was to highlight the main mechanism of action of glibenclamide and the influence of its derivatives, such as acyl-hydrazones, sulfonamides and sulfonylthioureas on β-cells potassium and calcium channels for insulin secretion as well as the contribution of these new compounds to restore glucose homeostasis. Furthermore, the role of glibenclamide-based novel structures that promise less excitability of β-cell in a long-term treatment with effectiveness and safety for diabetes therapy was discussed.

  8. Cloning, chromosomal localization, and functional expression of the alpha 1 subunit of the L-type voltage-dependent calcium channel from normal human heart

    NARCIS (Netherlands)

    Schultz, D; Mikala, G; Yatani, A; Engle, D B; Iles, D E; Segers, B; Sinke, R J; Weghuis, D O; Klöckner, U; Wakamori, M

    1993-01-01

    A unique structural variant of the cardiac L-type voltage-dependent calcium channel alpha 1 subunit cDNA was isolated from libraries derived from normal human heart mRNA. The deduced amino acid sequence shows significant homology to other calcium channel alpha 1 subunits. However, differences from t

  9. The mutant Moonwalker TRPC3 channel links calcium signaling to lipid metabolism in the developing cerebellum.

    Science.gov (United States)

    Dulneva, Anna; Lee, Sheena; Oliver, Peter L; Di Gleria, Katalin; Kessler, Benedikt M; Davies, Kay E; Becker, Esther B E

    2015-07-15

    The Moonwalker (Mwk) mouse is a model of dominantly inherited cerebellar ataxia caused by a gain-of-function mutation in the transient receptor potential (TRP) channel TRPC3. Here, we report impairments in dendritic growth and synapse formation early on during Purkinje cell development in the Mwk cerebellum that are accompanied by alterations in calcium signaling. To elucidate the molecular effector pathways that regulate Purkinje cell dendritic arborization downstream of mutant TRPC3, we employed transcriptomic analysis of developing Purkinje cells isolated by laser-capture microdissection. We identified significant gene and protein expression changes in molecules involved in lipid metabolism. Consistently, lipid homeostasis in the Mwk cerebellum was found to be disturbed, and treatment of organotypic cerebellar slices with ceramide significantly improved dendritic outgrowth of Mwk Purkinje cells. These findings provide the first mechanistic insights into the TRPC3-dependent mechanisms, by which activated calcium signaling is coupled to lipid metabolism and the regulation of Purkinje cell development in the Mwk cerebellum.

  10. A key role for STIM1 in store operated calcium channel activation in airway smooth muscle

    Directory of Open Access Journals (Sweden)

    Peel Samantha E

    2006-09-01

    Full Text Available Abstract Background Control of cytosolic calcium plays a key role in airway myocyte function. Changes in intracellular Ca2+ stores can modulate contractile responses, modulate proliferation and regulate synthetic activity. Influx of Ca2+ in non excitable smooth muscle is believed to be predominantly through store operated channels (SOC or receptor operated channels (ROC. Whereas agonists can activate both SOC and ROC in a range of smooth muscle types, the specific trigger for SOC activation is depletion of the sarcoplasmic reticulum Ca2+ stores. The mechanism underlying SOC activation following depletion of intracellular Ca2+ stores in smooth muscle has not been identified. Methods To investigate the roles of the STIM homologues in SOC activation in airway myocytes, specific siRNA sequences were utilised to target and selectively suppress both STIM1 and STIM2. Quantitative real time PCR was employed to assess the efficiency and the specificity of the siRNA mediated knockdown of mRNA. Activation of SOC was investigated by both whole cell patch clamp electrophysiology and a fluorescence based calcium assay. Results Transfection of 20 nM siRNA specific for STIM1 or 2 resulted in robust decreases (>70% of the relevant mRNA. siRNA targeted at STIM1 resulted in a reduction of SOC associated Ca2+ influx in response to store depletion by cyclopiazonic acid (60% or histamine but not bradykinin. siRNA to STIM2 had no effect on these responses. In addition STIM1 suppression resulted in a more or less complete abrogation of SOC associated inward currents assessed by whole cell patch clamp. Conclusion Here we show that STIM1 acts as a key signal for SOC activation following intracellular Ca2+ store depletion or following agonist stimulation with histamine in human airway myocytes. These are the first data demonstrating a role for STIM1 in a physiologically relevant, non-transformed endogenous expression cell model.

  11. Anti-Convulsant Activity of Boerhaavia diffusa: Plausible Role of Calcium Channel Antagonism

    Directory of Open Access Journals (Sweden)

    Mandeep Kaur

    2011-01-01

    Full Text Available “Ethnopharmacological” use of roots of Boerhaavia diffusa (B. diffusa in the treatment of epilepsy in Nigerian folk medicine and reports showing the presence of a calcium channel antagonistic compound “liriodendrin” in its roots, led us to undertake the present study. The study was designed to investigate the methanolic root extract of B. diffusa and its different fractions including liriodendrin-rich fraction for exploring the possible role of liriodendrin in its anti-convulsant activity. Air-dried roots of B. diffusa were extracted with methanol by cold maceration. The methanol soluble fraction of extract thus obtained was successively extracted to obtain liriodendrin-rich fraction and two side fractions, that is, chloroform fraction and phenolic compound fraction. Anti-convulsant activity of methanolic extract (1000, 1500 and 2000 mg kg-1, intraperitoneally (i.p. and its different fractions, that is, liriodendrin-rich fraction (10, 20 and 40 mg kg-1, i.p., chloroform fraction (20 mg kg-1, i.p. and phenolic compound fraction (1 mg kg-1, i.p. were studied in pentylenetetrazol (PTZ-induced seizures (75 mg kg-1, i.p.. The crude methanolic extract of B. diffusa and only its liriodendrin-rich fraction showed a dose-dependent protection against PTZ-induced convulsions. The liriodendrin-rich fraction also showed significant protection against seizures induced by BAY k-8644. These findings reiterated the anti-convulsant activity of methanolic extract of B. diffusa roots. Furthermore, it can be concluded that the observed anti-convulsant activity was due to its calcium channel antagonistic action as this activity was retained only in the liodendrin-rich fraction, which has additionally been confirmed by significant anti-convulsant activity of liriodendrin-rich fraction in BAY k-8644-induced seizures.

  12. Anti-Convulsant Activity of Boerhaavia diffusa: Plausible Role of Calcium Channel Antagonism.

    Science.gov (United States)

    Kaur, Mandeep; Goel, Rajesh Kumar

    2011-01-01

    "Ethnopharmacological" use of roots of Boerhaavia diffusa (B. diffusa) in the treatment of epilepsy in Nigerian folk medicine and reports showing the presence of a calcium channel antagonistic compound "liriodendrin" in its roots, led us to undertake the present study. The study was designed to investigate the methanolic root extract of B. diffusa and its different fractions including liriodendrin-rich fraction for exploring the possible role of liriodendrin in its anti-convulsant activity. Air-dried roots of B. diffusa were extracted with methanol by cold maceration. The methanol soluble fraction of extract thus obtained was successively extracted to obtain liriodendrin-rich fraction and two side fractions, that is, chloroform fraction and phenolic compound fraction. Anti-convulsant activity of methanolic extract (1000, 1500 and 2000 mg kg(-1), intraperitoneally (i.p.)) and its different fractions, that is, liriodendrin-rich fraction (10, 20 and 40 mg kg(-1), i.p., chloroform fraction (20 mg kg(-1), i.p.) and phenolic compound fraction (1 mg kg(-1), i.p.) were studied in pentylenetetrazol (PTZ)-induced seizures (75 mg kg(-1), i.p.). The crude methanolic extract of B. diffusa and only its liriodendrin-rich fraction showed a dose-dependent protection against PTZ-induced convulsions. The liriodendrin-rich fraction also showed significant protection against seizures induced by BAY k-8644. These findings reiterated the anti-convulsant activity of methanolic extract of B. diffusa roots. Furthermore, it can be concluded that the observed anti-convulsant activity was due to its calcium channel antagonistic action as this activity was retained only in the liodendrin-rich fraction, which has additionally been confirmed by significant anti-convulsant activity of liriodendrin-rich fraction in BAY k-8644-induced seizures.

  13. Calmodulin modulates the delay period between release of calcium from internal stores and activation of calcium influx via endogenous TRP1 channels.

    Science.gov (United States)

    Vaca, Luis; Sampieri, Alicia

    2002-11-01

    In the present study we have explored the role of calmodulin (CaM) and inositol 1,4,5-trisphosphate receptor (IP(3)R) in the communication process activated after the release of calcium from the endoplasmic reticulum (ER) and the activation of calcium influx via endogenous TRP1 channels from Chinese hamster ovary cells. Experiments using combined rapid confocal calcium and electrophysiology measurements uncovered a consistent delay of around 900 ms between the first detectable calcium released from the ER and the activation of the calcium current. This delay was evident with two different methods used to release calcium from the ER: either the blockade of the microsomal calcium ATPase with thapsigargin or activation of bradykinin receptors linked to the IP(3) cascade. Direct application of IP(3) or a peptide from the NH(2)-terminal region of the IP(3)R activated store operated calcium, reducing the delay period. Introduction of CaM into the cell via the patch pipette increased the delay period from 900 +/- 100 ms to 10 +/- 2.1 s (n = 18). Furthermore, the use of selective CaM antagonists W7 and trifluoperazine maleate resulted in a substantial reduction of the delay period to 200 +/- 100 ms with 5 microm trifluoperazine maleate (n = 16) and 150 +/- 50 ms with 500 nm W7 (n = 22). CaM reduced also the current density activated by thapsigargin or brandykinin to about 60% from control. The CaM antagonists did not affect significantly the current density. The results presented here are consistent with an antagonistic effect of IP(3)R and CaM for the activation of store operated calcium after depletion of the ER. The functional competition between the activating effect of IP(3)R and the inhibiting effect of CaM may modulate the delay period between the release of calcium from the ER and the activation of calcium influx observed in different cells, as well as the amount of current activated after depletion of the ER.

  14. Blockade of L-type calcium channel in myocardium and calcium-induced contractions of vascular smooth muscle by by CPU 86017

    Institute of Scientific and Technical Information of China (English)

    De-zai DAI; Hui-juan HU; Jing ZHAO; Xue-mei HAO; Dong-mei YANG; Pei-ai ZHOU; Cai-hong WU

    2004-01-01

    AIM: To assess the blockade by CPU 86017 on the L-type calcium channels in the myocardium and on the Ca2+related contractions of vascular smooth muscle. METHODS: The whole-cell patch-clamp was applied to investigate the blocking effect of CPU 86017 on the L-type calcium current in isolated guinea pig myocytes and contractions by KC1 or phenylephrine (Phe) of the isolated rat tail arteries were measured. RESULTS: Suppression of the L-type current of the isolated myocytes by CPU 86017 was moderate, in time- and concentration-dependent manner and with no influence on the activation and inactivation curves. The IC50 was 11.5 μmol/L. Suppressive effect of CPU 86017 on vaso-contractions induced by KC1 100 mmol/L, phenylephrine I μmol/Lin KH solution (phase 1),Ca2+ free KH solution ( phase 2), and by addition of CaCI2 into Ca2+-free KH solution (phase 3) were observed. The IC50 to suppress vaso-contractions by calcium entry via the receptor operated channel (ROC) and Voltage-dependent channel (VDC) was 0.324 μmol/L and 16.3 μmol/L, respectively. The relative potency of CPU 86017 to suppress vascular tone by Ca2+ entry through ROC and VDC is 1/187 of prazosin and 1/37 of verapamil, respectively.CONCLUSION: The blocking effects of CPU 86017 on the L-type calcium channel of myocardium and vessel are moderate and non-selective. CPU 86017 is approximately 50 times more potent in inhibiting ROC than VDC.

  15. Intracellular calcium level is an important factor influencing ion channel modulations by PLC-coupled metabotropic receptors in hippocampal neurons.

    Science.gov (United States)

    Sugawara, Yuto; Echigo, Ryousuke; Kashima, Kousuke; Minami, Hanae; Watanabe, Megumi; Nishikawa, Yuiko; Muranishi, Miho; Yoneda, Mitsugu; Ohno-Shosaku, Takako

    2013-05-28

    Signaling pathways involving phospholipase C (PLC) are involved in various neural functions. Understanding how these pathways are regulated will lead to a better understanding of their roles in neural functions. Previous studies demonstrated that receptor-driven PLCβ activation depends on intracellular Ca(2+) concentration ([Ca(2+)]i), suggesting the possibility that PLCβ-dependent cellular responses are basically Ca(2+) dependent. To test this possibility, we examined whether modulations of ion channels driven by PLC-coupled metabotropic receptors are sensitive to [Ca(2+)]i using cultured hippocampal neurons. Muscarinic activation triggered an inward current at -100 mV (the equilibrium potential for K(+)) in a subpopulation of neurons. This current response was suppressed by pirenzepine (an M1-preferring antagonist), PLC inhibitor, non-selective cation channel blocker, and lowering [Ca(2+)]i. Using the neurons showing no response at -100 mV, effects of muscarinic activation on K(+) channels were examined at -40 mV. Muscarinic activation induced a transient decrease of the holding outward current. This current response was mimicked and occluded by XE991, an M-current K(+) channel blocker, suppressed by pirenzepine, PLC inhibitor and lowering [Ca(2+)]i, and enhanced by elevating [Ca(2+)]i. Similar results were obtained when group I metabotropic glutamate receptors were activated instead of muscarinic receptors. These results clearly show that ion channel modulations driven by PLC-coupled metabotropic receptors are dependent on [Ca(2+)]i, supporting the hypothesis that cellular responses induced by receptor-driven PLCβ activation are basically Ca(2+) dependent.

  16. Selective cognitive deficits and reduced hippocampal brain-derived neurotrophic factor mRNA expression in small-conductance calcium-activated K+ channel deficient mice.

    Science.gov (United States)

    Jacobsen, J P R; Redrobe, J P; Hansen, H H; Petersen, S; Bond, C T; Adelman, J P; Mikkelsen, J D; Mirza, N R

    2009-09-29

    Small-conductance calcium-activated K(+) channels 1-3 (SK1-3) are important for neuronal firing regulation and are considered putative CNS drug targets. For instance non-selective SK blockers improve performance in animal models of cognition. The SK subtype(s) involved herein awaits identification and the question is difficult to address pharmacologically due to the lack of subtype-selective SK-channel modulators. In this study, we used doxycycline-induced conditional SK3-deficient (T/T) mice to address the cognitive consequences of selective SK3 deficiency. In T/T mice SK3 protein is near-eliminated from the brain following doxycycline treatment. We tested T/T and wild type (WT) littermate mice in five distinct learning and memory paradigms. In Y-maze spontaneous alternations and five-trial inhibitory avoidance the performance of T/T mice was markedly inferior to WT mice. In contrast, T/T and WT mice performed equally well in passive avoidance, object recognition and the Morris water maze. Thus, some aspects of working/short-term memory are disrupted in T/T mice. Using in situ hybridization, we further found the cognitive deficits in T/T mice to be paralleled by reduced brain-derived neurotrophic factor (BDNF) mRNA expression in the dentate gyrus and CA3 of the hippocampus. BDNF mRNA levels in the frontal cortex were not affected. BDNF has been crucially implicated in many cognitive processes. Hence, the biological substrate for the cognitive impairments in T/T mice could conceivably entail reduced trophic support of the hippocampus.

  17. Functional and pharmacological consequences of the distribution of voltage-gated calcium channels in the renal blood vessels

    DEFF Research Database (Denmark)

    Hansen, P B L

    2013-01-01

    -type is usually associated with vascular contractility. However, the L-, T- and P-/Q-types of calcium channels are present in the renal vasculature and are differentially involved in controlling vascular contractility, thereby contributing to regulation of kidney function and blood pressure. In the preglomerular...

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

    Science.gov (United States)

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

    2012-01-01

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

  19. Role for voltage gated calcium channels in calcitonin gene-related peptide release in the rat trigeminovascular system

    DEFF Research Database (Denmark)

    Amrutkar, D V; Ploug, K B; Olesen, J;

    2011-01-01

    Clinical and genetic studies have suggested a role for voltage gated calcium channels (VGCCs) in the pathogenesis of migraine. Release of calcitonin gene-related peptide (CGRP) from trigeminal neurons has also been implicated in migraine. The VGCCs are located presynaptically on neurons and are i...

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

    Science.gov (United States)

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

    2014-07-01

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

  1. The calcium-activated potassium channel KCa3.1 is an important modulator of hepatic injury

    DEFF Research Database (Denmark)

    Møller, Linda Maria Sevelsted; Fialla, Annette Dam; Schierwagen, Robert

    2016-01-01

    The calcium-activated potassium channel KCa3.1 controls different cellular processes such as proliferation and volume homeostasis. We investigated the role of KCa3.1 in experimental and human liver fibrosis. KCa3.1 gene expression was investigated in healthy and injured human and rodent liver. Ef...

  2. Increased Expression of the Calcium-Activated Chloride Channel in Hclca1 in Airways of Patients with Obstructive Chronic Bronchitis

    Directory of Open Access Journals (Sweden)

    Hans-Peter Hauber

    2005-01-01

    Full Text Available BACKGROUND: Interleukin (IL-9 and its effect on enhancing the human calcium-activated chloride channel 1 (hCLCA1 expression have been shown to induce mucin production. Increased expression of hCLCA1 may, in turn, contribute to mucus overproduction in chronic obstructive pulmonary disease (COPD with a chronic bronchitis (CB phenotype.

  3. Immunogenicity of P/Q-type calcium channel in small cell lung cancer: investigation of alpha1 subunit polyglutamine expansion.

    Science.gov (United States)

    Black, J L; Nelson, T R; Snow, K; Lennon, V A

    1999-12-01

    The ectopic expression of neuronal P/Q-type voltage-gated calcium channels in small cell lung carcinoma (SCLC) is thought to induce antisynaptic autoimmunity in the paraneoplastic Lambert-Eaton myasthenic syndrome. The gene CACNL1A4, encoding the principal (alpha1A) subunit of this calcium channel, is mutated in several inherited neurological disorders. One of these disorders (spinocerebellar ataxia, type 6, or SCA-6) involves the expansion of a trinucleotide (CAG) repeat unit. We hypothesized that a somatic CAG repeat instability of this gene in neoplastic cells might generate a non-self epitope capable of initiating autoimmunity to P/Q-type calcium channels. We therefore analyzed the CACNL1A4 gene in SCLC lines established from metastases derived from seven individual patients (four associated with Lambert-Eaton myasthenic syndrome, one associated with myasthenia gravis, and two not associated with neurological autoimmunity). We compared their CAG repeat numbers (determined by polymerase chain reaction (PCR) amplification followed by separation of products on a 6% polyacrylamide/8M urea gel) to published norms and to DNA from a patient with SCA-6. The number of CAG repeats in SCLC DNA fell within a normal range whether or not the neoplasm was complicated by neurological autoimmunity. Therefore, it is unlikely that somatically unstable CAG repeat units in the gene encoding the P/Q-type voltage-gated calcium channel account for this tumor protein's immunogenicity in the Lambert-Eaton myasthenic syndrome.

  4. Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels

    DEFF Research Database (Denmark)

    Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D;

    2001-01-01

    .2 protein was demonstrated by immunochemical labeling of rat preglomerular vasculature and juxtamedullary efferent arterioles and vasa recta. Cortical efferent arterioles were not immunopositive. Recordings of intracellular calcium concentration with digital fluorescence imaging microscopy showed......The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells...... showed coexpression of mRNAs for T-type subunits (Ca(V)3.1, Ca(V)3.2) and for an L-type subunit (Ca(V)1.2). The same expression pattern was observed in juxtamedullary efferent arterioles and outer medullary vasa recta. No calcium channel messages were detected in cortical efferent arterioles. Ca(V)1...

  5. Beta-blockers

    DEFF Research Database (Denmark)

    Arboe, Bente; Ulrik, Charlotte Suppli

    2013-01-01

    Recently, β-blockers have been suggested as a potential maintenance treatment option for asthma. The aim of this review is to provide an overview of the current knowledge of the potential benefits and risks of β-blocker therapy for asthma.......Recently, β-blockers have been suggested as a potential maintenance treatment option for asthma. The aim of this review is to provide an overview of the current knowledge of the potential benefits and risks of β-blocker therapy for asthma....

  6. Defining the role of calcium channel antagonists in heart failure due to systolic dysfunction.

    Science.gov (United States)

    Mahé, Isabelle; Chassany, Olivier; Grenard, Anne-Sophie; Caulin, Charles; Bergmann, Jean-François

    2003-01-01

    Calcium channel antagonists (CCAs) may either be divided into the dihydropyridines (e.g. amlodipine, felodipine, isradipine, lacidipine, nilvadipine, nifedipine, nicardipine etc.), the phenylalkylamines (e.g. verapamil) and the benzothiazepines (e.g. diltiazem) according to their chemical structure, or into first generation agents (nifedipine, verapamil and diltiazem) and second generation agents (subsequently developed dihydropyridine-derivatives). Second generation CCAs are characterized by greater selectivity for calcium channels in vascular smooth muscle cells than the myocardium, a longer duration of action and a small trough-to-peak variation in plasma concentrations. Heart failure is characterized by decreased cardiac output resulting in inadequate oxygen delivery to peripheral tissues. Although the accompanying neurohormonal activation, leading to vasoconstriction and increased blood pressure, is initially beneficial in increasing tissue perfusion, prolonged activation is detrimental because it increases afterload and further reduces cardiac output. At the level of the myocyte, heart failure is associated with increased intracellular calcium levels which are thought to impair diastolic function. These changes indicate that the CCAs would be beneficial in patients with heart failure. There has been a strong interest and increasing experience in the use of CCAs in patients with heart failure. Despite potential beneficial effects in initial small trials, findings from larger trials suggest that CCA may have detrimental effects upon survival and cardiovascular events. However, this may not necessarily be a 'class b' effect of the CCAs as there is considerable heterogeneity in the chemical structure of individual agents. Clinical experience with different CCAs in patients with heart failure includes trials that evaluated their effects on hemodynamic parameters, exercise tolerance and on symptomatology. However, the most relevant results are those from randomized

  7. Genotypic to expression profiling of bovine calcium channel, voltage-dependent, alpha-2/delta subunit 1 gene, and their association with bovine mastitis among Frieswal (HFX Sahiwal) crossbred cattle of Indian origin.

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    Deb, Rajib; Singh, Umesh; Kumar, Sushil; Kumar, Arun; Singh, Rani; Sengar, Gyanendra; Mann, Sandeep; Sharma, Arjava

    2014-04-01

    Calcium channel, voltage-dependent, alpha-2/delta subunit 1 (CACNA2D1) gene is considered to be an important noncytokine candidate gene influencing mastitis. Scanty of reports are available until today regarding the role play of CACNA2D1 gene on the susceptibility of bovine mastitis. We interrogated the CACNA2D1 G519663A [A>G] SNP by PCR-RFLP among two hundreds Frieswal (HF X Sahiwal) crossbred cattle of Indian origin. Genotypic frequency of AA (51.5, n=101) was comparatively higher than AG (35, n=70) and GG (14.5, n=29). Association of Somatic cell score (SCS) with genotypes revealed that, GG genotypes showing lesser count (less susceptible to mastitis) compare to AA and AG. Relative expression of CACNA2D1 transcript (in milk samples) was significantly higher among GG than AG and AA. Further we have also isolated blood sample from the all groups and PBMCs were cultured from each blood sample as per the standard protocol. They were treated with Calcium channel blocker and the expression level of the CACNA2D1 gene was evaluated by Real Time PCR. Results show that expression level decline in each genotypic group after treatment and expression level of GG are again significantly higher than AA and AG. Thus, it may be concluded that GG genotypic animals are favorable for selecting disease resistant breeds.

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

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    Ting-Ting Hong

    2010-02-01

    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

  9. Calcium-dependent modulation and plasma membrane targeting of the AKT2 potassium channel by the CBL4/ CIPK6 calcium sensor/protein kinase complex

    Institute of Scientific and Technical Information of China (English)

    Katrin Held; Jean-Baptiste Thibaud; J(o)rg Kudla; Francois Pascaud; Christian Eckert; Pawel Gajdanowicz; Kenji Hashimoto; Claire Corratgé-Faillie; Jan Niklas Offenborn; Beno(i)t Lacombe; Ingo Dreyer

    2011-01-01

    Potassium (K+) channel function is fundamental to many physiological processes. However, components and mechanisms regulating the activity of plant K+ channels remain poorly understood. Here, we show that the calcium (Ca2+)sensor CBL4 together with the interacting protein kinase CIPK6 modulates the activity and plasma membrane (PM)targeting of the K+ channel AKT2 from Arabidopsis thaliana by mediating translocation of AKT2 to the PM in plant cells and enhancing AKT2 activity in oocytes. Accordingly, akt2, cbl4 and cipk6 mutants share similar developmental and delayed flowering pheuotypes. Moreover, the isolated regulatory C-terminal domain of CIPK6 is sufficient for mediating CBL4- and Ca2+-dependent channel translocation from the endoplasmic reticulum membrane to the PM by a novel targeting pathway that is dependent on dual lipid modifications of CBL4 by myristoylation and palmitoylation. Thus, we describe a critical mechanism of ion-channel regulation where a Ca2+ sensor modulates K+ channel activity by promoting a kinase interaction-dependent but phosphorylation-independent translocation of the channel to the PM.

  10. Establishing homology between mitochondrial calcium uniporters, prokaryotic magnesium channels and chlamydial IncA proteins.

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    Lee, Andre; Vastermark, Ake; Saier, Milton H

    2014-08-01

    Mitochondrial calcium uniporters (MCUs) (TC no. 1.A.77) are oligomeric channel proteins found in the mitochondrial inner membrane. MCUs have two well-conserved transmembrane segments (TMSs), connected by a linker, similar to bacterial MCU homologues. These proteins and chlamydial IncA proteins (of unknown function; TC no. 9.B.159) are homologous to prokaryotic Mg(2+) transporters, AtpI and AtpZ, based on comparison scores of up to 14.5 sds. A phylogenetic tree containing all of these proteins showed that the AtpZ proteins cluster coherently as a subset within the large and diverse AtpI cluster, which branches separately from the MCUs and IncAs, both of which cluster coherently. The MCUs and AtpZs share the same two TMS topology, but the AtpIs have four TMSs, and IncAs can have either two (most frequent) or four (less frequent) TMSs. Binary alignments, comparison scores and motif analyses showed that TMSs 1 and 2 align with TMSs 3 and 4 of the AtpIs, suggesting that the four TMS AtpI proteins arose via an intragenic duplication event. These findings establish an evolutionary link interconnecting eukaryotic and prokaryotic Ca(2+) and Mg(2+) transporters with chlamydial IncAs, and lead us to suggest that all members of the MCU superfamily, including IncAs, function as divalent cation channels.

  11. BARP suppresses voltage-gated calcium channel activity and Ca2+-evoked exocytosis.

    Science.gov (United States)

    Béguin, Pascal; Nagashima, Kazuaki; Mahalakshmi, Ramasubbu N; Vigot, Réjan; Matsunaga, Atsuko; Miki, Takafumi; Ng, Mei Yong; Ng, Yu Jin Alvin; Lim, Chiaw Hwee; Tay, Hock Soon; Hwang, Le-Ann; Firsov, Dmitri; Tang, Bor Luen; Inagaki, Nobuya; Mori, Yasuo; Seino, Susumu; Launey, Thomas; Hunziker, Walter

    2014-04-28

    Voltage-gated calcium channels (VGCCs) are key regulators of cell signaling and Ca(2+)-dependent release of neurotransmitters and hormones. Understanding the mechanisms that inactivate VGCCs to prevent intracellular Ca(2+) overload and govern their specific subcellular localization is of critical importance. We report the identification and functional characterization of VGCC β-anchoring and -regulatory protein (BARP), a previously uncharacterized integral membrane glycoprotein expressed in neuroendocrine cells and neurons. BARP interacts via two cytosolic domains (I and II) with all Cavβ subunit isoforms, affecting their subcellular localization and suppressing VGCC activity. Domain I interacts at the α1 interaction domain-binding pocket in Cavβ and interferes with the association between Cavβ and Cavα1. In the absence of domain I binding, BARP can form a ternary complex with Cavα1 and Cavβ via domain II. BARP does not affect cell surface expression of Cavα1 but inhibits Ca(2+) channel activity at the plasma membrane, resulting in the inhibition of Ca(2+)-evoked exocytosis. Thus, BARP can modulate the localization of Cavβ and its association with the Cavα1 subunit to negatively regulate VGCC activity.

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

    Science.gov (United States)

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

    1980-01-01

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

  13. RGS12 interacts with the SNARE-binding region of the Cav2.2 calcium channel.

    Science.gov (United States)

    Richman, Ryan W; Strock, Jesse; Hains, Melinda D; Cabanilla, Nory Jun; Lau, King-Kei; Siderovski, David P; Diversé-Pierluissi, María

    2005-01-14

    Activation of GABAB receptors in chick dorsal root ganglion (DRG) neurons inhibits the Cav2.2 calcium channel in both a voltage-dependent and voltage-independent manner. The voltage-independent inhibition requires activation of a tyrosine kinase that phosphorylates the alpha1 subunit of the channel and thereby recruits RGS12, a member of the "regulator of G protein signaling" (RGS) proteins. Here we report that RGS12 binds to the SNARE-binding or "synprint" region (amino acids 726-985) in loop II-III of the calcium channel alpha1 subunit. A recombinant protein encompassing the N-terminal PTB domain of RGS12 binds to the synprint region in protein overlay and surface plasmon resonance binding assays; this interaction is dependent on tyrosine phosphorylation and yet is within a sequence that differs from the canonical NPXY motif targeted by other PTB domains. In electrophysiological experiments, microinjection of DRG neurons with synprint-derived peptides containing the tyrosine residue Tyr-804 altered the rate of desensitization of neurotransmitter-mediated inhibition of the Cav2.2 calcium channel, whereas peptides centered about a second tyrosine residue, Tyr-815, were without effect. RGS12 from a DRG neuron lysate was precipitated using synprint peptides containing phosphorylated Tyr-804. The high degree of conservation of Tyr-804 in the SNARE-binding region of Cav2.1 and Cav2.2 calcium channels suggests that this region, in addition to the binding of SNARE proteins, is also important for determining the time course of the modulation of calcium current via tyrosine phosphorylation.

  14. Expression and cellular localization of the voltage-gated calcium channel α2δ3 in the rodent retina.

    Science.gov (United States)

    Pérez de Sevilla Müller, Luis; Sargoy, Allison; Fernández-Sánchez, Laura; Rodriguez, Allen; Liu, Janelle; Cuenca, Nicolás; Brecha, Nicholas

    2015-07-01

    High-voltage-activated calcium channels are hetero-oligomeric protein complexes that mediate multiple cellular processes, including the influx of extracellular Ca(2+), neurotransmitter release, gene transcription, and synaptic plasticity. These channels consist of a primary α(1) pore-forming subunit, which is associated with an extracellular α(2)δ subunit and an intracellular β auxiliary subunit, which alter the gating properties and trafficking of the calcium channel. The cellular localization of the α(2)δ(3) subunit in the mouse and rat retina is unknown. In this study using RT-PCR, a single band at ∼ 305 bp corresponding to the predicted size of the α(2)δ(3) subunit fragment was found in mouse and rat retina and brain homogenates. Western blotting of rodent retina and brain homogenates showed a single 123-kDa band. Immunohistochemistry with an affinity-purified antibody to the α(2)δ(3) subunit revealed immunoreactive cell bodies in the ganglion cell layer and inner nuclear layer and immunoreactive processes in the inner plexiform layer and the outer plexiform layer. α(2)δ(3) immunoreactivity was localized to multiple cell types, including ganglion, amacrine, and bipolar cells and photoreceptors, but not horizontal cells. The expression of the α(2)δ(3) calcium channel subunit to multiple cell types suggests that this subunit participates widely in Ca-channel-mediated signaling in the retina.

  15. Effects of inorganic lead on voltage-sensitive calcium channels in N1E-115 neuroblastoma cells.

    Science.gov (United States)

    Audesirk, G; Audesirk, T

    1991-01-01

    N1E-115 mouse neuroblastoma cells have been reported to possess two types of voltage-sensitive calcium channels: Low voltage activated, rapidly inactivating T-type (type I) and high voltage activated, slowly inactivating L-type (type II). We studied the effects of acute in vitro exposure to inorganic lead on these calcium channels, using the whole-cell variant of patch clamping. Using salines with a high lead-buffering capacity, we found that both T-type and L-type channels are reversibly inhibited in a dose-dependent manner at free Pb2+ concentrations ranging from 20 nM to 14 microM. L-type channels are somewhat more sensitive to Pb2+ than T-type channels are (L-type: IC50 approx. 0.7 microM; T-type: IC50 approx. 1.3 microM). Both channels show small but significant inhibition (approx. 10%) at 20 nM free Pb2+. Pb2+ affects neither activation nor inactivation of T-type channels, but enhances inactivation of L-type channels at holding potentials around -60 to -40 mV. A peculiar phenomenon was observed in cells exposed to 2.3 microM free Pb2+. T-type channels were inhibited in all 20 cells studied. In 15 cells, L-type channels were also inhibited, but in the remaining 5 cells, current flow through L-type channels was enhanced by Pb2+ exposure.

  16. High affinity complexes of pannexin channels and L-type calcium channel splice-variants in human lung: Possible role in clevidipine-induced dyspnea relief in acute heart failure

    Directory of Open Access Journals (Sweden)

    Gerhard P. Dahl

    2016-08-01

    Research in Context: Clevidipine lowers blood pressure by inhibiting calcium channels in vascular smooth muscle. In patients with acute heart failure, clevidipine was shown to relieve breathing problems. This was only partially related to the blood pressure lowering actions of clevidipine and not conferred by another calcium channel inhibitor. We here found calcium channel variants in human lung that are more selectively inhibited by clevidipine, especially when associated with pannexin channels. This study gives a possible mechanism for clevidipine's relief of breathing problems and supports future clinical trials testing the role of clevidipine in the treatment of acute heart failure.

  17. Water Channels Are Involved in Stomatal Oscillations Encoded by Parameter-Specific Cytosolic Calcium Oscillations

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Earlier studies have shown that various stimuli can induce specific cytosolic calcium ([Ca2+]cyt) oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca2+]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean (Vicia faba L.)was used and a rapid ion-exchange treatment with two shifting buffers differing in K+ and Ca2+ concentrations was applied. The treatment for five transients at a 10-min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation is encoded by parameter-specific [Ca2+]cyt oscillation: the parameters of [Ca2+]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β-mercaptoethanol (an agent capable of reversing water channel inhibition by HgCl2). Other inhibitory treatments against ion transport (i.e. the application of LaCl3, EGTA, or tetraethylammonium chloride (TEACl))weakly impaired stomatal oscillation when the compounds were added after rapid ion-exchange treatment.If these compounds were added before rapid-ion exchange treatment, the inhibitory effect was much more apparent (except in the case of TEACI). The results of the present study suggest that water channels are involved in stomatal oscillation as a downstream element of [Ca2+]cyt oscillation signaling.

  18. Sustained calcium entry through P2X nucleotide receptor channels in human airway epithelial cells.

    Science.gov (United States)

    Zsembery, Akos; Boyce, Amanda T; Liang, Lihua; Peti-Peterdi, János; Bell, P Darwin; Schwiebert, Erik M

    2003-04-11

    Purinergic receptor stimulation has potential therapeutic effects for cystic fibrosis (CF). Thus, we explored roles for P2Y and P2X receptors in stably increasing [Ca(2+)](i) in human CF (IB3-1) and non-CF (16HBE14o(-)) airway epithelial cells. Cytosolic Ca(2+) was measured by fluorospectrometry using the fluorescent dye Fura-2/AM. Expression of P2X receptor (P2XR) subtypes was assessed by immunoblotting and biotinylation. In IB3-1 cells, ATP and other P2Y agonists caused only a transient increase in [Ca(2+)](i) derived from intracellular stores in a Na(+)-rich environment. In contrast, ATP induced an increase in [Ca(2+)](i) that had transient and sustained components in a Na(+)-free medium; the sustained plateau was potentiated by zinc or increasing extracellular pH. Benzoyl-benzoyl-ATP, a P2XR-selective agonist, increased [Ca(2+)](i) only in Na(+)-free medium, suggesting competition between Na(+) and Ca(2+) through P2XRs. Biochemical evidence showed that the P2X(4) receptor is the major subtype shared by these airway epithelial cells. A role for store-operated Ca(2+) channels, voltage-dependent Ca(2+) channels, or Na(+)/Ca(2+) exchanger in the ATP-induced sustained Ca(2+) signal was ruled out. In conclusion, these data show that epithelial P2X(4) receptors serve as ATP-gated calcium entry channels that induce a sustained increase in [Ca(2+)](i). In airway epithelia, a P2XR-mediated Ca(2+) signal may have therapeutic benefit for CF.

  19. Mapping of dihydropyridine binding residues in a less sensitive invertebrate L-type calcium channel (LCa v 1).

    Science.gov (United States)

    Senatore, Adriano; Boone, Adrienne; Lam, Stanley; Dawson, Taylor F; Zhorov, Boris; Spafford, J David

    2011-01-01

    Invertebrate L-type calcium channel, LCa(v) 1, isolated from the pond snail Lymnaea stagnalis is nearly indistinguishable from mammalian Ca(v) 1.2 (α1C) calcium channel in biophysical characteristics observed in vitro. These L-type channels are likely constrained within a narrow range of biophysical parameters to perform similar functions in the snail and mammalian cardiovascular systems. What distinguishes snail and mammalian L-type channels is a difference in dihydropyridine sensitivity: 100 nM isradipine exhibits a significant block of mammalian Ca(v) 1.2 currents without effect on snail LCa(v)1 currents. The native snail channel serves as a valuable surrogate for validating key residue differences identified from previous experimental and molecular modeling work. As predicted, three residue changes in LCa(v)1 (N_3o18, F_3i10, and I_4i12) replaced with DHP-sensing residues in respective positions of Ca(v) 1.2, (Q_3o18, Y_3i10, and M_4i12) raises the potency of isradipine block of LCa(v)1 channels to that of mammalian Ca(v) 1.2. Interestingly, the single N_3o18_Q mutation in LCa(v) 1 channels lowers DHP sensitivity even further and the triple mutation bearing enhanced isradipine sensitivity, still retains a reduced potency of agonist, (S)-Bay K8644.

  20. Sodium-calcium exchanger and R-type Ca(2+) channels mediate spontaneous [Ca(2+)]i oscillations in magnocellular neurones of the rat supraoptic nucleus.

    Science.gov (United States)

    Kortus, Stepan; Srinivasan, Chinnapaiyan; Forostyak, Oksana; Zapotocky, Martin; Ueta, Yoichi; Sykova, Eva; Chvatal, Alexandr; Verkhratsky, Alexei; Dayanithi, Govindan

    2016-06-01

    Isolated supraoptic neurones generate spontaneous [Ca(2+)]i oscillations in isolated conditions. Here we report in depth analysis of the contribution of plasmalemmal ion channels (Ca(2+), Na(+)), Na(+)/Ca(2+) exchanger (NCX), intracellular Ca(2+) release channels (InsP3Rs and RyRs), Ca(2+) storage organelles, plasma membrane Ca(2+) pump and intracellular signal transduction cascades into spontaneous Ca(2+) activity. While removal of extracellular Ca(2+) or incubation with non-specific voltage-gated Ca(2+) channel (VGCC) blocker Cd(2+) suppressed the oscillations, neither Ni(2+) nor TTA-P2, the T-type VGCC blockers, had an effect. Inhibitors of VGCC nicardipine, ω-conotoxin GVIA, ω-conotoxin MVIIC, ω-agatoxin IVA (for L-, N-, P and P/Q-type channels, respectively) did not affect [Ca(2+)]i oscillations. In contrast, a specific R-type VGCC blocker SNX-482 attenuated [Ca(2+)]i oscillations. Incubation with TTX had no effect, whereas removal of the extracellular Na(+) or application of an inhibitor of the reverse operation mode of Na(+)/Ca(2+) exchanger KB-R7943 blocked the oscillations. The mitochondrial uncoupler CCCP irreversibly blocked spontaneous [Ca(2+)]i activity. Exposure of neurones to Ca(2+) mobilisers (thapsigargin, cyclopiazonic acid, caffeine and ryanodine); 4-aminopyridine (A-type K(+) current blocker); phospholipase C and adenylyl cyclase pathways blockers U-73122, Rp-cAMP, SQ-22536 and H-89 had no effect. Oscillations were blocked by GABA, but not by glutamate, apamin or dynorphin. In conclusion, spontaneous oscillations in magnocellular neurones are mediated by a concerted action of R-type Ca(2+) channels and the NCX fluctuating between forward and reverse modes.

  1. A New Baroreceptor Sensitivity-Restoring Ca-Channel Blocker Diminishes Age-Related Morning Blood Pressure Increase in Hypertensive Patients: Open-Label Monitoring of Azelnidipine Treatment for Hypertension in the Early Morning (At-HOME Study

    Directory of Open Access Journals (Sweden)

    Mitsunori Sugiyama

    2010-01-01

    Full Text Available Background: Morning blood pressure (BP surge, which exhibits an age-related increase, is a risk factor for stroke in elderly hypertensive patients, independently of the 24-h BP level. We studied the effect of the new baroreceptor sensitivity (BRS-restoring Ca-channel blocker (CCB azelnidipine (AZ on this age-related morning BP increase. Methods: We conducted a 16-week prospective study to clarify the effect of morning dosing of AZ on home BPs measured in the morning and in the evening in 2,546 hypertensive patients (mean age, 65.1 years; female, 53.6%. Results: At baseline, ME-Dif (morning systolic BP [SBP]–evening SBP increased with age, independently of ME-Ave (average of the morning and evening SBPs. This age-related increase of ME-Dif was exaggerated by regular alcohol drinking and beta-blocker use. After AZ treatment (14.3 ± 3.6 mg/day, ME-AV and ME-Dif were significantly reduced independently of each other, with reductions of –18.1 ± 15.6 and –2.5 ± 13.2 mmHg, respectively (both p < 0.001. AZ treatment decreased age-related increase in ME-Dif particularly in patients who were regular consumers of alcohol and in beta-blocker users. Conclusions: The new BRS-restoring CCB AZ significantly reduced age-related increase in morning BP and had some potential benefit on cardiovascular protection in hypertension, particularly in elderly patients and/or consumers of alcohol.

  2. A cell model study of calcium influx mechanism regulated by calcium-dependent potassium channels in Purkinje cell dendrites.

    Science.gov (United States)