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Le Ribeuz H, Masson B, Dutheil M, Boët A, Beauvais A, Sabourin J, De Montpreville VT, Capuano V, Mercier O, Humbert M, Montani D, Antigny F. Involvement of SUR2/Kir6.1 channel in the physiopathology of pulmonary arterial hypertension. Front Cardiovasc Med 2023; 9:1066047. [PMID: 36704469 PMCID: PMC9871631 DOI: 10.3389/fcvm.2022.1066047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/20/2022] [Indexed: 01/12/2023] Open
Abstract
Aims We hypothesized that the ATP-sensitive K+ channels (KATP) regulatory subunit (ABCC9) contributes to PAH pathogenesis. ABCC9 gene encodes for two regulatory subunits of KATP channels: the SUR2A and SUR2B proteins. In the KATP channel, the SUR2 subunits are associated with the K+ channel Kir6.1. We investigated how the SUR2/Kir6.1 channel contributes to PAH pathogenesis and its potential as a therapeutic target in PAH. Methods and results Using in vitro, ex vivo, and in vivo approaches, we analyzed the localization and expression of SUR2A, SUR2B, and Kir6.1 in the pulmonary vasculature of controls and patients with PAH as in experimental pulmonary hypertension (PH) rat models and its contribution to PAH physiopathology. Finally, we deciphered the consequences of in vivo activation of SUR2/Kir6.1 in the monocrotaline (MCT)-induced PH model. We found that SUR2A, SUR2B, and Kir6.1 were expressed in the lungs of controls and patients with PAH and MCT-induced PH rat models. Organ bath studies showed that SUR2 activation by pinacidil induced relaxation of pulmonary arterial in rats and humans. In vitro experiments on human pulmonary arterial smooth muscle cells and endothelial cells (hPASMCs and hPAECs) in controls and PAH patients showed decreased cell proliferation and migration after SUR2 activation. We demonstrated that SUR2 activation in rat right ventricular (RV) cardiomyocytes reduced RV action potential duration by patch-clamp. Chronic pinacidil administration in control rats increased heart rate without changes in hemodynamic parameters. Finally, in vivo pharmacological activation of SUR2 on MCT and Chronic-hypoxia (CH)-induced-PH rats showed improved PH. Conclusion We showed that SUR2A, SUR2B, and Kir6.1 are presented in hPASMCs and hPAECs of controls and PAH patients. In vivo SUR2 activation reduced the MCT-induced and CH-induced PH phenotype, suggesting that SUR2 activation should be considered for treating PAH.
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Affiliation(s)
- Hélène Le Ribeuz
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France
| | - Bastien Masson
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France
| | - Mary Dutheil
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France,Hôptal Marie Lannelongue, Groupe Hospitalier Paris Saint-Joseph, Le Plessis Robinson, France
| | - Angèle Boët
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France
| | - Antoine Beauvais
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France
| | - Jessica Sabourin
- Inserm, UMR-S 1180, Signalisation et Physiopathologie Cardiovasculaire, Université Paris-Saclay, Orsay, France
| | | | - Véronique Capuano
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France,Hôptal Marie Lannelongue, Groupe Hospitalier Paris Saint-Joseph, Le Plessis Robinson, France
| | - Olaf Mercier
- Service de Chirurgie Thoracique, Vasculaire et Transplantation Cardio-Pulmonaire, Hôpital Marie Lannelongue, Groupe Hospitalier Paris Saint Joseph, Le Plessis Robinson, France
| | - Marc Humbert
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France,Assistance Publique–Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
| | - David Montani
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France,Assistance Publique–Hôpitaux de Paris (AP-HP), Service de Pneumologie et Soins Intensifs Respiratoires, Centre de Référence de l’Hypertension Pulmonaire, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
| | - Fabrice Antigny
- Université Paris-Saclay, Faculté de Médecine, Le Kremlin-Bicêtre, France,INSERM UMR_S 999 « Hypertension Pulmonaire Physiopathologie et Innovation Thérapeutique », Hôpital Marie Lannelongue, Le Plessis-Robinson, France,*Correspondence: Fabrice Antigny,
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Wang H, Wang C, Lu Y, Yan Y, Leng D, Tian S, Zheng D, Wang Z, Bai Y. Metformin Shortens Prolonged QT Interval in Diabetic Mice by Inhibiting L-Type Calcium Current: A Possible Therapeutic Approach. Front Pharmacol 2020; 11:614. [PMID: 32595491 PMCID: PMC7300225 DOI: 10.3389/fphar.2020.00614] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/20/2020] [Indexed: 12/11/2022] Open
Abstract
The incidence and mortality of cardiovascular disease in diabetic patients are 2-3 times higher than those in non-diabetic patients. Abnormal function of the L-type calcium channel in myocardial tissue might result in multiple cardiac disorders such as a prolonged QT interval. Therefore, QT prolongation is an independent risk factor of cardiovascular disease in patients with diabetes mellitus. Metformin, a hypoglycemic agent, is widely known to effectively reduce the occurrence of macrovascular diseases. The aim of the present study was to evaluate the effect of metformin on prolonged QT interval and to explore potential ionic mechanisms induced by diabetes. Diabetic mouse models were established with streptozotocin and an electrocardiogram was used to monitor the QT interval after 4 weeks of metformin treatment in each group. Action potential duration (APD) and L-type calcium current (ICa-L) were detected by patch-clamp in isolated mice ventricular cardiomyocytes and neonatal cardiomyocytes of mice. The expression levels of CACNA1C mRNA and Cav1.2 were measured by real-time PCR, western blot and immunofluorescence. A shortened QT interval was observed after 4 weeks of metformin treatment in diabetic mice. Patch-clamp results revealed that both APD and ICa-L were shortened in mouse cardiomyocytes. Furthermore, the expression levels of CACNA1C mRNA and Cav1.2 were decreased in the metformin group. The same results were also obtained in cultured neonatal mice cardiomyocytes. Overall, these results verify that metformin could shorten a prolonged QT interval by inhibiting the calcium current, suggesting that metformin may play a role in the electrophysiology underlying diabetic cardiopathy.
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Affiliation(s)
- Hui Wang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Cao Wang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Yuan Lu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Yan Yan
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Dongjing Leng
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Shanshan Tian
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Dongjie Zheng
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Zhiguo Wang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Yunlong Bai
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, China.,Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
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Arrhythmogenic drugs can amplify spatial heterogeneities in the electrical restitution in perfused guinea-pig heart: An evidence from assessments of monophasic action potential durations and JT intervals. PLoS One 2018; 13:e0191514. [PMID: 29352276 PMCID: PMC5774816 DOI: 10.1371/journal.pone.0191514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/06/2018] [Indexed: 01/01/2023] Open
Abstract
Non-uniform shortening of the action potential duration (APD90) in different myocardial regions upon heart rate acceleration can set abnormal repolarization gradients and promote arrhythmia. This study examined whether spatial heterogeneities in APD90 restitution can be amplified by drugs with clinically proved proarrhythmic potential (dofetilide, quinidine, procainamide, and flecainide) and, if so, whether these effects can translate to the appropriate changes of the ECG metrics of ventricular repolarization, such as JT intervals. In isolated, perfused guinea-pig heart preparations, monophasic action potentials and volume-conducted ECG were recorded at progressively increased pacing rates. The APD90 measured at distinct ventricular sites, as well as the JTpeak and JTend values were plotted as a function of preceding diastolic interval, and the maximum slopes of the restitution curves were determined at baseline and upon drug administration. Dofetilide, quinidine, and procainamide reverse rate-dependently prolonged APD90 and steepened the restitution curve, with effects being greater at the endocardium than epicardium, and in the right ventricular (RV) vs. the left ventricular (LV) chamber. The restitution slope was increased to a greater extent for the JTend vs. the JTpeak interval. In contrast, flecainide reduced the APD90 restitution slope at LV epicardium without producing effect at LV endocardium and RV epicardium, and reduced the JTpeak restitution slope without changing the JTend restitution. Nevertheless, with all agents, these effects translated to the amplified epicardial-to-endocardial and the LV-to-RV non-uniformities in APD90 restitution, paralleled by the increased JTend vs. JTpeak difference in the restitution slope. In summary, these findings suggest that arrhythmic drug profiles are partly attributable to the accentuated regional heterogeneities in APD90 restitution, which can be indirectly determined through ECG assessments of the JTend vs. JTpeak dynamics at variable pacing rates.
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Houshmand F, Faghihi M, Imani A, Kheiri S. Effect of different doses of oxytocin on cardiac electrophysiology and arrhythmias induced by ischemia. J Adv Pharm Technol Res 2017; 8:131-137. [PMID: 29184844 PMCID: PMC5680620 DOI: 10.4103/japtr.japtr_178_16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The onset of acute myocardial ischemia (MI) is accompanied by a rapid increase in electrical instability and often fatal ventricular arrhythmias. This study investigated that whether oxytocin (OT) can modulate ischemia-induced arrhythmias and considered relationships between the severity of arrhythmia and the electrocardiogram parameters during ischemia. OT (0.0001–1 μg) was administrated intraperitoneally 30 min before ischemia. To examine receptor involved, a selective OT-receptor antagonist, atosiban (ATO), was infused 10 min before OT. OT caused a significant and biphasic dose-dependent reduction in ectopic heart activity and arrhythmia score. OT doses that reduced ventricular arrhythmia elicited significant increase in QT interval. OT attenuated the electrophysiological changes associated with MI and there was significant direct relationship between QRS duration and arrhythmia score. ATO treatment reduced beneficial effects of OT on arrhythmogenesis. Nevertheless, ATO failed to alter OT effects on premature ventricular contractions. We assume that the ability of OT to modulate the electrical activity of the heart may play an important role in the antiarrhythmic actions of OT.
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Affiliation(s)
- Fariba Houshmand
- Department of Physiology, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, I.R.Iran
| | - Mahdieh Faghihi
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R.Iran
| | - Alireza Imani
- Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, I.R.Iran
| | - Soleiman Kheiri
- Department of Epidemiology and Biostatistic, Shahrekord University of Medical Sciences, Shahrekord, I.R.Iran
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Malik M. Drug-Induced QT/QTc Interval Shortening: Lessons from Drug-Induced QT/QTc Prolongation. Drug Saf 2016; 39:647-59. [DOI: 10.1007/s40264-016-0411-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Jin Q, Zhang N, Zhou J, Lin CJ, Pang Y, Gu G, Shen WF, Wu LQ. The effect of pinacidil on postshock activation and ventricular defibrillation threshold in canine hearts. Acta Pharmacol Sin 2012; 33:1488-94. [PMID: 23064720 DOI: 10.1038/aps.2012.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To determine the postshock activation patterns with both successful and failed shocks in a canine model of ventricular fibrillation, and whether piniacidil, an early after-depolarization (EAD) inhibitor, altered the defibrillation threshold (DFT) and postshock activation patterns. METHODS In 6 beagles, a basket catheter with 64 unipolar electrodes was placed in the LV for global endocardial mapping, a monophasic action potential catheter was inserted into the LV apex, and a catheter with the negative electrode in the right ventricle and the positive electrode in the superior vena cava was inserted for defibrillation. The DFT, 90% action potential duration (APD(90)) and activation recovery interval (ARI) were evaluated before and after pinacidil administration (loading dosage 0.5 mg/kg and maintenance dosage 0.5 mg·kg(-1)·h(-1), iv). Electrical heterogeneities were defined with the dispersion of ARI. After successful and failed shocks with near-DFT strength, the earliest postshock activation patterns (focal or nonfocal endocardial activation), interval and location were detected. RESULTS Pinacidil significantly decreased APD(90) (from 178±16 ms to 168±18 ms) and ARI from (152±10 ms to 143±10 ms) at pacing cycle length of 300 ms. The drug significantly increased VF activation rate (from 10.0±1.9 Hz to 10.8±2.0 Hz). The drug did not affect the dispersion of ARI, neither it changed DFT (baseline: 480±110 V; pinacidil: 425±55 V, P>0.05). The earliest postshock activation arose locally on the LV apical endocardium before and after the drug treatment. Pinacidil significantly prolonged the postshock cycle length of cycles 2 to 5 for the successful episodes but not for the failed episodes. CONCLUSION Pinacidil increases the postshock cycle length suggesting that EAD may play a role in postshock activation, while it fails to alter DFT suggesting that EAD produced by shock does not determine a defibrillation success or failure.
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Tang L, Joung B, Ogawa M, Chen PS, Lin SF. Intracellular calcium dynamics, shortened action potential duration, and late-phase 3 early afterdepolarization in Langendorff-perfused rabbit ventricles. J Cardiovasc Electrophysiol 2012; 23:1364-71. [PMID: 22809087 DOI: 10.1111/j.1540-8167.2012.02400.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION To elucidate the mechanism of late-phase 3 early after depolarization (EAD) in ventricular arrhythmogenesis, we hypothesized that intracellular calcium (Ca(i) ) overloading and action potential duration (APD) shortening may promote late-phase 3 EAD and triggered activity, leading to development of ventricular fibrillation (VF). METHODS AND RESULTS In isolated rabbit hearts, we performed microelectrode recording and simultaneous dual optical mapping of transmembrane potential (V(m) ) and Ca(i) transient on left ventricular endocardium. An I(KATP) channel opener, pinacidil, was used to abbreviate APD. Rapid pacing was then performed. Upon abrupt cessation of rapid pacing with cycle lengths of 60-200 milliseconds, there were APD(90) prolongation and the corresponding Ca(i) overloading in the first postpacing beats. The duration of Ca(i) transient recovered to 50% (DCaT(50) ) and 90% (DCaT(90) ) in the first postpacing beats was significantly longer than baseline. Abnormal Ca(i) elevation coupled with shortened APD produced late-phase 3 EAD induced triggered activity and VF. In additional 6 preparations, the heart tissues were treated with BAPTA-AM, a calcium chelator. BAPTA-AM significantly reduced the maximal Ca(i) amplitude (26.4 ± 3.5% of the control; P < 0.001) and the duration of Ca(i) transients in the mapped region, preventing the development of EAD and triggered activity that initiated VF. CONCLUSIONS I (KATP) channel activation along with Ca(i) overloading are associated with the development of late-phase 3 EAD and VF. Because acute myocardial ischemia activates the I(KATP) channel, late-phase 3 EADs may be a mechanism for VF initiation during acute myocardial ischemia.
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Affiliation(s)
- Liang Tang
- Department of Biomedical Engineering, University of Texas at San Antonio, TX, USA
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To establish a pharmacological experimental platform for the study of cardiac hypoxia using the microelectrode array. J Pharmacol Toxicol Methods 2009; 59:146-52. [DOI: 10.1016/j.vascn.2009.02.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 02/17/2009] [Indexed: 11/19/2022]
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Postema PG, Ritsema van Eck HJ, Opthof T, van Herpen G, van Dessel PFHM, Priori SG, Wolpert C, Borggrefe M, Kors JA, Wilde AAM. IK1 modulates the U-wave: insights in a 100-year-old enigma. Heart Rhythm 2008; 6:393-400. [PMID: 19251218 DOI: 10.1016/j.hrthm.2008.11.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 11/22/2008] [Indexed: 11/16/2022]
Affiliation(s)
- Pieter G Postema
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Schimpf R, Antzelevitch C, Haghi D, Giustetto C, Pizzuti A, Gaita F, Veltmann C, Wolpert C, Borggrefe M. To the Editor Response. Heart Rhythm 2008. [DOI: 10.1016/j.hrthm.2008.05.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Letters to the Editor. Heart Rhythm 2008; 5:1091; author reply 1091-2. [DOI: 10.1016/j.hrthm.2008.05.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Indexed: 11/22/2022]
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Milberg P, Tegelkamp R, Osada N, Schimpf R, Wolpert C, Breithardt G, Borggrefe M, Eckardt L. Reduction of Dispersion of Repolarization and Prolongation of Postrepolarization Refractoriness Explain the Antiarrhythmic Effects of Quinidine in a Model of Short QT Syndrome. J Cardiovasc Electrophysiol 2007; 18:658-64. [PMID: 17521304 DOI: 10.1111/j.1540-8167.2007.00813.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Short QT syndrome (SQTS) is a newly described ion channelopathy, characterized by a short QT interval resulting from an accelerated cardiac repolarization, associated with syncope, atrial fibrillation, and sudden cardiac death due to ventricular fibrillation. As therapeutic options in SQTS are still controversial, we examined antiarrhythmic mechanisms in an experimental model of SQTS. METHODS AND RESULTS Pinacidil, an I(K-ATP) channel opener, was administered in increasing concentrations (50-100 microM) in 48 Langendorff-perfused rabbit hearts and led to a significant reduction of action potential duration and QT interval, thereby mimicking SQTS. Eight simultaneously recorded monophasic action potentials demonstrated an increase in dispersion of repolarization, especially between the left and the right ventricle. During programmed ventricular stimulation with up to two extrastimuli, pinacidil significantly increased the inducibility of ventricular fibrillation (1 heart under baseline conditions, 29 hearts during pinacidil administration; P = 0.0001). Additional treatment with the I(Kr) blocker sotalol (100 microM) and the class I antiarrhythmic drugs flecainide (2 microM) and quinidine (0.5 microM) randomly assigned to three groups of 16 hearts led to prolongation of repolarization as well as refractory period. Sotalol or flecainide did not reduce the rate of inducibility of ventricular fibrillation significantly (P = 0.63; P = 0.219). However, quinidine reduced the inducibility of ventricular fibrillation by 73% (P = 0.008). The antiarrhythmic potential of quinidine was associated with a significantly greater prolongation of MAP duration, refractoriness, and postrepolarization refractoriness (PRR) as compared with sotalol and flecainide. Moreover, quinidine, in contrast to sotalol and flecainide, reduced dispersion of repolarization. CONCLUSION Pinacidil mimics SQTS via increasing potassium outward currents, thereby facilitating inducibility of ventricular fibrillation. Quinidine demonstrates superior antiarrhythmic properties in the treatment of ventricular fibrillation in this model as compared with sotalol and flecainide because of its effects on refractoriness, PRR, and by reducing dispersion of repolarization.
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Affiliation(s)
- Peter Milberg
- Department of Cardiology and Angiology, Hospital of the Westfälische Wilhelms-University, Münster, Germany.
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Wu SN, Chang HD, Sung RJ. Cocaine-induced inhibition of ATP-sensitive K+ channels in rat ventricular myocytes and in heart-derived H9c2 cells. Basic Clin Pharmacol Toxicol 2006; 98:510-7. [PMID: 16635111 DOI: 10.1111/j.1742-7843.2006.pto_354.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Cocaine use may cause coronary artery spasm and acute myocardial ischaemia/infarction. However, its effects on ATP-sensitive K+ (KATP) channel, an ion channel responsible for ischaemic preconditioning, remain unknown. In isolated rat ventricular myocytes with whole-cell experiments, cocaine can reverse action potential shortening and increased K+ current caused by the openers of ATP-sensitive K+ (KATP) channels. In inside-out patches, cocaine applied to intracellular surface suppressed KATP-channel activity in a concentration-dependent manner with an IC50 value of 9.2 microM; however, it did not modify the single-channel conductance of this channel. The change in the kinetic behaviour of KATP channels caused by cocaine is primarily the result of an increase in mean closed time and a decrease in mean open time. Cocaine-induced inhibition of KATP channels is independent of change in intracellular ATP concentrations. In heart-derived H9c2 cells, cocaine is also capable of suppressing KATP-channel activity. The present study provides evidence that cocaine can produce a depressant action on KATP channels in cardiac myocytes, and thus disturb ischaemic preconditioning in clinical settings.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Hospital, Tainan, Taiwan
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