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Naveed M, Mohammed ASA, Topal L, Kovács ZM, Dienes C, Ovári J, Szentandrássy N, Magyar J, Bányász T, Prorok J, Jost N, Virág L, Baczkó I, Varró A, Nánási PP, Horváth B. Selective Inhibition of Cardiac Late Na + Current Is Based on Fast Offset Kinetics of the Inhibitor. Biomedicines 2023; 11:2383. [PMID: 37760824 PMCID: PMC10525890 DOI: 10.3390/biomedicines11092383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/11/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023] Open
Abstract
The present study was designed to test the hypothesis that the selectivity of blocking the late Na+ current (INaL) over the peak Na+ current (INaP) is related to the fast offset kinetics of the Na+ channel inhibitor. Therefore, the effects of 1 µM GS967 (INaL inhibitor), 20 µM mexiletine (I/B antiarrhythmic) and 10 µM quinidine (I/A antiarrhythmic) on INaL and INaP were compared in canine ventricular myocardium. INaP was estimated as the maximum velocity of action potential upstroke (V+max). Equal amounts of INaL were dissected by the applied drug concentrations under APVC conditions. The inhibition of INaL by mexiletine and quinidine was comparable under a conventional voltage clamp, while both were smaller than the inhibitory effect of GS967. Under steady-state conditions, the V+max block at the physiological cycle length of 700 ms was 2.3% for GS967, 11.4% for mexiletine and 26.2% for quinidine. The respective offset time constants were 110 ± 6 ms, 456 ± 284 ms and 7.2 ± 0.9 s. These results reveal an inverse relationship between the offset time constant and the selectivity of INaL over INaP inhibition without any influence of the onset rate constant. It is concluded that the selective inhibition of INaL over INaP is related to the fast offset kinetics of the Na+ channel inhibitor.
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Affiliation(s)
- Muhammad Naveed
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
| | - Aiman Saleh A. Mohammed
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
| | - Leila Topal
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
| | - Zsigmond Máté Kovács
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
| | - Csaba Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
| | - József Ovári
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
| | - Norbert Szentandrássy
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, H-6720 Debrecen, Hungary
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
- Division of Sport Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
| | - János Prorok
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Loránd Eötvös Research Network, 1097 Szeged, Hungary;
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Loránd Eötvös Research Network, 1097 Szeged, Hungary;
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, H-6720 Szeged, Hungary; (M.N.); (A.S.A.M.); (L.T.); (N.J.); (L.V.); (I.B.); (A.V.)
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Loránd Eötvös Research Network, 1097 Szeged, Hungary;
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
- Division of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, H-6720 Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-6720 Debrecen, Hungary; (Z.M.K.); (C.D.); (J.O.); (N.S.); (J.M.); (T.B.); (B.H.)
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Cheng H, Charles I, James AF, Abdala AP, Hancox JC. QT c interval and ventricular action potential prolongation in the Mecp2 Null/+ murine model of Rett syndrome. Physiol Rep 2022; 10:e15437. [PMID: 36200140 PMCID: PMC9535259 DOI: 10.14814/phy2.15437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/27/2022] [Accepted: 08/06/2022] [Indexed: 06/16/2023] Open
Abstract
Rett Syndrome (RTT) is a congenital, X-chromosome-linked developmental disorder characterized by developmental delay, dysautonomia, and breathing irregularities. RTT is also associated with sudden death and QT intervals are prolonged in some RTT patients. Most individuals with RTT have mutations in the MECP2 gene. Whilst there is some evidence for QT prolongation in mouse models of RTT, there is comparatively little information on how loss of Mecp2 function affects ventricular action potentials (APs) and, to-date, none on ventricular APs from female RTT mice. Accordingly, the present study was conducted to determine ECG and ventricular AP characteristics of Mecp2Null/+ female mice. ECG recordings from 12-13 month old female Mecp2Null/+ mice showed prolonged rate corrected QT (QTc) intervals compared to wild-type (WT) controls. Although Mecp2Null/+ animals exhibited longer periods of apnoea than did controls, no correlation between apnoea length and QTc interval was observed. Action potentials (APs) from Mecp2Null/+ myocytes had longer APD90 values than those from WT myocytes and showed augmented triangulation. Application of the investigational INa,Late inhibitor GS-6615 (eleclazine; 10 μM) reduced both APD90 and AP triangulation in Mecp2Null/+ and WT myocytes. These results constitute the first direct demonstration of delayed repolarization in Mecp2Null/+ myocytes and provide further evidence that GS-6615 may have potential as an intervention against QT prolongation in RTT.
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Affiliation(s)
- Hongwei Cheng
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Ian Charles
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Andrew F. James
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Ana P. Abdala
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Jules C. Hancox
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
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Topal L, Polyák A, Tóth N, Ágoston G, Bencsik P, Kohajda Z, Prorok J, Déri S, Nagy N, Jost N, Virág L, Farkas AS, Varró A, Baczkó I. Endurance training-induced cardiac remodeling in a guinea pig athlete's heart model. Can J Physiol Pharmacol 2022; 100:993-1004. [PMID: 35834825 DOI: 10.1139/cjpp-2022-0073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Besides the health benefits of regular exercise, high-level training-above an optimal level-may have adverse effects. In this study, we investigated the effects of long-term vigorous training and its potentially detrimental structural-functional changes in a small animal athlete's heart model. Thirty-eight 4-month-old male guinea pigs were randomized into sedentary and exercised groups. The latter underwent a 15-week-long endurance-training program. To investigate the effects of the intense long-term exercise, in vivo (echocardiography, electrocardiography), ex vivo, and in vitro (histopathology, patch-clamp) measurements were performed. Following the training protocol, the exercised animals exhibited structural left ventricular enlargement and a significantly higher degree of myocardial fibrosis. Furthermore, resting bradycardia accompanied by elevated heart rate variability occurred, representing increased parasympathetic activity in the exercised hearts. The observed prolonged QTc intervals and increased repolarization variability parameters may raise the risk of electrical instability in exercised animals. Complex arrhythmias did not occur in either group, and there were no differences between the groups in ex vivo or cellular electrophysiological experiments. Accordingly, the high parasympathetic activity may promote impaired repolarization in conscious exercised animals. The detected structural-functional changes share similarities with the human athlete's heart; therefore, this model might be useful for investigations on cardiac remodeling.
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Affiliation(s)
- L Topal
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
| | - A Polyák
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- Department of Pediatrics and Pediatric Health Center, University of Szeged, Szeged, 6725, Hungary
| | - N Tóth
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
| | - G Ágoston
- Institute of Family Medicine, University of Szeged, Szeged, 6720, Hungary
| | - P Bencsik
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
| | - Zs Kohajda
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - J Prorok
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Sz Déri
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
| | - N Nagy
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - N Jost
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, 6720, Hungary
| | - L Virág
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, 6720, Hungary
| | - A S Farkas
- Department of Internal Medicine, Cardiology, University of Szeged, Szeged, 6725, Hungary
| | - A Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, 6720, Hungary
| | - I Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, 6720, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, 6720, Hungary
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Shen H, Dong SY, Ren MS, Wang R. Ventricular arrhythmia and sudden cardiac death in hypertrophic cardiomyopathy: From bench to bedside. Front Cardiovasc Med 2022; 9:949294. [PMID: 36061538 PMCID: PMC9433716 DOI: 10.3389/fcvm.2022.949294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/14/2022] [Indexed: 11/13/2022] Open
Abstract
Patients with hypertrophic cardiomyopathy (HCM) mostly experience minimal symptoms throughout their lifetime, and some individuals have an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). How to identify patients with a higher risk of ventricular arrythmias and SCD is the priority in HCM research. The American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) both recommend the use of risk algorithms to identify patients at high risk of ventricular arrhythmias, to be selected for implantation of implantable cardioverters/defibrillators (ICDs) for primary prevention of SCD, although major discrepancies exist. The present SCD risk scoring systems cannot accurately identify early-stage HCM patients with modest structural remodeling and mild disease manifestations. Unfortunately, SCD events could occur in young asymptomatic HCM patients and even as initial symptoms, prompting the determination of new risk factors for SCD. This review summarizes the studies based on patients' surgical specimens, transgenic animals, and patient-derived induced pluripotent stem cells (hiPSCs) to explore the possible molecular mechanism of ventricular arrhythmia and SCD. Ion channel remodeling, Ca2+ homeostasis abnormalities, and increased myofilament Ca2+ sensitivity may contribute to changes in action potential duration (APD), reentry circuit formation, and trigger activities, such as early aferdepolarization (EAD) or delayed afterdepolarization (DAD), leading to ventricular arrhythmia in HCM. Besides the ICD implantation, novel drugs represented by the late sodium current channel inhibitor and myosin inhibitor also shed light on the prevention of HCM-related arrhythmias. The ideal prevention strategy of SCD in early-stage HCM patients needs to be combined with gene screening, hiPSC-CM testing, machine learning, and advanced ECG studies, thus achieving individualized SCD prevention.
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Affiliation(s)
- Hua Shen
- Division of Adult Cardiac Surgery, Department of Cardiovascular Medicine, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Shi-Yong Dong
- Department of Cardiovascular Surgery, The First Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Ming-Shi Ren
- Division of Adult Cardiac Surgery, Department of Cardiovascular Medicine, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
- Graduate School, Chinese PLA General Hospital & Chinese PLA Medical School, Beijing, China
| | - Rong Wang
- Division of Adult Cardiac Surgery, Department of Cardiovascular Medicine, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
- Department of Cardiovascular Surgery, The First Medical Center, Chinese PLA General Hospital, Beijing, China
- *Correspondence: Rong Wang
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Horváth B, Szentandrássy N, Dienes C, Kovács ZM, Nánási PP, Chen-Izu Y, Izu LT, Banyasz T. Exploring the Coordination of Cardiac Ion Channels With Action Potential Clamp Technique. Front Physiol 2022; 13:864002. [PMID: 35370800 PMCID: PMC8966222 DOI: 10.3389/fphys.2022.864002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
The patch clamp technique underwent continual advancement and developed numerous variants in cardiac electrophysiology since its introduction in the late 1970s. In the beginning, the capability of the technique was limited to recording one single current from one cell stimulated with a rectangular command pulse. Since that time, the technique has been extended to record multiple currents under various command pulses including action potential. The current review summarizes the development of the patch clamp technique in cardiac electrophysiology with special focus on the potential applications in integrative physiology.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Norbert Szentandrássy
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Csaba Dienes
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | | | - Péter P. Nánási
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Leighton T. Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- *Correspondence: Tamas Banyasz,
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Horváth B, Kiss D, Dienes C, Hézső T, Kovács Z, Szentandrássy N, Almássy J, Magyar J, Bányász T, Nánási PP. Ion current profiles in canine ventricular myocytes obtained by the "onion peeling" technique. J Mol Cell Cardiol 2021; 158:153-62. [PMID: 34089737 DOI: 10.1016/j.yjmcc.2021.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/05/2021] [Accepted: 05/21/2021] [Indexed: 02/07/2023]
Abstract
The profiles of ion currents during the cardiac action potential can be visualized by the action potential voltage clamp technique. To obtain multiple ion current data from the same cell, the "onion peeling" technique, based on sequential pharmacological dissection of ion currents, has to be applied. Combination of the two methods allows recording of several ion current profiles from the same myocyte under largely physiological conditions. Using this approach, we have studied the densities and integrals of the major cardiac inward (ICa, INCX, INa-late) and outward (IKr, IKs, IK1) currents in canine ventricular cells and studied the correlation between them. For this purpose, canine ventricular cardiomyocytes were chosen because their electrophysiological properties are similar to those of human ones. Significant positive correlation was observed between the density and integral of ICa and IKr, and positive correlation was found also between the integral of ICa and INCX. No further correlations were detected. The Ca2+-sensitivity of K+ currents was studied by comparing their parameters in the case of normal calcium homeostasis and following blockade of ICa. Out of the three K+ currents studied, only IKs was Ca2+-sensitive. The density and integral of IKs was significantly greater, while its time-to-peak value was shorter at normal Ca2+ cycling than following ICa blockade. No differences were detected for IKr or IK1 in this regard. Present results indicate that the positive correlation between ICa and IKr prominently contribute to the balance between inward and outward fluxes during the action potential plateau in canine myocytes. The results also suggest that the profiles of cardiac ion currents have to be studied under physiological conditions, since their behavior may strongly be influenced by the intracellular Ca2+ homeostasis and the applied membrane potential protocol.
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