1
|
Yang C, Li Q, Hu F, Liu Y, Wang K. Inhibition of Cardiac Kv4.3/KChIP2 Channels by Sulfonylurea Drug Gliquidone. Mol Pharmacol 2024; 105:224-232. [PMID: 38164605 DOI: 10.1124/molpharm.123.000787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 11/09/2023] [Accepted: 12/04/2023] [Indexed: 01/03/2024] Open
Abstract
The Kv4.3 channel features fast N-type inactivation and also undergoes a slow C-type inactivation. The gain-of-function mutations of Kv4.3 channels cause an inherited disease called Brugada syndrome (BrS), characterized by a shortened duration of cardiac action potential repolarization and ventricular arrhythmia. The sulfonylurea drug gliquidone, an ATP-dependent K+ channel antagonist, is widely used for the treatment of type 2 diabetes. Here, we report a novel role of gliquidone in inhibiting Kv4.3 and Kv4.3/KChIP2 channels that encode the cardiac transient outward K+ currents responsible for the initial phase of action potential repolarization. Gliquidone results in concentration-dependent inhibition of both Kv4.3 and Kv4.3/KChIP2 fast or steady-state inactivation currents with an IC50 of approximately 8 μM. Gliquidone also accelerates Kv4.3 channel inactivation and shifts the steady-state activation to a more depolarizing direction. Site-directed mutagenesis and molecular docking reveal that the residues S301 in the S4 and Y312A and L321A in the S4-S5 linker are critical for gliquidone-mediated inhibition of Kv4.3 currents, as mutating those residues to alanine significantly reduces the potency for gliquidone-mediated inhibition. Furthermore, gliquidone also inhibits a gain-of-function Kv4.3 V392I mutant identified in BrS patients in voltage- and concentration-dependent manner. Taken together, our findings demonstrate that gliquidone inhibits Kv4.3 channels by acting on the residues in the S4 and the S4-S5 linker. Therefore, gliquidone may hold repurposing potential for the therapy of Brugada syndrome. SIGNIFICANCE STATEMENT: We describe a novel role of gliquidone in inhibiting cardiac Kv4.3 currents and the channel gain-of-function mutation identified from patients with Brugada syndrome, suggesting its repurposing potential for therapy for the heart disease.
Collapse
Affiliation(s)
- Chenxia Yang
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (C.Y., Q.L., F.H., Y.L., K.W.) and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Qinqin Li
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (C.Y., Q.L., F.H., Y.L., K.W.) and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Fang Hu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (C.Y., Q.L., F.H., Y.L., K.W.) and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (C.Y., Q.L., F.H., Y.L., K.W.) and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (C.Y., Q.L., F.H., Y.L., K.W.) and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| |
Collapse
|
2
|
Abstract
The physiological heart function is controlled by a well-orchestrated interplay of different ion channels conducting Na+, Ca2+ and K+. Cardiac K+ channels are key players of cardiac repolarization counteracting depolarizating Na+ and Ca2+ currents. In contrast to Na+ and Ca2+, K+ is conducted by many different channels that differ in activation/deactivation kinetics as well as in their contribution to different phases of the action potential. Together with modulatory subunits these K+ channel α-subunits provide a wide range of repolarizing currents with specific characteristics. Moreover, due to expression differences, K+ channels strongly influence the time course of the action potentials in different heart regions. On the other hand, the variety of different K+ channels increase the number of possible disease-causing mutations. Up to now, a plethora of gain- as well as loss-of-function mutations in K+ channel forming or modulating proteins are known that cause severe congenital cardiac diseases like the long-QT-syndrome, the short-QT-syndrome, the Brugada syndrome and/or different types of atrial tachyarrhythmias. In this chapter we provide a comprehensive overview of different K+ channels in cardiac physiology and pathophysiology.
Collapse
|
3
|
Inter-Regulation of K v4.3 and Voltage-Gated Sodium Channels Underlies Predisposition to Cardiac and Neuronal Channelopathies. Int J Mol Sci 2020; 21:ijms21145057. [PMID: 32709127 PMCID: PMC7404392 DOI: 10.3390/ijms21145057] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/04/2020] [Accepted: 07/10/2020] [Indexed: 12/13/2022] Open
Abstract
Background: Genetic variants in voltage-gated sodium channels (Nav) encoded by SCNXA genes, responsible for INa, and Kv4.3 channels encoded by KCND3, responsible for the transient outward current (Ito), contribute to the manifestation of both Brugada syndrome (BrS) and spinocerebellar ataxia (SCA19/22). We examined the hypothesis that Kv4.3 and Nav variants regulate each other’s function, thus modulating INa/Ito balance in cardiomyocytes and INa/I(A) balance in neurons. Methods: Bicistronic and other constructs were used to express WT or variant Nav1.5 and Kv4.3 channels in HEK293 cells. INa and Ito were recorded. Results: SCN5A variants associated with BrS reduced INa, but increased Ito. Moreover, BrS and SCA19/22 KCND3 variants associated with a gain of function of Ito, significantly reduced INa, whereas the SCA19/22 KCND3 variants associated with a loss of function (LOF) of Ito significantly increased INa. Auxiliary subunits Navβ1, MiRP3 and KChIP2 also modulated INa/Ito balance. Co-immunoprecipitation and Duolink studies suggested that the two channels interact within the intracellular compartments and biotinylation showed that LOF SCN5A variants can increase Kv4.3 cell-surface expression. Conclusion: Nav and Kv4.3 channels modulate each other’s function via trafficking and gating mechanisms, which have important implications for improved understanding of these allelic cardiac and neuronal syndromes.
Collapse
|
4
|
Wang J, Wen Y, Zhang Q, Yu S, Chen Y, Wu X, Zhang Y, Bao X. Gene mutational analysis in a cohort of Chinese children with unexplained epilepsy: Identification of a new KCND3 phenotype and novel genes causing Dravet syndrome. Seizure 2019; 66:26-30. [PMID: 30776697 DOI: 10.1016/j.seizure.2019.01.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 01/24/2019] [Accepted: 01/26/2019] [Indexed: 01/10/2023] Open
Abstract
PURPOSE This study aimed to investigate the genetic etiology of epilepsy in a cohort of Chinese children. METHODS Targeted next-generation sequencing (NGS) was performed for 120 patients with unexplained epilepsy, including 71 patients with early-onset epileptic encephalopathies, and 16 patients with Dravet syndrome (including three patients with a Dravet-like phenotype) but without SCN1A pathogenic variants. RESULTS Pathogenic variants of 14 genes were discovered in 22 patients (18%). A de novo KCND3 pathogenic variant (c.1174G > A, p.Val392Ile) was identified in a boy with refractory epilepsy, psychomotor regression, attention deficit, and visual decline. Pathogenic variants in other coding genes were excluded via whole exome sequencing. This KCND3 variant was previously confirmed to be pathogenic by Giudicessi, et al. However, the clinical profile was different: sudden death at 20 years old without any medical history of neurological disorders, nor with any diseases typically caused by KCND3 pathogenic variants such as Brugada syndrome, spinocerebellar ataxia type 19/22 or ataxia accompanied by epilepsy. This indicates that we have identified a new KCND3 phenotype. In addition, we also uncovered a GRIN1 pathogenic variant and a novel HCN1 pathogenic variant in the Dravet cohort. CONCLUSION Our study highlights the significant utility of NGS panels in the genetic diagnosis of pediatric epilepsy. Our findings indicate that KCND3 pathogenic variants may be responsible for a wider phenotypic spectrum than previously thought, by including childhood epileptic encephalopathy. Furthermore, this study provides evidence that GRIN1 and HCN1 are candidate genes for Dravet and Dravet-like phenotypes.
Collapse
Affiliation(s)
- Jiaping Wang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Yongxin Wen
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Qingping Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Shujie Yu
- Department of Neurology, Harbin Children's Hospital, Harbin 150010, Heilongjiang Province, China
| | - Yan Chen
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - YueHua Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China
| | - Xinhua Bao
- Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
| |
Collapse
|
5
|
Electrocardiographic J wave: Early repolarization, Brugada wave, and conduction delay. Heart Rhythm 2018; 16:81-82. [PMID: 30118884 DOI: 10.1016/j.hrthm.2018.08.007] [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: 08/02/2018] [Indexed: 11/21/2022]
|
6
|
Portero V, Wilders R, Casini S, Charpentier F, Verkerk AO, Remme CA. K V4.3 Expression Modulates Na V1.5 Sodium Current. Front Physiol 2018; 9:178. [PMID: 29593552 PMCID: PMC5857579 DOI: 10.3389/fphys.2018.00178] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 02/20/2018] [Indexed: 01/14/2023] Open
Abstract
In cardiomyocytes, the voltage-gated transient outward potassium current (Ito) is responsible for the phase-1 repolarization of the action potential (AP). Gain-of-function mutations in KCND3, the gene encoding the Ito carrying KV4.3 channel, have been associated with Brugada syndrome (BrS). While the role of Ito in the pro-arrhythmic mechanism of BrS has been debated, recent studies have suggested that an increased Ito may directly affect cardiac conduction. However, the effects of an increased Ito on AP upstroke velocity or sodium current at the cellular level remain unknown. We here investigated the consequences of KV4.3 overexpression on NaV1.5 current and consequent sodium channel availability. We found that overexpression of KV4.3 protein in HEK293 cells stably expressing NaV1.5 (HEK293-NaV1.5 cells) significantly reduced NaV1.5 current density without affecting its kinetic properties. In addition, KV4.3 overexpression decreased AP upstroke velocity in HEK293-NaV1.5 cells, as measured with the alternating voltage/current clamp technique. These effects of KV4.3 could not be explained by alterations in total NaV1.5 protein expression. Using computer simulations employing a multicellular in silico model, we furthermore demonstrate that the experimentally observed increase in KV4.3 current and concurrent decrease in NaV1.5 current may result in a loss of conduction, underlining the potential functional relevance of our findings. This study gives the first proof of concept that KV4.3 directly impacts on NaV1.5 current. Future studies employing appropriate disease models should explore the potential electrophysiological implications in (patho)physiological conditions, including BrS associated with KCND3 gain-of-function mutations.
Collapse
Affiliation(s)
- Vincent Portero
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands
| | - Simona Casini
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | | | - Arie O Verkerk
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands.,Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| |
Collapse
|
7
|
Ion Channel Disorders and Sudden Cardiac Death. Int J Mol Sci 2018; 19:ijms19030692. [PMID: 29495624 PMCID: PMC5877553 DOI: 10.3390/ijms19030692] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 12/19/2022] Open
Abstract
Long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia are inherited primary electrical disorders that predispose to sudden cardiac death in the absence of structural heart disease. Also known as cardiac channelopathies, primary electrical disorders respond to mutations in genes encoding cardiac ion channels and/or their regulatory proteins, which result in modifications in the cardiac action potential or in the intracellular calcium handling that lead to electrical instability and life-threatening ventricular arrhythmias. These disorders may have low penetrance and expressivity, making clinical diagnosis often challenging. However, because sudden cardiac death might be the first presenting symptom of the disease, early diagnosis becomes essential. Genetic testing might be helpful in this regard, providing a definite diagnosis in some patients. Yet important limitations still exist, with a significant proportion of patients remaining with no causative mutation identifiable after genetic testing. This review aims to provide the latest knowledge on the genetic basis of cardiac channelopathies and discuss the role of the affected proteins in the pathophysiology of each one of these diseases.
Collapse
|
8
|
Wu Y, Ai M, Bardeesi ASA, Xu L, Zheng J, Zheng D, Yin K, Wu Q, Zhang L, Huang L, Cheng J. Brugada syndrome: a fatal disease with complex genetic etiologies - still a long way to go. Forensic Sci Res 2017; 2:115-125. [PMID: 30483629 PMCID: PMC6197104 DOI: 10.1080/20961790.2017.1333203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 05/04/2017] [Indexed: 12/19/2022] Open
Abstract
Brugada syndrome (BrS) is an arrhythmogenic disorder which was first described in 1992. This disease is a channelopathy characterized by ST-segment elevations in the right precordial leads and is susceptible to sudden death. BrS is a fatal disease with gender and age preferences. It occurs mainly in young male subjects with a structurally normal heart and silently progresses to sudden death with no significant symptoms. The prevalence of BrS has been reported in the ranges of 5–20 per 10 000 people. The disease is more prevalent in Asia. Nowadays, numerous variations in 23 genes have been linked to BrS since the first gene SCN5A has been associated with BrS in 1998. Not only can clinical specialists apply these discoveries in risk assessment, diagnosis and personal medicine, but also forensic pathologists can make full use of these variations to conduct death cause identification. However, despite the progress in genetics, these associated genes can only account for approximately 35% of the BrS cases while the etiology of the remaining BrS cases is still unexplained. In this review, we discussed the prevalence, the genes associated with BrS and the application of molecular autopsy in forensic pathology. We also summarized the present obstacles, and provided a new insight into the genetic basis of BrS.
Collapse
Affiliation(s)
- Yeda Wu
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Mei Ai
- Forensic Science Center of WASTON Guangdong Province, Guangzhou, China
| | - Adham Sameer A Bardeesi
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Lunwu Xu
- The Branch Office of Yanping, Public Security Bureau of Nanping, Nanping, China
| | - Jingjing Zheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Da Zheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Kun Yin
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Qiuping Wu
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Liyong Zhang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Lei Huang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Jianding Cheng
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| |
Collapse
|
9
|
Regulation of human cardiac potassium channels by full-length KCNE3 and KCNE4. Sci Rep 2016; 6:38412. [PMID: 27922120 PMCID: PMC5138848 DOI: 10.1038/srep38412] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/09/2016] [Indexed: 12/23/2022] Open
Abstract
Voltage-gated potassium (Kv) channels comprise pore-forming α subunits and a multiplicity of regulatory proteins, including the cardiac-expressed and cardiac arrhythmia-linked transmembrane KCNE subunits. After recently uncovering novel, N-terminally extended (L) KCNE3 and KCNE4 isoforms and detecting their transcripts in human atrium, reported here are their functional effects on human cardiac Kv channel α subunits expressed in Xenopus laevis oocytes. As previously reported for short isoforms KCNE3S and KCNE4S, KCNE3L inhibited hERG; KCNE4L inhibited Kv1.1; neither form regulated the HCN1 pacemaker channel. Unlike KCNE4S, KCNE4L was a potent inhibitor of Kv4.2 and Kv4.3; co-expression of cytosolic β subunit KChIP2, which regulates Kv4 channels in cardiac myocytes, partially relieved Kv4.3 but not Kv4.2 inhibition. Inhibition of Kv4.2 and Kv4.3 by KCNE3L was weaker, and its inhibition of Kv4.2 abolished by KChIP2. KCNE3L and KCNE4L also exhibited subunit-specific effects on Kv4 channel complex inactivation kinetics, voltage dependence and recovery. Further supporting the potential physiological significance of the robust functional effects of KCNE4L on Kv4 channels, KCNE4L protein was detected in human atrium, where it co-localized with Kv4.3. The findings establish functional effects of novel human cardiac-expressed KCNE isoforms and further contribute to our understanding of the potential mechanisms influencing cardiomyocyte repolarization.
Collapse
|
10
|
Cubeddu LX. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias. Curr Cardiol Rev 2016; 12:141-54. [PMID: 26926294 PMCID: PMC4861943 DOI: 10.2174/1573403x12666160301120217] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 02/29/2016] [Indexed: 01/11/2023] Open
Abstract
Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.
Collapse
Affiliation(s)
- Luigi X Cubeddu
- Division of Cardio-Metabolic Research, Department of Pharmaceutical Sciences, Health professions Division, Nova Southeastern University, 3200 S. University Dr., Davie, FL, 333218, USA.
| |
Collapse
|
11
|
Abbott GW. KCNE4 and KCNE5: K(+) channel regulation and cardiac arrhythmogenesis. Gene 2016; 593:249-60. [PMID: 27484720 DOI: 10.1016/j.gene.2016.07.069] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 07/23/2016] [Accepted: 07/28/2016] [Indexed: 12/14/2022]
Abstract
KCNE proteins are single transmembrane-segment voltage-gated potassium (Kv) channel ancillary subunits that exhibit a diverse range of physiological functions. Human KCNE gene mutations are associated with various pathophysiological states, most notably cardiac arrhythmias. Of the five isoforms in the human KCNE gene family, KCNE4 and the X-linked KCNE5 are, to date, the least-studied. Recently, however, interest in these neglected genes has been stoked by their putative association with debilitating or lethal cardiac arrhythmias. The sometimes-overlapping functional effects of KCNE4 and KCNE5 vary depending on both their Kv α subunit partner and on other ancillary subunits within the channel complex, but mostly fall into two contrasting categories - either inhibition, or fine-tuning of gating kinetics. This review covers current knowledge regarding the molecular mechanisms of KCNE4 and KCNE5 function, human disease associations, and findings from very recent studies of cardiovascular pathophysiology in Kcne4(-/-) mice.
Collapse
Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Pharmacology and Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
| |
Collapse
|
12
|
Patocskai B, Barajas-Martinez H, Hu D, Gurabi Z, Koncz I, Antzelevitch C. Cellular and ionic mechanisms underlying the effects of cilostazol, milrinone, and isoproterenol to suppress arrhythmogenesis in an experimental model of early repolarization syndrome. Heart Rhythm 2016; 13:1326-34. [PMID: 26820510 DOI: 10.1016/j.hrthm.2016.01.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Early repolarization syndrome (ERS) is associated with polymorphic ventricular tachycardia (PVT) and ventricular fibrillation, leading to sudden cardiac death. OBJECTIVE The present study tests the hypothesis that the transient outward potassium current (Ito)-blocking effect of phosphodiesterase-3 (PDE-3) inhibitors plays a role in reversing repolarization heterogeneities responsible for arrhythmogenesis in experimental models of ERS. METHODS Transmembrane action potentials (APs) were simultaneously recorded from epicardial and endocardial regions of coronary-perfused canine left ventricular (LV) wedge preparations, together with a transmural pseudo-electrocardiogram. The Ito agonist NS5806 (7-15 μM) and L-type calcium current (ICa) blocker verapamil (2-3 μM) were used to induce an early repolarization pattern and PVT. RESULTS After stable induction of arrhythmogenesis, the PDE-3 inhibitors cilostazol and milrinone or isoproterenol were added to the coronary perfusate. All were effective in restoring the AP dome in the LV epicardium, thus abolishing the repolarization defects responsible for phase 2 reentry and PVT. Arrhythmic activity was suppressed in 7 of 8 preparations by cilostazol (10 μM), 6 of 7 by milrinone (2.5 μM), and 7 of 8 by isoproterenol (0.1-1 μM). Using voltage clamp techniques applied to LV epicardial myocytes, both cilostazol (10 μM) and milrinone (2.5 μM) were found to reduce Ito by 44.4% and 40.4%, respectively, in addition to their known effects to augment ICa. CONCLUSION Our findings suggest that PDE-3 inhibitors exert an ameliorative effect in the setting of ERS by producing an inward shift in the balance of current during the early phases of the epicardial AP via inhibition of Ito as well as augmentation of ICa, thus reversing the repolarization defects underlying the development of phase 2 reentry and ventricular tachycardia/ventricular fibrillation.
Collapse
Affiliation(s)
- Bence Patocskai
- Masonic Medical Research Laboratory, Utica, New York; Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | | | - Dan Hu
- Masonic Medical Research Laboratory, Utica, New York
| | - Zsolt Gurabi
- Masonic Medical Research Laboratory, Utica, New York; Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Koncz
- Masonic Medical Research Laboratory, Utica, New York; Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | | |
Collapse
|