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Shen R, Zuo D, Chen K, Yin Y, Tang K, Hou S, Han B, Xu Y, Liu Z, Chen H. K2P1 leak cation channels contribute to ventricular ectopic beats and sudden death under hypokalemia. FASEB J 2022; 36:e22455. [PMID: 35899468 DOI: 10.1096/fj.202200707r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/28/2022] [Accepted: 07/06/2022] [Indexed: 11/11/2022]
Abstract
Hypokalemia causes ectopic heartbeats, but the mechanisms underlying such cardiac arrhythmias are not understood. In reduced serum K+ concentrations that occur under hypokalemia, K2P1 two-pore domain K+ channels change ion selectivity and switch to conduct inward leak cation currents, which cause aberrant depolarization of resting potential and induce spontaneous action potential of human cardiomyocytes. K2P1 is expressed in the human heart but not in mouse hearts. We test the hypothesis that K2P1 leak cation channels contribute to ectopic heartbeats under hypokalemia, by analysis of transgenic mice, which conditionally express induced K2P1 specifically in hearts, mimicking K2P1 channels in the human heart. Conditional expression of induced K2P1 specifically in the heart of hypokalemic mice results in multiple types of ventricular ectopic beats including single and multiple ventricular premature beats as well as ventricular tachycardia and causes sudden death. In isolated mouse hearts that express induced K2P1, sustained ventricular fibrillation occurs rapidly after perfusion with low K+ concentration solutions that mimic hypokalemic conditions. These observed phenotypes occur rarely in control mice or in the hearts that lack K2P1 expression. K2P1-expressing mouse cardiomyocytes of transgenic mice much more frequently fire abnormal single and/or rhythmic spontaneous action potential in hypokalemic conditions, compared to wild type mouse cardiomyocytes without K2P1 expression. These findings confirm that K2P1 leak cation channels induce ventricular ectopic beats and sudden death of transgenic mice with hypokalemia and imply that K2P1 leak cation channels may play a critical role in human ectopic heartbeats under hypokalemia.
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Affiliation(s)
- Rongrong Shen
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Dongchuan Zuo
- Key Laboratory of Medical Electrophysiology, Institute of Cardiovascular Research, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Southwest Medical University, Luzhou, China.,Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
| | - Kuihao Chen
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA.,Department of Pharmacology, Ningbo University School of Medicine, Ningbo, China
| | - Yiheng Yin
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Kai Tang
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Shangwei Hou
- Key Laboratory for Translational Research and Innovative Therapeutics of Gastrointestinal Oncology, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bo Han
- Key Laboratory for Translational Research and Innovative Therapeutics of Gastrointestinal Oncology, Tongren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yawei Xu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China
| | - Zheng Liu
- Department of Cardiology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.,Pan-Vascular Research Institute, Heart, Lung, and Blood Center, Tongji University School of Medicine, Shanghai, China.,Cryo-Electron Microscopy Center, Southern University of Science and Technology, Shenzhen, China
| | - Haijun Chen
- Department of Biological Sciences, University at Albany, State University of New York, Albany, New York, USA
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Thu Kyaw M, Maung ZM. Hypokalemia-Induced Arrhythmia: A Case Series and Literature Review. Cureus 2022; 14:e22940. [PMID: 35411269 PMCID: PMC8989702 DOI: 10.7759/cureus.22940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2022] [Indexed: 12/12/2022] Open
Abstract
Electrolyte imbalances, particularly potassium disorders, are common in clinical practice. Potassium homeostasis plays a key role in regulating cell membrane excitability. Hypokalemia usually presents with cardiovascular and neuromuscular abnormalities. Hypokalemia can lead to clinically significant life-threatening arrhythmia. Typical electrocardiographic (ECG) features of hypokalemia include widespread ST depression, T wave inversion, and prominent U waves. However, hypokalemia may present with different types of arrhythmia, such as premature ventricular contractions, ventricular fibrillation, atrial fibrillation, and torsade de pointes. Thus, clinicians should be familiar with ECG manifestations of potassium disorders that may warrant timely diagnosis and effective management. Herein, we report three patients with arrhythmia who were found to have typical ECG characteristics of hypokalemia after resolution of arrhythmia and later proved to have low serum potassium levels.
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Depuydt AS, Peigneur S, Tytgat J. Review: HCN Channels in the Heart. Curr Cardiol Rev 2022; 18:e040222200836. [PMID: 35125083 PMCID: PMC9893134 DOI: 10.2174/1573403x18666220204142436] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/13/2021] [Accepted: 12/23/2021] [Indexed: 11/22/2022] Open
Abstract
Pacemaker cells are the basis of rhythm in the heart. Cardiovascular diseases, and in particular, arrhythmias are a leading cause of hospital admissions and have been implicated as a cause of sudden death. The prevalence of people with arrhythmias will increase in the next years due to an increase in the ageing population and risk factors. The current therapies are limited, have a lot of side effects, and thus, are not ideal. Pacemaker channels, also called hyperpolarizationactivated cyclic nucleotide-gated (HCN) channels, are the molecular correlate of the hyperpolarization- activated current, called Ih (from hyperpolarization) or If (from funny), that contribute crucially to the pacemaker activity in cardiac nodal cells and impulse generation and transmission in neurons. HCN channels have emerged as interesting targets for the development of drugs, in particular, to lower the heart rate. Nonetheless, their pharmacology is still rather poorly explored in comparison to many other voltage-gated ion channels or ligand-gated ion channels. Ivabradine is the first and currently the only clinically approved compound that specifically targets HCN channels. The therapeutic indication of ivabradine is the symptomatic treatment of chronic stable angina pectoris in patients with coronary artery disease with a normal sinus rhythm. Several other pharmacological agents have been shown to exert an effect on heart rate, although this effect is not always desired. This review is focused on the pacemaking process taking place in the heart and summarizes the current knowledge on HCN channels.
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Affiliation(s)
- Anne-Sophie Depuydt
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, O&N2, PO Box 922, Herestraat 49, 3000Leuven, Belgium
| | - Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, O&N2, PO Box 922, Herestraat 49, 3000Leuven, Belgium
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, O&N2, PO Box 922, Herestraat 49, 3000Leuven, Belgium
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Oknińska M, Paterek A, Zambrowska Z, Mackiewicz U, Mączewski M. Effect of Ivabradine on Cardiac Ventricular Arrhythmias: Friend or Foe? J Clin Med 2021; 10:4732. [PMID: 34682854 PMCID: PMC8537674 DOI: 10.3390/jcm10204732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 09/24/2021] [Accepted: 10/08/2021] [Indexed: 12/12/2022] Open
Abstract
Life-threatening ventricular arrhythmias, such as ventricular tachycardia and ventricular fibrillation remain an ongoing clinical problem and their prevention and treatment require optimization. Conventional antiarrhythmic drugs are associated with significant proarrhythmic effects that often outweigh their benefits. Another option, the implantable cardioverter defibrillator, though clearly the primary therapy for patients at high risk of ventricular arrhythmias, is costly, invasive, and requires regular monitoring. Thus there is a clear need for new antiarrhythmic treatment strategies. Ivabradine, a heartrate-reducing agent, an inhibitor of HCN channels, may be one of such options. In this review we discuss emerging data from experimental studies that indicate new mechanism of action of this drug and further areas of investigation and potential use of ivabradine as an antiarrhythmic agent. However, clinical evidence is limited, and the jury is still out on effects of ivabradine on cardiac ventricular arrhythmias in the clinical setting.
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Affiliation(s)
| | | | | | | | - Michał Mączewski
- Centre of Postgraduate Medical Education, Department of Clinical Physiology, ul. Marymoncka 99/103, 01-813 Warsaw, Poland; (M.O.); (A.P.); (Z.Z.); (U.M.)
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Gergs U, Brückner T, Hofmann B, Neumann J. The proarrhythmic effects of hypothermia in atria isolated from 5-HT 4-receptor-overexpressing mice. Eur J Pharmacol 2021; 906:174206. [PMID: 34048737 DOI: 10.1016/j.ejphar.2021.174206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022]
Abstract
We investigated whether hypothermia would be arrhythmogenic in mice that overexpress the human 5-HT4 receptor only in their cardiac myocytes (5-HT4-TG). Contractile studies were performed in isolated, electrically driven (1 Hz) left and spontaneously beating right atrial preparations of 5-HT4-TG and littermate wild-type control mice (WT). Hypothermia (23 °C) decreased the force of contraction in the mouse right and left atrial preparations. Moreover, the concentration-dependent positive inotropic effects of 5-HT were blunted but still shifted to lower 5-HT concentrations in the left 5-HT4-TG atria in hypothermia compared to normothermia (37 °C). Furthermore, hypothermia increased the incidence of right atrial arrhythmias in 5-HT4-TG more than in WT mice. In contrast, at 37 °C, lowering the potassium concentration from 5.2 to 2.0 mM also induced arrhythmias in the right atrium, but with a similar incidence in WT and 5-HT4-TG mice. In contrast, 10 μM d,l-sotalol and 300 μM erythromycin did not induce arrhythmias. Hypothermia was accompanied by the increased expression of heat shock protein 70 (HSP70) in WT but not in 5-HT4-TG mice. We concluded that without the stimulation of 5-HT4-receptors by exogenous agonists, a simple temperature reduction can increase arrhythmias in 5-HT4-TG mice. It is tempting to speculate that in human patients, 5-HT4 receptors might contribute to potentially deadly hypothermia-induced arrhythmias.
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Affiliation(s)
- Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Halle, Germany.
| | - Tobias Brückner
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Halle, Germany.
| | - Britt Hofmann
- Cardiac Surgery, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Halle, Germany.
| | - Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097, Halle, Germany.
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Effect of ivabradine on cardiac arrhythmias: Antiarrhythmic or proarrhythmic? Heart Rhythm 2021; 18:1230-1238. [PMID: 33737235 DOI: 10.1016/j.hrthm.2021.03.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 12/28/2022]
Abstract
Cardiac arrhythmias are a major source of mortality and morbidity. Unfortunately, their treatment remains suboptimal. Major classes of antiarrhythmic drugs pose a significant risk of proarrhythmia, and their side effects often outweigh their benefits. Therefore, implantable devices remain the only truly effective antiarrhythmic therapy, and new strategies of antiarrhythmic treatment are required. Ivabradine is a selective heart rate-reducing agent, an inhibitor of hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, currently approved for treatment of coronary artery disease and chronic heart failure. In this review, we focus on the clinical and basic science evidence for the antiarrhythmic and proarrhythmic effects of ivabradine. We attempt to dissect the mechanisms behind the effects of ivabradine and indicate the focus of future studies.
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Nakagawa T, Yasaka T, Nakashima N, Takeya M, Oshita K, Tsuda M, Yamaura K, Takano M. Expression of the pacemaker channel HCN4 in excitatory interneurons in the dorsal horn of the murine spinal cord. Mol Brain 2020; 13:127. [PMID: 32948209 PMCID: PMC7501643 DOI: 10.1186/s13041-020-00666-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 09/07/2020] [Indexed: 11/17/2022] Open
Abstract
In the central nervous system, hyperpolarization-activated, cyclic nucleotide-gated (HCN1–4) channels have been implicated in neuronal excitability and synaptic transmission. It has been reported that HCN channels are expressed in the spinal cord, but knowledge about their physiological roles, as well as their distribution profiles, appear to be limited. We generated a transgenic mouse in which the expression of HCN4 can be reversibly knocked down using a genetic tetracycline-dependent switch and conducted genetically validated immunohistochemistry for HCN4. We found that the somata of HCN4-immunoreactive (IR) cells were largely restricted to the ventral part of the inner lamina II and lamina III. Many of these cells were either parvalbumin- or protein kinase Cγ (PKCγ)-IR. By using two different mouse strains in which reporters are expressed only in inhibitory neurons, we determined that the vast majority of HCN4-IR cells were excitatory neurons. Mechanical and thermal noxious stimulation did not induce c-Fos expression in HCN4-IR cells. PKCγ-neurons in this area are known to play a pivotal role in the polysynaptic pathway between tactile afferents and nociceptive projection cells that contributes to tactile allodynia. Therefore, pharmacological and/or genetic manipulations of HCN4-expressing neurons may provide a novel therapeutic strategy for the pain relief of tactile allodynia.
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Affiliation(s)
- Taku Nakagawa
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.,Department of Anesthesiology, Graduate School of Medicine, Kyushu University, Fukuoka, 812-8582, Japan
| | - Toshiharu Yasaka
- Department of Health and Nutrition, Niigata University of Hearth and Welfare, Niigata, 950-3198, Japan
| | - Noriyuki Nakashima
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan
| | - Mitsue Takeya
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan
| | - Kensuke Oshita
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.,Department of Anesthesiology, Kurume University School of Medicine, Kurume, 830-0011, Japan
| | - Makoto Tsuda
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Ken Yamaura
- Department of Anesthesiology, Graduate School of Medicine, Kyushu University, Fukuoka, 812-8582, Japan
| | - Makoto Takano
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-Machi, Kurume, 830-0011, Japan.
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Zheng M, Kang L, Uchino T, Liu G, Wang Y, Ono K. Mitogen-activated protein kinase p38 modulates pacemaker ion channels differentiation in P19-derived pluripotent cells. J Physiol Sci 2020; 70:39. [PMID: 32895058 PMCID: PMC10717480 DOI: 10.1186/s12576-020-00766-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 08/28/2020] [Indexed: 11/10/2022]
Abstract
Signal regulators during early cardiogenetic differentiation for the cellular automaticity are largely unknown. Our investigations were designed to clarify the role of transcription factors and their modulators in P19-derived cardiomyocytes to the expression of cardiac pacemaker ion channels. Transcription factors Csx/Nkx2.5 and GATA4 but not MEF2C were markedly inhibited by p38 MAP kinase inhibition in a distinct manner; expression but not phosphorylation of GATA4 was reduced by inhibition of p38 MAP kinase actions. In the presence of an ERK1/2,5 inhibitor PD98059 or a JNK MAP kinase inhibitor SP600125, P19 cells successfully differentiated into cardiomyocytes displaying spontaneous beatings with expression of three types of pacemaker ion channels. We demonstrate that acquisition of cellular automaticity and the expression of pacemaker ion channels are regulated by the transcription factors, Csx/Nkx2.5 and GATA4, through intracellular signals including p38 MAP kinase in the process of P19-derived pluripotent cells differentiation into cardiomyocytes.
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Affiliation(s)
- Mingqi Zheng
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
- Department of Cardiovascular Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Lin Kang
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
- Department of Anatomy, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Tomoko Uchino
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
- Department of Anesthesiology, Oita University School of Medicine, Oita, Japan
| | - Gang Liu
- Department of Cardiovascular Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yan Wang
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.
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Rivolta I, Binda A, Masi A, DiFrancesco JC. Cardiac and neuronal HCN channelopathies. Pflugers Arch 2020; 472:931-951. [PMID: 32424620 DOI: 10.1007/s00424-020-02384-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 12/31/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. In the voltage range of activation, HCN channels carry an inward current mediated by Na+ and K+, termed If in the heart and Ih in neurons. Altered function of HCN channels, mainly HCN4, is associated with sinus node dysfunction and other arrhythmias such as atrial fibrillation, ventricular tachycardia, and atrioventricular block. In recent years, several data have also shown that dysfunctional HCN channels, in particular HCN1, but also HCN2 and HCN4, can play a pathogenic role in epilepsy; these include experimental data from animal models, and data collected over genetic mutations of the channels identified and characterized in epileptic patients. In the central nervous system, alteration of the Ih current could predispose to the development of neurodegenerative diseases such as Parkinson's disease; since HCN channels are widely expressed in the peripheral nervous system, their dysfunctional behavior could also be associated with the pathogenesis of neuropathic pain. Given the fundamental role played by the HCN channels in the regulation of the discharge activity of cardiac and neuronal cells, the modulation of their function for therapeutic purposes is under study since it could be useful in various pathological conditions. Here we review the present knowledge of the HCN-related channelopathies in cardiac and neurological diseases, including clinical, genetic, therapeutic, and physiopathological aspects.
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Affiliation(s)
- Ilaria Rivolta
- School of Medicine and Surgery, Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy
| | - Anna Binda
- School of Medicine and Surgery, Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy
| | - Alessio Masi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), section of Pharmacology and Toxicology, University of Florence, Florence, Italy
| | - Jacopo C DiFrancesco
- School of Medicine and Surgery, Milan Center for Neuroscience (NeuroMI), University of Milano-Bicocca, Monza, Italy. .,Department of Neurology, ASST San Gerardo Hospital, University of Milano-Bicocca, Via Pergolesi, 33, 20900, Monza, MB, Italy.
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Uchino T, Zheng MQ, Wang Y, Ono K. Cardiac specific transcription factor Csx/Nkx2.5 regulates transient-outward K + channel expression in pluripotent P19 cell-derived cardiomyocytes. J Physiol Sci 2020; 70:20. [PMID: 32213161 PMCID: PMC7096375 DOI: 10.1186/s12576-020-00748-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 03/12/2020] [Indexed: 01/31/2023]
Abstract
The homeobox-containing gene Csx/Nkx2.5 codes several cardiac transcription factors and plays a critical role in early cardiogenesis. We investigated the effect of Csx/Nkx2.5 on the expression of cardiac ion channels using P19-derived cardiomyocytes. P19CL6 cells and P19CL6 cells with Csx/Nkx2.5 overexpression (P19CL6-Csx cells) were induced to differentiate into cardiomyocytes by treatment with dimethyl sulfoxide. Action potentials and membrane currents were measured by whole cell patch clamp at different differentiation stage: the early stage (1–5 days after beating had begun) and the late stage (10–15 days after beating). Expression of Csx/Nkx2.5 mRNA was increased as the differentiation stages advanced in both P19CL6 and P19CL6-Csx cells. In action potential configuration, maximal diastolic potentials in P19CL6-Csx cells exhibited more hyperpolarized potential (‒ 64.2 mV) than those in P19CL6 cells (‒ 54.8 mV, p < 0.01) in the early stage. In P19CL6 cells, among 6 different voltage-gated and ligand-operated K+ channels expressed during the early stage, the transient-outward K+ channel was most predominant. By overexpression of Csx/Nkx2.5, developmental decrease in the transient-outward K+ channel was suppressed. Homeobox-containing gene Csx/Nkx2.5 modifies the amount of distinct ionic channels, during differentiation periods, predominantly changing the expression of the transient-outward K+ channel.
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Affiliation(s)
- Tomoko Uchino
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.,Department of Anesthesiology, Oita University School of Medicine, Oita, Japan
| | - Ming-Qi Zheng
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.,Department of Cardiovascular Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yan Wang
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.
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