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Lee HM, Hahn SJ, Choi BH. The antidiabetic drug rosiglitazone blocks Kv1.5 potassium channels in an open state. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY 2022; 26:135-144. [PMID: 35203063 PMCID: PMC8890944 DOI: 10.4196/kjpp.2022.26.2.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/15/2022] [Accepted: 01/17/2022] [Indexed: 11/15/2022]
Abstract
An antidiabetic drug, rosiglitazone is a member of the drug class of thiazolidinedione. Although restrictions on use due to the possibility of heart toxicity have been removed, it is still a drug that is concerned about side effects on the heart. We here examined, using Chinese hamster ovary cells, the action of rosiglitazone on Kv1.5 channels, which is a major determinant of the duration of cardiac action potential. Rosiglitazone rapidly and reversibly inhibited Kv1.5 currents in a concentration-dependent manner (IC50 = 18.9 µM) and accelerated the decay of Kv1.5 currents without modifying the activation kinetics. In addition, the deactivation of Kv1.5 current, assayed with tail current, was slowed by the drug. All of the results as well as the use-dependence of the rosiglitazone-mediated blockade indicate that rosiglitazone acts on Kv1.5 channels as an open channel blocker. This study suggests that the cardiac side effects of rosiglitazone might be mediated in part by suppression of Kv1.5 channels, and therefore, raises a concern of using the drug for diabetic therapeutics.
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Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Sciences, Jeonbuk National University Medical School, Jeonju 54097, Korea
| | - Sang June Hahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Sciences, Jeonbuk National University Medical School, Jeonju 54097, Korea
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2
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Li H, Zhuang W, Seo MS, An JR, Yang Y, Zha Y, Liang J, Xu ZX, Park WS. Inhibition of voltage-dependent K + channels in rabbit coronary arterial smooth muscle cells by the class Ic antiarrhythmic agent lorcainide. Eur J Pharmacol 2021; 904:174158. [PMID: 33971179 DOI: 10.1016/j.ejphar.2021.174158] [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: 04/11/2021] [Revised: 04/22/2021] [Accepted: 05/04/2021] [Indexed: 10/21/2022]
Abstract
Voltage-dependent K+ (Kv) channels play the role of returning the membrane potential to the resting state, thereby maintaining the vascular tone. Here, we used native smooth-muscle cells from rabbit coronary arteries to investigate the inhibitory effect of lorcainide, a class Ic antiarrhythmic agent, on Kv channels. Lorcainide inhibited Kv channels in a concentration-dependent manner with an IC50 of 4.46 ± 0.15 μM and a Hill coefficient of 0.95 ± 0.01. Although application of lorcainide did not change the activation curve, it shifted the inactivation curve toward a more negative potential, implying that lorcainide inhibits Kv channels by changing the channels' voltage sensors. The recovery time constant from channel inactivation increased in the presence of lorcainide. Furthermore, application of train steps (of 1 or 2 Hz) in the presence of lorcainide progressively augmented the inhibition of Kv currents, implying that lorcainide-induced inhibition of Kv channels is use (state)-dependent. Pretreatment with Kv1.5 or Kv2.1/2.2 inhibitors effectively reduced the amplitude of the Kv current but did not affect the inhibitory effect of lorcainide. Based on these results, we conclude that lorcainide inhibits vascular Kv channels in a concentration and use (state)-dependent manner by changing their inactivation gating properties. Considering the clinical efficacy of lorcainide, and the pathophysiological significance of vascular Kv channels, our findings should be considered when prescribing lorcainide to patients with arrhythmia and vascular disease.
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Affiliation(s)
- Hongliang Li
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China; Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment for Senile Diseases, Yangzhou University, Yangzhou, 225001, China
| | - Wenwen Zhuang
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China
| | - Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Yongqi Yang
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China
| | - Yiwen Zha
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China
| | - Jingyan Liang
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, 225001, Jiangsu, China.
| | - Zheng-Xin Xu
- Department of Pharmacology, School of Medicine, Yangzhou University, Yangzhou, 225000, Jiangsu, China.
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea.
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3
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Seo MS, An JR, Jung HS, Kang M, Heo R, Han ET, Yang SR, Park H, Jung WK, Choi IW, Bae YM, Na SH, Park WS. Suppression of voltage-gated K + channels by darifenacin in coronary arterial smooth muscle cells. Eur J Pharmacol 2020; 891:173707. [PMID: 33137332 DOI: 10.1016/j.ejphar.2020.173707] [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: 06/18/2020] [Revised: 10/22/2020] [Accepted: 10/29/2020] [Indexed: 10/23/2022]
Abstract
Darifenacin, an anticholinergic agent, has been used to treat overactive bladder syndrome. Despite its extensive clinical use, there is little information about the effect of darifenacin on vascular ion channels, specifically K+ channels. This study aimed to investigate the effect of the anti-muscarinic drug darifenacin on voltage-gated K+ (Kv) channels, vascular contractility, and coronary blood flow in rabbit coronary arteries. We used the whole-cell patch-clamp technique to evaluate the effect of darifenacin on Kv channels. Darifenacin inhibited the Kv current in a concentration-dependent manner. Applying 1 μM darifenacin shifted the activation and inactivation curves toward a more positive and negative potential, respectively. Darifenacin slowed the time constants of recovery from inactivation. Furthermore, blockade of the Kv current with darifenacin was increased gradually by applying a train of pulses, indicating that darifenacin inhibited Kv currents in a use- (state)-dependent manner. The darifenacin-mediated inhibition of Kv currents was associated with the Kv1.5 subtype, not the Kv2.1 or Kv7 subtype. Applying another anti-muscarinic drug atropine or ipratropium did not affect the Kv current or change the inhibitory effect of darifenacin. Isometric organ bath experiments using isolated coronary arteries were applied to evaluate whether darifenacin-induced inhibition of the Kv channel causes vasocontraction. Darifenacin substantially induced vasocontraction. Furthermore, darifenacin caused membrane depolarization and decreased coronary blood flow. From these results, we concluded that darifenacin inhibits the Kv currents in concentration- and use- (state)-dependent manners. Inhibition of the Kv current with darifenacin occurred by shifting the steady-state activation and inactivation curves regardless of its anti-muscarinic effect.
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Affiliation(s)
- Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Hee Seok Jung
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Minji Kang
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Ryeon Heo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Se-Ran Yang
- Department of Thoracic and Cardiovascular Surgery, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Hongzoo Park
- Department of Urology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering, and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, 48513, South Korea
| | - Il-Whan Choi
- Department of Microbiology, College of Medicine, Inje University, Busan, 48516, South Korea
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju, 27478, South Korea
| | - Sung Hun Na
- Department of Obstetrics and Gynecology, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea.
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 24341, South Korea.
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Thuma JB, Hooper SL. Choline and NMDG directly reduce outward currents: reduced outward current when these substances replace Na + is alone not evidence of Na +-activated K + currents. J Neurophysiol 2018; 120:3217-3233. [PMID: 30354793 DOI: 10.1152/jn.00871.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Choline chloride is often, and N-methyl-d-glucamine (NMDG) sometimes, used to replace sodium chloride in studies of sodium-activated potassium channels. Given the high concentrations used in sodium replacement protocols, it is essential to test that it is not the replacement substances themselves, as opposed to the lack of sodium, that cause any observed effects. We therefore compared, in lobster stomatogastric neurons and leech Retzius cells, the effects of applying salines in which choline chloride replaced sodium chloride, and in which choline hydroxide or sucrose was added to normal saline. We also tested, in stomatogastric neurons, the effect of adding NMDG to normal saline. These protocols allowed us to measure the direct effects (i.e., effects not due to changes in sodium concentration or saline osmolarity or ionic strength) of choline on stomatogastric and leech currents, and of NMDG on stomatogastric currents. Choline directly reduced transient and sustained depolarization-activated outward currents in both species, and NMDG directly reduced transient depolarization-activated outward currents in stomatogastric neurons. Experiments with lower choline concentrations showed that adding as little as 150 mM (stomatogastric) or 5 mM (leech) choline reduced at least some depolarization-activated outward currents. Reductions in outward current with choline chloride or NMDG replacement alone are thus not evidence of sodium-activated potassium currents. NEW & NOTEWORTHY We show that choline or N-methyl-d-glucamine (NMDG) directly (i.e., not due to changes in extracellular sodium) decrease outward currents. Prior work studying sodium-activated potassium channels in which sodium was replaced with choline or NMDG without an addition control may therefore be artifactual.
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Affiliation(s)
- Jeffrey B Thuma
- Department of Biological Sciences, Irvine Hall, Ohio University , Athens, Ohio
| | - Scott L Hooper
- Department of Biological Sciences, Irvine Hall, Ohio University , Athens, Ohio
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An JR, Li H, Seo MS, Park WS. Inhibition of voltage-dependent K + current in rabbit coronary arterial smooth muscle cells by the class Ic antiarrhythmic drug propafenone. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2018; 22:597-605. [PMID: 30181706 PMCID: PMC6115351 DOI: 10.4196/kjpp.2018.22.5.597] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/26/2018] [Accepted: 07/26/2018] [Indexed: 12/30/2022]
Abstract
In this study, we demonstrated the inhibitory effect of the Class Ic antiarrhythmic agent propafenone on voltage-dependent K+ (Kv) channels using freshly isolated coronary artery smooth muscle cells from rabbits. The Kv current amplitude was progressively inhibited by propafenone in a dose-dependent manner, with an apparent IC50 value of 5.04±1.05 µM and a Hill coefficient of 0.78±0.06. The application of propafenone had no significant effect on the steady-state activation and inactivation curves, indicating that propafenone did not affect the voltage-sensitivity of Kv channels. The application of train pulses at frequencies of 1 or 2 Hz progressively increased the propafenone-induced inhibition of the Kv current. Furthermore, the inactivation recovery time constant was increased after the application of propafenone, suggesting that the inhibitory action of propafenone on Kv current is partially use-dependent. Pretreatment with Kv1.5, Kv2.1 or Kv7 inhibitor did not change the inhibitory effect of propafenone on the Kv current. Together, these results suggest that propafenone inhibits the vascular Kv channels in a dose- and use-dependent manner, regardless of Na+ channel inhibition.
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Affiliation(s)
- Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
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Lee HM, Chai OH, Hahn SJ, Choi BH. Antidepressant drug paroxetine blocks the open pore of Kv3.1 potassium channel. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 22:71-80. [PMID: 29302214 PMCID: PMC5746514 DOI: 10.4196/kjpp.2018.22.1.71] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 10/27/2017] [Indexed: 12/20/2022]
Abstract
In patients with epilepsy, depression is a common comorbidity but difficult to be treated because many antidepressants cause pro-convulsive effects. Thus, it is important to identify the risk of seizures associated with antidepressants. To determine whether paroxetine, a very potent selective serotonin reuptake inhibitor (SSRI), interacts with ion channels that modulate neuronal excitability, we examined the effects of paroxetine on Kv3.1 potassium channels, which contribute to highfrequency firing of interneurons, using the whole-cell patch-clamp technique. Kv3.1 channels were cloned from rat neurons and expressed in Chinese hamster ovary cells. Paroxetine reversibly reduced the amplitude of Kv3.1 current, with an IC50 value of 9.43 µM and a Hill coefficient of 1.43, and also accelerated the decay of Kv3.1 current. The paroxetine-induced inhibition of Kv3.1 channels was voltage-dependent even when the channels were fully open. The binding (k+1) and unbinding (k−1) rate constants for the paroxetine effect were 4.5 µM−1s−1 and 35.8 s−1, respectively, yielding a calculated KD value of 7.9 µM. The analyses of Kv3.1 tail current indicated that paroxetine did not affect ion selectivity and slowed its deactivation time course, resulting in a tail crossover phenomenon. Paroxetine inhibited Kv3.1 channels in a usedependent manner. Taken together, these results suggest that paroxetine blocks the open state of Kv3.1 channels. Given the role of Kv3.1 in fast spiking of interneurons, our data imply that the blockade of Kv3.1 by paroxetine might elevate epileptic activity of neural networks by interfering with repetitive firing of inhibitory neurons.
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Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Science, Chonbuk National University Medical School, Jeonju 54097, Korea
| | - Ok Hee Chai
- Department of Anatomy, Institute for Medical Science, Chonbuk National University Medical School, Jeonju 54097, Korea
| | - Sang June Hahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Science, Chonbuk National University Medical School, Jeonju 54097, Korea
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Li H, Shin SE, Seo MS, An JR, Ha KS, Han ET, Hong SH, Choi IW, Lee DS, Yim MJ, Lee JM, Jung ID, Firth AL, Han IY, Park WS. Inhibitory effect of the tricyclic antidepressant amitriptyline on voltage-dependent K + channels in rabbit coronary arterial smooth muscle cells. Clin Exp Pharmacol Physiol 2017; 45:205-212. [PMID: 28945283 DOI: 10.1111/1440-1681.12857] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/19/2017] [Accepted: 09/19/2017] [Indexed: 02/03/2023]
Abstract
Amitriptyline, a tricyclic antidepressant (TCA) drug, is widely used in treatment of psychiatric disorders. However, the side effects of amitriptyline on vascular K+ channels remain to be determined. Therefore, we investigated the effect of the tricyclic antidepressant and serotonin reuptake inhibitor amitriptyline on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells, using the whole-cell patch clamp technique. The Kv current amplitudes were inhibited by amitriptyline in a concentration-dependent manner, with an apparent IC50 value of 2.2 ± 0.14 μmol/L and a Hill coefficient of 0.87 ± 0.03. Amitriptyline shifted the activation curve to a more positive potential, but had no significant effect on the inactivation curve, suggesting that amitriptyline altered the voltage sensitivity of Kv channels. Pretreatment with Kv1.5 and Kv1.2 channel inhibitors did not alter the inhibitory effect of amitriptyline on Kv channels. Additionally, application of train pulses (1 and 2 Hz) did not affect amitriptyline-induced inhibition of Kv currents, which suggested that the action of amitriptyline on Kv channels was not use (state)-dependent. From these results, we concluded that amitriptyline inhibited the channels in a concentration-dependent, but state-independent manner.
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Affiliation(s)
- Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Sung Eun Shin
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Il-Whan Choi
- Department of Microbiology, College of Medicine, Inje University, Busan, South Korea
| | - Dae-Sung Lee
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Seocheon, South Korea
| | - Mi-Jin Yim
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Seocheon, South Korea
| | - Jeong Min Lee
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Seocheon, South Korea
| | - In Duk Jung
- Department of Immunology, Laboratory of Dendritic Cell Differentiation and Regulation, School of Medicine, Konkuk University, Chungju, South Korea
| | - Amy L Firth
- Department of Pulmonary, Critical Care and Sleep Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Il Yong Han
- Department of Thoracic and Cardiovascular Surgery, Busan Paik Hospital, College of Medicine, Inje University, Busan, South Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
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Li H, Shin SE, Seo MS, An JR, Jung WK, Ha KS, Han ET, Hong SH, Bang H, Bae YM, Firth AL, Choi IW, Park WS. The PPARα activator fenofibrate inhibits voltage-dependent K + channels in rabbit coronary arterial smooth muscle cells. Eur J Pharmacol 2017; 812:155-162. [PMID: 28716724 DOI: 10.1016/j.ejphar.2017.07.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/03/2017] [Accepted: 07/13/2017] [Indexed: 11/29/2022]
Abstract
We examined the effects of the PPARα activator fenofibrate on voltage-dependent K+ (Kv) channels using a patch clamp technique in native rabbit coronary arterial smooth muscle cells. Kv current was inhibited by application of fenofibrate in a concentration-dependent manner, with an apparent IC50 value of 6.39 ± 0.53μM and a slope value (Hill coefficient) of 1.63 ± 0.10. Fenofibrate accelerated the decay rate of Kv channel inactivation. The rate constants of association and dissociation for fenofibrate were 0.81± 0.05μM-1s-1 and 4.70 ± 0.47s-1, respectively. Although fenofibrate did not affect the steady-state activation curves, fenofibrate shifted the inactivation curves toward a more negative potential. Application of train pulses (1 or 2Hz) progressively increased the fenofibrate-induced inhibition of the Kv channel, and the recovery time constant from inactivation was increased in the presence of fenofibrate, which suggested that the inhibitory effect of fenofibrate is use-dependent. Another PPARα activator, bezafibrate and PPARα inhibitor, GW 6471, did not affect the Kv current and also did not change the inhibitory effect of fenofibrate on the Kv current. From these results, we suggest that fenofibrate inhibited Kv current in a state-, time-, and use-dependent manner, completely independent of PPARα activation.
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Affiliation(s)
- Hongliang Li
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Sung Eun Shin
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Mi Seon Seo
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Jin Ryeol An
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering, and Center for Marine-Integrated Biomedical Technology (BK21 Plus) Pukyong National University, Busan 608-737, South Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Seok-Ho Hong
- Institute of Medical Sciences, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea
| | - Hyoweon Bang
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul 06974, South Korea
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju 380-701, South Korea
| | - Amy L Firth
- Department of Pulmonary, Critical Care and Sleep Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA 90033, USA
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine, Busan 614-735, South Korea.
| | - Won Sun Park
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon 200-701, South Korea.
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Kim HS, Li H, Kim HW, Shin SE, Jung WK, Ha KS, Han ET, Hong SH, Firth AL, Choi IW, Park WS. The selective serotonin reuptake inhibitor dapoxetine inhibits voltage-dependent K + channels in rabbit coronary arterial smooth muscle cells. Clin Exp Pharmacol Physiol 2017; 44:480-487. [PMID: 28058743 DOI: 10.1111/1440-1681.12723] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/18/2016] [Accepted: 12/30/2016] [Indexed: 11/30/2022]
Abstract
We investigated the inhibitory effect of dapoxetine, a selective serotonin reuptake inhibitor (SSRI), on voltage-dependent K+ (Kv) channels using native smooth muscle cells from rabbit coronary arteries. Dapoxetine inhibited Kv channel currents in a concentration-dependent manner, with an IC50 value of 2.68±0.94 μmol/L and a slope value (Hill coefficient) of 0.63±0.11. Application of 10 μmol/L dapoxetine accelerated the rate of inactivation of Kv currents. Although dapoxetine did not modify current activation kinetics, it caused a significant negative shift in the inactivation curves. Application of train step (1 or 2 Hz) progressively increased the inhibitory effect of dapoxetine on Kv channels. In addition, the recovery time constant was extended in its presence, suggesting that the longer recovery time constant from inactivation underlies a use-dependent inhibition of the channel. From these results, we conclude that dapoxetine inhibits Kv channels in a dose-, time-, use-, and state (open)-dependent manner, independent of serotonin reuptake inhibition.
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Affiliation(s)
- Han Sol Kim
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Hongliang Li
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Hye Won Kim
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Sung Eun Shin
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, South Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Seok-Ho Hong
- Institute of Medical Sciences, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, South Korea
| | - Amy L Firth
- Department of Pulmonary, Critical Care and Sleep Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine, Busan, South Korea
| | - Won Sun Park
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, South Korea
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10
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Kim HS, Li H, Kim HW, Shin SE, Seo MS, An JR, Ha KS, Han ET, Hong SH, Choi IW, Choi G, Lee DS, Park WS. Escitalopram, a selective serotonin reuptake inhibitor, inhibits voltage-dependent K + channels in coronary arterial smooth muscle cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:415-421. [PMID: 28706455 PMCID: PMC5507780 DOI: 10.4196/kjpp.2017.21.4.415] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 02/27/2017] [Accepted: 03/08/2017] [Indexed: 01/06/2023]
Abstract
We investigated the inhibitory effect of escitalopram, a selective serotonin reuptake inhibitor (SSRI), on voltage-dependent K+ (Kv) channels in freshly separated from rabbit coronary arterial smooth muscle cells. The application of escitalopram rapidly inhibited vascular Kv channels. Kv currents were progressively inhibited by an increase in the concentrations of escitalopram, suggesting that escitalopram inhibited vascular Kv currents in a concentration-dependent manner. The IC50 value and Hill coefficient for escitalopram-induced inhibition of Kv channels were 9.54±1.33 µM and 0.75±0.10, respectively. Addition of escitalopram did not alter the steady-state activation and inactivation curves, suggesting that the voltage sensors of the channels were not affected. Pretreatment with inhibitors of Kv1.5 and/or Kv2.1 did not affect the inhibitory action of escitalopram on vascular Kv channels. From these results, we concluded that escitalopram decreased the vascular Kv current in a concentration-dependent manner, independent of serotonin reuptake inhibition.
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Affiliation(s)
- Han Sol Kim
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Hye Won Kim
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Sung Eun Shin
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Jin Ryeol An
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine, Busan 47392, Korea
| | - Grace Choi
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Seocheon 33662, Korea
| | - Dae-Sung Lee
- Department of Applied Research, National Marine Biodiversity Institute of Korea, Seocheon 33662, Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
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11
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Kim HS, Li H, Kim HW, Shin SE, Choi IW, Firth AL, Bang H, Bae YM, Park WS. Selective serotonin reuptake inhibitor sertraline inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells. J Biosci 2017; 41:659-666. [PMID: 27966486 DOI: 10.1007/s12038-016-9645-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We examined the effects of the selective serotonin reuptake inhibitor (SSRI) sertraline on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells using the voltage-clamp technique. Sertraline decreased the Kv channel current in a dose-dependent manner, with an IC50 value of 0.18 mu M and a slope value (Hill coefficient) of 0.61. Although the application of 1 mu M sertraline did not affect the steady-state activation curves, sertraline caused a significant, negative shift in the inactivation curves. Pretreatment with another SSRI, paroxetine, had no significant effect on Kv currents and did not alter the inhibitory effects of sertraline on Kv currents. From these results, we concluded that sertraline dose-dependently inhibited Kv currents independently of serotonin reuptake inhibition by shifting inactivation curves to a more negative potential.
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Affiliation(s)
- Han Sol Kim
- Department of Physiology, Kangwon National University School of Medicine Chuncheon 200-701, South Korea
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12
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Inhibition of cloned hERG potassium channels by risperidone and paliperidone. Naunyn Schmiedebergs Arch Pharmacol 2017; 390:633-642. [DOI: 10.1007/s00210-017-1364-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 02/24/2017] [Indexed: 12/31/2022]
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13
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Shin SE, Li H, Kim HS, Kim HW, Seo MS, Ha KS, Han ET, Hong SH, Firth AL, Choi IW, Bae YM, Park WS. Nortriptyline, a tricyclic antidepressant, inhibits voltage-dependent K + channels in coronary arterial smooth muscle cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:225-232. [PMID: 28280416 PMCID: PMC5343056 DOI: 10.4196/kjpp.2017.21.2.225] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 11/30/2022]
Abstract
We demonstrated the effect of nortriptyline, a tricyclic antidepressant drug and serotonin reuptake inhibitor, on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells using a whole-cell patch clamp technique. Nortriptyline inhibited Kv currents in a concentration-dependent manner, with an apparent IC50 value of 2.86±0.52 µM and a Hill coefficient of 0.77±0.1. Although application of nortriptyline did not change the activation curve, nortriptyline shifted the inactivation current toward a more negative potential. Application of train pulses (1 or 2 Hz) did not change the nortriptyline-induced Kv channel inhibition, suggesting that the effects of nortiprtyline were not use-dependent. Preincubation with the Kv1.5 and Kv2.1/2.2 inhibitors, DPO-1 and guangxitoxin did not affect nortriptyline inhibition of Kv channels. From these results, we concluded that nortriptyline inhibited Kv channels in a concentration-dependent and state-independent manner independently of serotonin reuptake.
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Affiliation(s)
- Sung Eun Shin
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Han Sol Kim
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Hye Won Kim
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Mi Seon Seo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Seok-Ho Hong
- Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon 24341, Korea
| | - Amy L Firth
- Department of Pulmonary, Critical Care and Sleep Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA90033, USA
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine, Busan 48516, Korea
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju 27478, Korea
| | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
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14
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Wang S, Ding WG, Bai JY, Toyoda F, Wei MJ, Matsuura H. Regulation of human cardiac Kv1.5 channels by extracellular acidification. Pflugers Arch 2016; 468:1885-1894. [PMID: 27796577 DOI: 10.1007/s00424-016-1890-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 09/15/2016] [Accepted: 09/30/2016] [Indexed: 10/20/2022]
Abstract
Human Kv1.5 channels (hKv1.5) conduct the ultra-rapid delayed rectifier potassium current (I Kur), which plays an important role in action potential repolarization of atrial myocytes. The present study was undertaken to examine the effects of acidic pH on hKv1.5 wild-type (WT) and its pore mutant channels heterologously expressed in Chinese hamster ovary (CHO) cells using site-directed mutagenesis combined with whole-cell patch-clamp technique. Both extracellular and intracellular acidifications equally and reversely reduced the amplitude of hKv1.5 currents. The extracellular acidification significantly shifted the voltage dependence of current activation to more depolarized potentials and accelerated deactivation kinetics of the current. The ancillary β subunits Kvβ1.3 and Kvβ1.2, known to modify the pharmacological sensitivities of hKv1.5, enhanced the extracellular proton-induced inhibitory effect on hKv1.5 current. In addition, several mutants (T462C, T479A, T480A, and I508A) exhibited significantly higher sensitivity to acidic pH-induced inhibition compared with WT channel, whereas the inhibitory effect of acidic pH was markedly reduced in H463G mutant. These observations indicate that (1) extracellular acidification modifies hKv1.5 gating and activity, (2) β subunits and several residues (T462, T479, T480, and I508) play critical roles in determining the sensitivity of the channel to acidic exposure, and (3) H463 may be a critical sensor for the channel inhibition by extracellular protons.
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Affiliation(s)
- Shuang Wang
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.,Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, China
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Jia-Yu Bai
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Futoshi Toyoda
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
| | - Min-Jie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, China.
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.
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15
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Inhibitory effects of hesperetin on Kv1.5 potassium channels stably expressed in HEK 293 cells and ultra-rapid delayed rectifier K + current in human atrial myocytes. Eur J Pharmacol 2016; 789:98-108. [DOI: 10.1016/j.ejphar.2016.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 06/29/2016] [Accepted: 07/07/2016] [Indexed: 12/16/2022]
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16
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Monteillier A, Loucif A, Omoto K, Stevens EB, Lainez S, Saintot PP, Cao L, Pryde DC. Investigation of the structure activity relationship of flufenamic acid derivatives at the human TRESK channel K 2P 18.1. Bioorg Med Chem Lett 2016; 26:4919-4924. [DOI: 10.1016/j.bmcl.2016.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 11/30/2022]
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17
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Stereoselective Blockage of Quinidine and Quinine in the hERG Channel and the Effect of Their Rescue Potency on Drug-Induced hERG Trafficking Defect. Int J Mol Sci 2016; 17:ijms17101648. [PMID: 27690007 PMCID: PMC5085681 DOI: 10.3390/ijms17101648] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/03/2016] [Accepted: 09/20/2016] [Indexed: 01/01/2023] Open
Abstract
Diastereoisomers of quinidine and quinine are used to treat arrhythmia and malaria, respectively. It has been reported that both drugs block the hERG (human ether-a-go-go-related gene) potassium channel which is essential for myocardium repolarization. Abnormality of repolarization increases risk of arrhythmia. The aim of our research is to study and compare the impacts of quinidine and quinine on hERG. Results show that both drugs block the hERG channel, with quinine 14-fold less potent than quinidine. In addition, they presented distinct impacts on channel dynamics. The results imply their stereospecific block effect on the hERG channel. However, F656C-hERG reversed this stereoselectivity. The mutation decreases affinity of the two drugs with hERG, and quinine was more potent than quinidine in F656C-hERG blockage. These data suggest that F656 residue contributes to the stereoselective pocket for quinidine and quinine. Further study demonstrates that both drugs do not change hERG protein levels. In rescue experiments, we found that they exert no reverse effect on pentamidine- or desipramine-induced hERG trafficking defect, although quinidine has been reported to rescue trafficking-deficient pore mutation hERG G601S based on the interaction with F656. Our research demonstrated stereoselective effects of quinidine and quinine on the hERG channel, and this is the first study to explore their reversal potency on drug-induced hERG deficiency.
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18
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Șterbuleac D, Maniu CL. An antiarrhythmic agent as a promising lead compound for targeting the hEAG1 ion channel in cancer therapy: insights from molecular dynamics simulations. Chem Biol Drug Des 2016; 88:683-689. [PMID: 27254790 DOI: 10.1111/cbdd.12797] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 04/27/2016] [Accepted: 05/30/2016] [Indexed: 11/29/2022]
Abstract
Experimental evidence suggests that hERG and hEAG potassium channels may serve as important cancer therapy targets because either of the channel blockade or inactivation by different methods leads to inhibition of cancer cells growth and proliferation. However, there is no known hEAG specific blocker, and hERG blockade leads to adverse cardiac side effects, although it is currently used in treating certain types of arrhythmias. There have been some attempts to explain the channels blockade by clofilium, an antiarrhythmic agent, and the results lead to different possible binding modes. This study investigates for the first time the potential of using clofilium as a lead compound for finding a novel cancer therapy agent which may target ion channels. The implied findings from a comparative assessment of literature studies were verified using molecular dynamics simulations. The results indicate a particular structural difference between the two channels that could provide a novel and realistic way of using clofilium analogs which may target the hEAG1 ion channel in cancer therapy.
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Affiliation(s)
- Daniel Șterbuleac
- Department of Biology, Biophysics Laboratory, Alexandru Ioan Cuza University, Iași, Romania
| | - Călin Lucian Maniu
- Department of Biology, Biophysics Laboratory, Alexandru Ioan Cuza University, Iași, Romania.
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19
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Li H, Kim HS, Kim HW, Shin SE, Jung WK, Ha KS, Han ET, Hong SH, Firth AL, Bae YM, Choi IW, Park WS. The class III anti-arrhythmic agent, amiodarone, inhibits voltage-dependent K(+) channels in rabbit coronary arterial smooth muscle cells. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:713-21. [PMID: 27030392 DOI: 10.1007/s00210-016-1232-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 01/06/2023]
Abstract
We examined the inhibitory effect of amiodarone, a class III anti-arrhythmic agent, on voltage-dependent K(+) (Kv) currents in freshly isolated rabbit coronary arterial smooth muscle cells, using a whole-cell patch clamp technique. Amiodarone inhibited Kv currents in a concentration-dependent manner, with a half-maximal inhibitory concentration (IC50) value of 3.9 ± 1.44 μM and a Hill coefficient of 0.45 ± 0.14. Amiodarone did not have a significant effect on the steady-state activation of Kv channels, but shifted the inactivation current toward a more negative potential. Application of consecutive pulses progressively augmented the amiodarone-induced Kv channel inhibition. Another class III anti-arrhythmic agent, dofetilide, did not inhibit the Kv current or change the inhibitory effect of amiodarone on Kv channels. Therefore, these results strongly suggest that amiodarone inhibits Kv currents in a concentration- and state-dependent manner.
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Affiliation(s)
- Hongliang Li
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon, 200-701, South Korea
| | - Han Sol Kim
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon, 200-701, South Korea
| | - Hye Won Kim
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon, 200-701, South Korea
| | - Sung Eun Shin
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon, 200-701, South Korea
| | - Won-Kyo Jung
- Department of Biomedical Engineering, and Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, 608-737, South Korea
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, 200-701, South Korea
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, 200-701, South Korea
| | - Seok-Ho Hong
- Institute of Medical Sciences, Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, 200-701, South Korea
| | - Amy L Firth
- Department of Pulmonary, Critical Care and Sleep Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA, 90033, USA
| | - Young Min Bae
- Department of Physiology, Konkuk University School of Medicine, Chungju, 380-701, South Korea
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine, Busan, 614-735, South Korea.
| | - Won Sun Park
- Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon, 200-701, South Korea.
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20
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Abstract
The voltage gated Kv1.5 channels conduct the ultrarapid delayed rectifier current (IKur) and play critical role in repolarization of action potential duration. It is the most rapidly activated channel and has very little or no inactivated states. In human cardiac cells, these channels are expressed more extensively in atrial myocytes than ventricle. From the evidences of its localization and functions, Kv1.5 has been declared a selective drug target for the treatment of atrial fibrillation (AF). In this present study, we have tried to identify the rapidly activating property of Kv1.5 and studied its mode of inhibition using molecular modeling, docking, and simulation techniques. Channel in open conformation is found to be stabilized quickly within the dipalmitoylphosphatidylcholine membrane, whereas most of the secondary structure elements were lost in closed state conformation. The obvious reason behind its ultra-rapid property is possibly due to the amino acid alteration in S4-S5 linker; the replacement of Lysine by Glutamine and vice versa. The popular published drugs as well as newly identified lead molecules were able to inhibit the Kv1.5 in a very similar pattern, mainly through the nonpolar interactions, and formed sable complexes. V512 is found as the main contributor for the interaction along with the other important residues such as V505, I508, A509, V512, P513, and V516. Furthermore, two screened novel compounds show surprisingly better inhibitory potency and can be considered for the future perspective of antiarrhythmic survey.
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Affiliation(s)
- Rajabrata Bhuyan
- a BIF Centre, Department of Biochemistry & Biophysics , University of Kalyani , Nadia, Kalyani 741235 , West Bengal , India
| | - Alpana Seal
- b Department of Biochemistry & Biophysics , University of Kalyani , Nadia, Kalyani 741235 , West Bengal , India
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21
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Lee HM, Hahn SJ, Choi BH. Blockade of Kv1.5 channels by the antidepressant drug sertraline. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2016; 20:193-200. [PMID: 26937216 PMCID: PMC4770110 DOI: 10.4196/kjpp.2016.20.2.193] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/03/2016] [Accepted: 02/12/2016] [Indexed: 11/15/2022]
Abstract
Sertraline, a selective serotonin reuptake inhibitor (SSRI), has been reported to lead to cardiac toxicity even at therapeutic doses including sudden cardiac death and ventricular arrhythmia. And in a SSRI-independent manner, sertraline has been known to inhibit various voltage-dependent channels, which play an important role in regulation of cardiovascular system. In the present study, we investigated the action of sertraline on Kv1.5, which is one of cardiac ion channels. The eff ect of sertraline on the cloned neuronal rat Kv1.5 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Sertraline reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an IC 50 value and a Hill coefficient of 0.71 µM and 1.29, respectively. Sertraline accelerated the decay rate of inactivation of Kv1.5 currents without modifying the kinetics of current activation. The inhibition increased steeply between -20 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to +10 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance δ of 0.16. Sertraline slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of sertraline, were superimposed. Inhibition of Kv1.5 by sertraline was use-dependent. The present results suggest that sertraline acts on Kv1.5 currents as an open-channel blocker.
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Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
| | - Sang June Hahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
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22
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Bagal SK, Kemp MI, Bungay PJ, Hay TL, Murata Y, Payne CE, Stevens EB, Brown A, Blakemore DC, Corbett MS, Miller DC, Omoto K, Warmus JS. Discovery and optimisation of potent and highly subtype selective Nav1.8 inhibitors with reduced cardiovascular liabilities. MEDCHEMCOMM 2016. [DOI: 10.1039/c6md00281a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Potent and subtype selective Nav1.8 inhibitors were designed and optimised for selectivity over hERG ion channel inhibition.
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Affiliation(s)
| | - Mark I. Kemp
- Worldwide Medicinal Chemistry
- Pfizer Global R&D
- Sandwich
- UK
| | - Peter J. Bungay
- Pharmacokinetics, Dynamics & Metabolism
- Pfizer Global R&D
- Cambridge
- UK
| | - Tanya L. Hay
- Pharmacokinetics, Dynamics & Metabolism
- Pfizer Global R&D
- Sandwich
- UK
| | | | | | | | - Alan Brown
- Worldwide Medicinal Chemistry
- Pfizer Global R&D
- Cambridge
- UK
| | | | | | | | - Kiyoyuki Omoto
- Worldwide Medicinal Chemistry
- Pfizer Global R&D
- Cambridge
- UK
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23
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Lee HM, Hahn SJ, Choi BH. Blockade of Kv1.5 by paroxetine, an antidepressant drug. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2015; 20:75-82. [PMID: 26807026 PMCID: PMC4722194 DOI: 10.4196/kjpp.2016.20.1.75] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Revised: 09/23/2015] [Accepted: 10/21/2015] [Indexed: 12/24/2022]
Abstract
Paroxetine, a selective serotonin reuptake inhibitor (SSRI), has been reported to have an effect on several ion channels including human ether-a-go-go-related gene in a SSRI-independent manner. These results suggest that paroxetine may cause side effects on cardiac system. In this study, we investigated the effect of paroxetine on Kv1.5, which is one of cardiac ion channels. The action of paroxetine on the cloned neuronal rat Kv1.5 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Paroxetine reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an IC 50 value and a Hill coefficient of 4.11 µM and 0.98, respectively. Paroxetine accelerated the decay rate of inactivation of Kv1.5 currents without modifying the kinetics of current activation. The inhibition increased steeply between -30 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to 0 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance δ of 0.32. The binding (k+1) and unbinding (k-1) rate constants for paroxetine-induced block of Kv1.5 were 4.9 µM(-1)s(-1) and 16.1 s(-1), respectively. The theoretical K D value derived by k-1/k+1 yielded 3.3 µM. Paroxetine slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of paroxetine, were superimposed. Inhibition of Kv1.5 by paroxetine was use-dependent. The present results suggest that paroxetine acts on Kv1.5 currents as an open-channel blocker.
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Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
| | - Sang June Hahn
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Sciences, Chonbuk National University Medical School, Jeonju 54097, Korea
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24
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Bai J, Ding W, Kojima A, Seto T, Matsuura H. Putative binding sites for arachidonic acid on the human cardiac Kv 1.5 channel. Br J Pharmacol 2015; 172:5281-92. [PMID: 26292661 PMCID: PMC5341216 DOI: 10.1111/bph.13314] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 08/01/2015] [Accepted: 08/18/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE In human heart, the Kv 1.5 channel contributes to repolarization of atrial action potentials. This study examined the electrophysiological and molecular mechanisms underlying arachidonic acid (AA)-induced inhibition of the human Kv 1.5 (hKv 1.5) channel. EXPERIMENTAL APPROACH Site-directed mutagenesis was conducted to mutate amino acids that reside within the pore domain of the hKv 1.5 channel. Whole-cell patch-clamp method was used to record membrane currents through wild type and mutant hKv 1.5 channels heterologously expressed in CHO cells. Computer docking simulation was conducted to predict the putative binding site(s) of AA in an open-state model of the Kv 1.5 channel. KEY RESULTS The hKv 1.5 current was minimally affected at the onset of depolarization but was progressively reduced during depolarization by the presence of AA, suggesting that AA acts as an open-channel blocker. AA itself affected the channel at extracellular sites independently of its metabolites and signalling pathways. The blocking effect of AA was attenuated at pH 8.0 but not at pH 6.4. The blocking action of AA developed rather rapidly by co-expression of Kv β1.3. The AA-induced block was significantly attenuated in H463C, T480A, R487V, I502A, I508A, V512A and V516A, but not in T462C, A501V and L510A mutants of the hKv 1.5 channel. Docking simulation predicted that H463, T480, R487, I508, V512 and V516 are potentially accessible for interaction with AA. CONCLUSIONS AND IMPLICATIONS AA itself interacts with multiple amino acids located in the pore domain of the hKv 1.5 channel. These findings may provide useful information for future development of selective blockers of hKv 1.5 channels.
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Affiliation(s)
- Jia‐Yu Bai
- Department of PhysiologyShiga University of Medical ScienceOtsuJapan
| | - Wei‐Guang Ding
- Department of PhysiologyShiga University of Medical ScienceOtsuJapan
| | - Akiko Kojima
- Department of AnesthesiologyShiga University of Medical ScienceOtsuJapan
| | - Tomoyoshi Seto
- Department of AnesthesiologyShiga University of Medical ScienceOtsuJapan
| | - Hiroshi Matsuura
- Department of PhysiologyShiga University of Medical ScienceOtsuJapan
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25
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Kojima A, Ito Y, Ding WG, Kitagawa H, Matsuura H. Interaction of propofol with voltage-gated human Kv1.5 channel through specific amino acids within the pore region. Eur J Pharmacol 2015; 764:622-632. [PMID: 26256861 DOI: 10.1016/j.ejphar.2015.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 08/05/2015] [Indexed: 12/25/2022]
Abstract
The intravenous anesthetic propofol affects the function of a diversity of ligand-gated and voltage-gated ion channels. However, there is little information as to whether propofol directly interacts with voltage-gated ion channel proteins to modulate their functions. The Kv1.5 channel is activated by membrane depolarization during action potentials and contributes to atrial repolarization in the human heart. This study was undertaken to examine the effect of propofol on voltage-gated human Kv1.5 (hKv1.5) channel and to elucidate the underlying molecular determinants. Site-directed mutagenesis was carried out through six amino acids that reside within the pore domain of hKv1.5 channel. Whole-cell patch-clamp technique was used to record membrane currents through the wild type and mutant hKv1.5 channels heterologously expressed in Chinese hamster ovary cells. Propofol (≥5 μM) reversibly and concentration-dependently (IC50 of 49.3±9.4 μM; n=6) blocked hKv1.5 current. Propofol-induced block of hKv1.5 current gradually progressed during depolarizing voltage-clamp steps and was enhanced by higher frequency of activation, consistent with a preferential block of the channels in their open state. The degree of current block by propofol was significantly attenuated in T480A, I502A, I508A and V516A, but not in H463C and L510A mutants of hKv1.5 channel. Thus, several amino acids near the selectivity filter (Thr480) or within S6 (Ile502, Ile508 and Val516) are found to be critically involved in the blocking action of propofol. This study provides the first evidence suggesting that direct interaction with specific amino acids underlies the blocking action of propofol on voltage-gated hKv1.5 channel.
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Affiliation(s)
- Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
| | - Yuki Ito
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Hirotoshi Kitagawa
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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The calmodulin inhibitor CGS 9343B inhibits voltage-dependent K + channels in rabbit coronary arterial smooth muscle cells. Toxicol Appl Pharmacol 2015; 285:207-13. [DOI: 10.1016/j.taap.2015.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 03/05/2015] [Accepted: 03/10/2015] [Indexed: 11/18/2022]
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Hong DH, Li H, Kim HS, Kim HW, Shin SE, Jung WK, Na SH, Choi IW, Firth AL, Park WS, Kim DJ. The Effects of the Selective Serotonin Reuptake Inhibitor Fluvoxamine on Voltage-Dependent K + Channels in Rabbit Coronary Arterial Smooth Muscle Cells. Biol Pharm Bull 2015; 38:1208-13. [DOI: 10.1248/bpb.b15-00207] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Da Hye Hong
- Department of Physiology, Kangwon National University School of Medicine
| | - Hongliang Li
- Department of Physiology, Kangwon National University School of Medicine
| | - Han Sol Kim
- Department of Physiology, Kangwon National University School of Medicine
| | - Hye Won Kim
- Department of Physiology, Kangwon National University School of Medicine
| | - Sung Eun Shin
- Department of Physiology, Kangwon National University School of Medicine
| | - Won-Kyo Jung
- Department of Biomedical Engineering, Center for Marine-Integrated Biomedical Technology (BK21 Plus) Pukyong National University
| | - Sung Hun Na
- Department of Obstetrics and Gynecology, Kangwon National University Hospital, School of Medicine, Kangwon National University
| | - Il-Whan Choi
- Department of Microbiology, Inje University College of Medicine
| | | | - Won Sun Park
- Department of Physiology, Kangwon National University School of Medicine
| | - Dae-Joong Kim
- Department of Anatomy and Cell Biology, Kangwon National University School of Medicine
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Chae YJ, Kim DH, Lee HJ, Sung KW, Kwon OJ, Hahn SJ. Raloxifene inhibits cloned Kv4.3 channels in an estrogen receptor-independent manner. Pflugers Arch 2014; 467:1663-76. [PMID: 25231973 DOI: 10.1007/s00424-014-1602-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 12/16/2022]
Abstract
Raloxifene is widely used for the treatment and prevention of postmenopausal osteoporosis. We examined the effects of raloxifene on the Kv4.3 currents expressed in Chinese hamster ovary (CHO) cells using the whole-cell patch-clamp technique and on the long-term modulation of Kv4.3 messenger RNA (mRNA) by real-time PCR analysis. Raloxifene decreased the Kv4.3 currents with an IC50 of 2.0 μM and accelerated the inactivation and activation kinetics in a concentration-dependent manner. The inhibitory effects of raloxifene on Kv4.3 were time-dependent: the association and dissociation rate constants for raloxifene were 9.5 μM(-1) s(-1) and 23.0 s(-1), respectively. The inhibition by raloxifene was voltage-dependent (δ = 0.13). Raloxifene shifted the steady-state inactivation curves in a hyperpolarizing direction and accelerated the closed-state inactivation of Kv4.3. Raloxifene slowed the time course of recovery from inactivation, thus producing a use-dependent inhibition of Kv4.3. β-Estradiol and tamoxifen had little effect on Kv4.3. A preincubation of ICI 182,780, an estrogen receptor antagonist, for 1 h had no effect on the inhibitory effect of raloxifene on Kv4.3. The metabolites of raloxifene, raloxifene-4'-glucuronide and raloxifene-6'-glucuronide, had little or no effect on Kv4.3. Coexpression of KChIP2 subunits did not alter the drug potency and steady-state inactivation of Kv4.3 channels. Long-term exposure to raloxifene (24 h) significantly decreased the expression level of Kv4.3 mRNA. This effect was not abolished by the coincubation with ICI 182,780. Raloxifene inhibited Kv4.3 channels by interacting with their open state during depolarization and with the closed state at subthreshold potentials. This effect was not mediated via an estrogen receptor.
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Affiliation(s)
- Yun Ju Chae
- Department of Physiology, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701, South Korea
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Lee HJ, Sung KW, Hahn SJ. Effects of haloperidol on Kv4.3 potassium channels. Eur J Pharmacol 2014; 740:1-8. [PMID: 24998874 DOI: 10.1016/j.ejphar.2014.06.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 06/23/2014] [Accepted: 06/24/2014] [Indexed: 11/16/2022]
Abstract
Haloperidol is commonly used in clinical practice to treat acute and chronic psychosis, but it also has been associated with adverse cardiovascular events. We investigated the effects of haloperidol on Kv4.3 currents stably expressed in CHO cells using a whole-cell patch-clamp technique. Haloperidol did not significantly inhibit the peak amplitude of Kv4.3, but accelerated the decay rate of inactivation of Kv4.3 in a concentration-dependent manner. Thus, the effects of haloperidol on Kv4.3 were estimated from the integral of the Kv4.3 currents during the depolarization pulse. The Kv4.3 was decreased by haloperidol in a concentration-dependent manner with an IC50 value of 3.6 μM. Haloperidol accelerated the decay rate of Kv4.3 inactivation and activation kinetics in a concentration-dependent manner, thereby decreasing the time-to-peak. Haloperidol shifted the voltage dependence of the steady-state activation and inactivation of Kv4.3 in a hyperpolarizing direction. Haloperidol also caused an acceleration of the closed-state inactivation of Kv4.3. Haloperidol produced a use-dependent block of Kv4.3, which was accompanied by a slowing of recovery from the inactivation of Kv4.3. These results suggest that haloperidol blocks Kv4.3 by both interacting with the open state of Kv4.3 channels during depolarization and accelerating the closed-state inactivation at subthreshold membrane potentials.
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Affiliation(s)
- Hong Joon Lee
- Department of Pharmacology, Cell Death and Disease Research Center, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, , Seoul 137-701, Republic of Korea
| | - Ki-Wug Sung
- Department of Pharmacology, Cell Death and Disease Research Center, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, , Seoul 137-701, Republic of Korea.
| | - Sang June Hahn
- Department of Physiology, Cell Death and Disease Research Center, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701, Republic of Korea.
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Hong DH, Son YK, Li H, Jung ID, Park YM, Jung WK, Kim HS, Choi IW, Park WS. The calmodulin inhibitor and antipsychotic drug trifluoperazine inhibits voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells. Biochem Biophys Res Commun 2014; 443:321-5. [DOI: 10.1016/j.bbrc.2013.11.115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 11/26/2013] [Indexed: 10/25/2022]
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Park MH, Son YK, Hong DH, Choi IW, Kim DJ, Lee H, Bang H, Na SH, Li H, Jo SH, Park WS. The Ca2+ channel inhibitor efonidipine decreases voltage-dependent K+ channel activity in rabbit coronary arterial smooth muscle cells. Vascul Pharmacol 2013; 59:90-5. [DOI: 10.1016/j.vph.2013.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/12/2013] [Accepted: 07/12/2013] [Indexed: 12/22/2022]
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33
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Effect of mosapride on Kv4.3 potassium channels expressed in CHO cells. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:905-16. [DOI: 10.1007/s00210-013-0896-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/11/2013] [Indexed: 11/24/2022]
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34
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Hong DH, Choi IW, Son YK, Kim DJ, Na SH, Jung WK, Yoon YW, Park WS. The effect of PI3 kinase inhibitor LY294002 on voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells. Life Sci 2013; 92:916-22. [DOI: 10.1016/j.lfs.2013.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/21/2013] [Accepted: 03/15/2013] [Indexed: 10/27/2022]
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35
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Jeong I, Choi JS, Hahn SJ. Effects of fluoxetine on cloned Kv4.3 potassium channels. Brain Res 2013; 1500:10-8. [DOI: 10.1016/j.brainres.2013.01.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/16/2013] [Indexed: 11/28/2022]
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36
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Long Y, Lin Z, Xia M, Zheng W, Li Z. Mechanism of HERG potassium channel inhibition by tetra-n-octylammonium bromide and benzethonium chloride. Toxicol Appl Pharmacol 2013; 267:155-66. [PMID: 23313619 DOI: 10.1016/j.taap.2012.12.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/12/2012] [Accepted: 12/28/2012] [Indexed: 10/27/2022]
Abstract
Tetra-n-octylammonium bromide and benzethonium chloride are synthetic quaternary ammonium salts that are widely used in hospitals and industries for the disinfection and surface treatment and as the preservative agent. Recently, the activities of HERG channel inhibition by these compounds have been found to have potential risks to induce the long QT syndrome and cardiac arrhythmia, although the mechanism of action is still elusive. This study was conducted to investigate the mechanism of HERG channel inhibition by these compounds by using whole-cell patch clamp experiments in a CHO cell line stably expressing HERG channels. Tetra-n-octylammonium bromide and benzethonium chloride exhibited concentration-dependent inhibitions of HERG channel currents with IC(50) values of 4nM and 17nM, respectively, which were also voltage-dependent and use-dependent. Both compounds shifted the channel activation I-V curves in a hyperpolarized direction for 10-15mV and accelerated channel activation and inactivation processes by 2-fold. In addition, tetra-n-octylammonium bromide shifted the inactivation I-V curve in a hyperpolarized direction for 24.4mV and slowed the rate of channel deactivation by 2-fold, whereas benzethonium chloride did not. The results indicate that tetra-n-octylammonium bromide and benzethonium chloride are open-channel blockers that inhibit HERG channels in the voltage-dependent, use-dependent and state-dependent manners.
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Affiliation(s)
- Yan Long
- Key Laboratory of Regenerative Biology, Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
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37
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Xu XH, Sun HY, Zhang YH, Wu W, Chen KH, Liu Y, Deng CY, Yu XY, Jin MW, Li GR. Allitridi inhibits multiple cardiac potassium channels expressed in HEK 293 cells. PLoS One 2012; 7:e51550. [PMID: 23272117 PMCID: PMC3522701 DOI: 10.1371/journal.pone.0051550] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 11/02/2012] [Indexed: 02/02/2023] Open
Abstract
Allitridi (diallyl trisulfide) is an active compound (volatile oil) from garlic. The previous studies reported that allitridi had anti-arrhythmic effect. The potential ionic mechanisms are, however, not understood. The present study was designed to determine the effects of allitridi on cardiac potassium channels expressed in HEK 293 cells using a whole-cell patch voltage-clamp technique and mutagenesis. It was found that allitridi inhibited hKv4.3 channels (IC50 = 11.4 µM) by binding to the open channel, shifting availability potential to hyperpolarization, and accelerating closed-state inactivation of the channel. The hKv4.3 mutants T366A, T367A, V392A, and I395A showed a reduced response to allitridi with IC50s of 35.5 µM, 44.7 µM, 23.7 µM, and 42.4 µM. In addition, allitridi decreased hKv1.5, hERG, hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells with IC50s of 40.2 µM, 19.6 µM and 17.7 µM. However, it slightly inhibited hKir2.1 current (100 µM, inhibited by 9.8% at −120 mV). Our results demonstrate for the first time that allitridi preferably blocks hKv4.3 current by binding to the open channel at T366 and T367 of P-loop helix, and at V392 and I395 of S6 domain. It has a weak inhibition of hKv1.5, hERG, and hKCNQ1/hKCNE1 currents. These effects may account for its anti-arrhythmic effect observed in experimental animal models.
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Affiliation(s)
- Xiao-Hui Xu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hai-Ying Sun
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Yan-Hui Zhang
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Wei Wu
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Kui-Hao Chen
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yi Liu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chun-Yu Deng
- Research Centre, Guangdong General Hospital, Guangzhou, China
| | - Xi-Yong Yu
- Research Centre, Guangdong General Hospital, Guangzhou, China
| | - Man-Wen Jin
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- * E-mail: (GRL); (MWJ)
| | - Gui-Rong Li
- Department of Medicine, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
- Department of Physiology, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China
- * E-mail: (GRL); (MWJ)
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Yang T, Smith JA, Leake BF, Sanders CR, Meiler J, Roden DM. An allosteric mechanism for drug block of the human cardiac potassium channel KCNQ1. Mol Pharmacol 2012. [PMID: 23193163 DOI: 10.1124/mol.112.081513] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The intracellular aspect of the sixth transmembrane segment within the ion-permeating pore is a common binding site for many voltage-gated ion channel blockers. However, the exact site(s) at which drugs bind remain controversial. We used extensive site-directed mutagenesis coupled with molecular modeling to examine mechanisms in drug block of the human cardiac potassium channel KCNQ1. A total of 48 amino acid residues in the S6 segment, S4-S5 linker, and the proximal C-terminus of the KCNQ1 channel were mutated individually to alanine; alanines were mutated to cysteines. Residues modulating drug block were identified when mutant channels displayed <50% block on exposure to drug concentrations that inhibited wild-type current by ≥90%. Homology modeling of the KCNQ1 channel based on the Kv1.2 structure unexpectedly predicted that the key residue modulating drug block (F351) faces away from the permeating pore. In the open-state channel model, F351 lines a pocket that also includes residues L251 and V254 in S4-S5 linker. Docking calculations indicated that this pocket is large enough to accommodate quinidine. To test this hypothesis, L251A and V254A mutants were generated that display a reduced sensitivity to blockage with quinidine. Thus, our data support a model in which open state block of this channel occurs not via binding to a site directly in the pore but rather by a novel allosteric mechanism: drug access to a side pocket generated in the open-state channel configuration and lined by S6 and S4-S5 residues.
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Affiliation(s)
- Tao Yang
- John Oates Institute for Experimental Therapeutics, Departments of Medicine, Pharmacology and Center for Structural Biology, Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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Hong DH, Son YK, Choi IW, Park WS. The inhibitory effect of curcumin on voltage-dependent K⁺ channels in rabbit coronary arterial smooth muscle cells. Biochem Biophys Res Commun 2012; 430:307-12. [PMID: 23146635 DOI: 10.1016/j.bbrc.2012.10.132] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 10/31/2012] [Indexed: 11/19/2022]
Abstract
We investigated the effects of curcumin, the principal active compound of turmeric, on voltage-dependent K(+) (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells using the voltage-clamp technique. Curcumin reduced the Kv current in a dose-dependent manner with an apparent K(d) value of 1.07 ± 0.03 μM. Although curcumin did not alter the kinetics of Kv current activation, it predominantly accelerated the decay rate of channel inactivation. The association and dissociation rate constants of curcumin were 1.35 ± 0.05 μM(-1)s(-1) and 1.47 ± 0.17s(-1), respectively. Curcumin did not alter the steady-state activation or inactivation curves. Application of train pulses (1 or 2 Hz) increased curcumin-induced blockade of the Kv current, and the recovery time constant also increased in the presence of curcumin suggesting, that the inhibitory action of Kv currents by curcumin was use-dependent. From these results, we concluded that curcumin inhibited vascular Kv current in a state-, time-, and use-dependent manner.
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Affiliation(s)
- Da Hye Hong
- Department of Physiology, Kangwon National University School of Medicine, 1 Kangwondaehak-gil, Chuncheon 200-701, South Korea
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Zhou Q, Bett GCL, Rasmusson RL. Markov models of use-dependence and reverse use-dependence during the mouse cardiac action potential. PLoS One 2012; 7:e42295. [PMID: 22879935 PMCID: PMC3412869 DOI: 10.1371/journal.pone.0042295] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 07/02/2012] [Indexed: 11/18/2022] Open
Abstract
The fast component of the cardiac transient outward current, IKtof, is blocked by a number of drugs. The major molecular bases of IKtof are Kv4.2/Kv4.3 voltage-gated potassium channels. Drugs with similar potencies but different blocking mechanisms have differing effects on action potential duration (APD). We used in silico analysis to determine the effect of IKtof-blocking drugs with different blocking mechanisms on mouse ventricular myocytes. We used our existing mouse model of the action potential, and developed 4 new Markov formulations for IKtof, IKtos, IKur, IKs. We compared effects of theoretical IKtof-specific channel blockers: (1) a closed state, and (2) an open channel blocker. At concentrations lower or close to IC50, the drug which bound to the open state always had a much greater effect on APD than the drug which bound to the closed state. At concentrations much higher than IC50, both mechanisms had similar effects at very low pacing rates. However, an open state binding drug had a greater effect on APD at faster pacing rates, particularly around 10 Hz. In summary, our data indicate that drug effects on APD are strongly dependent not only on IC50, but also on the drug binding state.
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Affiliation(s)
- Qinlian Zhou
- Center for Cellular and Systems Electrophysiology, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Physiology and Biophysics, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Biomedical Engineering, State University of New York, University at Buffalo, Buffalo, New York, United States of America
| | - Glenna C. L. Bett
- Center for Cellular and Systems Electrophysiology, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Physiology and Biophysics, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Gynecology-Obstetrics, State University of New York, University at Buffalo, Buffalo, New York, United States of America
| | - Randall L. Rasmusson
- Center for Cellular and Systems Electrophysiology, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Physiology and Biophysics, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- Biomedical Engineering, State University of New York, University at Buffalo, Buffalo, New York, United States of America
- * E-mail:
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41
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Jeong I, Choi BH, Hahn SJ. Pergolide block of the cloned Kv1.5 potassium channels. Naunyn Schmiedebergs Arch Pharmacol 2012; 386:125-33. [DOI: 10.1007/s00210-012-0776-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 06/22/2012] [Indexed: 02/04/2023]
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42
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Son YK, Hong DH, Choi TH, Choi SW, Shin DH, Kim SJ, Jung ID, Park YM, Jung WK, Kim DJ, Choi IW, Park WS. The inhibitory effect of BIM (I) on L-type Ca²⁺ channels in rat ventricular cells. Biochem Biophys Res Commun 2012; 423:110-5. [PMID: 22634012 DOI: 10.1016/j.bbrc.2012.05.091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 02/04/2023]
Abstract
We investigated the effect of a specific protein kinase C (PKC) inhibitor, bisindolylmaleimide I [BIM (I)], on L-type Ca(2+) channels in rat ventricular myocytes. BIM (I) alone inhibited the L-type Ca(2+) current in a concentration-dependent manner, with a K(d) value of 3.31 ± 0.25 μM, and a Hill coefficient of 2.34 ± 0.23. Inhibition was immediate after applying BIM (I) in the bath solution and then it partially washed out. The steady-state activation curve was not altered by applying 3μ M BIM (I), but the steady-state inactivation curve shifted to a more negative potential with a change in the slope factor. Other PKC inhibitors, PKC-IP and chelerythrine, showed no significant effects either on the L-type Ca(2+) current or on the inhibitory effect of BIM (I) on the L-type Ca(2+) current. The results suggest that the inhibitory effect of BIM (I) on the L-type Ca(2+) current is independent of the PKC pathway. Thus, our results should be considered in studies using BIM (I) to inhibit PKC activity and ion channel modulation.
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Affiliation(s)
- Youn Kyoung Son
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Republic of Korea
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Valenzuela C, Moreno C, de la Cruz A, Macías Á, Prieto Á, González T. Stereoselective Interactions between Local Anesthetics and Ion Channels. Chirality 2012; 24:944-50. [DOI: 10.1002/chir.22051] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/14/2012] [Accepted: 02/28/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
| | - Cristina Moreno
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
| | - Alicia de la Cruz
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
| | - Álvaro Macías
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
| | - Ángela Prieto
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
| | - Teresa González
- Instituto de Investigaciones Biomédicas Alberto Sols; Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid; Madrid; Spain
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Jeong I, Kim SW, Yoon SH, Hahn SJ. Block of cloned Kv4.3 potassium channels by dapoxetine. Neuropharmacology 2012; 62:2261-6. [DOI: 10.1016/j.neuropharm.2011.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 12/05/2011] [Accepted: 12/07/2011] [Indexed: 11/30/2022]
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Choi JS, Hahn SJ. Duloxetine blocks cloned Kv4.3 potassium channels. Brain Res 2012; 1466:15-23. [PMID: 22618310 DOI: 10.1016/j.brainres.2012.05.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 05/14/2012] [Indexed: 12/31/2022]
Abstract
The effects of duloxetine were examined on cloned Kv4.3 channels stably expressed in CHO cells using the whole-cell patch-clamp technique. Duloxetine decreased the peak amplitude of Kv4.3 currents with an acceleration of the decay rate of current inactivation in a concentration-dependent manner. The IC(50) values required for the blocking effects of duloxetine on the peak amplitude and the integral of currents were 8.4 and 2.1μM, respectively. Duloxetine accelerated the rate of inactivation of Kv4.3 currents and thereby decreased the time-to-peak in a concentration-dependent manner. Analysis of the time dependence of the drug block produced estimates of 21.9μM(-1)s(-1) and 165.9s(-1), for the respective association (k(+1)) and dissociation (k(-1)) rate constants. The K(d) value (k(-1)/k(+1)) yielded 7.5μM, which approximates the experimental IC(50) value obtained from the concentration-response curve. The block of Kv4.3 by duloxetine was voltage-dependent at a membrane potential coinciding with the activation of the channels. At a more positive potential, however, the block was relieved. Duloxetine produced a hyperpolarizing shift in the voltage dependence of the steady-state inactivation of Kv4.3, and accelerated the closed-state inactivation of Kv4.3 in the subthreshold voltage range. Duloxetine induced a significant use-dependent block at frequencies of 1 and 2Hz. In the presence of duloxetine, the recovery from inactivation was slower than under control conditions. These results demonstrate that duloxetine exerts a concentration-dependent block of Kv4.3 by binding to the channels in the open and inactivated states and these actions may contribute to its analgesic effect in neuropathic pain.
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Affiliation(s)
- Jin-Sung Choi
- College of Pharmacy, Integrated Research Institute of Pharmaceutical, The Catholic University of Korea, 43-1 Yeokgok 2-dong, Wonmi-gu, Bucheon, Gyeonggi-do, Republic of Korea
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Jeong I, Yoon SH, Hahn SJ. Effects of dapoxetine on cloned Kv1.5 channels expressed in CHO cells. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:707-16. [PMID: 22538641 DOI: 10.1007/s00210-012-0754-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Accepted: 04/10/2012] [Indexed: 11/25/2022]
Abstract
The effects of dapoxetine were examined on cloned Kv1.5 channels stably expressed in Chinese hamster ovary cells using the whole-cell patch clamp technique. Dapoxetine decreased the peak amplitude of Kv1.5 currents and accelerated the decay rate of current inactivation in a concentration-dependent manner with an IC ( 50 ) of 11.6 μM. Kinetic analysis of the time-dependent effects of dapoxetine on Kv1.5 current decay yielded the apparent association (k (+1 )) and dissociation (k (-1 )) rate constants of 2.8 μM(-1) s(-1) and 34.2 s(-1), respectively. The theoretical K ( D ) value, derived by k (-1 )/k (+1 ), yielded 12.3 μM, which was reasonably similar to the IC ( 50 ) value obtained from the concentration-response curve. Dapoxetine decreased the tail current amplitude and slowed the deactivation process of Kv1.5, which resulted in a tail crossover phenomenon. The block by dapoxetine is voltage-dependent and steeply increased at potentials between -10 and +10 mV, which correspond to the voltage range of channel activation. At more depolarized potentials, a weaker voltage dependence was observed (δ=0.31). Dapoxetine had no effect on the steady-state activation of Kv1.5 but shifted the steady-state inactivation curves in a hyperpolarizing direction. Dapoxetine produced a use-dependent block of Kv1.5 at frequencies of 1 and 2 Hz and slowed the time course for recovery of inactivation. These effects were reversible after washout of the drug. Our results indicate that dapoxetine blocks Kv1.5 currents by interacting with the channel in both the open and inactivated states of the channel.
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Affiliation(s)
- Imju Jeong
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, South Korea
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Jeong I, Choi BH, Yoon SH, Hahn SJ. Carvedilol blocks the cloned cardiac Kv1.5 channels in a β-adrenergic receptor-independent manner. Biochem Pharmacol 2012; 83:497-505. [PMID: 22146582 DOI: 10.1016/j.bcp.2011.11.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/21/2011] [Accepted: 11/21/2011] [Indexed: 10/14/2022]
Abstract
Carvedilol, a non-selective β-adrenergic blocker, is widely used for the treatment of angina pectoris and hypertension. We examined the action of carvedilol on cloned Kv1.5 expressed in CHO cells, using the whole-cell patch clamp technique. Carvedilol reduced the peak amplitude of Kv1.5 and accelerated the inactivation rate in a concentration-dependent manner with an IC50 of 2.56 μM. Using a first-order kinetics analysis, we calculated k(+1) = 19.68 μM(-1)s(-1) for the association rate constant, and k(-1) = 44.89 s(-1) for the dissociation rate constant. The apparent K(D) (k(-1)/k(+1)) was 2.28 μM, which is similar to the IC50 value. Other β-adrenergic blockers (alprenolol, oxprenolol and carteolol) had little or no effect on Kv1.5 currents. Carvedilol slowed the deactivation time course, resulting in a tail crossover phenomenon. Carvedilol-induced block was voltage-dependent in the voltage range for channel activation, but voltage-independent in the voltage range for full activation. The voltage dependences for both steady-state activation and inactivation were unchanged by carvedilol. Carvedilol affected Kv1.5 in a use-dependent manner. When stimulation frequencies were increased to quantify a use-dependent block, however, the block by carvedilol was slightly increased with IC50 values of 2.56 μM at 0.1 Hz, 2.38 μM at 1 Hz and 2.03 μM at 2 Hz. Carvedilol also slowed the time course of recovery from inactivation of Kv1.5. These results indicate that carvedilol blocks Kv1.5 in a reversible, concentration-, voltage-, time-, and use-dependent manner, but only at concentrations slightly higher than therapeutic plasma concentrations in humans. These effects are probably relevant to an understanding of the ionic mechanism underlying the antiarrhythmic property of carvedilol.
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Affiliation(s)
- Imju Jeong
- Department of Physiology, Medical Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
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Hong DH, Yang D, Choi IW, Son YK, Jung WK, Kim DJ, Han J, Na SH, Park WS. The T-type Ca2+ Channel Inhibitor Mibefradil Inhibits Voltage-Dependent K+ Channels in Rabbit Coronary Arterial Smooth Muscle Cells. J Pharmacol Sci 2012; 120:196-205. [DOI: 10.1254/jphs.12104fp] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Jeong I, Choi BH, Hahn SJ. Rosiglitazone inhibits Kv4.3 potassium channels by open-channel block and acceleration of closed-state inactivation. Br J Pharmacol 2011; 163:510-20. [PMID: 21232039 DOI: 10.1111/j.1476-5381.2011.01210.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Rosiglitazone is a widely used oral hypoglycaemic agent, which improves insulin resistance in type 2 diabetes. Chronic rosiglitazone treatment is associated with a number of adverse cardiac events. The present study was designed to characterize the effects of rosiglitazone on cloned K(v)4.3 potassium channels. EXPERIMENTAL APPROACH The interaction of rosiglitazone with cloned K(v)4.3 channels stably expressed in Chinese hamster ovary cells was investigated using whole-cell patch-clamp techniques. KEY RESULTS Rosiglitazone decreased the currents carried by K(v)4.3 channels and accelerated the current inactivation, concentration-dependently, with an IC(50) of 24.5 µM. The association and dissociation rate constants for rosiglitazone were 1.22 µM(-1)·s(-1) and 31.30 s(-1) respectively. Block by rosiglitazone was voltage-dependent, increasing in the voltage range for channel activation; however, no voltage dependence was found in the voltage range required for full activation. Rosiglitazone had no effect on either the deactivation kinetics or the steady-state activation of K(v)4.3 channels. Rosiglitazone shifted the steady-state inactivation curves in the hyperpolarizing direction, concentration-dependently. The K(i) for the interaction between rosiglitazone and the inactivated state of K(v)4.3 channels was 1.49 µM, from the concentration-dependent shift in the steady-state inactivation curves. Rosiglitazone also accelerated the kinetics of the closed-state inactivation of K(v)4.3 channels. Rosiglitazone did not affect either use dependence or recovery from inactivation of K(v)4.3 currents. CONCLUSION AND IMPLICATIONS Our results indicate that rosiglitazone potently inhibits currents carried by K(v)4.3 channels by interacting with these channels in the open state and by accelerating the closed-state inactivation of K(v)4.3 channels.
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Affiliation(s)
- I Jeong
- Department of Physiology, Medical Research Centre, College of Medicine, The Catholic University of Korea, Seoul, Korea
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Son YK, Hong DH, Kim DJ, Firth AL, Park WS. Direct effect of protein kinase C inhibitors on cardiovascular ion channels. BMB Rep 2011; 44:559-65. [DOI: 10.5483/bmbrep.2011.44.9.559] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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