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Kim JH, Hwang S, Park SI, Lee HJ, Jung YJ, Jo SH. 3,3',4,4'-tetrachlorobiphenyl (PCB77) enhances human Kv1.3 channel currents and alters cytokine production. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2024; 28:323-333. [PMID: 38926840 PMCID: PMC11211760 DOI: 10.4196/kjpp.2024.28.4.323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/15/2024] [Accepted: 04/18/2024] [Indexed: 06/28/2024]
Abstract
Polychlorinated biphenyls (PCBs) were once used throughout various industries; however, because of their persistence in the environment, exposure remains a global threat to the environment and human health. The Kv1.3 and Kv1.5 channels have been implicated in the immunotoxicity and cardiotoxicity of PCBs, respectively. We determined whether 3,3',4,4'-tetrachlorobiphenyl (PCB77), a dioxin-like PCB, alters human Kv1.3 and Kv1.5 currents using the Xenopus oocyte expression system. Exposure to 10 nM PCB77 for 15 min enhanced the Kv1.3 current by approximately 30.6%, whereas PCB77 did not affect the Kv1.5 current at concentrations up to 10 nM. This increase in the Kv1.3 current was associated with slower activation and inactivation kinetics as well as right-shifting of the steady-state activation curve. Pretreatment with PCB77 significantly suppressed tumor necrosis factor-α and interleukin-10 production in lipopolysaccharide-stimulated Raw264.7 macrophages. Overall, these data suggest that acute exposure to trace concentrations of PCB77 impairs immune function, possibly by enhancing Kv1.3 currents.
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Affiliation(s)
- Jong-Hui Kim
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
- Interdisciplinary Graduate Program in BIT Medical Convergence, Chuncheon 24341, Korea
| | - Soobeen Hwang
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
- Interdisciplinary Graduate Program in BIT Medical Convergence, Chuncheon 24341, Korea
| | - Seo-In Park
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
- Interdisciplinary Graduate Program in BIT Medical Convergence, Chuncheon 24341, Korea
| | - Hyo-Ji Lee
- Department of Biological Sciences and Kangwon Radiation Convergence Research Support Center, Kangwon National University, Chuncheon 24341, Korea
| | - Yu-Jin Jung
- Interdisciplinary Graduate Program in BIT Medical Convergence, Chuncheon 24341, Korea
- Department of Biological Sciences and Kangwon Radiation Convergence Research Support Center, Kangwon National University, Chuncheon 24341, Korea
| | - Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University School of Medicine, Chuncheon 24341, Korea
- Interdisciplinary Graduate Program in BIT Medical Convergence, Chuncheon 24341, Korea
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Kim JH, Hwang S, Jo SH. Non-dioxin-like polychlorinated biphenyl 19 has distinct effects on human Kv1.3 and Kv1.5 channels. Toxicol Appl Pharmacol 2020; 411:115365. [PMID: 33316272 DOI: 10.1016/j.taap.2020.115365] [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: 09/09/2020] [Revised: 11/25/2020] [Accepted: 12/08/2020] [Indexed: 10/22/2022]
Abstract
Polychlorinated biphenyls (PCBs) are persistent and serious organic pollutants and can theoretically form 209 congeners. PCBs can be divided into two categories: dioxin-like (DL) and non-DL (NDL). NDL-PCBs, which lack aryl hydrocarbon receptor affinity, have been shown to perturb the functions of Jurkat T cells, cerebellar granule cells, and uterine cells. Kv1.3 and Kv1.5 channels are important in immune and heart functions, respectively. We investigated the acute effects of 2,2',6-trichlorinated biphenyl (PCB19), an NDL-PCB, on the currents of human Kv1.3 and Kv1.5 channels. PCB19 acutely blocked the Kv1.3 peak currents concentration-dependently with an IC50 of ~2 μM, without changing the steady-state current. The PCB19-induced inhibition of the Kv1.3 peak current occurred rapidly and voltage-independently, and the effect was irreversible, excluding the possibility of genomic regulation. PCB19 increased the time constants of both activation and inactivation of Kv1.3 channels, resulting in the slowing down of both ultra-rapid activation and intrinsic inactivation. However, PCB19 failed to alter the steady-state curves of activation and inactivation. Regarding the Kv1.5 channel, PCB19 affected neither the peak current nor the steady-state current at the same concentrations tested in the Kv1.3 experiments, showing selective inhibition of PCB19 on the Kv1.3 than the Kv1.5. The presented data indicate that PCB19 could acutely affect the human Kv1.3 channel through a non-genomic mechanism, possibly causing toxic effects on various human physiological functions related to the Kv1.3 channel, such as immune and neural systems.
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Affiliation(s)
- Jong-Hui Kim
- Department of Physiology, Institute of Bioscience and Biotechnology, Interdisciplinary Graduate Program in BIT Medical Convergence, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Soobeen Hwang
- Department of Physiology, Institute of Bioscience and Biotechnology, Interdisciplinary Graduate Program in BIT Medical Convergence, Kangwon National University School of Medicine, Chuncheon 24341, South Korea
| | - Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Interdisciplinary Graduate Program in BIT Medical Convergence, Kangwon National University School of Medicine, Chuncheon 24341, South Korea.
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The effect of anti-emetic drugs on rat embryonic heart activity. Reprod Toxicol 2019; 87:140-145. [PMID: 31199962 DOI: 10.1016/j.reprotox.2019.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 06/05/2019] [Accepted: 06/10/2019] [Indexed: 02/07/2023]
Abstract
Nausea and vomiting of pregnancy (NVP) is the most common medical complaint during pregnancy affecting up to 70% of pregnant women worldwide. Some antiemetic medications (AEM) (droperidol, domperidone, granisetron, metoclopramide and trifluoperazine) used to treat NVP have the unwanted side effect of hERG blockade. The hERG potassium channel is essential for normal heart rhythm in both the adult human and the human and rat embryo. Animal studies show hERG blockade in the embryo causes bradycardia and arrhythmia leading to cardiovascular malformations and other birth defects. Whole rat embryo in vitro culture was used to determine the effect of the above listed AEM and meclizine on the heart rate of Gestational day 13 rat embryos. These embryos are similar in size and heart development to 5-6-week human embryo. The results showed that all of the AEMs caused a concentration-dependent bradycardia. Droperidol had the lowest margin of safety.
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Kim DH, Lee SJ, Hahn SJ, Choi JS. Trifluoperazine blocks the human cardiac sodium channel, Na v1.5, independent of calmodulin. Biochem Biophys Res Commun 2016; 479:584-589. [PMID: 27666479 DOI: 10.1016/j.bbrc.2016.09.115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 09/22/2016] [Indexed: 11/20/2022]
Abstract
Trifluoperazine is a phenothiazine derivative which is mainly used in the management of schizophrenia and also acts as a calmodulin inhibitor. We used the whole-cell patch-clamp technique to study the effects of trifluoperazine on human Nav1.5 (hNav1.5) currents expressed in HEK293 cells. The 50% inhibitory concentration of trifluoperazine was 15.5 ± 0.3 μM and the Hill coefficient was 2.7 ± 0.1. The effects of trifluoperazine on hNav1.5 were completely and repeatedly reversible after washout. Trifluoperazine caused depolarizing shifts in the activation and hyperpolarizing shifts in the steady-state inactivation of hNav1.5. Trifluoperazine also showed strong use-dependent inhibition of hNav1.5. The blockade of hNav1.5 currents by trifluoperazine was not affected by the whole cell dialysis of the calmodulin inhibitory peptide. Our results indicated that trifluoperazine blocks hNav1.5 current in concentration-, state- and use-dependent manners rather than via calmodulin inhibition.
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Affiliation(s)
- Dong-Hyun Kim
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Su-Jin Lee
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea
| | - Sang June Hahn
- Department of Physiology, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Jin-Sung Choi
- College of Pharmacy, The Catholic University of Korea, Bucheon, Gyeonggi-do, 14662, South Korea.
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Yu J, Park MH, Choi SY, Jo SH. Cortisone and hydrocortisone inhibit human Kv1.3 activity in a non-genomic manner. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:653-61. [PMID: 25743574 DOI: 10.1007/s00210-015-1109-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/18/2015] [Indexed: 11/24/2022]
Abstract
Glucocorticoids are hormones released in response to stress that are involved in various physiological processes including immune functions. One immune-modulating mechanism is achieved by the Kv1.3 voltage-dependent potassium channel, which is expressed highly in lymphocytes including effector memory T lymphocytes (TEM). Although glucocorticoids are known to inhibit Kv1.3 function, the detailed inhibitory mechanism is not yet fully understood. Here we studied the rapid non-genomic effects of cortisone and hydrocortisone on the human Kv1.3 channel expressed in Xenopus oocytes. Both cortisone and hydrocortisone reduced the amplitude of the Kv1.3 channel current in a concentration-dependent manner. Both cortisone and hydrocortisone rapidly and irreversibly inhibited Kv1.3 currents, eliminating the possibility of genomic regulation. Inhibition rate was stable relative to the degree of depolarization. Kinetically, cortisone altered the activating gate of Kv1.3 and hydrocortisone interacted with this channel in an open state. These results suggest that cortisone and hydrocortisone inhibit Kv1.3 currents via a non-genomic mechanism, providing a mechanism for the immunosuppressive effects of glucocorticoids.
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Affiliation(s)
- Jing Yu
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University College of Medicine, Hyoja-Dong, Chuncheon, 200-701, Republic of Korea
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Yu J, Park MH, Jo SH. Inhibitory effects of cortisone and hydrocortisone on human Kv1.5 channel currents. Eur J Pharmacol 2014; 746:158-66. [PMID: 25449034 DOI: 10.1016/j.ejphar.2014.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/31/2014] [Accepted: 11/07/2014] [Indexed: 01/23/2023]
Abstract
Glucocorticoids are the primary hormones that respond to stress and protect organisms from dangerous situations. The glucocorticoids hydrocortisone and its dormant form, cortisone, affect the cardiovascular system with changes such as increased blood pressure and cardioprotection. Kv1.5 channels play a critical role in the maintenance of cellular membrane potential and are widely expressed in pancreatic β-cells, neurons, myocytes, and smooth muscle cells of the pulmonary vasculature. We examined the electrophysiological effects of both cortisone and hydrocortisone on human Kv1.5 channels expressed in Xenopus oocytes using a two-microelectrode voltage clamp technique. Both cortisone and hydrocortisone rapidly and irreversibly suppressed the amplitude of Kv1.5 channel current with IC50 values of 50.2±4.2μM and 33.4±3.2μM, respectively, while sustained the current trace shape of Kv1.5 current. The inhibitory effect of cortisone on Kv1.5 decreased progressively from -10mV to +30mV, while hydrocortisone׳s inhibition of the channel did not change across the same voltage range. Both cortisone and hydrocortisone blocked Kv1.5 channel currents in a non-use-dependent manner and neither altered the channel׳s steady-state activation or inactivation curves. These results show that cortisone and hydrocortisone inhibited Kv1.5 channel currents differently, and that Kv1.5 channels were more sensitive to hydrocortisone than to cortisone.
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Affiliation(s)
- Jing Yu
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University School of Medicine, Chuncheon 200-701, Republic of Korea
| | - Mi-Hyeong Park
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University School of Medicine, Chuncheon 200-701, Republic of Korea
| | - Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University School of Medicine, Chuncheon 200-701, Republic of Korea.
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Chae YJ, Choi BH, Choi JS, Hahn SJ. Block of Kv4.3 potassium channel by trifluoperazine independent of CaMKII. Neurosci Lett 2014; 578:159-64. [PMID: 24993295 DOI: 10.1016/j.neulet.2014.06.045] [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: 03/26/2014] [Revised: 06/12/2014] [Accepted: 06/23/2014] [Indexed: 11/24/2022]
Abstract
Trifluoperazine, a trifluoro-methyl phenothiazine derivative, is widely used in the management of schizophrenia and related psychotic disorders. We studied the effects of trifluoperazine on Kv4.3 currents expressed in CHO cells using the whole-cell patch-clamp technique. Trifluoperazine blocked Kv4.3 in a concentration-dependent manner with an IC50 value of 8.0±0.4 μM and a Hill coefficient of 2.1±0.1. Trifluoperazine also accelerated the inactivation and activation (time-to-peak) kinetics in a concentration-dependent manner. The effects of trifluoperazine on Kv4.3 were completely reversible after washout. The effects of trifluoperazine were not affected by the pretreatment of KN93, which is another CaMKII inhibitor. In addition, the inclusion of CaMKII inhibitory peptide 281-309 in the pipette solution did not modify the effect of trifluoperazine on Kv4.3. Trifluoperazine shifted the activation curve of Kv4.3 in a hyperpolarizing direction but did not affect the slope factor. The block of Kv4.3 by trifluoperazine was voltage-dependent with a steep increase across the voltage range of channel activation. Voltage dependence was also observed over the full range of activation (δ=0.18). Trifluoperazine slowed the time course for recovery from inactivation of Kv4.3. Our results indicated that trifluoperazine blocked Kv4.3 by preferentially binding to the open state of the channel. This effect was not mediated via the inhibition of CaMKII activity.
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Affiliation(s)
- Yun Ju Chae
- Department of Physiology, Cell Death and Disease Research Center, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
| | - Bok Hee Choi
- Department of Pharmacology, Institute for Medical Science, Chonbuk National University Medical School, Jeonju, Jeonbuk 561-180, Republic of Korea
| | - 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
| | - Sang June Hahn
- Department of Physiology, Cell Death and Disease Research Center, College of Medicine, The Catholic University of Korea, 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, Lee SH, Chu DH, Won KH, Choi BH, Choe H, Jo SH. Effect of azelastine on cardiac repolarization of guinea-pig cardiomyocytes, hERG K⁺ channel, and human L-type and T-type Ca²⁺ channel. J Pharmacol Sci 2013; 123:67-77. [PMID: 24005046 DOI: 10.1254/jphs.12239fp] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Azelastine is a second generation histamine H₁-receptor antagonist used as an anti-asthmatic and anti-allergic drug that can induce QT prolongation and torsades de pointes. We investigated the acute effects of azelastine on human ether-a-go-go-related gene (hERG) channels, action potential duration (APD), and L-type (I(Ca,L)) and T-type Ca²⁺ current (I(Ca,T)) to determine the electrophysiological basis for its proarrhythmic potential. Azelastine increased the APD at 90% of repolarization concentration dependently, with an IC₅₀ of 1.08 nM in guinea-pig ventricular myocytes. We examined the effects of azelastine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Azelastine induced a concentration-dependent decrease of the hERG current amplitude at the end of the voltage steps and tail currents. The IC₅₀ for the azelastine-induced block of the hERG currents expressed in HEK293 cells was 11.43 nM, while the drug inhibited I(Ca,L) and I(Ca,T) with IC₅₀ values of 7.60 and 26.21 μM, respectively. The S6 domain mutations, Y652A partially attenuated and F656A abolished hERG current block. These results suggest that azelastine is a potent blocker of hERG channels rather than I(Ca,L) or I(Ca,T), providing molecular mechanisms for the arrhythmogenic side effects during the clinical administration of azelastine.
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Affiliation(s)
- Mi-Hyeong Park
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Korea
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van Doorn WG, Çelikel FG, Pak C, Harkema H. Delay of iris flower senescence by cytokinins and jasmonates. PHYSIOLOGIA PLANTARUM 2013; 148:105-20. [PMID: 22974423 DOI: 10.1111/j.1399-3054.2012.01690.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 07/10/2012] [Indexed: 05/18/2023]
Abstract
It is not known whether tepal senescence in Iris flowers is regulated by hormones. We applied hormones and hormone inhibitors to cut flowers and isolated tepals of Iris × hollandica cv. Blue Magic. Treatments with ethylene or ethylene antagonists indicated lack of ethylene involvement. Auxins or auxin inhibitors also did not change the time to senescence. Abscisic acid (ABA) hastened senescence, but an inhibitor of ABA synthesis (norflurazon) had no effect. Gibberellic acid (GA3 ) slightly delayed senescence in some experiments, but in other experiments it was without effect, and gibberellin inhibitors [ancymidol or 4-hydroxy-5-isopropyl-2-methylphenyltrimethyl ammonium chloride-1-piperidine carboxylate (AMO-1618)] were ineffective as well. Salicylic acid (SA) also had no effect. Ethylene, auxins, GA3 and SA affected flower opening, therefore did reach the flower cells. Jasmonates delayed senescence by about 2.0 days. Similarly, cytokinins delayed senescence by about 1.5-2.0 days. Antagonists of the phosphatidylinositol signal transduction pathway (lithium), calcium channels (niguldipine and verapamil), calmodulin action [fluphenazine, trifluoroperazine, phenoxybenzamide and N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide hydrochloride (W-7)] or protein kinase activity [1-(5-isoquinolinesulfonyl)-2-methylpiperazine hydrochloride (H-7), N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide hydrochloride (H-8) and N-(2-aminoethyl)-5-isoquinolinesulfonamide dihydrochloride (H-9)] had no effect on senescence, indicating no role of a few common signal transduction pathways relating to hormone effects on senescence. The results indicate that tepal senescence in Iris cv. Blue Magic is not regulated by endogenous ethylene, auxin, gibberellins or SA. A role of ABA can at present not be excluded. The data suggest the hypothesis that cytokinins and jasmonates are among the natural regulators.
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Affiliation(s)
- Wouter G van Doorn
- Agrotechnology and Food Sciences Group (AFSG), Wageningen University Research Centre, Wageningen, The Netherlands.
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Lee BH, Lee SH, Chu D, Hyun JW, Choe H, Choi BH, Jo SH. Effects of the histamine H(1) receptor antagonist hydroxyzine on hERG K(+) channels and cardiac action potential duration. Acta Pharmacol Sin 2011; 32:1128-37. [PMID: 21892192 DOI: 10.1038/aps.2011.66] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To investigate the effects of hydroxyzine on human ether-a-go-go-related gene (hERG) channels to determine the electrolphysiological basis for its proarrhythmic effects. METHODS hERG channels were expressed in Xenopus oocytes and HEK293 cells, and the effects of hydroxyzine on the channels were examined using two-microelectrode voltage-clamp and patch-clamp techniques, respectively. The effects of hydroxyzine on action potential duration were examined in guinea pig ventricular myocytes using current clamp. RESULTS Hydroxyzine (0.2 and 2 μmol/L) significantly increased the action potential duration at 90% repolarization (APD(90)) in both concentration- and time-dependent manners. Hydroxyzine (0.03-3 μmol/L) blocked both the steady-state and tail hERG currents. The block was voltage-dependent, and the values of IC(50) for blocking the steady-state and tail currents at +20 mV was 0.18±0.02 μmol/L and 0.16±0.01 μmol/L, respectively, in HEK293 cells. Hydroxyzine (5 μmol/L) affected both the activated and the inactivated states of the channels, but not the closed state. The S6 domain mutation Y652A attenuated the blocking of hERG current by ~6-fold. CONCLUSION The results suggest that hydroxyzine could block hERG channels and prolong APD. The tyrosine at position 652 in the channel may be responsible for the proarrhythmic effects of hydroxyzine.
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Jo SH, Lee SY. Response of i(kr) and HERG currents to the antipsychotics tiapride and sulpiride. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2010; 14:305-10. [PMID: 21165329 DOI: 10.4196/kjpp.2010.14.5.305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 09/07/2010] [Accepted: 09/14/2010] [Indexed: 11/15/2022]
Abstract
The human ether-a-go-go-related gene (hERG) channel is important for repolarization in human myocardium and is a common target for drugs that prolong the QT interval. We studied the effects of two antipsychotics, tiapride and sulpiride, on hERG channels expressed in Xenopus oocytes and also on delayed rectifier K(+) currents in guinea pig cardiomyocytes. Neither the amplitude of the hERG outward currents measured at the end of the voltage pulse, nor the amplitude of hERG tail currents, showed any concentration-dependent changes with either tiapride or sulpiride (3~300 µM). However, our findings did show that tiapride increased the potential for half-maximal activation (V(1/2)) of HERG at 10~300 µM, whereas sulpiride increased the maximum conductance (G(max)) at 3, 10 and 100 µM. In guinea pig ventricular myocytes, bath applications of 100 and 500 µM tiapride at 36℃ blocked rapidly activating delayed rectifier K(+) current (I(Kr)) by 40.3% and 70.0%, respectively. Also, sulpiride at 100 and 500 µM blocked I(Kr) by 38.9% and 76.5%, respectively. However, neither tiapride nor sulpiride significantly affected the slowly activating delayed rectifier K(+) current (I(Ks)) at the same concentrations. Our findings suggest that the concentrations of the antipsychotics required to evoke a 50% inhibition of I(Kr) are well above the reported therapeutic plasma concentrations of free and total compound.
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Affiliation(s)
- Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University School of Medicine, Chuncheon 200-701, Korea
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Polak S, Wiśniowska B, Brandys J. Collation, assessment and analysis of literature in vitro data on hERG receptor blocking potency for subsequent modeling of drugs' cardiotoxic properties. J Appl Toxicol 2009; 29:183-206. [PMID: 18988205 DOI: 10.1002/jat.1395] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The assessment of the torsadogenic potency of a new chemical entity is a crucial issue during lead optimization and the drug development process. It is required by the regulatory agencies during the registration process. In recent years, there has been a considerable interest in developing in silico models, which allow prediction of drug-hERG channel interaction at the early stage of a drug development process. The main mechanism underlying an acquired QT syndrome and a potentially fatal arrhythmia called torsades de pointes is the inhibition of potassium channel encoded by hERG (the human ether-a-go-go-related gene). The concentration producing half-maximal block of the hERG potassium current (IC(50)) is a surrogate marker for proarrhythmic properties of compounds and is considered a test for cardiac safety of drugs or drug candidates. The IC(50) values, obtained from data collected during electrophysiological studies, are highly dependent on experimental conditions (i.e. model, temperature, voltage protocol). For the in silico models' quality and performance, the data quality and consistency is a crucial issue. Therefore the main objective of our work was to collect and assess the hERG IC(50) data available in accessible scientific literature to provide a high-quality data set for further studies.
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Affiliation(s)
- Sebastian Polak
- Toxicology Department, Faculty of Pharmacy, Medical Collage, Jagiellonian University, Poland.
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Hong HK, Jo SH. Block of HERG k channel by classic histamine h(1) receptor antagonist chlorpheniramine. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2009; 13:215-20. [PMID: 19885040 DOI: 10.4196/kjpp.2009.13.3.215] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 06/08/2009] [Accepted: 06/19/2009] [Indexed: 11/15/2022]
Abstract
Chlorpheniramine is a potent first-generation histamine H(1) receptor antagonist that can increase action potential duration and induce QT prolongation in several animal models. Since block of cardiac human ether-a-go-go-related gene (hERG) channels is one of leading causes of acquired long QT syndrome, we investigated the acute effects of chlorpheniramine on hERG channels to determine the electrophysiological basis for its proarrhythmic potential. We examined the effects of chlorpheniramine on the hERG channels expressed in Xenopus oocytes using two-microelectrode voltage-clamp techniques. Chlorpheniramine induced a concentration-dependent decrease of the current amplitude at the end of the voltage steps and hERG tail currents. The IC(50) of chlorpheniramine-dependent hERG block in Xenopus oocytes decreased progressively relative to the degree of depolarization. Chlorpheniramine affected the channels in the activated and inactivated states but not in the closed states. The S6 domain mutations Y652A and F656A partially attenuated (Y652A) or abolished (F656A) the hERG current block. These results suggest that the H(1) antihistamine, chlorpheniramine is a blocker of the hERG channels, providing a molecular mechanism for the drug-induced arrhythmogenic side effects.
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Affiliation(s)
- Hee-Kyung Hong
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Chuncheon 200-701, Korea
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Jo SH, Hong HK, Chong SH, Lee HS, Choe H. H(1) antihistamine drug promethazine directly blocks hERG K(+) channel. Pharmacol Res 2009; 60:429-37. [PMID: 19497368 DOI: 10.1016/j.phrs.2009.05.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 05/24/2009] [Accepted: 05/25/2009] [Indexed: 12/01/2022]
Abstract
Promethazine is a phenothiazine derivative with antihistaminic (H(1)), sedative, antiemetic, anticholinergic, and antimotion sickness properties that can induce QT prolongation, which may lead to torsades de pointes. Since block of cardiac human ether-a-go-go-related gene (hERG) channels is one of the leading causes of acquired long QT syndrome, we investigated the acute effects of promethazine on hERG channels to determine the electrophysiological basis for its proarrhythmic potential. Promethazine increased the action potential duration at 90% of repolarization (APD(90)) in a concentration-dependent manner, with an IC(50) of 0.73microM when action potentials were elicited under current clamp in guinea pig ventricular myocytes. We examined the effects of promethazine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Promethazine induced a concentration-dependent decrease of the current amplitude at the end of the voltage steps and hERG tail currents. The IC(50) of promethazine dependent hERG block in Xenopus oocytes decreased progressively relative to the degree of depolarization. The IC(50) for the promethazine-induced block of the hERG currents in HEK293 cells at 36 degrees C was 1.46microM at +20mV. Promethazine affected the channels in the activated and inactivated states but not in the closed states. The S6 domain mutations, Y652A and F656A partially attenuated (Y652A) or abolished (F656A) the hERG current block. These results suggest that promethazine is a blocker of the hERG channels, providing a molecular mechanism for the arrhythmogenic side effects during the clinical administration of promethazine.
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Affiliation(s)
- Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Chuncheon, Republic of Korea.
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16
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Qin J, Zima AV, Porta M, Blatter LA, Fill M. Trifluoperazine: a rynodine receptor agonist. Pflugers Arch 2009; 458:643-51. [PMID: 19277699 DOI: 10.1007/s00424-009-0658-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 02/24/2009] [Indexed: 11/28/2022]
Abstract
Trifluoperazine (TFP), a phenothiazine, is a commonly used antipsychotic drug whose therapeutic effects are attributed to its central anti-adrenergic and anti-dopaminergic actions. However, TFP is also a calmodulin (CaM) antagonist and alters the Ca(2+) binding properties of calsequestrin (CSQ). The CaM and CSQ proteins are known modulators of sarcoplasmic reticulum (SR) Ca(2+) release in ventricular myocytes. We explored TFP actions on cardiac SR Ca(2+) release in cells and single type-2 ryanodine receptor (RyR2) channel activity in bilayers. In intact and permeabilized ventricular myocytes, TFP produced an initial activation of RyR2-mediated SR Ca(2+) release and over time depleted SR Ca(2+) content. At the single channel level, TFP or nortryptiline (NRT; a tricyclic antidepressant also known to modify CSQ Ca(2+) binding) increased the open probability (Po) of CSQ-free channels with an EC(50) of 5.2 microM or 8.9 microM (respectively). This Po increase was due to elevated open event frequency at low drug concentrations while longer mean open events sustained Po at higher drug concentrations. Activation of RyR2 by TFP occurred in the presence or absence of CaM. TFP may also inhibit SR Ca uptake as well as increase RyR2 opening. Our results suggest TFP and NRT can alter RyR2 function by interacting with the channel protein directly, independent of its actions on CSQ or CaM. This direct action may contribute to the clinical adverse cardiac side effects associated with these drugs.
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Affiliation(s)
- Jia Qin
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, 1750 W. Harrison Ave, Chicago, IL, 60612, USA
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17
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Plasmodium falciparum: Growth response to potassium channel blocking compounds. Exp Parasitol 2008; 120:280-5. [DOI: 10.1016/j.exppara.2008.07.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/23/2022]
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18
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Clomipramine block of the hERG K+ channel: Accessibility to F656 and Y652. Eur J Pharmacol 2008; 592:19-25. [DOI: 10.1016/j.ejphar.2008.06.094] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 06/19/2008] [Accepted: 06/27/2008] [Indexed: 11/23/2022]
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Jo SH, Hong HK, Chong SH, Choe H. Protriptyline block of the human ether-à-go-go-related gene (HERG) K+ channel. Life Sci 2008; 82:331-40. [PMID: 18191158 DOI: 10.1016/j.lfs.2007.12.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 11/30/2007] [Accepted: 12/04/2007] [Indexed: 11/18/2022]
Abstract
Protriptyline, a tricyclic antidepressant for psychiatric disorders, can induce prolonged QT, torsades de pointes, and sudden death. We studied the effects of protriptyline on human ether-à-go-go-related gene (HERG) channels expressed in Xenopus oocytes and HEK293 cells. Protriptyline induced a concentration-dependent decrease in current amplitudes at the end of the voltage steps and HERG tail currents. The IC(50) for protriptyline block of HERG current in Xenopus oocytes progressively decreased relative to the degree of depolarization, from 142.0 microM at -40 mV to 91.7 microM at 0 mV to 52.9 microM at +40 mV. The voltage dependence of the block could be fit with a monoexponential function, and the fractional electrical distance was estimated to be delta=0.93. The IC(50) for the protriptyline-induced blockade of HERG currents in HEK293 cells at 36 degrees C was 1.18 microM at +20 mV. Protriptyline affected channels in the activated and inactivated states, but not in the closed states. HERG blockade by protriptyline was use-dependent, exhibiting a more rapid onset and a greater steady-state block at higher frequencies of activation. Our findings suggest that inhibition of HERG currents may contribute to the arrhythmogenic side effects of protriptyline.
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Affiliation(s)
- Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Chuncheon 200-701, South Korea.
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20
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Stork D, Timin EN, Berjukow S, Huber C, Hohaus A, Auer M, Hering S. State dependent dissociation of HERG channel inhibitors. Br J Pharmacol 2007; 151:1368-76. [PMID: 17592502 PMCID: PMC2189824 DOI: 10.1038/sj.bjp.0707356] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Inhibition of HERG channels prolongs the ventricular action potential and the QT interval with the risk of torsade de pointes arrhythmias and sudden cardiac death. Many drugs induce greater inhibition of HERG channels when the cell membrane is depolarized frequently. The dependence of inhibition on the pulsing rate may yield different IC(50) values at different frequencies and thus affect the quantification of HERG channel block. We systematically compared the kinetics of HERG channel inhibition and recovery from block by 8 blockers at different frequencies. EXPERIMENTAL APPROACH HERG channels were expressed heterologously in Xenopus oocytes and currents were measured with the two-electrode voltage clamp technique. KEY RESULTS Frequency-dependent block was observed for amiodarone, cisapride, droperidol and haloperidol (group 1) whereas bepridil, domperidone, E-4031 and terfenadine (group 2) induced similar pulse-dependent block at all frequencies. With the group 1 compounds, HERG channels recovered from block in the presence of drug (recovery being voltage-dependent). No substantial recovery from block was observed with the second group of compounds. Washing out of bepridil, domperidone, E-4031 and terfenadine was substantially augmented by frequent pulsing. Mutation D540K in the HERG channel (which exhibits reopening at negative voltages) facilitated recovery from block by these compounds at -140 mV. CONCLUSION AND IMPLICATIONS Drug molecules dissociate at different rates from open and closed HERG channels ('use-dependent' dissociation). Our data suggest that apparently 'trapped' drugs (group 2) dissociated from the open channel state whereas group 1 compounds dissociated from open and resting states.
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Affiliation(s)
- D Stork
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
| | - E N Timin
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
| | - S Berjukow
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
| | - C Huber
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
| | - A Hohaus
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
| | - M Auer
- Novartis Institute for Biomedical Research Vienna Discovery Technologies, Innovative Screening Technologies Vienna, Austria
| | - S Hering
- Department of Pharmacology and Toxicology, University of Vienna Vienna, Austria
- Author for correspondence:
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Jo SH, Hong HK, Jung SJ, Chong SH, Yun JH, Koh YS, Choe H. Maprotiline block of the human ether-a-go-go-related gene (HERG) K+ channel. Arch Pharm Res 2007; 30:453-60. [PMID: 17489361 DOI: 10.1007/bf02980219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Maprotiline, an atypical antidepressant, can induce prolonged QT and torsades de pointes. We studied the effects of maprotiline on human ether-a-go-go-related gene (HERG) channels expressed in Xenopus oocytes and HEK293 cells. Maprotiline induced a concentration-dependent decrease in current amplitudes at the end of the voltage steps and tail currents of HERG. The V1/2 values in the absence and presence of 1-20 microM maprotiline were not significantly different, while the values decreased according to the concentrations of the drug at 50-300 microM. The IC50 for a maprotiline block of HERG current in Xenopus oocytes did not change according to depolarization; 39.5 +/- 3.2 microM at -40 mV and 43.6 +/- 2.8 microM at +40 mV. The block of HERG by maprotiline was examined after treatment of trinitrobenzene sulfonic acid (TNBS), an amino-group reagent that neutralizes the positively charged amino-groups of peptide N-terminal and lysine residues. TNBS inhibited the change of V1/2 values induced by 50-300 mM maprotiline, and aggravated the drug-induced gmax decrease. The IC50 for the maprotiline-induced blockade of HERG currents in HEK293 cells at 36 degrees C was 0.13 microM at +20 mV. Our findings suggest that the arrhythmogenic side effects of maprotiline are caused by a blockade of HERG and possibly by a blockade of delayed rectifier K+ channel.
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Affiliation(s)
- Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Chuncheon, Korea.
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Kim MD, Eun SY, Jo SH. Blockade of HERG human K+ channel and IKr of guinea pig cardiomyocytes by prochlorperazine. Eur J Pharmacol 2006; 544:82-90. [PMID: 16860311 DOI: 10.1016/j.ejphar.2006.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 05/27/2006] [Accepted: 06/02/2006] [Indexed: 11/19/2022]
Abstract
Prochlorperazine, a drug for the symptomatic control of nausea, vomiting and psychiatric disorders, can induce prolonged QT, torsades de pointes and sudden death. We studied the effects of prochlorperazine on human ether-a-go-go-related gene (HERG) channels expressed in Xenopus oocytes and also in the delayed rectifier K+ current of guinea pig cardiomyocytes. Prochlorperazine induced a concentration-dependent decrease in current amplitudes at the end of the voltage steps and tail currents of HERG. The IC50 for a prochlorperazine block of HERG current in Xenopus oocytes progressively decreased relative to the degree of depolarization, from 42.1 microM at -40 mV to 37.4 microM at 0 mV to 22.6 microM at +40 mV. The block of HERG by prochlorperazine was use-dependent, exhibiting a more rapid onset and a greater steady-state block at higher frequencies of activation, while there was partial relief of the block with reduced frequencies. In guinea pig ventricular myocytes, bath applications of 0.5 and 1 muM prochlorperazine at 36 degrees C blocked rapidly activating delayed rectifier K+ current by 38.9% and 76.5%, respectively, but did not significantly block slowly activating delayed rectifier K+ current. Our findings suggest that the arrhythmogenic side effects of prochlorperazine are caused by a blockade of HERG and the rapid component of the delayed rectifier K+ current rather than by a blockade of the slow component.
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Affiliation(s)
- Moon-Doo Kim
- Department of Psychiatry, Cheju National University College of Medicine, Jeju, Korea
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23
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Lee SY, Kim YJ, Kim KT, Choe H, Jo SH. Blockade of HERG human K+ channels and IKr of guinea-pig cardiomyocytes by the antipsychotic drug clozapine. Br J Pharmacol 2006; 148:499-509. [PMID: 16633353 PMCID: PMC1751795 DOI: 10.1038/sj.bjp.0706744] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 02/13/2006] [Accepted: 03/10/2006] [Indexed: 11/09/2022] Open
Abstract
Clozapine, a commonly used antipsychotic drug, can induce QT prolongation, which may lead to torsades de pointes and sudden death. To investigate the arrhythmogenic side effects of clozapine, we studied the impact of clozapine on human ether-a-go-go-related gene (HERG) channels expressed in Xenopus oocytes and HEK293 cells, and on the delayed rectifier K(+) currents of guinea-pig cardiomyocytes. Clozapine dose-dependently decreased the amplitudes of the currents at the end of voltage steps, and the tail currents of HERG. The IC(50) for the clozapine blockade of HERG currents in Xenopus oocytes progressively decreased relative to depolarization (39.9 microM at -40 mV, 28.3 microM at 0 mV and 22.9 microM at +40 mV), whereas the IC(50) for the clozapine-induced blockade of HERG currents in HEK293 cells at 36 degrees C was 2.5 microM at +20 mV. The clozapine-induced blockade of HERG currents was time dependent: the fractional current was 0.903 of the control at the beginning of the pulse, but declined to 0.412 after 4 s at a test potential of 0 mV. The clozapine-induced blockade of HERG currents was use-dependent, exhibiting more rapid onset and greater steady state blockade at higher frequencies of activation, with a partial relief of blockade observed when the frequency of activation was decreased. In guinea-pig ventricular myocytes held at 36 degrees C, treatment with 1 and 5 microM clozapine blocked the rapidly activating delayed rectifier K(+) current (I(Kr)) by 24.7 and 79.6%, respectively, but did not significantly block the slowly activating delayed rectifier K(+) current (I(Ks)). Our findings collectively suggest that blockade of HERG currents and I(Kr), but not I(Ks), may contribute to the arrhythmogenic side effects of clozapine.
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Affiliation(s)
- So-Young Lee
- Department of Life Science, Pohang University of Science and Technology, Pohang, Korea
| | - Young-Jin Kim
- Department of Physiology, Research Institute for Biomacromolecules, Ulsan University College of Medicine, Seoul 138-736, Korea
| | - Kyong-Tai Kim
- Department of Life Science, Pohang University of Science and Technology, Pohang, Korea
| | - Han Choe
- Department of Physiology, Research Institute for Biomacromolecules, Ulsan University College of Medicine, Seoul 138-736, Korea
| | - Su-Hyun Jo
- Department of Physiology, Cheju National University College of Medicine, Jeju 690-756, Korea
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Kim E, Tam M, Siems WF, Kang C. Effects of drugs with muscle-related side effects and affinity for calsequestrin on the calcium regulatory function of sarcoplasmic reticulum microsomes. Mol Pharmacol 2005; 68:1708-15. [PMID: 16141311 DOI: 10.1124/mol.105.016253] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The tight regulation of Ca2+ release to and clearance from the cytosol is essential for normal excitation-contraction coupling in both skeletal and cardiac muscles. Calsequestrin (CSQ) is one of the major components in the sarcoplasmic reticulum (SR) of both skeletal and cardiac muscle. Previously, we showed that several pharmaceutical drugs, such as phenothiazine derivatives, tricyclic antidepressants, anthracycline derivatives, and other hydrophobic compounds bind CSQ with K(d) values in the micromolar range and significantly reduce the Ca2+ binding capacity of cardiac CSQ (Mol Pharmacol 67:97-104, 2005). Because of its key role in Ca2+ regulation, this interference with CSQ function could well produce adverse physiological consequences and potentially be linked to the known muscle-related side effects of these drugs. To further understand the molecular mechanism of undesirable drug effects or adverse drug reactions among those compounds, we examined their effect on the SR microsome. The results clearly showed that these compounds affect Ca2+ release and reduce the total Ca2+ content of the purified SR microsomes, matching well with our previous results with purified recombinant CSQ. Liquid chromatography-mass spectrometry/mass spectrometry showed that the antipsychotic drug trifluoperazine penetrates well into the SR microsome as expected from the reported and calculated log S (aqueous solubility) and log P (partition coefficient) values among the phenothiazine derivatives. We therefore propose that a certain portion of the muscle-related (both cardiac and skeletal) complications of these drugs is caused by the altered Ca2+ regulation of the SR mediated by their adverse interaction with CSQ.
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Affiliation(s)
- Eunjung Kim
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4660, USA
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Yu Y, Yu BP, Wang FQ. Expression of ether-a-go-go-related gene in gastrointestinal tract of normal CD1 mice. Shijie Huaren Xiaohua Zazhi 2005; 13:1842-1845. [DOI: 10.11569/wcjd.v13.i15.1842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the expression of ether-a-go-go-related gene (ERG) mRNA and protein and its different distributions in the gastrointestinal tract of CD1 mice.
METHODS: The expression of ERG K+ current related protein was examined by immunohistochemistry and the expression of ERG mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization in the tissues of stomach, jejunum, ileum and colon from adult CD1 mice. Then the distribution of ERG was analyzed.
RESULTS: ERG was positively expressed in all the tissues of stomach, jejunum, ileum and colon. The positive cells mainly distributed in the muscular layer. A small number of positive cells distributed in the mucosa and chorion. The levels of ERG expression in stomach and colon were significantly higher than those in jejunum and ileum (4.30±0.95, 3.60±0.70 vs2.70±0.82, 2.30±1.06; P<0.05).
CONCLUSION: ERG is expressed in the gastrointestinal tract of CD1 mice. Furthermore, the expression is differential at different sites.
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