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Hwang S, Yoon B, Jo SH. Inhibitory effects of N-methyl-D-aspartate (NMDA) and α 1-adrenergic receptor antagonist ifenprodil on human Kv1.5 channel. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:3149-3161. [PMID: 37166464 DOI: 10.1007/s00210-023-02521-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 05/04/2023] [Indexed: 05/12/2023]
Abstract
Ifenprodil has been known to reduce cardiac contractility and cerebral vasodilation by antagonizing α1-adrenergic and N-methyl D-aspartate receptor-mediated intracellular signals. This study aimed to investigate the direct effect of ifenprodil on the human voltage-gated Kv1.5 channel (hKv1.5) by using a Xenopus oocyte expression system and a two-microelectrode voltage clamp technique. The amplitudes of hKv1.5 currents, including peak and steady state, were suppressed in a concentration-dependent manner (IC50; 43.1 and 35.5 μM, respectively) after 6 min of ifenprodil treatment. However, these effects were ~ 80% reversed by washout, suggesting that ifenprodil directly inhibited the hKv1.5 independent of membrane receptors or intracellular signals. The inhibition rate of steady state showed voltage dependence, wherein the rates increased according to test voltage depolarization. Ifenprodil reduced the time constants of hKv1.5 inactivation but has higher effects on activation. hKv1.5 inhibition by ifenprodil showed use dependency because the drug more rapidly reduced the current at the higher activation frequencies, and subsequent reduction in frequency after high activation frequency caused a partial channel block relief. Therefore, ifenprodil directly blocked the hKv1.5 in an open state and accelerated the time course of the channel inactivation, which provided a biophysical mechanism for the hKv1.5 blocking effects of ifenprodil.
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Affiliation(s)
- Soobeen Hwang
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University College of Medicine, Hyoja-Dong, Chuncheon, 200-701, Korea
| | - Byeongjun Yoon
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University College of Medicine, Hyoja-Dong, Chuncheon, 200-701, Korea
| | - Su-Hyun Jo
- Department of Physiology, Institute of Bioscience and Biotechnology, BK21 plus Graduate Program, Kangwon National University College of Medicine, Hyoja-Dong, Chuncheon, 200-701, Korea.
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2
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Lee HM, Yoon SH, Kim MG, Hahn SJ, Choi BH. Effects of rosiglitazone, an antidiabetic drug, on Kv3.1 channels. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2023; 27:95-103. [PMID: 36575937 PMCID: PMC9806636 DOI: 10.4196/kjpp.2023.27.1.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/20/2022] [Accepted: 10/22/2022] [Indexed: 12/29/2022]
Abstract
Rosiglitazone is a thiazolidinedione-class antidiabetic drug that reduces blood glucose and glycated hemoglobin levels. We here investigated the interaction of rosiglitazone with Kv3.1 expressed in Chinese hamster ovary cells using the whole-cell patch-clamp technique. Rosiglitazone rapidly and reversibly inhibited Kv3.1 currents in a concentration-dependent manner (IC50 = 29.8 μM) and accelerated the decay of Kv3.1 currents without modifying the activation kinetics. The rosiglitazone-mediated inhibition of Kv3.1 channels increased steeply in a sigmoidal pattern over the voltage range of -20 to +30 mV, whereas it was voltage-independent in the voltage range above +30 mV, where the channels were fully activated. The deactivation of Kv3.1 current, measured along with tail currents, was also slowed by the drug. In addition, the steady-state inactivation curve of Kv3.1 by rosiglitazone shifts to a negative potential without significant change in the slope value. All the results with the use dependence of the rosiglitazone-mediated blockade suggest that rosiglitazone acts on Kv3.1 channels as an open channel blocker.
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Affiliation(s)
- Hyang Mi Lee
- Department of Pharmacology, Institute for Medical Sciences, Jeonbuk National University Medical School, Jeonju 54097, Korea
| | - Seong Han Yoon
- Department of Pharmacology, Institute for Medical Sciences, Jeonbuk National University Medical School, Jeonju 54097, Korea
| | - Min-Gul Kim
- 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,Correspondence Bok Hee Choi, E-mail:
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3
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Djillani A, Pietri M, Mazella J, Heurteaux C, Borsotto M. Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin. Pharmacol Ther 2018; 194:185-198. [PMID: 30291907 DOI: 10.1016/j.pharmthera.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Depression is a devastating mood disorder and a leading cause of disability worldwide. Depression affects approximately one in five individuals in the world and represents heavy economic and social burdens. The neurobiological mechanisms of depression are not fully understood, but evidence highlights the role of monoamine neurotransmitter balance. Several antidepressants (ADs) are marketed to treat depression and related mood disorders. However, despite their efficacy, they remain nonspecific and unsafe because they trigger serious adverse effects. Therefore, developing new molecules for new targets in depression has become a real necessity. Eight years ago, spadin was described as a natural peptide with AD properties. This 17-amino acid peptide blocks TREK-1 channels, an original target in depression. Compared to the classical AD drugs such as fluoxetine, which requires 3-4 weeks for the AD effect to manifest, spadin acts rapidly within only 4 days of treatment. The AD properties are associated with increased neurogenesis and synaptogenesis in the brain. Despite the advantages of this fast-acting AD, the in vivo stability is weak and does not last for >7 h. The present review summarizes different strategies such as retro-inverso strategy, cyclization, and shortening the spadin sequence that has led to the development and optimization of spadin as an AD. Shortened spadin analogs present increased inhibition potency for TREK-1, an improved AD activity, and prolonged in vivo bioavailability. Finally, we also discuss about other inhibitors of TREK-1 channels with a proven efficacy in treating depression in the clinic, such as fluoxetine.
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Affiliation(s)
- Alaeddine Djillani
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France; Université Côte d'Azur, CNRS, IPMC, France
| | - Mariel Pietri
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France; Université Côte d'Azur, CNRS, IPMC, France
| | - Jean Mazella
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France; Université Côte d'Azur, CNRS, IPMC, France
| | - Catherine Heurteaux
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France; Université Côte d'Azur, CNRS, IPMC, France
| | - Marc Borsotto
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France; Université Côte d'Azur, CNRS, IPMC, France.
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4
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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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5
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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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6
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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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7
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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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8
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Fujii M, Hayashi K, Ohya S, Yamamura H, Imaizumi Y. New screening system for selective blockers of voltage-gated K(+) channels using recombinant cell lines dying upon single action potential. J Pharmacol Sci 2013; 123:147-58. [PMID: 24096832 DOI: 10.1254/jphs.13063fp] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
To develop a simple screening system for blockers of voltage-gated Kv1.3 and Kv1.5 channels, new cell lines co-expressing mutated Nav1.5 (IFM/Q3), Kir2.1 (Kir), and Kv1.3 or Kv1.5 were introduced as IFM/Q3+Kir+Kv1.3 and IFM/Q3+Kir+Kv1.5, respectively. Electrical stimulation (ES) of a cell line, IFM/Q3+Kir, induced prolonged action potentials due to the slow inactivation of IFM/Q3 and subsequent cell death. Additional co-expression of Kv1.3 or Kv1.5 to IFM/Q3+Kir shortened the evoked action potentials and prevented cell death. In the presence of margatoxin, a selective Kv1.3-blocker, ES induced cell death in IFM/Q3+Kir+Kv1.3, but not in IFM/Q3+Kir+Kv1.5. In the presence of 4-aminopyridine, a non-selective Kv-channel blocker, ES application elicited cell death in both cell lines. The IC50s of acacetin, a Kv1.5-blocker, was 10.2 μM in IFM/Q3+Kir+Kv1.3 and almost identical to that in IFM/Q3+Kir+Kv1.5 (7.6 μM). The IC50s of citalopram, a 5-HT uptake-inhibitor, were 1.8 μM in IFM/Q3+Kir+Kv1.3 and 1.5 μM in IFM/Q3+Kir+Kv1.5, respectively. These IC50s were comparable to those determined electrophysiologically. In conclusion, acacetin and citalopram block both Kv1.3 and Kv1.5 without selectivity. The Kv1.3 or Kv1.5 channel inhibition assay using these new cell lines may be applicable to high-throughput screening because of its simplicity, accuracy, and high cost-performance.
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Affiliation(s)
- Masato Fujii
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Japan
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Chae YJ, Jeon JH, Lee HJ, Kim IB, Choi JS, Sung KW, Hahn SJ. Escitalopram block of hERG potassium channels. Naunyn Schmiedebergs Arch Pharmacol 2013; 387:23-32. [DOI: 10.1007/s00210-013-0911-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 08/21/2013] [Indexed: 01/25/2023]
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10
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Chae YJ, Choi JS, Hahn SJ. Inhibition of Kv4.3 potassium channels by trazodone. Naunyn Schmiedebergs Arch Pharmacol 2013; 386:711-9. [DOI: 10.1007/s00210-013-0870-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/08/2013] [Indexed: 11/28/2022]
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Cardamone L, Salzberg MR, O'Brien TJ, Jones NC. Antidepressant therapy in epilepsy: can treating the comorbidities affect the underlying disorder? Br J Pharmacol 2013; 168:1531-54. [PMID: 23146067 PMCID: PMC3605864 DOI: 10.1111/bph.12052] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 10/24/2012] [Accepted: 10/29/2012] [Indexed: 12/20/2022] Open
Abstract
There is a high incidence of psychiatric comorbidity in people with epilepsy (PWE), particularly depression. The manifold adverse consequences of comorbid depression have been more clearly mapped in recent years. Accordingly, considerable efforts have been made to improve detection and diagnosis, with the result that many PWE are treated with antidepressant drugs, medications with the potential to influence both epilepsy and depression. Exposure to older generations of antidepressants (notably tricyclic antidepressants and bupropion) can increase seizure frequency. However, a growing body of evidence suggests that newer ('second generation') antidepressants, such as selective serotonin reuptake inhibitors or serotonin-noradrenaline reuptake inhibitors, have markedly less effect on excitability and may lead to improvements in epilepsy severity. Although a great deal is known about how antidepressants affect excitability on short time scales in experimental models, little is known about the effects of chronic antidepressant exposure on the underlying processes subsumed under the term 'epileptogenesis': the progressive neurobiological processes by which the non-epileptic brain changes so that it generates spontaneous, recurrent seizures. This paper reviews the literature concerning the influences of antidepressants in PWE and in animal models. The second section describes neurobiological mechanisms implicated in both antidepressant actions and in epileptogenesis, highlighting potential substrates that may mediate any effects of antidepressants on the development and progression of epilepsy. Although much indirect evidence suggests the overall clinical effects of antidepressants on epilepsy itself are beneficial, there are reasons for caution and the need for further research, discussed in the concluding section.
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Affiliation(s)
- L Cardamone
- Department of Medicine (RMH), University of Melbourne, Melbourne, Victoria, Australia
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12
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Garg V, Sachse FB, Sanguinetti MC. Tuning of EAG K(+) channel inactivation: molecular determinants of amplification by mutations and a small molecule. ACTA ACUST UNITED AC 2012; 140:307-24. [PMID: 22930803 PMCID: PMC3434097 DOI: 10.1085/jgp.201210826] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ether-à-go-go (EAG) and EAG-related gene (ERG) K+ channels are close homologues but differ markedly in their gating properties. ERG1 channels are characterized by rapid and extensive C-type inactivation, whereas mammalian EAG1 channels were previously considered noninactivating. Here, we show that human EAG1 channels exhibit an intrinsic voltage-dependent slow inactivation that is markedly enhanced in rate and extent by 1–10 µM 3-nitro-N-(4-phenoxyphenyl) benzamide, or ICA105574 (ICA). This compound was previously reported to have the opposite effect on ERG1 channels, causing an increase in current magnitude by inhibition of C-type inactivation. The voltage dependence of 2 µM ICA-induced inhibition of EAG1 current was half-maximal at −73 mV, 62 mV negative to the half-point for channel activation. This finding suggests that current inhibition by the drug is mediated by enhanced inactivation and not open-channel block, where the voltage half-points for current inhibition and channel activation are predicted to overlap, as we demonstrate for clofilium and astemizole. The mutation Y464A in the S6 segment also induced inactivation of EAG1, with a time course and voltage dependence similar to that caused by 2 µM ICA. Several Markov models were investigated to describe gating effects induced by multiple concentrations of the drug and the Y464A mutation. Models with the smallest fit error required both closed- and open-state inactivation. Unlike typical C-type inactivation, the rate of Y464A- and ICA-induced inactivation was not decreased by external tetraethylammonium or elevated [K+]e. EAG1 channel inactivation introduced by Y464A was prevented by additional mutation of a nearby residue located in the S5 segment (F359A) or pore helix (L434A), suggesting a tripartite molecular model where interactions between single residues in S5, S6, and the pore helix modulate inactivation of EAG1 channels.
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Affiliation(s)
- Vivek Garg
- Department of Physiology, University of Utah, Salt Lake City, UT 84112, USA
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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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14
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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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Getz A, Xu F, Zaidi W, Syed NI. The antidepressant fluoxetine but not citalopram suppresses synapse formation and synaptic transmission between Lymnaea neurons by perturbing presynaptic and postsynaptic machinery. Eur J Neurosci 2011; 34:221-34. [DOI: 10.1111/j.1460-9568.2011.07757.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Li GR, Dong MQ. Pharmacology of Cardiac Potassium Channels. CARDIOVASCULAR PHARMACOLOGY - HEART AND CIRCULATION 2010; 59:93-134. [DOI: 10.1016/s1054-3589(10)59004-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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