1
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Dos Santos DR, Fiais GA, Oliveira HA, Ribas TB, Souza RO, Tsosura TVS, Matsushita DH, Ervolino E, Dornelles RCM, Nakamune ACDMS, Chaves-Neto AH. Assessment of redox state and biochemical parameters of salivary glands in rats treated with anti-obesity drug sibutramine hydrochloride. Clin Oral Investig 2022; 26:5833-5846. [PMID: 35556176 DOI: 10.1007/s00784-022-04539-1] [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: 08/31/2021] [Accepted: 05/04/2022] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To investigate the effects of anti-obesity drug sibutramine hydrochloride (SB) on redox state and biochemical parameters in the salivary glands. MATERIALS AND METHODS Adult male Wistar rats were randomly divided into the following groups (n = 8 per group): control rats treated with vehicle (C) and rats treated with SB (10 mg/kg/day) by intragastric gavage for 28 days. The parotid (PG) and submandibular (SMG) glands were processed using histomorphometric analysis, and total protein, amylase, mucin, and oxidative damage to lipids were determined by measuring the formation of thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), uric acid (UA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and AKT phosphorylation. RESULTS SB decreased the acinar area, and increased the stromal area in PG, while no effect on the morphometric parameters was observed in SMG. SB also increased oxidative damage to lipids (TBARs). The SB group showed lower total protein, amylase, TAC, UA, tGSH, SOD, CAT, and GPx than the C group in PG, while in SMG, SB decreased total protein, mucin, tGSH, SOD, CAT, and GPx. However, increased AKT phosphorylation observed in both salivary glands suggests that SB exerts low-intensity oxidative stress. CONCLUSIONS SB impaired enzymatic and non-enzymatic antioxidant defenses in the salivary glands of rats. CLINICAL RELEVANCE Chronic treatment with SB could mitigate salivary gland dysfunction due to disturbance of redox state.
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Affiliation(s)
- Damáris Raissa Dos Santos
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Gabriela Alice Fiais
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Henrique Arnaldo Oliveira
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil
| | - Tayná Buffulin Ribas
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil
| | - Rayne Oliveira Souza
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil
| | - Thaís Verônica Saori Tsosura
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Doris Hissako Matsushita
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Edilson Ervolino
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil
| | - Rita Cássia Menegati Dornelles
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Ana Cláudia de Melo Stevanato Nakamune
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil.,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil
| | - Antonio Hernandes Chaves-Neto
- Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Rodovia Marechal Rondon, km 527/528, Aracatuba, São Paulo, CEP 16018-805, Brazil. .,Programa de Pós-Graduação Multicêntrico Em Ciências Fisiológicas-SBFIs, Department of Basic Sciences, School of Dentistry of Araçatuba- UNESP - Universidade Estadual Paulista, Aracatuba, São Paulo, Brazil.
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2
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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3
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Park J, Cho KH, Lee HJ, Choi JS, Rhie DJ. Open channel block of Kv1.4 potassium channels by aripiprazole. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2020; 24:545-553. [PMID: 33093275 PMCID: PMC7585592 DOI: 10.4196/kjpp.2020.24.6.545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 10/07/2020] [Accepted: 10/07/2020] [Indexed: 11/15/2022]
Abstract
Aripiprazole is a quinolinone derivative approved as an atypical antipsychotic drug for the treatment of schizophrenia and bipolar disorder. It acts as with partial agonist activities at the dopamine D2 receptors. Although it is known to be relatively safe for patients with cardiac ailments, less is known about the effect of aripiprazole on voltage-gated ion channels such as transient A-type K+ channels, which are important for the repolarization of cardiac and neuronal action potentials. Here, we investigated the effects of aripiprazole on Kv1.4 currents expressed in HEK293 cells using a whole-cell patch-clamp technique. Aripiprazole blocked Kv1.4 channels in a concentration-dependent manner with an IC50 value of 4.4 μM and a Hill coefficient of 2.5. Aripiprazole also accelerated the activation (time-to-peak) and inactivation kinetics. Aripiprazole induced a voltage-dependent (δ = 0.17) inhibition, which was use-dependent with successive pulses on Kv1.4 currents without altering the time course of recovery from inactivation. Dehydroaripiprazole, an active metabolite of aripiprazole, inhibited Kv1.4 with an IC50 value of 6.3 μM (p < 0.05 compared with aripiprazole) with a Hill coefficient of 2.0. Furthermore, aripiprazole inhibited Kv4.3 currents to a similar extent in a concentration-dependent manner with an IC50 value of 4.9 μM and a Hill coefficient of 2.3. Thus, our results indicate that aripiprazole blocked Kv1.4 by preferentially binding to the open state of the channels.
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Affiliation(s)
- Jeaneun Park
- Department of Physiology, 3Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Kwang-Hyun Cho
- Department of Physiology, 3Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Hong Joon Lee
- Department of Physiology, 3Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Jin-Sung Choi
- College of Pharmacy, Integrated Research Institute of Pharmaceutical, The Catholic University of Korea, Bucheon 14662, Korea
| | - Duck-Joo Rhie
- Department of Physiology, 3Catholic Neuroscience Institute, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
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Bassetto Junior CAZ, Passianoto LVG, González ERP, Varanda WA. Benzenesulfonamides act as open-channel blockers on K V3.1 potassium channel. Amino Acids 2019; 51:355-364. [PMID: 30361851 DOI: 10.1007/s00726-018-2669-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Accepted: 10/19/2018] [Indexed: 10/28/2022]
Abstract
KV3.1 blockers can serve as modulators of the rate of action potential firing in neurons with high rates of firing such as those of the auditory system. We studied the effects of several bioisosteres of N-alkylbenzenesulfonamides, and molecules derived from sulfanilic acid on KV3.1 channels, heterologously expressed in L-929 cells, using the whole-cell patch-clamp technique. Only the N-alkyl-benzenesulfonamides acted as open-channel blockers on KV3.1, while molecules analogous to PABA (p-aminobenzoic acid) and derived from sulfanilic acids did not block the channel. The IC50 of six N-alkyl-benzenesulfonamides ranged from 9 to 55 µM; and the Hill coefficient suggests the binding of two molecules to block KV3.1. Also, the effects of all molecules on KV3.1 were fully reversible. We look for similar features amongst the molecules that effectively blocked the channel and used them to model a blocker prototype. We found that bulkier groups and amino-lactams decreased the effectiveness of the blockage, while the presence of NO2 increased the effectiveness of the blockage. Thus, we propose N-alkylbenzenesulfonamides as a new class of KV3.1 channel blockers.
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Affiliation(s)
- Carlos Alberto Zanutto Bassetto Junior
- Fine Organic Chemistry Laboratory, Department of Chemistry and Biochemistry, Faculty of Science and Technology, São Paulo State University (Unesp)-Campus of Presidente Prudente, São Paulo, SP, CEP 19060-900, Brazil
| | - Luana Vitorino Gushiken Passianoto
- Fine Organic Chemistry Laboratory, Department of Chemistry and Biochemistry, Faculty of Science and Technology, São Paulo State University (Unesp)-Campus of Presidente Prudente, São Paulo, SP, CEP 19060-900, Brazil
| | - Eduardo René Pérez González
- Fine Organic Chemistry Laboratory, Department of Chemistry and Biochemistry, Faculty of Science and Technology, São Paulo State University (Unesp)-Campus of Presidente Prudente, São Paulo, SP, CEP 19060-900, Brazil.
| | - Wamberto Antonio Varanda
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
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5
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Bassetto Junior CAZ, Varanda WA, González ERP. 4-Chloro-3-nitro-N-butylbenzenesulfonamide acts on K V3.1 channels by an open-channel blocker mechanism. Amino Acids 2017; 49:1895-1906. [PMID: 28900735 DOI: 10.1007/s00726-017-2488-0] [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: 06/14/2017] [Accepted: 09/07/2017] [Indexed: 12/01/2022]
Abstract
The effects of 4-chloro-3-nitro-N-butylbenzenesulfonamide (SMD2) on KV3.1 channels, heterologous expressed in L-929 cells, were studied with the whole cell patch-clamp technique. SMD2 blocks KV3.1 in a reversible and use-dependent manner, with IC50 around 10 µM, and a Hill coefficient around 2. Although the conductance vs. voltage relationship in control condition can be described by a single Boltzmann function, two terms are necessary to describe the data in the presence of SMD2. The activation and deactivation time constants are weakly voltage dependent both for control and in the presence of SMD2. SMD2 does not change the channel selectivity and tail currents show a typical crossover phenomenon. The time course of inactivation has a fast and a slow component, and SMD2 significantly decreased their values. Steady-state inactivation is best described by a Boltzmann equation with V 1/2 (the voltage where the probability to find the channels in the inactivated state is 50%) and K (slope factor) equals to -22.9 ± 1.5 mV and 5.3 ± 0.9 mV for control, and -30.3 ± 1.3 mV and 6 ± 0.8 mV for SMD2, respectively. The action of SMD2 is enhanced by high frequency stimulation, and by the time the channel stays open. Taken together, our results suggest that SMD2 blocks the open conformation of KV3.1. From a pharmacological and therapeutic point of view, N-alkylsulfonamides may constitute a new class of pharmacological modulators of KV3.1.
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Affiliation(s)
- Carlos Alberto Zanutto Bassetto Junior
- Fine Organic Chemistry Laboratory, Department of Chemistry and Biochemistry, Faculty of Science and Technology, São Paulo State University (Unesp)-Campus of Presidente Prudente, Presidente Prudente, SP, Brazil. .,Post-Graduate Program in Science and Material Technology, Presidente Prudente, SP, Brazil.
| | - Wamberto Antonio Varanda
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Eduardo René Pérez González
- Fine Organic Chemistry Laboratory, Department of Chemistry and Biochemistry, Faculty of Science and Technology, São Paulo State University (Unesp)-Campus of Presidente Prudente, Presidente Prudente, SP, Brazil.,Post-Graduate Program in Science and Material Technology, Presidente Prudente, SP, Brazil
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6
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Chen L, Tuo B, Dong H. Regulation of Intestinal Glucose Absorption by Ion Channels and Transporters. Nutrients 2016; 8:nu8010043. [PMID: 26784222 PMCID: PMC4728656 DOI: 10.3390/nu8010043] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/18/2015] [Accepted: 01/06/2016] [Indexed: 12/14/2022] Open
Abstract
The absorption of glucose is electrogenic in the small intestinal epithelium. The major route for the transport of dietary glucose from intestinal lumen into enterocytes is the Na+/glucose cotransporter (SGLT1), although glucose transporter type 2 (GLUT2) may also play a role. The membrane potential of small intestinal epithelial cells (IEC) is important to regulate the activity of SGLT1. The maintenance of membrane potential mainly depends on the activities of cation channels and transporters. While the importance of SGLT1 in glucose absorption has been systemically studied in detail, little is currently known about the regulation of SGLT1 activity by cation channels and transporters. A growing line of evidence suggests that cytosolic calcium ([Ca2+]cyt) can regulate the absorption of glucose by adjusting GLUT2 and SGLT1. Moreover, the absorption of glucose and homeostasis of Ca2+ in IEC are regulated by cation channels and transporters, such as Ca2+ channels, K+ channels, Na+/Ca2+ exchangers, and Na+/H+ exchangers. In this review, we consider the involvement of these cation channels and transporters in the regulation of glucose uptake in the small intestine. Modulation of them may be a potential strategy for the management of obesity and diabetes.
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Affiliation(s)
- Lihong Chen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
| | - Hui Dong
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
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7
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Cheikh A, Benkhalifa R, Landoulsi Z, Chatti I, Ayeb ME. Inhibition of human Kv3.1 current expressed in Xenopus oocytes by the toxic venom fraction of Androctonus australis hector. Arch Pharm Res 2013; 37:1445-53. [PMID: 23771502 DOI: 10.1007/s12272-013-0176-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 06/03/2013] [Indexed: 10/26/2022]
Abstract
AahG50, the toxic fraction of Androctonus australis hector venom, was studied on human Kv3.1 channels activation, stably expressed in Xenopus oocytes using the two-electrode voltage clamp technique. AahG50 reduced Kv3.1 currents in a reversible concentration-dependent manner, with an IC50 value and a Hill coefficient of 40.4 ± 0.2 μg/ml and 1.3 ± 0.05, respectively. AahG50 inhibited IKv3.1 without modifying the current activation kinetics. The AahG50-induced inhibition of Kv3.1 channels was voltage-dependent, with a gradual increase at lower concentrations and over the voltage range of channels opening. However, at higher concentrations, the inhibition exhibited voltage dependence only in the first range of channels opening from -20 to +10 mV, but demonstrates a low degree of voltage-dependence when channels are fully activated. In the literature, toxins have previously been isolated from AahG50, KAaH1 and KAaH2 and were reported not to have any effect on IKv3.1. The present article's findings suggest that AahG50 may contain a peptidic component active on Kv3.1 channels, which inhibits IKv3.1 in a selective manner.
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Affiliation(s)
- Amani Cheikh
- Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis, BP 74, 1002, Tunis, Tunisia,
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8
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Borges CS, Missassi G, Pacini ESA, Kiguti LRA, Sanabria M, Silva RF, Banzato TP, Perobelli JE, Pupo AS, Kempinas WG. Slimmer or fertile? Pharmacological mechanisms involved in reduced sperm quality and fertility in rats exposed to the anorexigen sibutramine. PLoS One 2013; 8:e66091. [PMID: 23776614 PMCID: PMC3680400 DOI: 10.1371/journal.pone.0066091] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/01/2013] [Indexed: 11/29/2022] Open
Abstract
Sperm acquire motility and fertility capacity during epididymal transit, under the control of androgens and sympathetic innervations. It is already known that the acceleration of epididymal sperm transit time can lead to lower sperm quality. In a previous work we showed that rats exposed to the anorexigen sibutramine, a non-selective serotonin-norepinephrine reuptake inhibitor, presented faster sperm transit time, lower epididymal sperm reserves and potentiation of the tension of epididymal duct to norepinephrine exposed acutely in vitro to sibutramine. In the present work we aimed to further investigate pharmacological mechanisms involved in these alterations and the impact on rat sperm quality. For this, adult male Wistar rats were treated with sibutramine (10 mg/kg/day) or vehicle for 30 days. Sibutramine decreased final body, seminal vesicle, ventral prostate and epididymal weights, as well as sperm transit time in the epididymal cauda. On the contrary of the in vitro pharmacological assays, in which sibutramine was added directly to the bath containing strips of distal epididymal cauda, the ductal tension was not altered after in vivo sub-chronic exposure to sibutramine. However, there is pharmacological evidence that the endogenous epididymal norepinephrine reserves were reduced in these animals. It was also shown that the decrease in prostate weight can be related to increased tension developed of the gland, due to sibutramine sympathomimetic effects. In addition, our results showed reduced sperm quality after in utero artificial insemination, a more sensitive procedure to assess fertility in rodents. The epididymal norepinephrine depletion exerted by sibutramine, associated with decreases in sperm transit time, quantity and quality, leading to reduced fertility in this experimental model, reinforces the concerns about the possible impact on fertility of man taking sibutramine as well as other non-selective serotonin-norepinephrine reuptake inhibitors, especially considering the lower reproductive efficiency of humans compared to males of other species.
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Affiliation(s)
- Cibele S. Borges
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Gabriela Missassi
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Enio S. A. Pacini
- Department of Pharmacology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Luiz Ricardo A. Kiguti
- Department of Pharmacology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Marciana Sanabria
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Raquel F. Silva
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Thais P. Banzato
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Juliana E. Perobelli
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - André S. Pupo
- Department of Pharmacology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Wilma G. Kempinas
- Department of Morphology, Institute of Biosciences, UNESP - Univ Estadual Paulista, Botucatu, São Paulo, Brazil
- * E-mail:
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9
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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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10
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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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11
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Liu Y, Xu XH, Liu Z, Du XL, Chen KH, Xin X, Jin ZD, Shen JZ, Hu Y, Li GR, Jin MW. Effects of the natural flavone trimethylapigenin on cardiac potassium currents. Biochem Pharmacol 2012; 84:498-506. [PMID: 22583923 DOI: 10.1016/j.bcp.2012.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 04/30/2012] [Accepted: 05/01/2012] [Indexed: 11/17/2022]
Abstract
The natural flavones and polymethylflavone have been reported to have cardiovascular protective effects. In the present study, we determined whether quecertin, apigenin and their methylated compounds (3,7,3',4'-tetramethylquecertin, 3,5,7,3',4'-pentamethylquecertin, 7,4'-dimethylapigenin, and 5,7,4'-trimethylapigenin) would block the atrial specific potassium channel hKv1.5 using a whole-cell patch voltage-clamp technique. We found that only trimethylapigenin showed a strong inhibitory effect on hKv1.5 channel current. This compound suppressed hKv1.5 current in HEK 293 cell line (IC₅₀=6.4 μM), and the ultra-rapid delayed rectify K⁺ current I(Kur) in human atrial myocytes (IC₅₀=8.0 μM) by binding to the open channels and showed a use- and frequency-dependent manner. In addition, trimethylapigenin decreased transient outward potassium current (I(to)) in human atrial myocytes, inhibited acetylcholine-activated K⁺ current (IC₅₀=6.8μM) in rat atrial myocytes. Interestingly, trimethylapigenin had a weak inhibition of hERG channel current. Our results indicate that trimethyapigenin significantly inhibits the atrial potassium currents hKv1.5/I(Kur) and I(KACh), which suggests that trimethylapigenin may be a potential candidate for anti-atrial fibrillation.
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Affiliation(s)
- Yi Liu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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12
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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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Zhan XQ, He YL, Yao JJ, Zhuang JL, Mei YA. The antidepressant citalopram inhibits delayed rectifier outward K+ current in mouse cortical neurons. J Neurosci Res 2011; 90:324-36. [DOI: 10.1002/jnr.22744] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 06/08/2011] [Accepted: 06/21/2011] [Indexed: 01/04/2023]
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Wu HJ, Wu W, Sun HY, Qin GW, Wang HB, Wang P, Yalamanchili HK, Wang J, Tse HF, Lau CP, Vanhoutte PM, Li GR. Acacetin causes a frequency- and use-dependent blockade of hKv1.5 channels by binding to the S6 domain. J Mol Cell Cardiol 2011; 51:966-73. [PMID: 21906601 DOI: 10.1016/j.yjmcc.2011.08.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/01/2011] [Accepted: 08/21/2011] [Indexed: 11/18/2022]
Abstract
We have demonstrated that the natural flavone acacetin selectively inhibits ultra-rapid delayed rectifier potassium current (I(Kur)) in human atria. However, molecular determinants of this ion channel blocker are unknown. The present study was designed to investigate the molecular determinants underlying the ability of acacetin to block hKv1.5 channels (coding I(Kur)) in human atrial myocytes using the whole-cell patch voltage-clamp technique to record membrane current in HEK 293 cells stably expressing the hKv1.5 gene or transiently expressing mutant hKv1.5 genes generated by site-directed mutagenesis. It was found that acacetin blocked hKv1.5 channels by binding to both closed and open channels. The blockade of hKv1.5 channels by acacetin was use- and frequency-dependent, and the IC(50) of acacetin for inhibiting hKv1.5 was 3.5, 3.1, 2.9, 2.1, and 1.7μM, respectively, at 0.2, 0.5, 1, 3, and 4Hz. The mutagenesis study showed that the hKv1.5 mutants V505A, I508A, and V512A in the S6-segment remarkably reduced the channel blocking properties by acacetin (IC(50), 29.5μM for V505A, 19.1μM for I508A, and 6.9μM for V512A). These results demonstrate the novel information that acacetin mainly blocks open hKv1.5 channels by binding to their S6 domain. The use- and rate-dependent blocking of hKv1.5 by acacetin is beneficial for anti-atrial fibrillation.
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Affiliation(s)
- Hui-Jun Wu
- Department and Medicine, Li Ka Shing Faculty of Medicine, the University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Kim HJ, Ahn HS, Choi BH, Hahn SJ. Inhibition of Kv4.3 by genistein via a tyrosine phosphorylation-independent mechanism. Am J Physiol Cell Physiol 2010; 300:C567-75. [PMID: 21148405 DOI: 10.1152/ajpcell.00031.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effects of genistein, a protein tyrosine kinase (PTK) inhibitor, on voltage-dependent K(+) (Kv) 4.3 channel were examined using the whole cell patch-clamp techniques. Genistein inhibited Kv4.3 in a reversible, concentration-dependent manner with an IC(50) of 124.78 μM. Other PTK inhibitors (tyrphostin 23, tyrphostin 25, lavendustin A) had no effect on genistein-induced inhibition of Kv4.3. Orthovanadate, an inhibitor of protein phosphatases, did not reverse the inhibition of Kv4.3 by genistein. We also tested the effects of two inactive structural analogs: genistin and daidzein. Whereas Kv4.3 was unaffected by genistin, daidzein inhibited Kv4.3, albeit with a lower potency. Genistein did not affect the activation and inactivation kinetics of Kv4.3. Genistein-induced inhibition of Kv4.3 was voltage dependent with a steep increase over the channel opening voltage range. In the full-activation voltage range positive to +20 mV, no voltage-dependent inhibition was found. Genistein had no significant effect on steady-state activation, but shifted the voltage dependence of the steady-state inactivation of Kv4.3 in the hyperpolarizing direction in a concentration-dependent manner. The K(i) for the interaction between genistein and the inactivated state of Kv4.3, which was estimated from the concentration-dependent shift in the steady-state inactivation curve, was 1.17 μM. Under control conditions, closed-state inactivation was fitted to a single exponential function, and genistein accelerated closed-state inactivation. Genistein induced a weak use-dependent inhibition. These results suggest that genistein directly inhibits Kv4.3 by interacting with the closed-inactivated state of Kv4.3 channels. This effect is not mediated via inhibition of the PTK activity, because other types of PTK inhibitors could not prevent the inhibitory action of genistein.
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Affiliation(s)
- Hee Jae Kim
- Dept. of Physiology, College of Medicine, The Catholic Univ. of Korea, 505 Banpo-dong, Socho-gu, Seoul 137-701, Korea
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He YL, Zhan XQ, Yang G, Sun J, Mei YA. Amoxapine inhibits the delayed rectifier outward K+ current in mouse cortical neurons via cAMP/protein kinase A pathways. J Pharmacol Exp Ther 2009; 332:437-45. [PMID: 19915071 DOI: 10.1124/jpet.109.159160] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ion channels are known to be modulated by antidepressant drugs, but the molecular mechanisms are not known. We have shown that the antidepressant drug amoxapine suppresses rectifier outward K(+) (I(K)) currents in mouse cortical neurons. At a concentration of 10 to 500 muM, amoxapine reversibly inhibited I(K) in a dose-dependent manner and modulated both steady-state activation and inactivation properties. The application of forskolin or dibutyryl cAMP mimicked the inhibitory effect of amoxapine on I(K) and abolished further inhibition by amoxapine. N-[2-(p-Bromocinnamylamino)ethyl]-5-iso-quinolinesulphonamide (H-89), a protein kinase A (PKA) inhibitor, augmented I(K) amplitudes and completely eliminated amoxapine inhibition of I(K). Amoxapine was also found to significantly increase intracellular cAMP levels. The effects of amoxapine on I(K) were abolished by preincubation with 5-hydroxytryptamine (5-HT) and the antagonists of 5-HT(2) receptor. Moreover, intracellular application of guanosine 5'-[gammathio]-triphosphate increased I(K) amplitudes and prevented amoxapine-induced inhibition. The selective Kv2.1 subunit blocker Jingzhaotoxin-III reduced I(K) amplitudes by 30% and also significantly abolished the inhibitory effect of amoxapine. Together these results suggest that amoxapine inhibits I(K) in mouse cortical neurons by cAMP/PKA-dependent pathway associated with the 5-HT receptor, and suggest that the Kv2.1 alpha-subunit may be the target for this inhibition.
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Affiliation(s)
- Yan-Lin He
- nstitutes of Brain Science, School of Life Sciences and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China
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Nojimoto FD, Piffer RC, Kiguti LRDA, Lameu C, de Camargo ACM, Pereira OCM, Pupo AS. Multiple effects of sibutramine on ejaculation and on vas deferens and seminal vesicle contractility. Toxicol Appl Pharmacol 2009; 239:233-40. [PMID: 19482040 DOI: 10.1016/j.taap.2009.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/19/2009] [Accepted: 05/22/2009] [Indexed: 11/25/2022]
Abstract
Sibutramine is an inhibitor of norepinephrine and 5-HT reuptake largely used in the management of obesity. Although a fairly safe drug, postmarketing adverse effects of sibutramine were reported including abnormal ejaculation in men. This study investigates the effects of sibutramine on ejaculation and vas deferens and seminal vesicle contractility. Adult male rats received sibutramine (5; 20; or 50 mg kg(-1), ip) and after 60 min were exposed to receptive females for determination of ejaculation parameters. The vasa deferentia and seminal vesicles of untreated rats were mounted in isolated organ baths for recording of isometric contractions and HEK293 cells loaded with fluorescent calcium indicator were used to measure intracellular Ca(2+) transients. Sibutramine 5 and 20 mg kg(-1) reduced ejaculation latency whereas 50 mg kg(-1) increased ejaculation latency. Sibutramine 3 to 30 microM greatly increased the sensitivity of the seminal vesicle and vas deferens to norepinephrine, but at concentrations higher than 10 microM there were striking depressions of maximal contractions induced by norepinephrine, carbachol and CaCl(2). In HEK293 cells, sibutramine 10 to 100 microM inhibited intracellular Ca(2+) transients induced by carbachol. Depending on the doses, sibutramine either facilitates or inhibits ejaculation. Apart from its actions in the central nervous system, facilitation of ejaculation may result from augmented sensitivity of smooth muscles to norepinephrine while reductions of intracellular Ca(2+) may be involved in the delayed ejaculation observed with high doses of sibutramine.
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Affiliation(s)
- Fernanda D Nojimoto
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, SP 18618000, Brazil
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Sodi R, Dubuis E, Shenkin A, Hart G. B-type natriuretic peptide (BNP) attenuates the L-type calcium current and regulates ventricular myocyte function. ACTA ACUST UNITED AC 2008; 151:95-105. [PMID: 18616964 DOI: 10.1016/j.regpep.2008.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 05/22/2008] [Accepted: 06/15/2008] [Indexed: 10/21/2022]
Abstract
A fundamental question in physiology is how hormones regulate the functioning of a cell or organ. It was therefore the aim of this study to investigate the effect(s) of BNP-32 on calcium handling by ventricular myocytes obtained from the rat left ventricle. We specifically tested the hypothesis that BNP-32 decreased the L-type calcium current (I(Ca,L)). Perforated patch clamp technique was used to record I(Ca,L) and action potential (AP) in voltage and current clamp mode, respectively. Myocyte shortening was measured using a photodiode array edge-detection system and intracellular calcium transients were measured by fluorescence photometry. Western blotting was used to determine the relative change in the expression of proteins. At the concentrations tested, BNP-32 significantly decreased cell shortening in a dose-dependent manner; increased the phase II slope of the AP by 53.0%; increased the APD(50) by 16.9%; reduced the I(Ca,L) amplitude with a 22.9% decrease in the peak amplitude and reduced Ca(2+)-dependent inactivation; increased the V(1/2) activation of the L-type calcium channel by 51.1% and decreased V(1/2) inactivation by 31.8%; and, intracellular calcium transient amplitude was significantly decreased by 32.0%, whereas the time to peak amplitude and T(1/2) were both significantly increased by 38.7% and 89.4% respectively. Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a) protein expression was reduced by BNP-32. These data suggest that BNP-32 regulates ventricular myocyte function by attenuating I(Ca,L), altering the AP and reducing SERCA2a activity and/or expression. This study suggests a novel constitutive mechanism for the autocrine action of BNP on the L-type calcium channel in ventricular myocytes.
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Affiliation(s)
- R Sodi
- Department of Clinical Biochemistry & Metabolic Medicine, Royal Liverpool & Broadgreen University Hospital, Prescot street, Liverpool L7 8XP, United Kingdom.
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Nerbonne JM, Gerber BR, Norris A, Burkhalter A. Electrical remodelling maintains firing properties in cortical pyramidal neurons lacking KCND2-encoded A-type K+ currents. J Physiol 2008; 586:1565-79. [PMID: 18187474 DOI: 10.1113/jphysiol.2007.146597] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Considerable experimental evidence has accumulated demonstrating a role for voltage-gated K(+) (Kv) channel pore-forming (alpha) subunits of the Kv4 subfamily in the generation of fast transient outward K(+), I(A), channels. Immunohistochemical data suggest that I(A) channels in hippocampal and cortical pyramidal neurons reflect the expression of homomeric Kv4.2 channels. The experiments here were designed to define directly the role of Kv4.2 in the generation of I(A) in cortical pyramidal neurons and to determine the functional consequences of the targeted deletion of Kv4.2 on the resting and active membrane properties of these cells. Whole-cell voltage-clamp recordings, obtained from visual cortical pyramidal neurons isolated from mice in which the KCND2 (Kv4.2) locus was disrupted (Kv4.2-/- mice), revealed that I(A) is indeed eliminated. In addition, the densities of other Kv current components, specifically I(K) and I(ss), are increased significantly (P < 0.001) in most ( approximately 80%) Kv4.2-/- cells. The deletion of KCND2 (Kv4.2) and the elimination of I(A) is also accompanied by the loss of the Kv4 channel accessory protein KChIP3, suggesting that in the absence of Kv4.2, the KChIP3 protein is targeted for degradation. The expression levels of several Kv alpha subunits (Kv4.3, Kv1.4, Kv2.1, Kv2.2), however, are not measurably altered in Kv4.2-/- cortices. Although I(A) is eliminated in Kv4.2-/- pyramidal neurons, the mean +/- s.e.m. current threshold for action potential generation and the waveforms of action potentials are indistinguishable from those recorded from wild-type cells. Repetitive firing is also maintained in Kv4.2-/- cortical pyramidal neurons, suggesting that the increased densities of I(K) and I(ss) compensate for the in vivo loss of I(A).
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Affiliation(s)
- Jeanne M Nerbonne
- Department of Molecular Biology and Pharmacology, Box 8103, Washington University Medical School, 660 South Euclid Avenue, St Louis, MO 63110-1093, USA.
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