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Govindaiah G, Campbell PW, Guido W. Differential Distribution of Ca 2+ Channel Subtypes at Retinofugal Synapses. eNeuro 2020; 7:ENEURO. [PMID: 33097488 DOI: 10.1523/ENEURO.0293-20.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/06/2020] [Accepted: 10/20/2020] [Indexed: 02/06/2023] Open
Abstract
Retinofugal synapses serve as models for understanding how sensory signals from the periphery are relayed to the brain. Past studies have focused primarily on understanding the postsynaptic glutamatergic receptor subtypes involved in signal transmission, but the mechanisms underlying glutamate release at presynaptic retinal terminals remains largely unknown. Here we explored how different calcium (Ca2+) channel subtypes regulate glutamatergic excitatory synaptic transmission in two principal retinorecipient targets, the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) of the mouse. We used an in vitro slice preparation to record the synaptic responses of dLGN and SC neurons evoked by the electrical stimulation of optic tract (OT) fibers before and during the application of selective Ca2+ channel blockers. We found that synaptic responses to paired or repetitive OT stimulation were highly sensitive to extracellular levels of Ca2+ and to selective antagonists of voltage gated Ca2+ channels, indicating that these channels regulate the presynaptic release of glutamate at retinal synapses in both dLGN and SC. Bath application of selective Ca2+ channel blockers revealed that P/Q-type Ca2+ channels primarily operate to regulate glutamate release at retinal synapses in dLGN, while N-type Ca2+ channels dominate release in the SC.
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Goswami C, Dezaki K, Wang L, Inui A, Seino Y, Yada T. Ninjin'yoeito Targets Distinct Ca 2+ Channels to Activate Ghrelin-Responsive vs. Unresponsive NPY Neurons in the Arcuate Nucleus. Front Nutr 2020; 7:104. [PMID: 32766273 PMCID: PMC7379896 DOI: 10.3389/fnut.2020.00104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 06/08/2020] [Indexed: 12/22/2022] Open
Abstract
Appetite loss or anorexia substantially deteriorates quality of life in various diseases, and stand upstream of frailty. Neuropeptide Y (NPY) in the hypothalamic arcuate nucleus (ARC) and ghrelin released from stomach are potent inducers of appetite. We previously reported that Ninjin'yoeito, a Japanese kampo medicine comprising twelve herbs, restores food intake, and body weight in cisplatin-treated anorectic mice. Furthermore, Ninjin'yoeito increased cytosolic Ca2+ concentration ([Ca2+]i) in not only ghrelin-responsive but ghrelin-unresponsive NPY neurons in ARC. The cellular lineage/differentiation of ghrelin-unresponsive neuron is less defined but might alter along with aging and diet. This study examined the occupancy of ghrelin-unresponsive neurons among ARC NPY neurons in adult mice fed normal chow, and explored the mechanisms underlying Ninjin'yoeito-induced [Ca2+]i increases in ghrelin-unresponsive vs. ghrelin-responsive NPY neurons. Single ARC neurons were subjected to [Ca2+]i measurement and subsequent immunostaining for NPY. Ghrelin failed to increase [Ca2+]i in 42% of ARC NPY neurons. Ninjin'yoeito (10 μg/ml)-induced increases in [Ca2+]i were abolished in Ca2+ free condition in ghrelin-responsive and ghrelin-unresponsive ARC NPY neurons. Ninjin'yoeito-induced [Ca2+]i increases were inhibited by N-type Ca2+ channel blocker ω-conotoxin in the majority (17 of 20), while by L-type Ca2+ channel blocker nitrendipine in the minority (2 of 23), of ghrelin-responsive neurons. In contrast, Ninjin'yoeito-induced [Ca2+]i increases were inhibited by nitrendipine in the majority (14 of 17), while by ω-conotoxin in the minority (8 of 24), of ghrelin-unresponsive neurons. These results indicate that ghrelin-unresponsive neurons occur substantially among NPY neurons of ARC in adult mice fed normal chow. Ninjin'yoeito preferentially target N-type and L-type Ca2+ channels in the majority of ghrelin-responsive and ghrelin-unresponsive neurons, respectively, to increase [Ca2+]i. We suggest ARC N- and L-type Ca2+ channels as potential targets for activating, respectively, ghrelin-responsive, and unresponsive NPY neurons to treat anorexia.
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Affiliation(s)
- Chayon Goswami
- Division of Integrative Physiology, Center for Integrative Physiology, Kansai Electric Power Medical Research Institute, Kobe, Japan.,Division of Diabetes, Metabolism and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan.,Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan.,Department of Biochemistry and Molecular Biology, Bangladesh Agricultural University, Mymensingh, Bangladesh
| | - Katsuya Dezaki
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan.,Faculty of Pharmacy, Iryo Sosei University, Iwaki, Japan
| | - Lei Wang
- Division of Integrative Physiology, Center for Integrative Physiology, Kansai Electric Power Medical Research Institute, Kobe, Japan.,Division of Diabetes, Metabolism and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan.,Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Akio Inui
- Pharmacological Department of Herbal Medicine, Kagoshima University Graduate School of Medical & Dental Sciences, Kagoshima, Japan
| | - Yutaka Seino
- Division of Integrative Physiology, Center for Integrative Physiology, Kansai Electric Power Medical Research Institute, Kobe, Japan.,Center for Diabetes Research, Division of Diabetes and Endocrinology, Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Toshihiko Yada
- Division of Integrative Physiology, Center for Integrative Physiology, Kansai Electric Power Medical Research Institute, Kobe, Japan.,Division of Diabetes, Metabolism and Endocrinology, Kobe University Graduate School of Medicine, Kobe, Japan.,Division of Integrative Physiology, Department of Physiology, Jichi Medical University School of Medicine, Tochigi, Japan.,Pharmacological Department of Herbal Medicine, Kagoshima University Graduate School of Medical & Dental Sciences, Kagoshima, Japan
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Tajiri K, Guichard JB, Qi X, Xiong F, Naud P, Tardif JC, Costa AD, Aonuma K, Nattel S. An N-/L-type calcium channel blocker, cilnidipine, suppresses autonomic, electrical, and structural remodelling associated with atrial fibrillation. Cardiovasc Res 2020; 115:1975-1985. [PMID: 31119260 DOI: 10.1093/cvr/cvz136] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 03/18/2019] [Accepted: 05/16/2019] [Indexed: 12/15/2022] Open
Abstract
AIMS Autonomic dysfunction can promote atrial fibrillation (AF) and results from AF-related remodelling. N-type Ca2+-channels (NTCCs) at sympathetic nerve terminals mediate Ca2+-entry that triggers neurotransmitter release. AF-associated remodelling plays an important role in AF pathophysiology but the effects of NTCC inhibition on such remodelling is unknown. Here, we investigated the ability of a clinically available Ca2+-channel blocker (CCB) with NTCC-blocking activity to suppress the arrhythmogenic effects of AF-promoting remodelling in dogs. METHODS AND RESULTS Mongrel dogs were kept in AF by right atrial tachypacing at 600 bpm. Four groups were studied under short-term AF (7 days): (i) Shams, instrumented but without tachypacing (n = 5); (ii) a placebo group, tachypaced while receiving placebo (n = 6); (iii) a control tachypacing group receiving nifedipine (10 mg orally twice-daily; n = 5), an L-type CCB; and (iv) a cilnidipine group, subjected to tachypacing and treatment with cilnidipine (10 mg orally twice-daily; n = 7), an N-/L-type CCB. With cilnidipine therapy, dogs with 1-week AF showed significantly reduced autonomic changes reflected by heart rate variability (decreases in RMSSD and pNN50) and plasma norepinephrine concentrations. In addition, cilnidipine-treated dogs had decreased extracellular matrix gene expression vs. nifedipine-dogs. As in previous work, atrial fibrosis had not yet developed after 1-week AF, so three additional groups were studied under longer-term AF (21 days): (i) Shams, instrumented without tachypacing or drug therapy (n = 8); (ii) a placebo group, tachypaced while receiving placebo (n = 8); (iii) a cilnidipine group, subjected to tachypacing during treatment with cilnidipine (10 mg twice-daily; n = 8). Cilnidipine attenuated 3-week AF effects on AF duration and atrial conduction, and suppressed AF-induced increases in fibrous-tissue content, decreases in connexin-43 expression and reductions in sodium-channel expression. CONCLUSIONS Cilnidipine, a commercially available NTCC-blocking drug, prevents AF-induced autonomic, electrical and structural remodelling, along with associated AF promotion.
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Affiliation(s)
- Kazuko Tajiri
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada.,Department of Cardiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan
| | - Jean-Baptiste Guichard
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada.,Department of Cardiology, University Hospital of Saint-Étienne, University Jean Monnet, Saint-Étienne, France
| | - Xiaoyan Qi
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada
| | - Feng Xiong
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada
| | - Patrice Naud
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada
| | - Jean-Claude Tardif
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada
| | - Antoine Da Costa
- Department of Cardiology, University Hospital of Saint-Étienne, University Jean Monnet, Saint-Étienne, France
| | - Kazutaka Aonuma
- Department of Cardiology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan
| | - Stanley Nattel
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Belanger St E, Montreal, Quebec, Canada.,Department of Pharmacology and Therapeutics, McGill University, Promenade Sir-William-Osler, Montreal, Quebec, Canada.,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Hufelandstr. 55, Essen, Germany.,IHU LIRYC and Fondation Bordeaux Université, Avenue du Haut Lévêque, Pessac, Bordeaux, France
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Zhang K, Zhao Z, Lan L, Wei X, Wang L, Liu X, Yan H, Zheng J. Sigma-1 Receptor Plays a Negative Modulation on N-type Calcium Channel. Front Pharmacol 2017; 8:302. [PMID: 28603497 PMCID: PMC5445107 DOI: 10.3389/fphar.2017.00302] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 05/10/2017] [Indexed: 12/30/2022] Open
Abstract
The sigma-1 receptor is a 223 amino acids molecular chaperone with a single transmembrane domain. It is resident to eukaryotic mitochondrial-associated endoplasmic reticulum and plasma membranes. By chaperone-mediated interactions with ion channels, G-protein coupled receptors and cell-signaling molecules, the sigma-1 receptor performs broad physiological and pharmacological functions. Despite sigma-1 receptors have been confirmed to regulate various types of ion channels, the relationship between the sigma-1 receptor and N-type Ca2+ channel is still unclear. Considering both sigma-1 receptors and N-type Ca2+ channels are involved in intracellular calcium homeostasis and neurotransmission, we undertake studies to explore the possible interaction between these two proteins. In the experiment, we confirmed the expression of the sigma-1 receptors and the N-type calcium channels in the cholinergic interneurons (ChIs) in rat striatum by using single-cell reverse transcription-polymerase chain reaction (scRT-PCR) and immunofluorescence staining. N-type Ca2+ currents recorded from ChIs in the brain slice of rat striatum was depressed when sigma-1 receptor agonists (SKF-10047 and Pre-084) were administrated. The inhibition was completely abolished by sigma-1 receptor antagonist (BD-1063). Co-expression of the sigma-1 receptors and the N-type calcium channels in Xenopus oocytes presented a decrease of N-type Ca2+ current amplitude with an increase of sigma-1 receptor expression. SKF-10047 could further depress N-type Ca2+ currents recorded from oocytes. The fluorescence resonance energy transfer (FRET) assays and co-immunoprecipitation (Co-IP) demonstrated that sigma-1 receptors and N-type Ca2+ channels formed a protein complex when they were co-expressed in HEK-293T (Human Embryonic Kidney -293T) cells. Our results revealed that the sigma-1 receptors played a negative modulation on N-type Ca2+ channels. The mechanism for the inhibition of sigma-1 receptors on N-type Ca2+ channels probably involved a chaperone-mediated direct interaction and agonist-induced conformational changes in the receptor-channel complexes on the cell surface.
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Affiliation(s)
- Kang Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Zhe Zhao
- Department of Neurobiology, Beijing Institute of Basic Medical SciencesBeijing, China
| | - Liting Lan
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Xiaoli Wei
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Liyun Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Xiaoyan Liu
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Haitao Yan
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
| | - Jianquan Zheng
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and ToxicologyBeijing, China
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Kim YH, Ahn DS, Joeng JH, Chung S. Suppression of peripheral sympathetic activity underlies protease-activated receptor 2-mediated hypotension. Korean J Physiol Pharmacol 2014; 18:489-95. [PMID: 25598663 PMCID: PMC4296038 DOI: 10.4196/kjpp.2014.18.6.489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 09/02/2014] [Accepted: 09/23/2014] [Indexed: 11/15/2022]
Abstract
Protease-activated receptor (PAR)-2 is expressed in endothelial cells and vascular smooth muscle cells. It plays a crucial role in regulating blood pressure via the modulation of peripheral vascular tone. Although some reports have suggested involvement of a neurogenic mechanism in PAR-2-induced hypotension, the accurate mechanism remains to be elucidated. To examine this possibility, we investigated the effect of PAR-2 activation on smooth muscle contraction evoked by electrical field stimulation (EFS) in the superior mesenteric artery. In the present study, PAR-2 agonists suppressed neurogenic contractions evoked by EFS in endothelium-denuded superior mesenteric arterial strips but did not affect contraction elicited by the external application of noradrenaline (NA). However, thrombin, a potent PAR-1 agonist, had no effect on EFS-evoked contraction. Additionally, ω-conotoxin GVIA (CgTx), a selective N-type Ca2+ channel (ICa-N) blocker, significantly inhibited EFS-evoked contraction, and this blockade almost completely occluded the suppression of EFS-evoked contraction by PAR-2 agonists. Finally, PAR-2 agonists suppressed the EFS-evoked overflow of NA in endothelium-denuded rat superior mesenteric arterial strips and this suppression was nearly completely occluded by ω-CgTx. These results suggest that activation of PAR-2 may suppress peripheral sympathetic outflow by modulating activity of ICa-N which are located in peripheral sympathetic nerve terminals, which results in PAR-2-induced hypotension.
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Affiliation(s)
- Young-Hwan Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Duck-Sun Ahn
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Ji-Hyun Joeng
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
| | - Seungsoo Chung
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752, Korea
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Kim YH, Ahn DS, Kim MO, Joeng JH, Chung S. Protease-activated receptor 2 activation inhibits N-type Ca2+ currents in rat peripheral sympathetic neurons. Mol Cells 2014; 37:804-11. [PMID: 25410909 PMCID: PMC4255100 DOI: 10.14348/molcells.2014.0167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/02/2014] [Accepted: 09/17/2014] [Indexed: 11/27/2022] Open
Abstract
The protease-activated receptor (PAR)-2 is highly expressed in endothelial cells and vascular smooth muscle cells. It plays a crucial role in regulating blood pressure via the modulation of peripheral vascular tone. Although several mechanisms have been suggested to explain PAR-2-induced hypotension, the precise mechanism remains to be elucidated. To investigate this possibility, we investigated the effects of PAR-2 activation on N-type Ca(2+) currents (I(Ca-N)) in isolated neurons of the celiac ganglion (CG), which is involved in the sympathetic regulation of mesenteric artery vascular tone. PAR-2 agonists irreversibly diminished voltage-gated Ca(2+) currents (I(Ca)), measured using the patch-clamp method, in rat CG neurons, whereas thrombin had little effect on I(Ca). This PAR-2-induced inhibition was almost completely prevented by ω-CgTx, a potent N-type Ca(2+) channel blocker, suggesting the involvement of N-type Ca(2+) channels in PAR-2-induced inhibition. In addition, PAR-2 agonists inhibited I(Ca-N) in a voltage-independent manner in rat CG neurons. Moreover, PAR-2 agonists reduced action potential (AP) firing frequency as measured using the current-clamp method in rat CG neurons. This inhibition of AP firing induced by PAR-2 agonists was almost completely prevented by ω-CgTx, indicating that PAR-2 activation may regulate the membrane excitability of peripheral sympathetic neurons through modulation of N-type Ca(2+) channels. In conclusion, the present findings demonstrate that the activation of PAR-2 suppresses peripheral sympathetic outflow by modulating N-type Ca(2+) channel activity, which appears to be involved in PAR-2-induced hypotension, in peripheral sympathetic nerve terminals.
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Affiliation(s)
- Young-Hwan Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | - Duck-Sun Ahn
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | | | - Ji-Hyun Joeng
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752,
Korea
| | - Seungsoo Chung
- Department of Physiology, Yonsei University College of Medicine, Seoul 120-752,
Korea
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Lee HK, Lee KH, Cho ES. Bile Acid Inhibition of N-type Calcium Channel Currents from Sympathetic Ganglion Neurons. Korean J Physiol Pharmacol 2012; 16:25-30. [PMID: 22416216 PMCID: PMC3298822 DOI: 10.4196/kjpp.2012.16.1.25] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/30/2011] [Accepted: 01/08/2012] [Indexed: 12/17/2022]
Abstract
Under some pathological conditions as bile flow obstruction or liver diseases with the enterohepatic circulation being disrupted, regurgitation of bile acids into the systemic circulation occurs and the plasma level of bile acids increases. Bile acids in circulation may affect the nervous system. We examined this possibility by studying the effects of bile acids on gating of neuronal (N)-type Ca2+ channel that is essential for neurotransmitter release at synapses of the peripheral and central nervous system. N-type Ca2+ channel currents were recorded from bullfrog sympathetic neuron under a cell-attached mode using 100 mM Ba2+ as a charge carrier. Cholic acid (CA, 10-6 M) that is relatively hydrophilic thus less cytotoxic was included in the pipette solution. CA suppressed the open probability of N-type Ca2+ channel, which appeared to be due to an increase in null (no activity) sweeps. For example, the proportion of null sweep in the presence of CA was ~40% at +40 mV as compared with ~8% in the control recorded without CA. Other single channel properties including slope conductance, single channel current amplitude, open and shut times were not significantly affected by CA being present. The results suggest that CA could modulate N-type Ca2+ channel gating at a concentration as low as 10-6 M. Bile acids have been shown to activate nonselective cation conductance and depolarize the cell membrane. Under pathological conditions with increased circulating bile acids, CA suppression of N-type Ca2+ channel function may be beneficial against overexcitation of the synapses.
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Affiliation(s)
- Hye Kyung Lee
- Department of Pharmacology, University of Ulsan College of Medicine, Seoul 138-736, Korea
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