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Müller P, Draguhn A, Egorov AV. Persistent sodium currents in neurons: potential mechanisms and pharmacological blockers. Pflugers Arch 2024:10.1007/s00424-024-02980-7. [PMID: 38967655 DOI: 10.1007/s00424-024-02980-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Revised: 06/07/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024]
Abstract
Persistent sodium current (INaP) is an important activity-dependent regulator of neuronal excitability. It is involved in a variety of physiological and pathological processes, including pacemaking, prolongation of sensory potentials, neuronal injury, chronic pain and diseases such as epilepsy and amyotrophic lateral sclerosis. Despite its importance, neither the molecular basis nor the regulation of INaP are sufficiently understood. Of particular significance is a solid knowledge and widely accepted consensus about pharmacological tools for analysing the function of INaP and for developing new therapeutic strategies. However, the literature on INaP is heterogeneous, with varying definitions and methodologies used across studies. To address these issues, we provide a systematic review of the current state of knowledge on INaP, with focus on mechanisms and effects of this current in the central nervous system. We provide an overview of the specificity and efficacy of the most widely used INaP blockers: amiodarone, cannabidiol, carbamazepine, cenobamate, eslicarbazepine, ethosuximide, gabapentin, GS967, lacosamide, lamotrigine, lidocaine, NBI-921352, oxcarbazepine, phenytoine, PRAX-562, propofol, ranolazine, riluzole, rufinamide, topiramate, valproaic acid and zonisamide. We conclude that there is strong variance in the pharmacological effects of these drugs, and in the available information. At present, GS967 and riluzole can be regarded bona fide INaP blockers, while phenytoin and lacosamide are blockers that only act on the slowly inactivating component of sodium currents.
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Affiliation(s)
- Peter Müller
- Department Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen , Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
| | - Andreas Draguhn
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
| | - Alexei V Egorov
- Institute for Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Im Neuenheimer Feld 326, 69120, Heidelberg, Germany
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Lin MH, Lin JF, Yu MC, Wu SN, Wu CL, Cho HY. Characterization in Potent Modulation on Voltage-Gated Na + Current Exerted by Deltamethrin, a Pyrethroid Insecticide. Int J Mol Sci 2022; 23:ijms232314733. [PMID: 36499059 PMCID: PMC9737322 DOI: 10.3390/ijms232314733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/20/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Deltamethrin (DLT) is a type-II pyrethroid ester insecticide used in agricultural and domestic applications as well as in public health. However, transmembrane ionic channels perturbed by this compound remain largely unclear, although the agent is thought to alter the gating characteristics of voltage-gated Na+ (NaV) channel current. In this study, we reappraised whether and how it and other related compounds can make any further modifications on voltage-gated Na+ current (INa) in pituitary tumor (GH3) cells. Cell exposure to DLT produced a differential and dose-dependent stimulation of peak (transient, INa(T)) or sustained (late, INa(L)) INa; consequently, the EC50 value required for DLT-stimulated INa(T) or INa(L) was determined to be 11.2 or 2.5 μM, respectively. However, neither the fast nor slow component in the inactivation time constant of INa(T) activated by short depolarizing pulse was changed with the DLT presence; conversely, tefluthrin (Tef), a type-I pyrethroid insecticide, can accentuate INa with a slowing in inactivation time course of the current. The INa(L) augmented by DLT was attenuated by further application of either dapagliflozin (Dapa) or amiloride, but not by chlorotoxin. During pulse train (PT) stimulation, with the Tef or DLT presence, the cumulative inhibition of INa(T) became slowed; moreover, following PT stimuli, a large tail current with a slowly recovering process was observed. Alternatively, during rapid depolarizing pulse, the amplitude of INa(L) and tail INa (INa(Tail)) for each depolarizing pulse became progressively increased by adding DLT, not by Tef. The recovery time constant following PT stimulation with continued presence of Tef or DLT was shortened by further addition of Dapa. The voltage-dependent hysteresis (Hys(V)) of persistent INa was differentially augmented by Tef or DLT. Taken together, the magnitude, gating, frequency dependence, as well as Hys(V) behavior of INa exerted by the presence of DLT or Tef might exert a synergistic impact on varying functional activities of excitable cells in culture or in vivo.
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Affiliation(s)
- Mao-Hsun Lin
- Division of Neurology, Department of Internal Medicine, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi City 600, Taiwan
| | - Jen-Feng Lin
- Department of Emergency Medicine, Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi City 600, Taiwan
| | - Meng-Cheng Yu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 701, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 701, Taiwan
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 701, Taiwan
- Department of Post-Baccalaureate Medicine, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334; Fax: 886-6-2362780
| | - Chao-Liang Wu
- Ditmanson Medical Foundation Chiayi Christian Hospital, Chiayi City 600, Taiwan
| | - Hsin-Yen Cho
- Department of Physiology, National Cheng Kung University Medical College, Tainan 701, Taiwan
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Shiau AL, Liao CS, Tu CW, Wu SN, Cho HY, Yu MC. Characterization in Effective Stimulation on the Magnitude, Gating, Frequency Dependence, and Hysteresis of INa Exerted by Picaridin (or Icaridin), a Known Insect Repellent. Int J Mol Sci 2022; 23:ijms23179696. [PMID: 36077093 PMCID: PMC9456182 DOI: 10.3390/ijms23179696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/21/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
Picaridin (icaridin), a member of the piperidine chemical family, is a broad-spectrum arthropod repellent. Its actions have been largely thought to be due to its interaction with odorant receptor proteins. However, to our knowledge, to what extent the presence of picaridin can modify the magnitude, gating, and/or the strength of voltage-dependent hysteresis (Hys(V)) of plasmalemmal ionic currents, such as, voltage-gated Na+ current [INa], has not been entirely explored. In GH3 pituitary tumor cells, we demonstrated that with exposure to picaridin the transient (INa(T)) and late (INa(L)) components of voltage-gated Na+ current (INa) were differentially stimulated with effective EC50’s of 32.7 and 2.8 μM, respectively. Upon cell exposure to it, the steady-state current versus voltage relationship INa(T) was shifted to more hyperpolarized potentials. Moreover, its presence caused a rightward shift in the midpoint for the steady-state inactivate curve of the current. The cumulative inhibition of INa(T) induced during repetitive stimuli became retarded during its exposure. The recovery time course from the INa block elicited, following the conditioning pulse stimulation, was satisfactorily fitted by two exponential processes. Moreover, the fast and slow time constants of recovery from the INa block by the same conditioning protocol were noticeably increased in the presence of picaridin. However, the fraction in fast or slow component of recovery time course was, respectively, increased or decreased with an increase in picaridin concentrations. The Hys(V)’s strength of persistent INa (INa(P)), responding to triangular ramp voltage, was also enhanced during cell exposure to picaridin. The magnitude of resurgent INa (INa(R)) was raised in its presence. Picaritin-induced increases of INa(P) or INa(R) intrinsically in GH3 cells could be attenuated by further addition of ranolazine. The predictions of molecular docking also disclosed that there are possible interactions of the picaridin molecule with the hNaV1.7 channel. Taken literally, the stimulation of INa exerted by the exposure to picaridin is expected to exert impacts on the functional activities residing in electrically excitable cells.
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Affiliation(s)
- Ai-Li Shiau
- Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Chih-Szu Liao
- Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Chi-Wen Tu
- Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334; Fax: +886-6-2362780
| | - Hsin-Yen Cho
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
| | - Meng-Cheng Yu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
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Wu SN, Wu CL, Cho HY, Chiang CW. Effective Perturbations by Small-Molecule Modulators on Voltage-Dependent Hysteresis of Transmembrane Ionic Currents. Int J Mol Sci 2022; 23:ijms23169453. [PMID: 36012718 PMCID: PMC9408818 DOI: 10.3390/ijms23169453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
The non-linear voltage-dependent hysteresis (Hys(V)) of voltage-gated ionic currents can be robustly activated by the isosceles-triangular ramp voltage (Vramp) through digital-to-analog conversion. Perturbations on this Hys(V) behavior play a role in regulating membrane excitability in different excitable cells. A variety of small molecules may influence the strength of Hys(V) in different types of ionic currents elicited by long-lasting triangular Vramp. Pirfenidone, an anti-fibrotic drug, decreased the magnitude of Ih's Hys(V) activated by triangular Vramp, while dexmedetomidine, an agonist of α2-adrenoceptors, effectively suppressed Ih as well as diminished the Hys(V) strength of Ih. Oxaliplatin, a platinum-based anti-neoplastic drug, was noted to enhance the Ih's Hys(V) strength, which is thought to be linked to the occurrence of neuropathic pain, while honokiol, a hydroxylated biphenyl compound, decreased Ih's Hys(V). Cell exposure to lutein, a xanthophyll carotenoid, resulted in a reduction of Ih's Hys(V) magnitude. Moreover, with cell exposure to UCL-2077, SM-102, isoplumbagin, or plumbagin, the Hys(V) strength of erg-mediated K+ current activated by triangular Vramp was effectively diminished, whereas the presence of either remdesivir or QO-58 respectively decreased or increased Hys(V) magnitude of M-type K+ current. Zingerone, a methoxyphenol, was found to attenuate Hys(V) (with low- and high-threshold loops) of L-type Ca2+ current induced by long-lasting triangular Vramp. The Hys(V) properties of persistent Na+ current (INa(P)) evoked by triangular Vramp were characterized by a figure-of-eight (i.e., ∞) configuration with two distinct loops (i.e., low- and high-threshold loops). The presence of either tefluthrin, a pyrethroid insecticide, or t-butyl hydroperoxide, an oxidant, enhanced the Hys(V) strength of INa(P). However, further addition of dapagliflozin can reverse their augmenting effects in the Hys(V) magnitude of the current. Furthermore, the addition of esaxerenone, mirogabalin, or dapagliflozin was effective in inhibiting the strength of INa(P). Taken together, the observed perturbations by these small-molecule modulators on Hys(V) strength in different types of ionic currents evoked during triangular Vramp are expected to influence the functional activities (e.g., electrical behaviors) of different excitable cells in vitro or in vivo.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Post-Baccalaureate Medicine, National Sun Yat-sen University, Kaohsiung 804201, Taiwan
- Correspondence: ; Tel.: +886-6-2353535 (ext. 5334); Fax: +886-6-2362780
| | - Chao-Liang Wu
- Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi City 60002, Taiwan
| | - Hsin-Yen Cho
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
| | - Chi-Wu Chiang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
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Characterization in Inhibitory Effectiveness of Carbamazepine in Voltage-Gated Na + and Erg-Mediated K + Currents in a Mouse Neural Crest-Derived (Neuro-2a) Cell Line. Int J Mol Sci 2022; 23:ijms23147892. [PMID: 35887240 PMCID: PMC9321339 DOI: 10.3390/ijms23147892] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 12/18/2022] Open
Abstract
Carbamazepine (CBZ, Tegretol®) is an anticonvulsant used in the treatment of epilepsy and neuropathic pain; however, several unwanted effects of this drug have been noticed. Therefore, the regulatory actions of CBZ on ionic currents in electrically excitable cells need to be reappraised, although its efficacy in suppressing voltage-gated Na+ current (INa) has been disclosed. This study was undertaken to explore the modifications produced by CBZ on ionic currents (e.g., INa and erg-mediated K+ current [IK(erg)]) measured from Neuro-2a (N2a) cells. In these cells, we found that this drug differentially suppressed the peak (transient, INa(T)) and sustained (late, INa(L)) components of INa in a concentration-dependent manner with effective IC50 of 56 and 18 μM, respectively. The overall current–voltage relationship of INa(T) with or without the addition of CBZ remained unchanged; however, the strength (i.e., ∆area) in the window component of INa (INa(W)) evoked by the short ascending ramp pulse (Vramp) was overly lessened in the CBZ presence. Tefluthrin (Tef), a synthetic pyrethroid, known to stimulate INa, augmented the strength of the voltage-dependent hysteresis (Hys(V)) of persistent INa (INa(P)) in response to the isosceles-triangular Vramp; moreover, further application of CBZ attenuated Tef-mediated accentuation of INa(P)’s Hys(V). With a two-step voltage protocol, the recovery of INa(T) inactivation seen in Neuro-2a cells became progressively slowed by adding CBZ; however, the cumulative inhibition of INa(T) evoked by pulse train stimulation was enhanced during exposure to this drug. Neuro-2a-cell exposure to CBZ (100 μM), the magnitude of erg-mediated K+ current measured throughout the entire voltage-clamp steps applied was mildly inhibited. The docking results regarding the interaction of CBZ and voltage-gate Na+ (NaV) channel predicted the ability of CBZ to bind to some amino-acid residues in NaV due to the existence of a hydrogen bond or hydrophobic contact. It is conceivable from the current investigations that the INa (INa(T), INa(L), INa(W), and INa(P)) residing in Neuro-2a cells are susceptible to being suppressed by CBZ, and that its block on INa(L) is larger than that on INa(T). Collectively, the magnitude and gating of NaV channels produced by the CBZ presence might have an impact on its anticonvulsant and analgesic effects occurring in vivo.
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The Evidence for Effective Inhibition of INa Produced by Mirogabalin ((1R,5S,6S)-6-(aminomethyl)-3-ethyl-bicyclo [3.2.0] hept-3-ene-6-acetic acid), a Known Blocker of Ca V Channels. Int J Mol Sci 2022; 23:ijms23073845. [PMID: 35409204 PMCID: PMC8998350 DOI: 10.3390/ijms23073845] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 01/27/2023] Open
Abstract
Mirogabalin (MGB, Tarlige®), an inhibitor of the α2δ-1 subunit of voltage-gated Ca2+ (CaV) channels, is used as a way to alleviate peripheral neuropathic pain and diabetic neuropathy. However, to what extent MGB modifies the magnitude, gating, and/or hysteresis of various types of plasmalemmal ionic currents remains largely unexplored. In pituitary tumor (GH3) cells, we found that MGB was effective at suppressing the peak (transient, INa(T)) and sustained (late, INa(L)) components of the voltage-gated Na+ current (INa) in a concentration-dependent manner, with an effective IC50 of 19.5 and 7.3 μM, respectively, while the KD value calculated on the basis of minimum reaction scheme was 8.2 μM. The recovery of INa(T) inactivation slowed in the presence of MGB, although the overall current-voltage relation of INa(T) was unaltered; however, there was a leftward shift in the inactivation curve of the current. The magnitude of the window (INa(W)) or resurgent INa (INa(R)) evoked by the respective ascending or descending ramp pulse (Vramp) was reduced during cell exposure to MGB. MGB-induced attenuation in INa(W) or INa(R) was reversed by the further addition of tefluthrin, a pyrethroid insecticide known to stimulate INa. MGB also effectively lessened the strength of voltage-dependent hysteresis of persistent INa in response to the isosceles triangular Vramp. The cumulative inhibition of INa(T), evoked by pulse train stimulation, was enhanced in its presence. Taken together, in addition to the inhibition of CaV channels, the NaV channel attenuation produced by MGB might have an impact in its analgesic effects occurring in vivo.
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Cho HY, Chen PC, Chuang TH, Yu MC, Wu SN. Activation of Voltage-Gated Na+ Current by GV-58, a Known Activator of CaV Channels. Biomedicines 2022; 10:biomedicines10030721. [PMID: 35327523 PMCID: PMC8945347 DOI: 10.3390/biomedicines10030721] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/10/2022] [Accepted: 03/17/2022] [Indexed: 02/04/2023] Open
Abstract
GV-58 ((2R)-2-[(6-{[(5-methylthiophen-2-yl)methyl]amino}-9-propyl-9H-purin-2-yl)amino]butan-1-ol) is recognized to be an activator of N- and P/Q-type Ca2+ currents. However, its modulatory actions on other types of ionic currents in electrically excitable cells remain largely unanswered. This study was undertaken to explore the possible modifications caused by GV-58 in ionic currents (e.g., voltage-gated Na+ current [INa], A-type K+ current [IK(A)], and erg-mediated K+ current [IK(erg)]) identified from pituitary GH3 lactotrophs. GH3 cell exposure to GV-58 enhanced the transient and late components of INa with varying potencies; consequently, the EC50 values of GV-58 required for its differential increase in peak and late INa in GH3 cells were estimated to be 8.9 and 2.6 μM, respectively. The INa in response to brief depolarizing pulse was respectively stimulated or suppressed by GV-58 or tetrodotoxin, but it failed to be altered by ω-conotoxin MVIID. Cell exposure to this compound increased the recovery of INa inactivation evoked by two-pulse protocol based on a geometrics progression; however, in its presence, there was a slowing in the inactivation rate of current decay evoked by a train of depolarizing pulses. The existence of GV-58 also resulted in an increase in the amplitude of ramp-induced resurgent and window INa. The presence of this compound inhibited IK(A) magnitude, accompanied by a shortening in inactivation time course of the current; however, it mildly decreased IK(erg). Under current-clamp conditions, GV-58 increased the frequency of spontaneous action potentials in GH3 cells. Moreover, in NSC-34 motor neuron-like cells, the presence of GV-58 not only raised INa amplitude but also reduced current inactivation. Taken together, the overall work provides a noticeable yet unidentified finding which implies that, in addition to its agonistic effect on Ca2+ currents, GV-58 may concertedly modify the amplitude and gating kinetics of INa in electrically excitable cells, hence modifiying functional activities in these cells.
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Affiliation(s)
- Hsin-Yen Cho
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (P.-C.C.); (T.-H.C.); (M.-C.Y.)
| | - Pei-Chun Chen
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (P.-C.C.); (T.-H.C.); (M.-C.Y.)
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
| | - Tzu-Hsien Chuang
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (P.-C.C.); (T.-H.C.); (M.-C.Y.)
| | - Meng-Cheng Yu
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (P.-C.C.); (T.-H.C.); (M.-C.Y.)
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan City 70101, Taiwan; (H.-Y.C.); (P.-C.C.); (T.-H.C.); (M.-C.Y.)
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City 70101, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334; Fax: +886-6-2362780
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Hung TY, Wu SN, Huang CW. The Integrated Effects of Brivaracetam, a Selective Analog of Levetiracetam, on Ionic Currents and Neuronal Excitability. Biomedicines 2021; 9:biomedicines9040369. [PMID: 33916190 PMCID: PMC8067033 DOI: 10.3390/biomedicines9040369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/17/2021] [Accepted: 03/26/2021] [Indexed: 12/22/2022] Open
Abstract
Brivaracetam (BRV) is recognized as a novel third-generation antiepileptic drug approved for the treatment of epilepsy. Emerging evidence has demonstrated that it has potentially better efficacy and tolerability than its analog, Levetiracetam (LEV). This, however, cannot be explained by their common synaptic vesicle-binding mechanism. Whether BRV can affect different ionic currents and concert these effects to alter neuronal excitability remains unclear. With the aid of patch clamp technology, we found that BRV concentration dependently inhibited the depolarization-induced M-type K+ current (IK(M)), decreased the delayed-rectifier K+ current (IK(DR)), and decreased the hyperpolarization-activated cation current in GH3 neurons. However, it had a concentration-dependent inhibition on voltage-gated Na+ current (INa). Under an inside-out patch configuration, a bath application of BRV increased the open probability of large-conductance Ca2+-activated K+ channels. Furthermore, in mHippoE-14 hippocampal neurons, the whole-cell INa was effectively depressed by BRV. In simulated modeling of hippocampal neurons, BRV was observed to reduce the firing of the action potentials (APs) concurrently with decreases in the AP amplitude. In animal models, BRV ameliorated acute seizures in both OD-1 and lithium-pilocarpine epilepsy models. However, LEV had effects in the latter only. Collectively, our study demonstrated BRV’s multiple ionic mechanism in electrically excitable cells and a potential concerted effect on neuronal excitability and hyperexcitability disorders.
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Affiliation(s)
- Te-Yu Hung
- Department of Pediatrics, Chi-Mei Medical Center, Tainan 71004, Taiwan;
| | - Sheng-Nan Wu
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (S.-N.W.); (C.-W.H.)
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Correspondence: (S.-N.W.); (C.-W.H.)
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Inhibitory Effectiveness of Gomisin A, a Dibenzocyclooctadiene Lignan Isolated from Schizandra chinensis, on the Amplitude and Gating of Voltage-Gated Na + Current. Int J Mol Sci 2020; 21:ijms21228816. [PMID: 33233411 PMCID: PMC7700137 DOI: 10.3390/ijms21228816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022] Open
Abstract
Gomisin A (Gom A), a lignan isolated from Schisandra chinensis, has been reported produce numerous biological activities. However, its action on the ionic mechanisms remains largely unanswered. The present experiments were undertaken to investigate the possible perturbations of Gom A or other related compounds on different types of membrane ionic currents in electrically excitable cells (i.e., pituitary GH3 and pancreatic INS-1 cells). The exposure to Gom A led to the differential inhibition of peak and end-pulse components of voltage-gated Na+ current (INa) in GH3 cells with effective IC50 of 6.2 and 0.73 μM, respectively. The steady-state inactivation curve of INa in the presence of Gom A was shifted towards a more hyperpolarized potential. However, neither changes in the overall current-voltage relationship nor those for the gating charge of the current were demonstrated. The application of neither morin (10 μM) nor hesperidin (10 μM) perturbed the strength of INa, while sesamine could suppress it. However, in the continued presence of Gom A, the addition of sesamine failed to suppress INa further. Gom A also effectively suppressed the strength of persistent INa activated by long ramp voltage command, and further application of tefluthrin effectively attenuated Gom A-mediated inhibition of the current. The presence of Gom A mildly inhibited erg-mediated K+ current, while a lack of change in the amplitude of hyperpolarization-activated cation current was observed in its presence. Under cell-attached current recordings, the exposure to Gom A resulted in the decreased firing of spontaneous action currents with a minimal change in AC amplitude. In pancreatic INS-1 cells, the presence of Gom A was also noticed to inhibit peak and end-pulse components of INa differentially with the IC50 of 5.9 and 0.84 μM, respectively. Taken together, the emerging results presented herein provide the evidence that Gom A can differentially inhibit peak and sustained INa in endocrine cells (e.g., GH3 and INS-1 cells).
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Chang WT, Wu SN. Activation of voltage-gated sodium current and inhibition of erg-mediated potassium current caused by telmisartan, an antagonist of angiotensin II type-1 receptor, in HL-1 atrial cardiomyocytes. Clin Exp Pharmacol Physiol 2018; 45:797-807. [PMID: 29617054 DOI: 10.1111/1440-1681.12943] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/11/2018] [Accepted: 03/23/2018] [Indexed: 12/19/2022]
Abstract
Telmisartan (TEL) is a non-peptide blocker of angiotensin II type-1 (AT1 ) receptor. However, the mechanisms through which this drug interacts directly with ion currents in hearts remain largely unclear. Herein, we aim to investigate the effects of TEL the on ionic currents and membrane potential of murine HL-1 cardiomyocytes. In whole-cell recordings, addition of TEL stimulated the peak and late components of voltage-gated Na+ currents (INa ) with different potencies. The EC50 values required to achieve the stimulatory effect of this drug on peak and late INa were 0.2 and 1.2 μmol/L, respectively, and the current-voltage relationship of peak INa shifted toward less-depolarized potentials during exposure to TEL. Telmisartan not only increased peak INa but also prolonged the inactivation time course of late INa . Amiodarone (Amio) or ranolazine (Ran), but not angiotensin II, could reverse TEL-mediated effects. The drug enhanced the recovery rate of INa inactivation and exerted an inhibitory effect on erg-mediated K+ and L-type Ca2+ currents. In whole-cell current-clamp recordings, addition of the drug resulted in prolongation of the duration of action potentials (APs) in a dose-dependent manner in HL-1 cells; Amio or Ran could reverse this increase in AP durations. Telmisartan-mediated prolongation of AP was attenuated in KCNH2 siRNA-transfected HL-1 cells. In cultured smooth muscle cells of the human coronary artery, TEL enhanced INa amplitudes and slowed current inactivation. Stimulation by TEL of INa in HL-1 cells did not simply increase current magnitude but altered current kinetics, thereby suggesting state-dependent activation. Telmisartan may have greater affinity to the open/inactivated state than to the resting state residing in NaV channels. Collectively, TEL-mediated stimulation of INa and inhibition of IK(erg) could be an important ionic mechanism underlying the increased cell excitability of HL-1 cells; these actions, however, cannot be entirely explained by its blockade of AT1 receptor.
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Affiliation(s)
- Wei-Ting Chang
- Division of Cardiovascular Medicine, Chi-Mei Medical Center, Tainan, Taiwan.,Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan
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Lo YC, Tseng YT, Liu CM, Wu BN, Wu SN. Actions of KMUP-1, a xanthine and piperazine derivative, on voltage-gated Na(+) and Ca(2+) -activated K(+) currents in GH3 pituitary tumour cells. Br J Pharmacol 2015; 172:5110-22. [PMID: 26276211 DOI: 10.1111/bph.13276] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/06/2015] [Accepted: 08/07/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE 7-[2-[4-(2-Chlorophenyl)piperazinyl]ethyl]-1,3-dimethylxanthine (KMUP-1) is a xanthine-based derivative. It has soluble GC activation and K(+) -channel opening activity. Effects of this compound on ion currents in pituitary GH3 cells were investigated in this study. EXPERIMENTAL APPROACH The aim of this study was to evaluate effects of KMUP-1 on the amplitude and gating of voltage-gated Na(+) current (INa ) in pituitary GH3 cells and in HEKT293T cells expressing SCN5A. Both the amplitude of Ca(2+) -activated K(+) current and the activity of large-conductance Ca(2+) -activated K(+) (BKCa ) channels were also studied. KEY RESULTS KMUP-1 depressed the transient and late components of INa with different potencies. The IC50 values required for its inhibitory effect on transient and late INa were 22.5 and 1.8 μM respectively. KMUP-1 (3 μM) shifted the steady-state inactivation of INa to a hyperpolarized potential by -10 mV, despite inability to alter the recovery of INa from inactivation. In cell-attached configuration, KMUP-1 applied to bath increased BKCa -channel activity; however, in inside-out patches, this compound applied to the intracellular surface had no effect on it. It prolonged the latency in the generation of action currents elicited by triangular voltage ramps. Additionally, KMUP-1 decreased the peak INa with a concomitant increase of current inactivation in HEKT293T cells expressing SCN5A. CONCLUSIONS AND IMPLICATIONS Apart from activating BKCa channels, KMUP-1 preferentially suppresses late INa . The effects of KUMP-1 on ion currents presented here constitute an underlying ionic mechanism of its actions.
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Affiliation(s)
- Yi-Ching Lo
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Ting Tseng
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Graduate Institute of Natural Products, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chi-Ming Liu
- Department of Nursing, Tzu Hui Institute of Technology, Pingtung, Taiwan
| | - Bin-Nan Wu
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan.,Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan
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Huang CW, Hung TY, Wu SN. The inhibitory actions by lacosamide, a functionalized amino acid, on voltage-gated Na+ currents. Neuroscience 2015; 287:125-36. [DOI: 10.1016/j.neuroscience.2014.12.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Revised: 06/18/2014] [Accepted: 07/01/2014] [Indexed: 12/19/2022]
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Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells. BMC Neurosci 2012; 13:129. [PMID: 23095258 PMCID: PMC3502467 DOI: 10.1186/1471-2202-13-129] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/23/2012] [Indexed: 12/19/2022] Open
Abstract
Background The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Results Whole-cell patch-clamp results showed that differentiation (9 days) didn’t change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Conclusion Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.
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Wu SN, Yeh CC, Huang HC, So EC, Lo YC. Electrophysiological characterization of sodium-activated potassium channels in NG108-15 and NSC-34 motor neuron-like cells. Acta Physiol (Oxf) 2012; 206:120-34. [PMID: 22533628 DOI: 10.1111/j.1748-1716.2012.02438.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/09/2011] [Accepted: 03/19/2012] [Indexed: 12/13/2022]
Abstract
AIMS The electrical properties of Na(+) -activated K(+) current (I(K(Na)) ) and its contribution to spike firing has not been characterized in motor neurons. METHODS We evaluated how activation of voltage-gated K(+) current (I(K) ) at the cellular level could be coupled to Na(+) influx through voltage-gated Na(+) current (I(N) (a) ) in two motor neuron-like cells (NG108-15 and NSC-34 cells). RESULTS Increasing stimulation frequency altered the amplitudes of both I(Na) and I(K) simultaneously. With changes in stimulation frequency, the kinetics of both I(Na) inactivation and I(K) activation were well correlated at the same cell. Addition of tetrodotoxin or ranolazine reduced the amplitudes of both I(Na) and I(K) simultaneously. Tefluthrin (Tef) increased the amplitudes of both I(Na) and I(K) throughout the voltages ranging from -30 to + 10 mV. In cell-attached recordings, single-channel conductance from a linear current-voltage relation was 94 ± 3 pS (n = 7). Tef (10 μm) enhanced channel activity with no change in single-channel conductance. Tef increased spike firing accompanied by enhanced facilitation of spike-frequency adaptation. Riluzole (10 μm) reversed Tef-stimulated activity of K(Na) channels. In motor neuron-like NSC-34 cells, increasing stimulation frequency altered the kinetics of both I(Na) and I(K) . Modelling studies of motor neurons were simulated to demonstrate that the magnitude of I(K(Na)) modulates AP firing. CONCLUSIONS There is a direct association of Na(+) and K(Na) channels which can provide the rapid activation of K(Na) channels required to regulate AP firing occurring in motor neurons.
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Affiliation(s)
| | - C.-C. Yeh
- Department of Physiology; National Cheng Kung University Medical College; Tainan City; Taiwan
| | - H.-C. Huang
- Department of Physiology; National Cheng Kung University Medical College; Tainan City; Taiwan
| | - E. C. So
- Department of Anesthesia; Chi Mei Medical Center; Tainan City; Taiwan
| | - Y.-C. Lo
- Department of Pharmacology; Kaohsiung Medical University; Kaohsiung City; Taiwan
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Verkerk AO, van Ginneken ACG, Wilders R. Sodium current inhibition by nanosecond pulsed electric field (nsPEF)--fact or artifact? Bioelectromagnetics 2012; 34:162-4. [PMID: 22961353 DOI: 10.1002/bem.21754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/11/2012] [Indexed: 11/10/2022]
Abstract
In two recent publications in Bioelectromagnetics it has been demonstrated that the voltage-gated sodium current (I(Na)) is inhibited in response to a nanosecond pulsed electric field (nsPEF). At the same time, there was an increase in a non-inactivating "leak" current (I(leak)), which was attributed to the formation of nanoelectropores or larger pores in the plasma membrane. We demonstrate that the increase in I(leak), in combination with a residual series resistance, leads to an error in the holding potential in the patch clamp experiments and an unanticipated inactivation of the sodium channels. We conclude that the observed inhibition of I(Na) may be largely, if not fully, artifactual.
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Affiliation(s)
- Arie O Verkerk
- Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Characterizing the effects of Eugenol on neuronal ionic currents and hyperexcitability. Psychopharmacology (Berl) 2012; 221:575-87. [PMID: 22160139 DOI: 10.1007/s00213-011-2603-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 11/26/2011] [Indexed: 01/24/2023]
Abstract
RATIONALE Eugenol (EUG, 4-allyl-2-methoxyphenol), the main component of essential oil extracted from cloves, has various uses in medicine because of its potential to modulate neuronal excitability. However, its effects on the ionic mechanisms remains incompletely understood. OBJECTIVES We aimed to investigate EUG's effects on neuronal ionic currents and excitability, especially on voltage-gated ion currents, and to verify the effects on a hyperexcitability-temporal lobe seizure model. METHODS With the aid of patch-clamp technology, we first investigated the effects of EUG on ionic currents in NG108-15 neuronal cells differentiated with cyclic AMP. We then used modified Pinsky-Rinzel simulation modeling to evaluate its effects on spontaneous action potentials (APs). Finally, we investigated its effects on pilocarpine-induced seizures in rats. RESULTS EUG depressed the transient and late components of I(Na) in the neurons. It not only increased the degree of I(Na) inactivation, but specifically suppressed the non-inactivating I(Na) (I(Na(NI))). Its inhibition of I (Na(NI)) was reversed by tefluthrin. In addition, EUG diminished L-type Ca(2+) current and delayed rectifier K(+) current only at higher concentrations. EUG's effects on APs frequency reduction was verified by the simulation modeling. In pilocarpine-induced seizures, the EUG-treated rats showed no shorter seizure latency but a lower seizure severity and mortality than the control rats. The EUG's effect on seizure severity was occluded by the I(Na(NI)) antagonist riluzole. CONCLUSION The synergistic blocking effects of I (Na) and I(Na(NI)) contributes to the main mechanism through which EUG affects the firing of neuronal APs and modulate neuronal hyperexcitability such as pilocarpine-induced temporal lobe seizures.
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Kahlig KM, Lepist I, Leung K, Rajamani S, George AL. Ranolazine selectively blocks persistent current evoked by epilepsy-associated Naν1.1 mutations. Br J Pharmacol 2011; 161:1414-26. [PMID: 20735403 DOI: 10.1111/j.1476-5381.2010.00976.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Mutations of SCN1A, the gene encoding the pore-forming subunit of the voltage-gated sodium channel Na(V) 1.1, have been associated with a spectrum of genetic epilepsies and a familial form of migraine. Several mutant Na(V) 1.1 channels exhibit increased persistent current due to incomplete inactivation and this biophysical defect may contribute to altered neuronal excitability in these disorders. Here, we investigated the ability of ranolazine to preferentially inhibit increased persistent current evoked by mutant Na(V) 1.1 channels. EXPERIMENTAL APPROACH Human wild-type (WT) and mutant Na(V) 1.1 channels were expressed heterologously in human tsA201 cells and whole-cell patch clamp recording was used to assess tonic and use-dependent ranolazine block. KEY RESULTS Ranolazine (30 µM) did not affect WT Na(V) 1.1 channel current density, activation or steady-state fast inactivation but did produce mild slowing of recovery from inactivation. Ranolazine blocked persistent current with 16-fold selectivity over tonic block of peak current and 3.6-fold selectivity over use-dependent block of peak current. Similar selectivity was observed for ranolazine block of increased persistent current exhibited by Na(V) 1.1 channel mutations representing three distinct clinical syndromes, generalized epilepsy with febrile seizures plus (R1648H, T875M), severe myoclonic epilepsy of infancy (R1648C, F1661S) and familial hemiplegic migraine type 3 (L263V, Q1489K). In vitro application of achievable brain concentrations (1, 3 µM) to cells expressing R1648H channels was sufficient to suppress channel activation during slow voltage ramps, consistent with inhibition of persistent current. CONCLUSIONS AND IMPLICATIONS Our findings support the feasibility of using selective suppression of increased persistent current as a potential new therapeutic strategy for familial neurological disorders associated with certain sodium channel mutations.
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Affiliation(s)
- Kristopher M Kahlig
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232-0275, USA
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Chen BS, Wu SN. Functional role of the activity of ATP-sensitive potassium channels in electrical behavior of hippocampal neurons: Experimental and theoretical studies. J Theor Biol 2011; 272:16-25. [DOI: 10.1016/j.jtbi.2010.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 10/13/2010] [Accepted: 12/01/2010] [Indexed: 11/17/2022]
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