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Chen CS, So EC, Wu SN. Modulating Hyperpolarization-Activated Cation Currents through Small Molecule Perturbations: Magnitude and Gating Control. Biomedicines 2023; 11:2177. [PMID: 37626674 PMCID: PMC10452073 DOI: 10.3390/biomedicines11082177] [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: 06/09/2023] [Revised: 07/10/2023] [Accepted: 07/27/2023] [Indexed: 08/27/2023] Open
Abstract
The hyperpolarization-activated cation current (Ih) exhibits a slowly activating time course of the current (Ih) when the cell membrane is hyperpolarized for an extended duration. It is involved in generating electrical activity in various excitable cells. Numerous structurally distinct compounds or herbal drugs have the potential to impact both the magnitude and gating kinetics of this current. Brivaracetam, a chemical analog of levetiracetam known to be a ligand for synaptic vesicle protein 2A, could directly suppress the Ih magnitude. Carisbamate, an anticonvulsant agent, not only inhibited the Ih amplitude but also reduced the strength of voltage-dependent hysteresis (Hys(V)) associated with Ih. Cilobradine, similar to ivabradine, inhibited the amplitude of Ih; however, it also suppressed the amplitude of delayed-rectifier K+ currents. Dexmedetomidine, an agonist of α2-adrenergic receptor, exerted a depressant action on Ih in a concentration-dependent fashion. Suppression of Ih amplitude was observed when GAL-021, a breathing control modulator, was present at a concentration exceeding 30 μM. Lutein, one of the few xanthophyll carotenoids, was able to suppress the Ih amplitude as well as to depress Hys(V)'s strength of Ih. Pirfenidone, a pyridine derivative known to be an anti-fibrotic agent, depressed the Ih magnitude in a concentration- and voltage-dependent fashion. Tramadol, a synthetic centrally active analgesic, was shown to reduce the Ih magnitude, independent of its interaction with opioid receptors. Various herbal drugs, including ent-kaurane-type diterpenoids from Croton tonkinensis, Ganoderma triterpenoids, honokiol, and pterostilbene, demonstrated efficacy in reducing the magnitude of Ih. Conversely, oxaliplatin, a platinum-based chemotherapeutic compound, was observed to effectively increase the Ih amplitude. Collectively, the regulatory effects of these compounds or herbal drugs on cellular function can be partly attributed to their perturbations on Ih.
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Affiliation(s)
- Cheng-Shih Chen
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan; (C.-S.C.); (E.C.S.)
| | - Edmund Cheung So
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan; (C.-S.C.); (E.C.S.)
| | - Sheng-Nan Wu
- School of Medicine, National Sun Yat Sen University College of Medicine, Kaohsiung 804, Taiwan
- Department of Medical Education & Research, An Nan Hospital, China Medical University, Tainan 70965, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan 701, Taiwan
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Ding W, Zhang X, Yin X, Zhang Q, Wang Y, Guo C, Chen Y. Ganoderma lucidum aqueous extract inducing PHGPx to inhibite membrane lipid hydroperoxides and regulate oxidative stress based on single-cell animal transcriptome. Sci Rep 2022; 12:3139. [PMID: 35210474 PMCID: PMC8873301 DOI: 10.1038/s41598-022-06985-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 02/10/2022] [Indexed: 11/09/2022] Open
Abstract
In this study, the single-cell eukaryotic model organism Tetrahymena thermophila was used as an experimental material to reveal the anti-aging mechanism of Ganoderma lucidum aqueous extract. After treatment with the G. lucidum aqueous extract, the logarithmic phase was extended, and the maximum density of T. thermophila increased to 5.5 × 104 cells/mL. The aqueous extract was more effective than the main active monomers of G. lucidum. The membrane integrity in the cell including mitochondria and nucleus appeared improvement after treatment with the G. lucidum aqueous extract, which observed by ammonia silver staining and transmission electron microscopy. Gene Ontology (GO) functional enrichment of the differentially expressed genes in transcriptome showed that the G. lucidum aqueous extract promoted the biological metabolic process of membrane components. According to Kyoto Encyclopedia of Genes and Genomes (KEGG), the glutathione metabolism process was enhanced in both growth phases. Protein–protein interaction (PPI) network analysis illustrated that phospholipid hydroperoxide glutathione peroxidase (PHGPx) played a key role in the anti-aging mechanism. The results suggested that G. lucidum aqueous extract improved the GPX activity as well as reduced the malondialdehyde content and cell damage. More importantly, the expression of PHGPx was promoted to reduce the oxidation degree of the membrane lipids and enhance the integrity of the membrane to achieve anti-aging effects.
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Affiliation(s)
- Wenqiao Ding
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China.,College of Biology and Food Engineering, Jilin Institute of Chemical Technology, Jilin, 132022, China
| | - Xueying Zhang
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China
| | - Xiaoyu Yin
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China
| | - Qing Zhang
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China
| | - Ying Wang
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China
| | - Changhong Guo
- Key Laboratory of Molecular Cytogenetics and Genetic Breeding of Heilongjiang Province, College of Life Science and Technology, Harbin Normal University, Harbin, 150025, China
| | - Ying Chen
- Key Laboratory of Biodiversity of Aquatic Organisms, Harbin Normal University, Harbin, 150025, China. .,School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China.
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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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Hung TY, Huang CW, Wu SN. High ability of zileuton ((±)-1-(1-benzo[b]thien-2-ylethyl)-1-hydroxyurea) to stimulate I K(Ca) but suppress I K(DR) and I K(M) independently of 5-lipoxygenase inhibition. Eur J Pharmacol 2020; 887:173482. [PMID: 32795513 DOI: 10.1016/j.ejphar.2020.173482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 08/07/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022]
Abstract
Zileuton (Zyflo®) is regarded to be an inhibitor of 5-lipoxygenase. Although its effect on Ca2+-activated K+ currents has been reported, its overall ionic effects on neurons are uncertain. In whole-cell current recordings, zileuton increased the amplitude of Ca2+-activated K+ currents with an EC50 of 3.2 μM in pituitary GH3 lactotrophs. Furthermore, zileuton decreased the amplitudes of both delayed-rectifier K+ current (IK(DR)) and M-type K+ current (IK(M)). Conversely, no modification of hyperpolarization-activated cation current (Ih) was demonstrated in its presence of zileuton, although the subsequent addition of cilobradine effectively suppressed the current. In inside-out current recordings, the addition of zileuton to the bath increased the probability of large-conductance Ca2+-activated K+ (BKCa) channels; however, the subsequent addition of GAL-021 effectively reversed the stimulation of channel activity. The kinetic analyses showed an evident shortening in the slow component of mean closed time of BKCa channels in the presence of zileuton, with minimal change in mean open time or that in the fast component of mean closed time. The elevation of BKCa channels caused by zileuton was also observed in hippocampal mHippoE-14 neurons, without any modification of single-channel amplitude. In conclusion, except for its suppression of 5-lipoxygenase, our results indicate that zileuton does not exclusively act on BKCa channels, and its inhibitory effects on IK(DR) and IK(M) may combine to exert strong influence on the functional activities of electrically excitable cells in vivo.
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Affiliation(s)
- Te-Yu Hung
- Department of Pediatrics, Chi-Mei Medical Center, Tainan, Taiwan
| | - Chin-Wei Huang
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, 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; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung City, Taiwan.
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Liu PY, Chang WT, Wu SN. Characterization of the Synergistic Inhibition of IK(erg) and IK(DR) by Ribociclib, a Cyclin-Dependent Kinase 4/6 Inhibitor. Int J Mol Sci 2020; 21:ijms21218078. [PMID: 33138174 PMCID: PMC7663338 DOI: 10.3390/ijms21218078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 12/13/2022] Open
Abstract
Ribociclib (RIB, LE011, Kisqali®), an orally administered inhibitor of cyclin-dependent kinase-4/6 (CDK-4/6) complex, is clinically effective for the treatment of several malignancies, including advanced breast cancer. However, information regarding the effects of RIB on membrane ion currents is limited. In this study, the addition of RIB to pituitary tumor (GH3) cells decreased the peak amplitude of erg-mediated K+ current (IK(erg)), which was accompanied by a slowed deactivation rate of the current. The IC50 value for RIB-perturbed inhibition of deactivating IK(erg) in these cells was 2.7 μM. In continued presence of μM RIB, neither the subsequent addition of 17β-estradiol (30 μM), phorbol 12-myristate 13-acetate (10 μM), or transforming growth factor-β (1 μM) counteracted the inhibition of deactivating IK(erg). Its presence affected the decrease in the degree of voltage-dependent hysteresis for IK(erg) elicitation by long-duration triangular ramp voltage commands. The presence of RIB differentially inhibited the peak or sustained component of delayed rectifier K+ current (IK(DR)) with an effective IC50 of 28.7 or 11.4 μM, respectively, while it concentration-dependently decreased the amplitude of M-type K+ current with IC50 of 13.3 μM. Upon 10-s long membrane depolarization, RIB elicited a decrease in the IK(DR) amplitude, which was concomitant with an accelerated inactivation time course. However, the inability of RIB (10 μM) to modify the magnitude of the hyperpolarization-activated cation current was disclosed. The mean current–voltage relationship of IK(erg) present in HL-1 atrial cardiomyocytes was inhibited in the presence of RIB (10 μM). Collectively, the hyperpolarization-activated cation current was observed. RIB-mediated perturbations in ionic currents presented herein are upstream of its suppressive action on cytosolic CDK-4/6 activities and partly participates in its modulatory effects on the functional activities of pituitary tumor cells (e.g., GH3 cells) or cardiac myocytes (e.g., HL-1 cells).
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Affiliation(s)
- Pin-Yen Liu
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, National Cheng Kung University Hospital, Tainan 704, Taiwan;
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan;
| | - Wei-Ting Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan;
- Division of Cardiovascular Medicine, Chi-Mei Medical Center, Tainan 710, Taiwan
- Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 704, Taiwan
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 704, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334; Fax: +886-6-2362780
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Chang WT, Ragazzi E, Liu PY, Wu SN. Effective block by pirfenidone, an antifibrotic pyridone compound (5-methyl-1-phenylpyridin-2[H-1]-one), on hyperpolarization-activated cation current: An additional but distinctive target. Eur J Pharmacol 2020; 882:173237. [PMID: 32525005 PMCID: PMC7276140 DOI: 10.1016/j.ejphar.2020.173237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/26/2020] [Accepted: 05/29/2020] [Indexed: 12/26/2022]
Abstract
Pirfenidone (PFD), a pyridone compound, is well recognized as an antifibrotic agent tailored for the treatment of idiopathic pulmonary fibrosis. Recently, through its anti-inflammatory and anti-oxidant effects, PFD based clinical trial has also been launched for the treatment of coronavirus disease (COVID-19). To what extent this drug can perturb membrane ion currents remains largely unknown. Herein, the exposure to PFD was observed to depress the amplitude of hyperpolarization-activated cation current (Ih) in combination with a considerable slowing in the activation time of the current in pituitary GH3 cells. In the continued presence of ivabradine or zatebradine, subsequent application of PFD decreased Ih amplitude further. The presence of PFD resulted in a leftward shift in Ih activation curve without changes in the gating charge. The addition of this compound also led to a reduction in area of voltage-dependent hysteresis evoked by long-lasting inverted triangular (downsloping and upsloping) ramp pulse. Neither the amplitude of M-type nor erg-mediated K+ current was altered by its presence. In whole-cell potential recordings, addition of PFD reduced the firing frequency, and this effect was accompanied by the depression in the amplitude of sag voltage elicited by hyperpolarizing current stimulus. Overall, this study highlights evidence that PFD is capable of perturbing specific ionic currents, revealing a potential additional impact on functional activities of different excitable cells.
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Affiliation(s)
- Wei-Ting Chang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, Chi-Mei Medical Center, Tainan, 71004, Taiwan; Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, 71004, Taiwan.
| | - Eugenio Ragazzi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131, Padova, Italy
| | - Ping-Yen Liu
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, 70101, Taiwan; Division of Cardiology, Internal Medicine, College of Medicine, National Cheng Kung University Hospital, Tainan, 70401, Taiwan.
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.
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Kuo PC, Kao ZH, Lee SW, Wu SN. Effects of Sesamin, the Major Furofuran Lignan of Sesame Oil, on the Amplitude and Gating of Voltage-Gated Na + and K + Currents. Molecules 2020; 25:molecules25133062. [PMID: 32635522 PMCID: PMC7411736 DOI: 10.3390/molecules25133062] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/01/2020] [Accepted: 07/01/2020] [Indexed: 12/17/2022] Open
Abstract
Sesamin (SSM) and sesamolin (SesA) are the two major furofuran lignans of sesame oil and they have been previously noticed to exert various biological actions. However, their modulatory actions on different types of ionic currents in electrically excitable cells remain largely unresolved. The present experiments were undertaken to explore the possible perturbations of SSM and SesA on different types of ionic currents, e.g., voltage-gated Na+ currents (INa), erg-mediated K+ currents (IK(erg)), M-type K+ currents (IK(M)), delayed-rectifier K+ currents (IK(DR)) and hyperpolarization-activated cation currents (Ih) identified from pituitary tumor (GH3) cells. The exposure to SSM or SesA depressed the transient and late components of INa with different potencies. The IC50 value of SSM needed to lessen the peak or sustained INa was calculated to be 7.2 or 0.6 μM, while that of SesA was 9.8 or 2.5 μM, respectively. The dissociation constant of SSM-perturbed inhibition on INa, based on the first-order reaction scheme, was measured to be 0.93 μM, a value very similar to the IC50 for its depressant action on sustained INa. The addition of SSM was also effective at suppressing the amplitude of resurgent INa. The addition of SSM could concentration-dependently inhibit the IK(M) amplitude with an IC50 value of 4.8 μM. SSM at a concentration of 30 μM could suppress the amplitude of IK(erg), while at 10 μM, it mildly decreased the IK(DR) amplitude. However, the addition of neither SSM (10 μM) nor SesA (10 μM) altered the amplitude or kinetics of Ih in response to long-lasting hyperpolarization. Additionally, in this study, a modified Markovian model designed for SCN8A-encoded (or NaV1.6) channels was implemented to evaluate the plausible modifications of SSM on the gating kinetics of NaV channels. The model demonstrated herein was well suited to predict that the SSM-mediated decrease in peak INa, followed by increased current inactivation, which could largely account for its favorable decrease in the probability of the open-blocked over open state of NaV channels. Collectively, our study provides evidence that highlights the notion that SSM or SesA could block multiple ion currents, such as INa and IK(M), and suggests that these actions are potentially important and may participate in the functional activities of various electrically excitable cells in vivo.
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Affiliation(s)
- Ping-Chung Kuo
- School of Pharmacy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan;
| | - Zi-Han Kao
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; (Z.-H.K.); (S.-W.L.)
| | - Shih-Wei Lee
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; (Z.-H.K.); (S.-W.L.)
| | - Sheng-Nan Wu
- Department of Physiology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; (Z.-H.K.); (S.-W.L.)
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan
- Correspondence: ; Tel.: +886-6-235-3535-5334; Fax: +886-6-2362780
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Lu TL, Lu TJ, Wu SN. Inhibitory Effective Perturbations of Cilobradine (DK-AH269), A Blocker of HCN Channels, on the Amplitude and Gating of Both Hyperpolarization-Activated Cation and Delayed-Rectifier Potassium Currents. Int J Mol Sci 2020; 21:ijms21072416. [PMID: 32244431 PMCID: PMC7177279 DOI: 10.3390/ijms21072416] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/17/2020] [Accepted: 03/28/2020] [Indexed: 12/19/2022] Open
Abstract
Cilobradine (CIL, DK-AH269), an inhibitor of hyperpolarization-activated cation current (Ih), has been observed to possess pro-arrhythmic properties. Whether and how CIL is capable of perturbing different types of membrane ionic currents existing in electrically excitable cells, however, is incompletely understood. In this study, we intended to examine possible modifications by it or other structurally similar compounds of ionic currents in pituitary tumor (GH3) cells and in heart-derived H9c2 cells. The standard whole-cell voltage-clamp technique was performed to examine the effect of CIL on ionic currents. GH3-cell exposure to CIL suppressed the density of hyperpolarization-evoked Ih in a concentration-dependent manner with an effective IC50 of 3.38 μM. Apart from its increase in the activation time constant of Ih during long-lasting hyperpolarization, the presence of CIL (3 μM) distinctly shifted the steady-state activation curve of Ih triggered by a 2-s conditioning pulse to a hyperpolarizing direction by 10 mV. As the impedance-frequency relation of Ih was studied, its presence raised the impedance magnitude at the resonance frequency induced by chirp voltage. CIL also suppressed delayed-rectifier K+ current (IK(DR)) followed by the accelerated inactivation time course of this current, with effective IC50 (measured at late IK(DR)) or KD value of 3.54 or 3.77 μM, respectively. As the CIL concentration increased 1 to 3 μM, the inactivation curve of IK(DR) elicited by 1- or 10-s conditioning pulses was shifted to a hyperpolarizing potential by approximately 10 mV, and the recovery of IK(DR) inactivation during its presence was prolonged. The peak Na+ current (INa) during brief depolarization was resistant to being sensitive to the presence of CIL, yet to be either decreased by subsequent addition of A-803467 or enhanced by that of tefluthrin. In cardiac H9c2 cells, unlike the CIL effect, the addition of either ivabradine or zatebradine mildly led to a lowering in IK(DR) amplitude with no conceivable change in the inactivation time course of the current. Taken together, the compound like CIL, which was tailored to block hyperpolarization-activated cation (HCN) channels effectively, was also capable of altering the amplitude and gating of IK(DR), thereby influencing the functional activities of electrically excitable cells, such as GH3 cells.
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Affiliation(s)
- Te-Ling Lu
- School of Pharmacy, China Medical University, Taichung 40402, Taiwan;
| | - Te-Jung Lu
- Department of Medical Laboratory Science and Biotechnology, Chung Hwa University of Medical Technology, Tainan 71703, Taiwan;
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan
- Correspondence:
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Characterization of Effectiveness in Concerted Ih Inhibition and IK(Ca) Stimulation by Pterostilbene (Trans-3,5-dimethoxy-4'-hydroxystilbene), a Stilbenoid. Int J Mol Sci 2020; 21:ijms21010357. [PMID: 31948124 PMCID: PMC6981816 DOI: 10.3390/ijms21010357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 12/31/2019] [Accepted: 01/02/2020] [Indexed: 12/13/2022] Open
Abstract
Pterostilbene (PTER), a natural dimethylated analog of resveratrol, has been demonstrated to produce anti-neoplastic or neuroprotective actions. However, how and whether this compound can entail any perturbations on ionic currents in electrically excitable cells remains unknown. In whole-cell current recordings, addition of PTER decreased the amplitude of macroscopic Ih during long-lasting hyperpolarization in GH3 cells in a concentration-dependent manner, with an effective IC50 value of 0.84 μM. Its presence also shifted the activation curve of Ih along the voltage axis to a more hyperpolarized potential, by 11 mV. PTER at a concentration greater than 10 μM could also suppress l-type Ca2+ and transient outward K+ currents in GH3 cells. With the addition of PTER, IK(Ca) amplitude was increased, with an EC50 value of 2.23 μM. This increase in IK(Ca) amplitude was attenuated by further addition of verruculogen, but not by tolbutamide or TRAM-39. Neither atropine nor nicotine, in the continued presence of PTER, modified the PTER-stimulated IK(Ca). PTER (10 μM) slightly suppressed the amplitude of l-type Ca2+ current and transient outward K+ current. The presence of PTER (3 μM) was also effective at increasing the open-state probability of large-conductance Ca2+-activated K+ (BKCa) channels identified in hippocampal mHippoE-14 neurons; however, its inability to alter single-channel conductance was detected. Our study highlights evidence to show that PTER has the propensity to perturb ionic currents (e.g., Ih and IK(Ca)), thereby influencing the functional activities of neurons, and neuroendocrine or endocrine cells.
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