Effect of Capsaicin on Delayed Rectifier K<SUP>⁢</SUP> Current in Adult Rat Dorsal Root Ganglion Neurons

Junghyun Hahn,Sungkwon Chung,Hyoweon Bang 대한생리학회-대한약리학회 2000 The Korean Journal of Physiology & Pharmacology Vol.4 No.1

<P> K<SUP>⁢ </SUP>currents play multiple roles in the excitability of dorsal root ganglion (DRG) neurons. Influences on these currents change the shape of the action potential, its firing threshold and the resting membrane potential. In this study, whole cell configuration of patch clamp technique had been applied to record the blocking effect of capsaicin, a lipophilic alkaloid, on the delayed rectifier K<SUP>⁢ </SUP>current in cultured small diameter DRG neurons of adult rat. Capsaicin reduced the amplitude of K<SUP>⁢ </SUP>current in dose dependent manner, and the concentration-dependence curve was well described by the Hill equation with <I>K</I><SUB>D </SUB>value of 19.1μM. The blocking effect of capsaicin was reversible. Capsaicin (10 μM) shifted the steady- state inactivation curve in the hyperpolarizing direction by about 15 mV and increased the rate of inactivation. The voltage dependence of activation was not affected by capsaicin. These multiple effects of capsaicin may suggest that capsaicin bind to the region of K<SUP>⁢</SUP> channel, participating in inactivation process.

The Inhibition of TREK2 Channel by an Oxidizing Agent, 5,5 -dithio- bis (2-nitrobenzoic acid), via Interaction with the C-terminus Distal to the 353rd Amino Acid

Kyoung Sun Park,Hyoweon Bang,Eun-Young Shin,Chan Hyung Kim,Yangmi Kim 대한생리학회-대한약리학회 2008 The Korean Journal of Physiology & Pharmacology Vol.12 No.4

TREK (TWIK-RElated K⁺ channels) and TRAAK (TWIK-Related Arachidonic acid Activated K⁺ channels) were expressed in COS-7 cells, and the channel activities were recorded from inside-out membrane patches using holding potential of −40 mV in symmetrical 150 mM K⁺ solution. Intra</SUP>cellular application of an oxidizing agent, 5,5 -dithio-bis (2-nitrobenzoic acid) (DTNB), markedly decreased the activity of the TREK2, and the activity was partially reversed by the reducing agent, dithiothreitol (DTT). In order to examine the possibility that the target sites for the oxidizing agents might be located in the C-terminus of TREK2, two chimeras were constructed: TREK2 (1-383)/TASK3C and TREK2 (1-353)/TASK3C. The channel activity in the TREK2 (1-383)/TASK3C chimera was still inhibited by DTNB, but not in the TREK2 (1-353)/TASK3C chimera. These results indicate that TREK2 is inhibited by oxidation, and that the target site for oxidation is located between the amino acid residues 353 and 383 in the C-terminus of the TREK2 protein.

Modulation of Large Conductance Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> Channel of Skin Fibroblast (CRL-1474) by Cyclic Nucleotides

Jihyun Yun,Seungtae Kim,Hyoweon Bang 대한생리학회-대한약리학회 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.2

Potassium channels in human skin fibroblast have been studied as a possible site of Alzheimer disease pathogenesis. Fibroblasts in Alzheimer disease show alterations in signal transduction pathway such as changes in Ca<SUP>2⁢</SUP> homeostasis and/or Ca<SUP>2⁢</SUP>-activated kinases, phosphatidylinositol cascade, protein kinase C activity, cAMP levels and absence of specific K<SUP>⁢</SUP> channel. However, little is known so far about electrophysiological and pharmacological characteristics of large-conductance Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> (BK<SUB>Ca</SUB>) channel in human fibroblast (CRL-1474). In the present study, we found Iberiotoxin- and TEA-sensitive outward rectifying oscillatory current with whole-cell recordings. Single channel analysis showed large conductance K<SUP>⁢</SUP> channels (106 pS of chord conductance at ⁢40 mV in physiological K<SUP>⁢</SUP> gradient). The 106 pS channels were activated by membrane potential and [Ca<SUP>2⁢</SUP>]<SUB>i</SUB>, consistent with the known pro</SUB>perties of BK<SUB>Ca</SUB> channels. BK<SUB>Ca</SUB> channels in CRL-1474 were positively regulated by adenylate cyclase activator (10μM forskolin), 8-Br-cyclic AMP (300μM) or 8-Br-cyclic GMP (300μM). These results suggest that human skin fibroblasts (CR-1474) have typical BK<SUB>Ca</SUB> channel and this channel could be modulated by c-AMP and c-GMP. The electrophysiological characteristics of fibroblasts might be used as the diagnostic clues for Alzheimer disease.

TASK-1 Channel Promotes Hydrogen Peroxide Induced Apoptosis

Jihyun Yun,Seungtae Kim,Hyoweon Bang 대한생리학회-대한약리학회 2005 The Korean Journal of Physiology & Pharmacology Vol.9 No.1

Hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) causes oxidative stress and is considered as an inducer of cell death in various tissues. Two-pore domain K<SUP>⁢</SUP> (K<SUB>2p</SUB>) channels may mediate K<SUP>⁢</SUP> efflux during apoptotic volume decreases (AVD) in zygotes and in mouse embryos. In the present study, we sought to elucidate linkage between K<SUB>2p</SUB> channels and cell death by H<SUB>2</SUB>O<SUB>2</SUB>. Thus K<SUB>2p</SUB> channels (TASK-1, TASK-3, TREK-1, TREK-2) were stably transfected in HEK-293 cells, and cytotoxicity assay was preformed using cell counting kit-8 (CCK-8). Cell survival rates were calculated using the cytotoxicity assay data and dose-response curve was fitted to the H<SUB>2</SUB>O<SUB>2</SUB> concentration. Ionic currents were recorded in cell-attached mode. The bath solution was the normal Ringer solution and the pipette solution was high K<SUP>⁢</SUP> solution. In HEK-293 cells expressing TREK-1, TREK-2, TASK-3, H<SUB>2</SUB>O<SUB>2</SUB> induced cell death did not change in comparison to non-transfected HEK-293. In HEK-293 cells expressing TASK-1, however, dose-response curve was significantly shifted to the left. It means that H<SUB>2</SUB>O<SUB>2</SUB> induced cell death was increased. In cell attached-mode recording, application of H<SUB>2</SUB>O<SUB>2</SUB> (300μM) increased activity of all K<SUB>2P</SUB> channels. However, a low concentration of H<SUB>2</SUB>O<SUB>2</SUB> (50μM) increased only TASK-1 channel activity. These results indicate that TASK-1 might participate in K<SUP>⁢</SUP> efflux by H<SUB>2</SUB>O<SUB>2</SUB> at low concentration, thereby inducing AVD.

Effects of Pharmacological Modulators of Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> Channels on Proliferation of Human Dermal Fibroblast

Jihyun Yun,Taeho Kim,Soonchul Myung,Hyoweon Bang,Inja Lim 대한생리학회-대한약리학회 2006 The Korean Journal of Physiology & Pharmacology Vol.10 No.2

Employing electrophysiological and cell proliferation assay techniques, we studied the effects of Ca<SUP>2⁢</SUP>- activated K<SUP>⁢</SUP> channel modulators on the proliferation of human dermal fibroblasts, which is important in wound healing. Macroscopic voltage-dependent outward K<SUP>⁢</SUP> currents were found at about ⁣40 mV stepped from a holding potential of ⁣70 mV. The amplitude of K<SUP>⁢</SUP> current was increased by NS1619, a specific large-conductance Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> (BK) channel activator, but decreased by iberiotoxin (IBTX), a specific BK channel inhibitor. To investigate the presence of an intermediate-conductance Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> (IK) channels, we pretreated the fibroblasts with low dose of TEA to block BK currents, and added 1-EBIO (an IK activator). 1-EBIO recovered the currents inhibited by TEA. When various Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> channel modulators were added into culture media for 1∼3 days, NS1619 or 1-EBIO inhibited the cell proliferation. On the other hand, IBTX, clotrimazole or apamin, a small conductance Ca<SUP>2⁢</SUP>-activated K<SUP>⁢</SUP> channel (SK) inhibitor, increased it. These results suggest that BK, IK, and SK channels might be involved in the proliferation of human dermal fibroblasts, which is inversely related to the channel activation.

백서 척수 후근 신경절에 존재하는 Mechanosensitive Two-pore Domain 포다슘 통로의 전기생리학적 특성

임인자,강경태,방효원 중앙대학교 의과대학 의과학연구소 2001 中央醫大誌 Vol.26 No.2

Mechanosensitive two-pore potassium channel families have been newly identified only within the last few years. They are found in different types of cells and species. Three potassium channels named TRAAK, TREK-1 and TREK-2 are activated by applying negative pressure or unsaturated free fatty acids to the cell membrane. We investigated the exstence and electrophysiological characteristics of mechanosenstive two-pore potassium channels in rat dorsale root ganglion neurones(DRGs). TRAAK,TREK-1 AND TREK-2 mRNA ARE EXPRESSED IN drg neurones DRG neurones as judged by reverse transcriptase-polymerase chain reaction. The expression level of TREK-2 mRNA is 30% compare to that of TRAAK and TREK-1. On the electrophysiological recording, however, the most common type of the currets in DRG neurones were activated by membrane stretch. The mechanosensitive pot assium channels of DRG neurones were also activated by arachidonic acid and alkalic pH. These results show that mechanosensitive potassium channels-TRAAK, TREK-1 and TREK-2 are expressed in DRG neurnes and they may exist as more complicated forms than the cloned potassium channels.

3,4,5-Tricaffeoylquinic Acid Inhibits the Lipopolysaccharide-Stimulated Production of Inflammatory Mediators in Keratinocytes

Lee, Seon Ae,Jung, Eun Byul,Lee, Seon Hwa,Kim, Yun Jeong,Bang, Hyoweon,Seo, Seong Jun,Choi, Young Wook,Kim, Manh Heun,Lee, Min Won,Lee, Chung Soo S. Karger AG 2012 Pharmacology Vol. No.

<P>Abstract</P><P><B><I>Background and Purpose:</I></B> Microbial product lipopolysaccharide (LPS) has been shown to be involved in the pathogenesis of inflammatory skin diseases. Caffeoyl derivatives have demonstrated anti-inflammatory and antioxidant effects. However, the effect of 3,4,5-tricaffeoylquinic acid (3,4,5-triCQA) on the production of microbial product-induced inflammatory mediators in keratinocytes has not yet been studied. <B><I>Experimental Approach:</I></B> Using human keratinocytes, we investigated the effect of 3,4,5-triCQA on the LPS-stimulated production of inflammatory mediators in relation to the nuclear factor (NF)-κB, Akt and ERK pathways. <B><I>Results:</I></B> 3,4,5-triCQA inhibited the LPS-induced expression of Toll-like receptor 4, and the production of cytokines and chemokines in keratinocytes. 3,4,5-triCQA, Bay 11-7085, Aκt inhibitor and ERK inhibitor each attenuated the LPS-induced production of inflammatory mediators by inhibiting the NF-κB, Akt and ERK pathways.<B><I> Conclusions and Implications:</I></B> 3,4,5-triCQA may attenuate the LPS-stimulated production of inflammatory mediators in keratinocytes by suppressing the Toll-like receptor 4 expression-mediated activation of the Akt, ERK and NF-κB pathways. 3,4,5-triCQA may exert a preventive effect against microbial product-induced inflammatory skin diseases.</P><P>Copyright © 2012 S. Karger AG, Basel</P>

Nitric Oxide Synthase Mediates Carbon Monoxide-Induced Stimulation of L-type Calcium Currents in Human Jejunal Smooth Muscle Cells

Inja Lim,Jihyun Yun,Seungtae Kim,Soonchul Myung,Taeho Kim,Hyoweon Bang 대한생리학회-대한약리학회 2004 The Korean Journal of Physiology & Pharmacology Vol.13 No.1

Exogenous carbon monoxide (0.2%) increases L-type calcium (Ca<SUP>2⁢</SUP>) current in human jejunal circular smooth muscle cells. The stimulatory effect of carbon monoxide (CO) on L-type Ca<SUP>2⁢</SUP> current is inhibited by pre-application of L-NNA, a classical competitive inhibitor of nitric oxide synthase (NOS) with no significant isoform selectivity (Lim, 2003). In the present study, we investigated which isoform of NOS affected CO induced stimulation of L-type Ca<SUP>2⁢</SUP> current in human jejunal circular smooth muscle cells. Cells were voltage clamped by whole-cell mode patch clamp technique, and membrane currents were recorded with 10 mM barium as the charge carrier. Before the addition of CO, cells were pretreated with each inhibitor of three NOS isoforms for 15 minutes. CO-stimulating effect on L-type Ca<SUP>2⁢</SUP> current was partially blocked by N-(3-(Amino-methyl) benzyl) acetamidine·2HCl (1400W, an iNOS inhibitor). On the other hand, 3-bromo-7-nitroindazole (BNI, a nNOS inhibitor) or N<SUP>5</SUP>-(1-Iminoethyl)-L-ornithine dihydrochloride (L-NIO, an eNOS inhibitor) completely blocked the CO effect. These data suggest that low dose of exogenous CO may stimulate all NOS isoforms to increase L-type Ca<SUP>2⁢</SUP> channel through nitric oxide (NO) pathway in human jejunal circular smooth muscle cells.

Improvement Characteristics of Bio-active Materials Coated Fabric on Rat Muscular Mitochondria

Lee, Donghee,Kim, Young-Won,Kim, Jung-Ha,Yang, Misuk,Bae, Hyemi,Lim, Inja,Bang, Hyoweon,Go, Kyung-Chan,Yang, Gwang-Wung,Rho, Yong-Hwan,Park, Hyo-Suk,Park, Eun-Ho,Ko, Jae-Hong The Korean Society of Pharmacology 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.3

This study surveys the improvement characteristics in old-aged muscular mitochondria by bio-active materials coated fabric (BMCF). To observe the effects, the fabric (10 and 30%) was worn to old-aged rat then the oxygen consumption efficiency and copy numbers of mitochondria, and mRNA expression of apoptosis- and mitophagy-related genes were verified. By wearing the BMCF, the oxidative respiration significantly increased when using the 30% materials coated fabric. The mitochondrial DNA copy number significantly decreased and subsequently recovered in a dose-dependent manner. The respiratory control ratio to mitochondrial DNA copy number showed a dose-dependent increment. As times passed, Bax, caspase 9, PGC-$1{\alpha}$ and ${\beta}$-actin increased, and Bcl-2 decreased in a dose-dependent manner. However, the BMCF can be seen to have had no effect on Fas receptor. PINK1 expression did not change considerably and was inclined to decrease in control group, but the expression was down-regulated then subsequently increased with the use of the BMCF in a dose-dependent manner. Caspase 3 increased and subsequently decreased in a dose-dependent manner. These results suggest that the BMCF invigorates mitophagy and improves mitochondrial oxidative respiration in skeletal muscle, and in early stage of apoptosis induced by the BMCF is not related to extrinsic death-receptor mediated but mitochondria-mediated signaling pathway.

Expression of potassium channel genes predicts clinical outcome in lung cancer

Ko, Eun-A,Kim, Young-Won,Lee, Donghee,Choi, Jeongyoon,Kim, Seongtae,Seo, Yelim,Bang, Hyoweon,Kim, Jung-Ha,Ko, Jae-Hong The Korean Society of Pharmacology 2019 The Korean Journal of Physiology & Pharmacology Vol.23 No.6

Lung cancer is the most common cause of cancer deaths worldwide and several molecular signatures have been developed to predict survival in lung cancer. Increasing evidence suggests that proliferation and migration to promote tumor growth are associated with dysregulated ion channel expression. In this study, by analyzing high-throughput gene expression data, we identify the differentially expressed $K^+$ channel genes in lung cancer. In total, we prioritize ten dysregulated $K^+$ channel genes (5 up-regulated and 5 down-regulated genes, which were designated as K-10) in lung tumor tissue compared with normal tissue. A risk scoring system combined with the K-10 signature accurately predicts clinical outcome in lung cancer, which is independent of standard clinical and pathological prognostic factors including patient age, lymph node involvement, tumor size, and tumor grade. We further indicate that the K-10 potentially predicts clinical outcome in breast and colon cancers. Molecular signature discovered through $K^+$ gene expression profiling may serve as a novel biomarker to assess the risk in lung cancer.