• The Korean Journal of Physiology and Pharmacology
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• 제17권2호
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• pp.175-180
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• 2013

Resveratrol is a phytoalexin found in grapes, red wine, and berries. Resveratrol has been known to have many beneficial health effects, such as anti-cancer, neuroprotective, anti-inflammatory, and life-prolonging effects. However, relatively little is known about the effects of resveratrol on the regulation of ligand-gated ion channels. We have previously reported that resveratrol regulates subsets of homomeric ligand-gated ion channels such as those of 5-$HT_{3A}$ receptors. The ${\gamma}$-aminobutyric $acid_C$($GABA_C$) receptor is mainly expressed in retinal bipolar cells and plays an important role in visual processing. In the present study, we examined the effects of resveratrol on the channel activity of homomeric $GABA_C$ receptor expressed in Xenopus oocytes injected with cRNA encoding human $GABA_C$ ${\rho}$ subunits. Our data show that the application of GABA elicits an inward peak current ($I_{GABA}$) in oocytes that express the $GABA_C$ receptor. Resveratrol treatment had no effect on oocytes injected with $H_2O$ or with $GABA_C$ receptor cRNA. Co-treatment with resveratrol and GABA inhibited $I_{GABA}$ in oocytes with $GABA_C$ receptors. The inhibition of $I_{GABA}$ by resveratrol was in a reversible and concentration-dependent manner. The $IC_{50}$ of resveratrol was $28.9{\pm}2.8{\mu}M$ in oocytes expressing $GABA_C$ receptor. The inhibition of $I_{GABA}$ by resveratrol was in voltage-independent and non-competitive manner. These results indicate that resveratrol might regulate $GABA_C$ receptor expression and that this regulation might be one of the pharmacological actions of resveratrol on the nervous system.

• The Korean Journal of Physiology and Pharmacology
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• 제2권2호
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• pp.165-172
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• 1998

Under certain pathophysiological conditions, such as inflammation and ischemia, the concentration of H^+$ ion in the tissue surrounding neurons is changed. Variations in H^+$ concentration are known to alter the conduction and/of the gating properties of several types of ion channels. Several types of K^+$ channels are modulated by pH. In this study, the whole cell configuration of the patch clamp technique has been applied to the recording of the responses of change of external pH on the delayed rectifier K^+$ current of cultured DRG neurons of rat. Outward K^+$ currents were examined in DRG cells, and the Charybdotoxin and Mn^{2+}$ could eliminate Ca^{2+}-dependent$ K^+$ currents from outward K^+$ currents. This outward K^+$ current was activated around -60 mV by step depolarizing pulses from holding potential -70 mV. Outward K^+$ currents were decreased by low external pH. Activation and steady-state inactivation curve were shifted to the right by acidification, while there was small change by alkalization. These results suggest that H^+$ could be alter the sensory modality by changing and modifying voltage-dependent K^+$ currents, which participated in repolarization.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2962-2968
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• 2009

The photodissociation dynamics of 1,2-bromochloroethane ($C_2H_4BrCl$) was investigated near 234 nm. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br($^2P_{3/2}$) and Br${\ast}($^2P_{1/2}$) atoms. The total translational energy distributions for the Br and Br${\ast}$ channels were well characterized by Gaussian functions with average translational energies of 100 and 84 kJ/mol, respectively. The recoil anisotropies for the Br and Br${\ast}$ channels were measured to be ${\beta}$ = 0.49 ${\pm}$ 0.05 for Br and 1.55 ${\pm}$ 0.05 for Br${\ast}$. The relative quantum yield for Br${\ast}$ was found to be ${\Phi}_{Br{\ast}}$ = 0.33 ${\pm}$ 0.03. The probability of nonadiabatic transition between A' states was estimated to be 0.46. The relevant nonadiabatic dynamics is discussed in terms of interaction between potential energy surfaces in Cs symmetry.

• Animal cells and systems
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• 제2권4호
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• pp.471-476
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• 1998

The G protein-activated inwardly rectifying $K^＋$ channel (GIRK1) was coex-pressed in Xenopus oocytes along with the $5-HT_{1A}$ receptor, a 7-helix receptor known to be coupled to $K^＋$ channels in many neural tissues. Thus, the activation of the $5-HT_{1A}$ receptor by its agonist leads to the opening of GIRK1. The GIRK1 current was measured using the two electrode voltage clamp technique with bath application of 5-HT in the presence of various external potassium concentrations $[K^＋]_0$. GIRK1 showed a strong inward rectification since only hyperpolarizing voltages evoked inward currents. $K^{+}$ was the major ion carrier as evidenced by about 44㎷ voltage shift corresponding to a 10-fold external 〔$K^＋$〕 change. 5-HT induced a concentration-dependent inward $K^＋$ current ($EC_{50}{\equation omitted}10.7nM$) which was blocked by $Ba^{2＋}$. Pertussis toxin (PTX) pre-treatment reduced the $K^＋$ current by as much as about 70%, suggesting that PTX-sensitive G protein ($G_i or G_o$ type) are involved in the $5-HT_{1A}$ receptor-GIRK1 coupling in Xenopus oocytes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.49-53
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• 2005

The objective of this research was to establish the size limitation of micro metal forming and analyze the formability of foil. Flat-rolled ultra thin metallic copper foil($3{\mu}m$ in thickness) was used as a forming material and foil was annealed to improve the formability at the temperature of $385^{\circ}C$. Forming die was fabricated by using etching technique of DRIE(deep reactive ion etching) and HNA isotropic etching. For the forming die and coupe. foil were vacuum packed and the forming was conducted as applying hydrostatic pressure of 250MPa to the vacuum packed unit. We successfully obtained the micro channels of $12\~14{\mu}m$ width and $9{\mu}m$ depth from micro forming process we designed. We also investigated the thickness strain distribution of foil from experiment and FE simulation result. Micro channels had a good formability of smooth surface and size accuracy. We expect that micro metal forming technology will be applied to production of micro parts.

• Archives of Plastic Surgery
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• 제42권1호
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• pp.11-19
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• 2015

Background Wound healing is an interaction of a complex signaling cascade of cellular events, including inflammation, proliferation, and maturation. $K^+$ channels modulate the mitogen-activated protein kinase (MAPK) signaling pathway. Here, we investigated whether $K^+$ channel-activated MAPK signaling directs collagen synthesis and angiogenesis in wound healing. Methods The human skin fibroblast HS27 cell line was used to examine cell viability and collagen synthesis after potassium chloride (KCl) treatment by Cell Counting Kit-8 (CCK-8) and western blotting. To investigate whether $K^+$ ion channels function upstream of MAPK signaling, thus affecting collagen synthesis and angiogenesis, we examined alteration of MAPK expression after treatment with KCl (channel inhibitor), NS1619 (channel activator), or kinase inhibitors. To research the effect of KCl on angiogenesis, angiogenesis-related proteins such as thrombospondin 1 (TSP1), anti-angiogenic factor, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), pro-angiogenic factor were assayed by western blot. Results The viability of HS27 cells was not affected by 25 mM KCl. Collagen synthesis increased dependent on time and concentration of KCl exposure. The phosphorylations of MAPK proteins such as extracellular-signal-regulated kinase (ERK) and p38 increased about 2.5-3 fold in the KCl treatment cells and were inhibited by treatment of NS1619. TSP1 expression increased by 100%, bFGF expression decreased by 40%, and there is no significant differences in the VEGF level by KCl treatment, TSP1 was inhibited by NS1619 or kinase inhibitors. Conclusions Our results suggest that KCl may function as a therapeutic agent for wound healing in the skin through MAPK signaling mediated by the $K^+$ ion channel.

• 한국발생생물학회지:발생과생식
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• 제4권2호
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• pp.243-250
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• 2000

To find the mechanism underlying the ADP-induced increase in the outward current in ovulated mouse oocytes, we examined changes in voltage-dependent currents using the whole cell voltage clamp technique and the internal perfusion technique. Eggs were collected from the oviduct of superovulated mice with PMSG and hCG. Membrane potential was held at -60 mV (or -80 mV in the case of recording $Ca^{2＋}$ currents) and step depolarizations or hyperpolarizations were applied for 300 ms. By step depolarizations, outward currents comprising steady-state and time-dependent components were elicited. They were generated in response to the positive potential more than 20 mV with severe outward rectification and were blocked by external TEA, a specific $K^{＋}$ channel blocker, suggesting that they be carried via $K^{＋}$ channels. Internally-perused 5 mM ADP gradually increased outward $K^{＋}$ currents (IK) 1 min after perfusion of ADP and reached slowly to maximum (150~170％) 5 min later over the positive potential range, implying that ADP might not be acted directly to the $K^{＋}$ channels. IK were decreased by 5 mM ATP without affecting the steady-state component of outward current. In contrast to the effect of ADP and ATP on IK, both effect of ATP and ADP on inward $Ca^{2＋}$ currents (ICa) could not be detected due to the continuous decrease in current amplitudes with time-lapse ("run-down" phenomena). To check if there is a G protein-involved regulation in the ionic current of mouse oocytes, 1 mM GTP was applied to the cytoplasmic side, and the outward current and inward currents were recorded. ICa was promptly increased in the presence of GTP whereas IK was not changed. from these results, it is concluded that the ATP-dependent regulation is likely linked in the ADP-induced increase in the outward $K^{＋}$ current, and G protein-involved cellular signalling might affect ion channels carrying $Ca^{2＋}$ and $K^{＋}$ in mouse oocytes.

• Biomolecules & Therapeutics
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• 제20권6호
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• pp.550-555
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• 2012

TRPA1 and TRPV1 are members of the TRP superfamily of structurally related, nonselective cation channels. TRPA1 and TRPV1 are often co-expressed in sensory neurons and play an important role in somatosense such as cold, pain, and irritants. The first leaves of Kalopanax pictus Nakai (Araliaceae) have long been used as a culinary ingredient in Korea because of their unique chemesthetic flavor. In this study, we observed the intracellular $Ca^{2+}$ response to cultured cells expressing human TRPA1 (hTRPA1) and human TRPV1 (hTRPV1) by $Ca^{2+}$ imaging analysis to investigate the ability of the first leaves of K. pictus to activate the hTRPA1 and hTRPV1. An 80% ethanol extract of K. pictus (KPEx) increased intracellular $Ca^{2+}$ influx in a response time- and concentration-dependent manner via either hTRPA1 or hTRPV1. KPEx-induced response to hTRPA1 was markedly attenuated by ruthenium red, a general blocker of TRP channels, and HC-030031, a specific antagonist of TRPA1. In addition, the intracellular $Ca^{2+}$ influx attained with KPEx to hTRPV1 was mostly blocked by ruthenium red, and capsazepine, a specific antagonist of TRPV1. These results indicate that KPEx selectively activates both hTRPA1 and hTRPV1, which may provide evidence that the first leaves of K. pictus primarily activate TRPA1 and TRPV1 to induce their unique chemesthetic sense.

• The Korean Journal of Physiology and Pharmacology
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• 제15권5호
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• pp.279-283
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• 2011

Quercetin (3,3',4',5,7-pentahydroxyflavone) is an attractive therapeutic flavonoid for cancer treatment because of its beneficial properties including apoptotic, antioxidant, and antiproliferative effects on cancer cells. However, the exact mechanism of action of quercetin on ion channel modulation is poorly understood in bladder cancer 253J cells. In this study, we demonstrated that large conductance $Ca^{2+}$-activated $K^+$ ($BK_{Ca}$) or MaxiK channels were functionally expressed in 253J cells, and quercetin increased $BK_{Ca}$ current in a concentration dependent and reversible manner using a whole cell patch configuration. The half maximal activation concentration ($IC_{50}$) of quercetin was $45.5{\pm}7.2{\mu}m$. The quercetin-evoked $BK_{Ca}$ current was inhibited by tetraethylammonium (TEA; 5 mM) a non-specific $BK_{Ca}$ blocker and iberiotoxin (IBX; 100 nM) a $BK_{Ca}$-specific blocker. Quercetin-induced membrane hyperpolarization was measured by fluorescence-activated cell sorting (FACS) with voltage sensitive dye, bis (1,3-dibutylbarbituric acid) trimethine oxonol ($DiBAC_4$2(3); 100 nM). Quercetin-evoked hyperpolarization was prevented by TEA. Quercetin produced an antiproliferative effect ($30.3{\pm}13.5%$) which was recovered to $53.3{\pm}10.5%$ and $72.9{\pm}3.7%$ by TEA and IBX, respectively. Taken together our results indicate that activation of $BK_{Ca}$ channels may be considered an important target related to the action of quercetin on human bladder cancer cells.

• 한방비만학회지
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• 제18권2호
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• pp.57-63
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• 2018

Objectives: Metabolic syndrome is defined by a cluster of major cardiovascular risk factors: obesity, insulin resistance, dyslipidemia, and arterial hypertension. Several members of a large family of nonselective cation entry channels, e.g., transient receptor potential vanilloid 4 (TRPV4) channels have been associated with the development of dyslipidemia and hypertension. The purpose of this study was to investigate the effects of Leejung-tang (Lizhong-tang), Rikkunshito, and Bojungikgi-tang (Buzhongyiqi-tang) on TRPV4 channel. Methods: Human embryonic kidney 293 cells stably transfected with the TRPV4 expression vectors were maintained in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 1% penicillin/streptomycin, $5{\mu}g/mL$ blasticidin, and 0.4 mg/mL zeocin in a humidified 20% $O_2/10%$ $CO_2$ atmosphere at $37^{\circ}C$. Whole-cell patch clamp recordings were obtained using an Axopatch 700B amplifier and pClamp v.10.4 software (Molecular Devices, San Jose, CA, USA), and signals were digitalized at 5 kHz using Digidata 1422A. Results: Leejung-tang and Rikkunshito (10, 30 and 50 mg/mL) had no effects on the TRPV4 whole-cell currents at dose dependent manner. However, Bojungikgi-tang (10, 30, and 50 mg/mL) inhibited the TRPV4 whole-cell currents in a dose dependent manner and the half maximal inhibitory concentration (IC50) of Bojungikgi-tang was 18.2 mg/mL. Conclusions: These results suggest that Bojungikgi-tang plays an important roles to inhibit the TRPV4 channel, suggesting that Bojungikgi-tang is considered one of the candidate agents for the treatment of metabolic syndrome such as dyslipidemia and hypertension.