• The Korean Journal of Physiology and Pharmacology
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• 제8권2호
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• pp.101-110
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• 2004

Voltage-sensitive release mechanism was pharmacologically dissected from the $Ca^{2+}-induced\;Ca^{2+}\;release$ in the SR $Ca^{2+}$ release in the rat ventricular myocytes patch-clamped in a whole-cell mode. SR $Ca^{2+}$ release process was monitored by using forward-mode $Na^+-Ca^{2+}$ exchange after restriction of the interactions between $Ca^{2+}$ from SR and $Na^+-Ca^{2+}$ exchange within micro-domains with heavy cytosolic $Ca^{2+}$ buffering with 10 mM BAPTA. During stimulation every 10 s with a pulse roughly mimicking action potential, the initial outward current gradually turned into a huge inward current of $-12.9{\pm}0.5\;pA/pF$. From the inward current, two different inward $I_{NCX}s$ were identified. One was $10\;{\mu}M$ ryanodine-sensitive, constituting $14.2{\pm}2.3%$. It was completely blocked by $CdCl_2$ (0.1 mM and 0.5 mM) and by $Na^+-depletion$. The other was identified by 5 mM $NiCl_2$ after suppression of $I_{CaL}$ and ryanodine receptor, constituting $14.8{\pm}1.6%$. This latter was blocked by either 10 mM caffeine-induced SR $Ca^{2+}-depletion$ or 1 mM tetracaine. IV-relationships illustrated that the latter was activated until the peak in $30{\sim}35\;mV$ lower voltages than the former. Overall, it was concluded that the SR $Ca^{2+}$ release process in the rat ventricular myocytes is mediated by the voltage-sensitive release mechanism in addition to the $Ca^{2+}-induced-Ca^{2+}\;release$.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.294-294
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• 1994

To investigate analgesic mechanism of capsaicin and its analogues (capsaicinoids), release of adenosine was measured by high performance liquid chromatography from dorsal spinal cord synaptosomes, Exposure of synaptosomes to K$\^$+/ and morphine produced a dose dependent release of adenosine in the presence of Ca$\^$++/. Capsaicin (0.1, 1, 10 M), and its analogues 6-paradol (1, 10 M), NE-19550 (1, 10, 100 M), DMNE (1, 10, 100 M) and KR 25018 (0.1, 1, 10 M) produced a dose dependent release of adenosine in the presence of Ca$\^$++/. Nifedipine, L-type voltage sensitive calcium channel blocker, inhibited K$\^$+/ (6, 12 mM)- and morphine (10 M)-evoked release of adenosine completely, but inhibited capsaicin, and capsaicinoids-evoked release of adenosine partially. Capsazepine, a novel capsaicin select ive antagonist, blocked only capsaicin and capsaicinoids induced release of adenosine. Therefore, the adenosine release by capsaicin and capsaicinoids having antinociceptive effects involve activation of capsaicin specific receptor and capsaicin sensitive Ca$\^$++/ channel.

• 약학회지
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• 제43권1호
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• pp.55-60
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• 1999

To investigate analgesic mechanism of capsaicin and its analogues (capaicinoids) adenosine release was measured by high performance liquid chromatography from rat spinal cord synaptosomes. Exposure of synaptosomes to $K^+$ and morphine produced a dose dependent release of adenosine in the presence of $Ca^{++}$. Capsaicin (0.1, 1, $10{\;}{\mu}M$), and its analogues: NE-19550 (1, 10, $100{\;}{\mu}M$), DMNE (1, 10, $100{\;}{\mu}M$) and KR 25018 (0.1, 1, $10{\;}{\mu}M$) produced a concentration dependent release of adenosine in the presence of $Ca^{++}$. Nifedifine, L-type voltage sensitive calcium channel blocker, inhibited $K^+$ (6, 12 mM)-and morphine ($10{\;}{\mu}M$)-evoked release of adenosine partially. Capsazepine, a novel capsaicin selective antagonist, blocked only capsaicin and capsaicinoids induced release of adenoside. Therefore, it is suggested that the adenosine release by capsaicin and capsaicinoids having antinociceptive effects involves actvation of capsaicin specific receptor and capsaicin sensitive $Ca^{++}$. channel.

• Animal cells and systems
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• 제1권1호
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• pp.81-86
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• 1997

We studied the mechanism of arachidonic acid on the secretion of a neurotransmitter in rat pheochromocytoma PC12 cells. Arachidonic acid inhibited the 70 mM $K^+$-induced secretion of norepinephrine. Arachidonic acid also inhibited the 70 mM $K^+$-induced $Ca^{2+}$ mobilization which is due to the opening of the voltage-sensitive $Ca^{2+}$ channels (VSCC). Both the half maximal inhibitory concentration ($IC_{50}$) of the norepinephrine secretion and VSCC coincided at 30 uM. The major oxidized metabolites of arachidonic acid, prostaglandins did not mimic the inhibitory effect of arachidonic acid. Nordihydroguaiaretic acid (NDGA) and indomethacin which are inhibitors of lipoxygenase and cyclooxygenase, respectively, did not block the inhibitory effect of arachidonic acid. The results suggest that arachidonic acid serves as a signal itself, not in the form of metabolites. The pretreatment of various $K^+$ channel blockers such as 4-aminopyridine, tetraethylarnmonium, glipizide, or glibenclamide also did not show any effect on the inhibitory effect of arachidonic acid. Through these results we suggest that arachidonic acid regulates VSCC directly and affects the secretion of neurotransmitters.

• Archives of Pharmacal Research
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• 제28권6호
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• pp.709-715
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• 2005

The purpose of this study was to investigate the effect of atropine on peripheral vasodilation and the mechanisms involved. The isometric tension of rat mesenteric artery rings was recorded in vitro on a myograph. The results showed that atropine, at concentrations greater than 1$\mu$M, relaxed the noradrenalin (NA)-precontracted rat mesenteric artery in a concentration-dependent manner. Atropine-induced vasodilatation was mediated, in part, by an endothelium-dependent mechanism, to which endothelium-derived hyperpolarizing factor may contribute. Atropine was able to shift the NA-induced concentration-response curve to the right, in a non-parallel manner, suggesting the mechanism of atropine was not mediated via the ${\alpha}_1$-adrenoreceptor. The $\beta$-adrenoreceptor and ATP sensitive potassium channel, a voltage dependent calcium channel, were not involved in the vasodilatation. However, atropine inhibited the contraction derived from NA and $CaCl_2$ in $Ca^{2+}$-free medium, in a concentration dependent manner, indicating the vasodilatation was related to the inhibition of extracellular $Ca^{2+}$ influx through the receptor-operated calcium channels and intracellular $Ca^{2+}$ release from the $Ca^{2+}$ store. Atropine had no effect on the caffeine-induced contraction in the artery segments, indicating the inhibition of intracellular $Ca^{2+}$ release as a result of atropine most likely occurs via the IP3 pathway rather than the ryanodine receptors. Our results suggest that atropine-induced vasodilatation is mainly from artery smooth muscle cells due to inhibition of the receptor-mediated $Ca^{2+}$-influx and $Ca^{2+}$-release, and partly from the endothelium mediated by EDHF.

• The Korean Journal of Physiology and Pharmacology
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• 제23권6호
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• pp.427-448
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• 2019

Nociceptin/orphanin FQ (N/OFQ) and its receptor, nociceptin opioid peptide (NOP) receptor, are localized in brain areas implicated in depression including the amygdala, bed nucleus of the stria terminalis, habenula, and monoaminergic nuclei in the brain stem. N/OFQ inhibits neuronal excitability of monoaminergic neurons and monoamine release from their terminals by activation of G protein-coupled inwardly rectifying $K^+$ channels and inhibition of voltage sensitive calcium channels, respectively. Therefore, NOP receptor antagonists have been proposed as a potential antidepressant. Indeed, mounting evidence shows that NOP receptor antagonists have antidepressant-like effects in various preclinical animal models of depression, and recent clinical studies again confirmed the idea that blockade of NOP receptor signaling could provide a novel strategy for the treatment of depression. In this review, we describe the pharmacological effects of N/OFQ in relation to depression and explore the possible mechanism of NOP receptor antagonists as potential antidepressants.

• 대한수의학회지
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• 제43권4호
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• pp.587-595
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• 2003

The aim of this study was to investigate trazodone's effect on vasorelaxation and blood pressure lowering and to examine its underlying mechanism of action in isolated thoracic aorta and anesthesized rats. Precontracted aortic rings with high KCl were relaxed with trazodone, at concentrations of $50{\mu}M$ or greater. However, precontracted rings with phenylephrine (PE) were relaxed with trazodone, at concentrations of $0.03{\mu}M$ or greater, in a concentration-dependent manner. These relaxant effects of trazodone on endothelium intact rat aortic rings were significantly greater than those on denuded rings. The trazodone-induced relaxations were suppressed by nitric oxide synthase (NOS) inhibitors, N(G)-nitro-L-arginine (L-NNA) and N(omega)-nitro-L-arginine methyl ester (L-NAME), guanylate cyclase inhibitors, methylene blue and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a $Ca^{2+}$-activated $K^+$ channel blocker, tetrabutylammonium (TBA), a $Ca^{2+}$ channel blocker, nifedipine, $Na^+$ channel blockers, lidocaine and procaine, and removal of extracellular $Na^+$, but not by aminoguanidine, 2-nitro-4-carboxyphenyl-n, n-diphenylcarbamate (NCDC), indomethacin, glibenclamide and clotrimazole. In vivo, infusion of trazodone elicited significant decrease in arterial blood pressure. Trazodone-induced decrease in blood pressure was markedly inhibited by pretreatment of intravenous injection of saponin, L-NNA, methylene blue, TBA, lidocaine or nifedipine. These findings suggest that the endothelium-dependent relaxation and decrease in blood pressure induced by trazodone is mediated by release of NO from the endothelium, activation of TBA-sensitive $Ca^{2+}$-activated $K^+$ channels or inhibition of $Ca^{2+}$ entry through voltage-gated channel.

• 대한약리학회지
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• 제32권3호
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• pp.357-371
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• 1996

리튬(Lithium)은 임상에서 조울병 치료에 이용되고 있다. 본 연구는 흰쥐 적출 관류부신 으로부터 catecholamine (CA) 분비에 대한 리튬의 작용을 검색 하고 그 기전을 규명하고자 하여 얻어진 결과는 다음과 같다. 정상 Krebs-bicarbonate 용액내의 $Na^+$ (118.4 mM)을 리튬으로 대치하여 관류하였을때 CA 분비는 점차적인 증가를 나타내었으며, $30{\sim}60$분에서 최대 분비작용을 나타내었다. Li-Krebs액은 모든 실험에서 부신정맥을 통해서 2시간동안 관류하였다. Li-Krebs에 의한 CA 분비반응은 $Ca^{++}-free$ Krebs액으로 전처치한 상태에서 유의하게 억제되었다. 이와같은 Li-Krebs 액에 의한 CA 분비작용은 nicardipine ($10^{-6}$ M), TMB-8 ($10^{-5}$ M) 및 chlorisondamine ($10^{-6}$ M) 등을 20 분간 각각 전처치 하였을때 현저히 감약되었으나 pirenzepine ($2{\times}10^{-6}$ M)에 의해서는 별다른 영향을 받지 않았다. $Na^+$ pump 억제제인 ouabain ($10^{-4}$ M)으로 20 분간 전처치한 후 Li-Krebs에 의한 CA 유리작용은 뚜렷이 억제되었다. 더우기 tetrodotoxin ($5{\times}10^{-7}$ M)으로 20 분간 전처치 하였을때도 Li-Krebs에 의한 CA 분비반응은 현저히 감약되었다. 이상과 같은 실험결과를 종합하여 보면, 리튬은 흰쥐 부신수질의 크롬 친화성 세포내에 측적됨으로써 칼슘의존성의 CA 분비작용을 일으키며, 이러한 분비작용은 i) 크롬친화성 세포의 탈분극과 이어서 voltage-sensitive 칼슘채널의 개방과 ii) $[Li]_i-[Ca]_0$ counter-transport system의 활성화를 통한 두가지 작용기전에 의해서 매개되는 것으로 생각된다.

• Journal of Ginseng Research
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• 제24권4호
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• pp.168-175
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• 2000

Xenopus oocytes를 이용하여 인삼의 유효 성분으로 알려진 Ginseng total saponin(GTS)의 신호 전달 기작을 two electrode voltage clamp 방법을 이용하여 연구하였다. GTS는 세포 바깥에 처리했을 때 -2OmV보다 더 positive한 voltage에서 커다란 outward current를 유도하였다. 그러나, 세포 안쪽에 GTS를 injection할 경우 아무런 효과가 없는 것으로 나타났다. GTS처리에 의한 outward current유발 효과는 GTS 투여 용량에 의존적인 것으로 나타났다(EC$_{50}$ : 4.4 $\mu\textrm{g}$/ml). GTS의 작용은 $Ca^{2+}$-activated Cl- channel blocker인 niflumic acid에 의하여 차단되었다. 칼슘 chelator인 BAPIA와 IP$_3$ 수용체 길항제인 heparin을 세포내 injection에 의하여 차단되었다. 또한 active phospholipase C inhibitor(PLC)인U-73122를 세포 바깥에 전처리할 경우에도 GTS의 작용이 부분적으로 억제되는 것으로 나타났다. 백일해 독소를 전처리할 경우GTS의 작용은 억제되지 않은 것으로 나타났으나, GTP analog인 GTP${\gamma}$S를 세포내 injection할 경우 GTS의 작용은 억제되는 것으로 나타났다. 이러한 연구 결과는 GTS가 oocytes세포막 성분과 상호 작용에 의하여 $Ca^{2+}$-activated Cl- channel이 열리도록 하고, 이 과정에 PLC활성 및 백일해 독소에 민감하지 않은 G단백질활성 및 IP3에 민감한 세포내 $Ca^{2+}$-activated로부터 칼슘 방출을 유도하는 것으로 나타났다났다

• The Korean Journal of Physiology and Pharmacology
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• 제5권6호
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• pp.487-494
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• 2001

During depolarization, extrusion of $Ca^{2+}$ from sarcoplasmic reticulum through forward-mode $Na^+-Ca^{2+}$ exchange was studied in the rat ventricular myocytes patch-clamped in whole-cell configuration. In order to confine the $Ca^{2+}$ responses in a micro-domain by limiting the $Ca^{2+}$ diffusion time, rat ventricular myocytes were dialyzed with high (14 mM) EGTA. $K^+$ current was suppressed by substituting KCl with 105 mM CsCl and 20 mM TEA in the pipette filling solution and by omitting KCl in the external Tyrode solution. $Cl^-$ current was suppressed by adding 0.1 mM DIDS in the external Tyrode solution. During stimulation roughly mimicking action potential, the initial outward current was converted into inward current, $47{\pm}1%$ of which was suppressed by 0.1 mM $CdCl_2.$ 10 mM caffeine increased the remaining inward current after $CdCl_2$ in a cAMP-dependent manner. This caffeine-induced inward current was blocked by $1\;{\mu}M$ ryanodine, $10\;{\mu}M$ thapsigargin, 5 mM $NiCl_2,$ or by $Na^+\;and\;Ca^{2+}$ omission, but not by $0.1\;{\mu}M$ isoproterenol. The $I{\sim}V$ relationship of the caffeine-induced current elicited inward current from -45 mV to +3 mV with the peak at -25 mV. Taken together, it is concluded that, during activation of the rat ventricular myocyte, forward-mode $Na^+-Ca^{2+}$ exchange extrudes a fraction of $Ca^{2+}$ released from sarcoplasmic reticulum mainly by voltage-sensitive release mechanism in a micro-domain in the t-tubule, which is functionally separable from global $Ca^{2+}{_i}$ by EGTA.