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KMID : 0352720000240040168
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Journal of Ginseng Research
2000 Volume.24 No. 4 p.168 ~ p.175
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Mechanism of Ca2+-activated Cl- Channel Activation by Ginsenosides in Xenopus Oocytes
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Seung Yeol Nah/Seok Choi
Se Yeon Jung/Seong Hwan Rho/Sung Ryong Ko/Hye Won Rhim/Chul Seung Park/Seung Yeol Nah
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Abstract
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Relatively little is known about the signaling mechanism of ginseng saponins (ginsenosides), active ingredients of ginseng, in non-neuronal cells. Here, we describe that ginsenosides utilize a common pathway of receptor-mediated signaling pathway in Xenopus oocytes: increase in intracellular
Ca2+ concentration via phospholipase C (PLC) and Ca2+ mobilization. Ginsenosides induced a marked and robust artivation of Ca2+-activated Cl- channels in Xenopus oocytes. The effect of ginsenosides was completely reversible, in a dose-dependent manner with EC50 of 4.4 μg/mi, and specifically blocked by niflumic acid, an inhibitor of Ca2+-activated Cl- channel. Intracellular injection of BAPIA abolished the effect of ginsenosides. Intracellular injection of GTPγS also abolished the effect of ginsenosides. The effect of gin senosides on Ca2+-activated Cl- currents was greatly reduced by the intracellular injection of heparin, an IP3 receptorantagonist or the pretreatment of PLC inhibitor. These results indicate that ginsenosides activate endogenous Ca2+-activated Cl- channels via the activation of PLC and the release of Ca2+ from the IP3-sensitive intracellular store following the initial interaction with membrane component(s) from extracellular side. This signaling pathway of ginsenosides may be one of the action mechanisms for the pharmacological effects of ginseng.ts of ginseng.
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KEYWORD
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Ginseng, Ginsenosides, PLC, Ca2+-activated Cl- channels, Xenopus oocytes,
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