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KMID : 0352719990230040230
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Journal of Ginseng Research
1999 Volume.23 No. 4 p.230 ~ p.234
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Ginseng Saponins Enhance Maxi Ca2+-activated K+ Currents of the Rabbit Coronary Artery Smooth Muscle Cells
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정인덕/1Induk Chung
2Nak Doo Kim
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Abstract
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Potassium channels play an important role in regulating vascular smooth muscle tone. Four types of K+ channels areknown to be expressed in vascular smooth muscle cells, and maxi Ca2+?activatedK+ channel (BKCa) is a dominant type of K+ channels in these cells. Because total ginseng saponins and ginsenoside Rg3 cause vasodilation with unclear mechanisms, we hypothesized that total ginseng saponins and ginsenoside Rg3 induce vasodilation via activation of maxi Ca2+?activatedK+ channels. Whole-cell BKe. currents were voltage-dependent with half maximum activation at -14 mV, and the currents were sensitive to nanomolar ChTX and millimolar TEA. External application of total ginseng saponins increased the anlplitude of the whole-cell BKe. current in a concentration-dependent manner. Single-channel analysis indicates that total ginseng saponins caused the channel opening for a longer period of time. Ginsenoside Rg3 increased the amplitude of whole-cell KCa currents without affecting voltage dependence of the currents and increased single-channel open time. Hence, the results suggest that ginseng saponin-induced vasodilation may be due to activation of KCa.
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