人参皂甙Rg_1对培养心肌细胞钙通道阻滞作用的单通道分析

Single channel analysis of the blockade effect of ginsenoside Rg_1 on calcium channel of cultured myocardiocytes in rats

用细胞吸附（Ｃｅｌｌ－ａｔｔａｃｈｅｄ）的膜片钳（Ｐａｔｃｈｃｌａｍｐ）方法，在培养２４～４８ｈ的Ｗｉｓｔａｒ大鼠乳鼠心室肌细胞上，研究Ｒｇ１对心肌细胞钙通道的影响。由－７０ｍＶ的保持电位新跃至－１０ｍＶ诱发Ｔ型钙通道的活动，由－５０ｍＶ阶跃至＋１０ｍＶ诱发Ｌ型钙通道的活动，在－６０ｍＶ的保持电压下，记录Ｂ型钙通道的活动。向浸浴液中分别加入Ｒｇ１，钙通道阻断剂Ｖｅｒａｐａｍｉｌ，钙通道激动剂ＢａｙＫ８６４４，使其终浓度分别为５０μｇ／ｍｌ，３７．５μｇ／ｍｌ和５μｍｏｌ／Ｌ。记录加药前后三型钙通道的电活动。结果发现：Ｒｇ１可使三型钙通道的平均开放时间缩短，平均关闭时间延长，对三型钙通道的Ｂａ（２＋）流幅值无明显影响，其作用与Ｖｅｒａｐａｍｉｌ相似，与ＢａｙＫ８６４４相反。实验首次证明Ｒｇ１对心肌细胞钙通道有阻滞作用，其机制在于使钙通道的平均开放时间缩短，平均关闭时间延长，开放概率减小。

The calcium current flowing through the calcium channels of 24 to 48-hour cultured myocardiocytes of Wistar rats was recorded with the cell-attached configuration of patch clamp technique. The activity of L-type calcium channel was induced with holding potentials stepping from-50 to +10mV.That of T-type calcium channel with holding potentials stepping from-70 to-10 mV and the spontaneous single channel activty of B-type calcium channel was recorded at a holding potential of-60 mV. Ginsenoside Rg150μg/ml, verapamil 37.5μg/ml, a calcium channel blocker and Bay K 8644 5μmol/L, a calcium chennel activator were added to the bath solution and the electric activity of the 3 calcium channels were recorded before and after the administration of 3 agents. It was found that Rg1 was able to shorten the open phase and prolong the close phase of the 3 channels but exerted no effect on the magnitude of the calcium current flowing through the 3 channels. The action of Rg1 was similar to that of verapamil but opposite to that of Bay K 8644. The study confirms that Rg1 exertes blockade effect on the calcium channel of myocardiocytes with the mechanism to shorten the open phase,prolong the close phase and reduce the open probability.