赤土茯苓苷对正常和高钾除极豚鼠心室乳头状肌动作电位的影响

目的研究赤土茯苓苷（Ｓｍｉ）对离体豚鼠正常心室乳头状肌及高Ｋ＋除极乳头状肌细胞动作电位的影响。方法采用标准微电极技术。结果Ｓｍｉ较大剂量时（５０ｍｇ·Ｌ－１、１００ｍｇ·Ｌ－１）明显提高正常动作电位（ＡＰ）的０相上升最大速度（Ｖｍａｘ）和动作电位幅度（ＡＰＡ）；延长动作电位时程（ＡＰＤ）。Ｓｍｉ较小剂量（２ｍｇ·Ｌ－１、１０ｍｇ·Ｌ－１、５０ｍｇ·Ｌ－１）时显著降低高Ｋ＋除极后，由异丙肾上腺素（Ｉｓｏ）诱发出的慢反应动作电位（ＳＡＰ）的Ｖｍａｘ和ＡＰＡ，并缩短ＳＡＰ的ＡＰＤ。对ＣａＣｌ２（３ｍｍｏｌ·Ｌ－１诱发出的ＳＡＰ无影响；此作用与普萘洛尔（Ｐｒｏ）在（１５μｍｏｌ·Ｌ－１）时所产生的作用相似，上述作用随剂量增加而增强。结论Ｓｍｉ具有β受体阻滞样作用。

Effect of smiglabrin on action potentials of normal and highK depolarized papillary muscled of guinea pig

AIM To investigate the effect of Smi on action potential of isolated guinea pig papillary muscles in normal and K rich tyrodes solution (27 mmolL-1). METHOD Used standard glass microeletrode technique. RESULTS Smi increased the Vmax, APA and prolonged APD of normal action potentials at concentration (50 mgL-1,100 mgL-1). Smi decreased the Vmax, APA and shortened APD of repolarization of the slow action potentials induced by Iso in guinea pig papillary muscles superfused with K rich Tyrode solution (27 mmolL-1) at concentration(2, 10, 50 mgL-1). But no effect of this action on the slow action potentials induced by CaCl2 (3 mmolL-1). The action of Pro (2 molL-1)were similar to those of Smi. CONCLUSIONBZSmi may have receptor antagonist action.