白花前胡甲素对豚鼠心室肌单细胞迟发性外向钾电流的影响

用全细胞膜片钳制方法观察了中药白花前胡有效成分白花前胡甲素（Ｐｄ一Ｉａ）对豚鼠·Ｃ室肌单细胞迟发性外向钾电流（Ｉｋ）的影响。Ｐｄ一Ｉａ以剂量依赖的方式增加Ｉｋ，其阈浓度接近ｌｎｍｏｌ·Ｌ－１，ＥＣ５０约０．２μｍｏｌ·Ｌ－１，最大效应浓度约１μｍｏｌ·Ｌ－１增加Ｉｋ２．５±０．５倍（Ｐ＜０．０１），Ｐｄ一１３的此种作用通过冲洗可部分消退。从电流一电压关系可知：人的激活电压接近４０ｍＶ，ｌｐｍｏｌ·Ｌ－１ｐｄ一Ｉａ使Ｖ１／２最大左移７ｍＶ，曲线的斜率改变－０．６５ｍＶ，经比较无统计学意义，提示Ｐｄ一Ｉａ对Ｉｋ的激活动力学过程无明显影响。以上结果表明，Ｐｄ一Ｉａ能促进Ｋ＋通道开放。

Effect of d1-praeruptorin A on delayed outward potassium current in single ventricular cell of guinea pig

By using a whole-cell patch clampmethod,the effect of d1-praeruptorin A(Pd-Ia)ondelayed outward potassium current(Ik)was investi-gated in single ventricular cell of guinea pig. Pd-Iaenhaneed Ik dose-dependently.Its threshold concen-tration for activating Ik was near 1 nmol·L-1,theEC50 was 0.2 μmol·L-1,and the maximum effectiveconcentration was 1 μmol·L-1.Pd-Ia increased Ikbv2.52± 0.53 folds(P<0.01,n=5),and the effectcould be reversed by washing.I-V relationship show-ed that the activated potential of Ik was near-40mV, V1/2(half-maximum voltage) shifted about 7mV in the negative direction,and the slope of thecurve changed -0.65 mV(P>0.05,n=5).These re-sults indicated that Pd-Ia could open the K+ chan-nel and increase Ik.It might be a new potassium chan-nel opener.