碘杂环化合物IHC－72对心肌慢反应动作电位影响的浓度和时间依赖性

采用常规玻璃微电极技术研究３，６－二甲氨基－二苯骈碘杂环依地酸盐（ＩＨＣ－７２）对豚鼠右室乳头肌慢反应动作电位（ＳＡＰ）的影响。２．５４μｍｏｌ／ＬＩＨＣ－７２对ＳＡＰ各参数均无影响。２５．４，１０１．６μｍｏｌ／Ｌ　ＩＨＣ－７２对ＳＡＰ幅值（ＡＰＡ）的抑制率分别为７．４％、１９．３％，对０相最大上升速率（Ｖｍａｘ）的抑制率分别为２．５％、３９．１％（Ｐ均＜０．０５或０．０１）。１０１．６μｍｏｌ／ＬＩＨＣ－７２灌流５，１０，２０ｍｉｎ对ＡＰＡ的抑制率分别为３．３％、１０％和２１％，对Ｖｍａｘ的抑制率分别为１５．２％、２２．９％和３８．３％（Ｐ均＜０．０１），故ＩＨＣ－７２对ＡＰＡ、Ｖｍａｘ的抑制具有浓度和时间依赖性。ＩＨＣ－７２还能缩短ＳＡＰ复极５０％、１００％的时程（ＡＰＤ５０、ＡＰＤ１００），相对延长其有效不应期（ＥＲＰ）；而对静息膜电位（ＲＭＰ）无明显影响。１０１．６μｍｏｌ／ＬＩＨＣ－７２对ＳＡＰ的抑制与５μｍｏｌ／ＬＶｅｒａｐａｍｉｌ效应相当。结果揭示ＩＨＣ－７２具有钙拮抗作用。

Concentration and Time-dependent Effects of 3,6-Dimethylamino-Dibenzopyriodonium Edetate on Slow Response Action Potential

The effects of 3,6-dimethylamino-dibenzopyriodonium edetate (IHC-72) on the slow response action potential(SAP) of isolated guinea pig right ventricular papillary muscles were studied with standard microelectrode technique. 2.54μmol/L IHC-72 did not affect the parameters of SAP,25.4, 101.6μmol/L IHC-72 inhibited action potential amplitude(APA)of SAP by 7.4%, 19.3% (P both < 0.01), and inhibited maximum upstroke velocity(Vmax) of SAP by 2.5%, and 39.1% (P<0.05 or 0.01). 101.6μmol/L IHC-72 inhibited APA in 5, 10, 20 min by 3.3%, 10%, and 21% (Pall <0.01), inhibited Vmax by 15.2%,22.9% and 38.3%(P all <0.01). So IHC-72 inhibited APA,Vmax exhibiting concentration and time-dependence. IHC-72 also shortened action potential duration at 50%, 100% repolarization(APD50, APD100). The effective refractory period(ERP) was relatively prolonged, resting membrane potential(RMP) was not influenced. It indicates that 101.6 μmol/L IHC-72 has a direct inhibitory effect on slow calcium inward current, and its inhibitory effect is almost equal to that of 5 μmol/L Verapamil.