蛇床子素对心肌慢反应动作电位及右心房自搏频率的影响

Effects of osthole on slow action potentials and right atria frequency

用细胞内微电极技术，观察了蛇床子素（Ｏｓｔ）对离体豚鼠乳头状肌ＢａＣｌ２高ＫＣｌ除极化及家兔窦房结慢反应动作电位的影响。结果表明。Ｏｓｔ抑制Ｂａ２＋诱发的自发电活动：降低高Ｋ＋除极化慢反应动作电位的幅度（ＡＰＡ）及动作电垃最大上升速率（Ｖｍａｘ），并缩短５０％动作电垃时程（ＡＰＤ５０），延长９０％动作电位时程（ＡＰＤ９０）；对家兔离体窦房结优势起搏细胞窦搏周期（ＳＣＬ），ＡＰＡ及Ｖｍａｘ亦有抑制作用。此外，对离体豚鼠右房负性频率作用。似与激动Ｍ胆碱能受体或阻滞β肾上腺圭能受体无关，与钙拮抗剂维拉帕米相似．结果提示。Ｏｓｔ具有钙拮抗作用．

The effects of osthole(Ost) were stu-died on the slow action potentials by high KCl(25mmol·L-1),BaCl2(1 mmol·L-1)in guinea pigpapillary muscles and in sinoatrial node cells of rahbitbV means of conventional glass microelectrodes.Ost dose-dependently inhibited the ventricularautorhythmicity induced by Ba2+,and cycle of sponta-neous beat was prolonged.In K+-depolarizedpapillary muscles,Ost decreased the maximal upstrokevelocity(Vmax),action potential amplitude(APA),shortened action potential duration at 50%repolarization(APD50)and lengthened acti o n poten-tial duration at 90% repolarization(APD90) Effect ofOst on sinoatrial node dominant pacemaker A cellshowed that APA and Vmax were inhibited.sponta-neous cycle length(SCL)Was prolonged. In addition,itwas examined that the effects of Ost and verapamil(Ver) on the isolated atria with sinoatrial node,Ost pro-duced neither M-cholinergic receptor stimulating norβ-adrenergic receptor blocking effects,and the aboveactions were similar to those of Ver These results indi-cate that Ost possesses calcium antagonistic effect, which would contribute to the antiarrhythmic action.