尼莫地平对离体豚鼠左心房的抑制作用及其机理探讨

尼莫地平(50μmol/L)明显减低豚鼠左心室收缩幅度,其强度与戊脉安(25μmol/L)相当;明显抑制正阶梯现象,但不象戊脉安那样使其翻转成负阶梯现象;明显抑制静息后增强效应;逆转或预防哇巴因诱发的心律失常。以上结果提示尼莫地平既能减少胞外Ca~(2+)通过Ca~(2+)通道内流,又能减少胞内贮Ca~(2+)释放。

THE INHIBITORY EFFECTS OF NIMODIPINE IN ISOLATED GUINEA PIG LEFT ATRIUM AND THIER MECHANISM OF ACTIONS

Fifteen min after adding nimodipine 50 μmol/L, the contractility of the left atrial muscle decreased from 100 % of control to 55.5 +4.2 o/o and its inhibitory effect was equal to the effect of verapamil (25 μmol/L ) . Nim at the same concentration inhibited strongly the positive staircase phenomenon but could not reverse it into the negative staircase phenomenon as verapamil 25 μmol/L did. The same concentration of Nim suppressed significantly the post rest contraction. On the contrary, the post rest contraction was not affected by verapamil at 25 μmol/L. In addition, Nim 50 μmol/L reversed or prevented significantly the ouabain-induced arrhythmias in isolated left atria. These results suggest that the negative ino-trbpism of Nim may be related not only to the inhibition of Ca2 + influx to the cells and also to the decrease of the intercellular Ca2+ release and that Nim might present the possibility in treating arrhythmias or other heart disease