甲基葡糖苷对豚鼠离体心房的正性肌力作用

Positive inotropic effect of methyl polyglycoside on isolated guinea pig atria

目的 观察甲基葡糖苷对豚鼠离体心房的正性肌力作用 ,并探讨其作用机制。方法 采用豚鼠离体左右心房 ,测定药物对心房肌收缩力、右心房心率 ,以及对静息后收缩和正阶梯现象的影响 ,并测定大鼠心肌细胞膜Na+ K+ ATP酶活性。结果 甲基葡糖苷显著增强心房肌收缩力 ,减慢右心房心率 ,且呈剂量依赖性 ;能明显增强左心房静息后收缩和正阶梯现象 ,并能显著抑制大鼠心肌细胞膜Na+ K+ ATP酶活性。结论 甲基葡糖苷具有加强心房肌收缩力 ,降低右心房心率的作用 ,其正性变力作用可能与抑制心肌细胞膜Na+ K+ ATP酶活性 。

AIM To study the positive inotropic effect of methyl polyglycoside (Mpg) on isolated guinea pig atria and its mechanism. METHODS The effects of Mpg on contractility, beat rate of right atria, post rest contraction and positive staircase phenomenon were observed in isolated guinea pig left and right atria. Na + K + ATP ase activity of rat myocardial cell membrane was measured. RESULTS Mpg (0 01～3 mmol·L -1 ) produced a concentration dependent increase in myocardial contractility of atria and decrease in beat rate of right atria. Mpg markedly enhanced the post-rest contraction and the positive staircase phenomenon induced by increasing stimulation frequency in left atria, and inhibited Na + K + ATP ase activity of rat myocardial cell membrane. CONCLUSION The results suggest that Mpg can strengthen myocardial contractility of atria and decrease beat rate of right atria. Its positive inotropic effect may be related to inhibiting Na + K + ATP ase activity of myocardial cell membrane, increasing the transmembrane influx of calcium and the amount of calcium released from intracellular stores.