链霉素对牵张所致乳头肌动作电位变化的影响

Experimental Study on Effects of Strepto mycin on Stretch-induced Action Potential Changes of Normal Isolated Papillary Muscles

目的 研究机械牵张对正常状态下离体豚鼠乳头肌动作电位的影响。方法 利用标准玻璃微电极技术 ,记录并观察乳头肌细胞动作电位各参数的变化。结果 5 0 0mg及以上强度的牵张在对照组可使动作电位的Vmax、RP、APA、APD2 0 和APD50 明显下降 ,APD90 显著延长 ,而在链霉素 (2 0 0 μmol/L)组上述指标的变化幅度较小。随着牵张力的加大 ,两组动作电位各参数的变化幅度都逐渐增大 ,牵张后动作电位恢复正常的时间逐渐延长 ,但 5 0 0mg及以上强度的牵张前后链霉素 (5 0 0 μmol/L)组上述指标差异无显著性意义。结论 机械牵张 (5 0 0mg及以上强度 )可导致正常条件下乳头肌动作电位的显著变化 ,而链霉素可以浓度依赖性地抑制牵张对乳头肌动作电位的影响。

Objective To investigate the effects of mechanical stretch unde r normal conditions on action potential in isolated papillary muscles of guinea pig hearts.Methods The intracellular standard glass microelectrode techniq ue was used, and effects of different stretch on action potential were studied i n normal isolated papillary muscles in the absence or presence of streptomycin. Results In control group, 500 mg, 1000 mg and 1500 mg stretch s ignificantly reduced Vmax, RP, APA, APD 20和APD 50 of action potential , and all obviously prolonged the APD 90. However, in streptomycin (200 μm ol/L) group, streptomycin could distinctly decrease the effects of stretch on AP of normal papillary muscles. Furthermore, with the force of stretch increased, the changing range of 6 parameters of AP was gradually enlarged and the time whe n AP recovered to order was gently elongated in above-mentioned two groups. But streptomycin (500 μmol/L) could completely abolish the effects of stretch on A P. Conclusion Under normal conditions, not less than 500 mg stretc h force on isolated papillary muscles of guinea pigs caused significant changes of their AP parameters, which could be inhibited by streptomycin in a concentrat ion-dependent manner.