吗啡对豚鼠心肌电生理的影响

Electrophysiological effects of morphine on guinea pig papillary muscles

目的观察吗啡对离体豚鼠心肌快反应动作电位(AP)和L-型钙通道的影响。方法采用玻璃微电极技术在豚鼠心室肌细胞上研究吗啡(1×10-5、1×10-4、1×10-3mol/L)对正常及异丙肾上腺素(ISO)致豚鼠心室肌细胞动作电位的作用。结果吗啡1×10-5、1×10-4与1×10-3mol/L,能缩短动作电位时程(n=10,P<0.01),呈剂量依赖性,而动作电位幅值(APA)、0相上升最大速度(Vmax)无明显变化;吗啡又能对抗由异丙肾上腺素(ISO)致豚鼠心室肌细胞动作电位;应用L型钙通道开放剂Bay K8644(0.25μmol)可增加动作电位时程(APD)、复极化50%时间(APD50)、复极化90%时间(APD90)(n=10,P<0.01),加入吗啡可完全逆转Bay K8644(0.25μmol)对乳头肌细胞的兴奋效应。结论吗啡明显缩短APD;并能对抗由ISO引起的早后除极;能对抗L型钙通道开放剂BayK644对乳头肌细胞的兴奋效应,其机理与钙拮抗有关。

Objective To study the effeets of Morphine on fast response aetion potential （AP） and L-type calcium channel in isolated guinea pigs ventrieular myoeytes. Methods The standard intraeellular glass mieroeleeteode was used, and the action of the drug was observed in the same cell.This study investigated the effects of Morphine（1 ×10^-5 , 1 ×10^-4 , 1×10^-3 mol/L） on aetion potential, and L-type ealeium ettrrent （ ICa. L） indueed by isoproterenol（ISO） in guinea pig isolated ventrieular myoeytes. Results Administration of 1 ×10^-5 , 1 ×10^-4 , 1×10^-3 mol/L Morphine caused a significant shortening of the action potential duration and no significant changes in action potential amplitude （APA） and the maximal rate of rise of phase 0（Vmax）, Morphine siguifieantly attenuated the effeet of IOS. The effeets of morphine on normal papillary muscles ean be antagonized by Bay K8644 （0.25 μmol）, a L-type ealeium channel agonist. Conclusion Morphine shortens the APD and eompletely inhibited EAD indueed by ISO; Morphine has a direct inhibitory effect on calcium rivalry.