乙酰胆碱对离体豚鼠心室肌的直接作用机制探讨

The mechanisms underlying the effects of acetylcholine on isolated guinea-pig ventricular myocytes

目的 :研究乙酰胆碱 (ACh)对离体豚鼠心室肌的直接负性作用及机制。方法 :采用标准玻璃微电极细胞内记录技术记录动作电位 (AP)及肌力换能器记录心肌收缩力 (FC)的方法观察 ACh对离体豚鼠心室肌的作用 ,并观察几种受体或通道水平的阻断剂阿托品、氯化铯 (Cs Cl)、氯化镉 (Cd Cl2 )对 ACh直接作用的影响。结果 :10 - 5 mol/LACh对心室肌动作电位持续时间 (APD)及 FC的抑制率分别为 7.31%和 37.5 7% (P<0 .0 5 ) ,10 - 5 mol/L阿托品和 2 0 m mol/L Cs Cl可阻断该作用 ,0 .1m mol/L Cd Cl2 对该作用无影响。结论 :10 - 5 m ol/L ACh对离体豚鼠心室肌有直接负性作用 ,ACh的作用与毒蕈碱型胆碱受体及 K+电流有关 ,而与 Ca2 +电流的关系可能不大。

AIM: To investigate the mechanisms underlying the effects of ACh on isolated guinea pig ventricular myocytes. METHODS: Using standard microelectrodes and force transducer we recorded the effects of ACh (10 -5 mol/L) and various blockers such as atropine, CsCl and CdCl 2 on the action potential and force contraction in isolated ventricular myocytes of guinea pig. RESULTS: ACh(10 -5 mol/L) reduced the duration of action potential and twitch tensions by 7.31% and 37.57% respectively ( P <0.05),which could be blocked by atropine, CsCl, but not by CdCl 2. CONCLUSION: ACh (10 -5 mol/L) could cause a negative chronotropic and inotropic effects on guinea pig ventricular myocytes. These effects are related to the muscarinic receptor and the potassium channel and may not related to the calcium channel.