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目的 :观察副交感神经递质乙酰胆碱 ( acetylcholine,Ach)对单个豚鼠心房肌细胞、豚鼠心房肌毒蕈碱钾型通道 ( IK,Ach)、动作电位 ( action potential)及其对心房肌收缩力脱敏 ( desensitization)的影响。方法 :采用全细胞膜片钳记录技术、标准玻璃微电极细胞内记录技术及肌力换能器等分别研究 Ach对单个豚鼠心房肌细胞或心房肌组织的心肌收缩力、动作电位及 IK,Ach离子流不同层次的脱敏作用。结果 :( 1) Ach对心房肌组织有降低收缩力的作用 ,且随时间延长 Ach作用逐渐降低 ,即出现脱敏现象 ,并呈时间依赖性。 ( 2 ) Ach可使心房肌细胞动作电位时程缩短 ,亦出现脱敏。 ( 3) Ach可以激活一种内向整流的钾通道 (即 IK,Ach) ,IK,Ach离子流的脱敏分为快、慢两个时相。结论 :Ach降低心房肌组织收缩力的作用有脱敏现象 ,脱敏的发生可能与心房肌细胞APD的脱敏及 Ik,Ach电流的脱敏等有关
OBJECTIVE: To observe the effects of acetylcholine (Ach), a parasympathetic neurotransmitter, on the activity of atrial myocytes in a single guinea pig atrial myocytes, guinea pig atrialkinensis muscarinic potassium channels (IK, Ach), action potentials (desensitization) influence. METHODS: Whole-cell patch-clamp recording technique, standard glass microelectrode intracellular recording technique and muscle transducer were used to study the effects of Ach on myocardial contractility, action potential and IK, Ach ion in single atrial guinea pig atrial myocytes Desensitization of different levels of flow. Results: (1) Ach reduced the contractility of atrial muscle tissue, and with the passage of time, the effect of Ach gradually decreased, that is desensitization occurred in a time-dependent manner. (2) Ach can shorten the action potential duration of atrial myocytes, but also desensitization. (3) Ach can activate an inward rectifier potassium channel (ie IK, Ach), IK, Ach ion flow desensitization is divided into fast and slow two phases. CONCLUSION: Ach can reduce the contraction of atrial tissue with desensitization. Desensitization may be related to the desensitization of APD and the desensitization of Ik and Ach currents in atrial myocytes