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目的 :研究迷走神经递质乙酰胆碱 (ACh)对离体豚鼠心房肌细胞动作电位 (AP)的影响及其对心房肌的脱敏 ,探讨脱敏可能发生的机制。方法 :采用标准玻璃微电极细胞内记录方法 ,观察不同浓度 (0 .0 1,0 .1,1μm ol/ L) ACh对心房肌细胞 AP的影响及对动作电位时程 (APD)和收缩力的脱敏现象 ,并观察了受体或通道水平的阻断剂阿托品、氯化铯 (Cs Cl)对 ACh所致的心房肌 APD脱敏的影响。结果 :10 .0 1,0 .1,1μm ol/ L ACh分别缩短 APD的变化率为 (6 .0 2± 1.0 4) % ,(14.2 0± 3.79) % ,(30 .2 0± 3.6 5 ) %。 2 0 .0 1μmol/ L ACh对心房肌细胞没有脱敏 ;0 .1μm ol/ L ACh对心房肌细胞 APD有轻微脱敏 ,脱敏持续时间为 1m in;而 1μmol/ L ACh对心房肌细胞 APD脱敏明显 ,脱敏持续时间为 5 m in。 31μmol/ L 阿托品与 2 0 m mol/ L Cs Cl并不能阻断 1μmol/ L ACh对心房肌细胞APD的脱敏。结论 :ACh缩短 APD的作用随浓度增大而增大 ;ACh对离体豚鼠心房肌细胞 APD的脱敏有浓度依赖性与时间依赖性 ;脱敏的发生可能与毒蕈碱型胆碱能受体及 Ik,ACh电流有关。
Aims: To study the effect of ACh, an inhibitor of vagal neurotransmission, on the action potential (AP) of atrial myocytes and the desensitization of atrial myocardium in guinea pigs, and to explore the possible mechanism of desensitization. Methods: Standard glass microelectrode intracellular recording method was used to observe the effect of ACh with different concentrations (0. 0 1 .1 and 1 μmol / L) on the AP of atrial myocytes and the effect on the action potential duration (APD) and contractility , And observed the effect of ACh-induced APD desensitization on atrial and ventricular myocytes induced by atropine or CsCl, a blocker of receptor or channel level. Results: The change rates of APD were (10.02 ± 1.04)%, (14.2 ± 3.79)%, (30.0 ± 3.6)%, )%. 2 0 0 1μmol / L ACh did not desensitize atrial myocytes; 0.1μmol / L ACh slightly desensitized APD of atrial myocytes, the duration of desensitization was 1m in; while 1μmol / L ACh had no effect on atrial myocytes APD desensitization obvious desensitization duration of 5 m in. 31μmol / L atropine and 20μmol / L CsCl did not block the desensitization of atrial myocytes APD by 1μmol / L ACh. CONCLUSION: The effect of shortening the APD of ACh increased with increasing concentration. The desensitization of ACh on APD of isolated atrial myocytes in vitro was concentration-dependent and time-dependent. The desensitization may be related to muscarinic cholinergic Body and Ik, ACh current.