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本研究用单个细胞动作电位作为心肌兴奋的指标,观察在体心脏窦性心率及起搏心率时,迷走神经刺激对正常和急性缺血心肌有效不应期(ERP)的影响。在自然心率条件下,迷走神经刺激可使正常和急性缺血的心室肌ERP都延长,但急性缺血心肌ERP延长的程度比正常心肌更明显,因而使正常和缺血心肌之间ERP的离散程度减小。起搏固定心率时,迷走神经对ERP仍表现出延长作用,但程度明显减轻,说明ERP延长主要是心率减慢的继发性作用,迷定神经的直接作用较小。这些结果提示,迷走神经刺激使心室肌ERP延长,致正常区和缺血区ERP离散程度减轻,这对于防止折返性心律失常具有重要意义,也可能是迷走神经对心脏的保护作用机制。
In this study, single cell action potential was used as an indicator of cardiac excitability to observe the effect of vagal nerve stimulation on effective refractory period (ERP) in normal and acute ischemic myocardium during both sinus rhythm and pacemaker heart rate. Under natural heart rate, vagal stimulation stimulates ERP in both normal and acute ischemic ventricular muscles, but the extent of ERP in acute ischemic myocardium is more pronounced than that in normal myocardium, resulting in a discrepancy in ERP between normal and ischemic myocardium Decrease When pacing fixed heart rate, the vagus nerve still showed an extension effect on ERP, but the degree was significantly reduced, indicating that the prolongation of ERP was mainly the secondary effect of slowing of heart rate, and the direct effect of minerolism was small. These results suggest that vagal stimulation can prolong the ERP of ventricular muscle, resulting in the reduction of ERP in the normal and ischemic areas. This is of great importance for the prevention of reentrant arrhythmias and may also be the protective mechanism of the vagus nerve on the heart.