记录心肌单相动作电位时血流动力学改变的机理

THE MECHANISM OF HEMODYNAMIC CHANGE DURING THE TIME OF RECORDING MONOPHASIC ACTION POTENTIAL OF MYOCARDIUM

12只家兔用于记录心肌单相动作电位（MAP）对血流动力学影响的机理分析．在开胸去心包、心室外膜用1％procaine局麻、去双侧减压神经、去双侧颈迷走神经、心得安和立其丁各0．5mg．kg-1i．v．后，记录MAP时血压降低中心静脉压升高．血压降低与相应对照的百分比分别为28％、21％、27％、23％和24％．在去除心室内局部机械压力感受器的换能作用和由迷走神经传递的降压冲动以及交感性神经激素对心血管的影响之后，记录心外股MAP仍出现显著的血压降低。提示记录MAP时血流动力学改变的机理，主要是电极作用力影响了心脏正常的好缩功能．致心收缩力降低，心输出量减少，血压降低和中心静脉压升高．

The mechanism of hemodynamic change during recording monophasic action potential(MAP) of myocardiurn was analysed in 12 rabbits. A fall in the artertal blood pressure (Bp ) and 3rise of the central venous pressure (Cvp) were observed in the period of recording MAP of the epicardium after each of the following treatmcnts: a ) pericardiectomy, b) the epicardium of the left andright ventricles anesthetized locally with 1% procainc. c ) depressor - ectomy, d ) vagotomy and e )propranolol and regitine 0. 5 mg. kg-1i. v, respectively. The percentage of reduction in Bp comparedwith its relative control was 28. 24. 27. 23 and 24, re`prctively. A considerable fall in Bp was detectedduring recording MAP after the transduction of local mech - pressure receptors in both vcntricles, thedepress renex mediated by vagi and the sympathetic neurohumoral effect on the cardiovasa were removed. It is concluded that normal contraction and relaxation of the heart caused by the force of thecontact electrode on the rnyocardium is the main factor which results in the change in hemodynamics.The depress reflex mediated by vagi is the secondary factor in the course of recording MAP.