用心室压力钳方法研究家兔左心室单相动作电位的变化

Changes of Monophasic Action Potential in Rabbit Left Ventricles Induced by Ventricular Pressure-Clamping Method

目的构建小动物心室压力钳方法,观察机械刺激对心脏电活动的影响,探索心脏机械电反馈现象及其机制。方法应用自行构建的心室压力钳方法,在心室肌细胞动作电位末期牵张左心室,观察心室单相动作电位时程的变化。结果当左心室分别被强度为130 mmHg、140 mmHg、150 mmHg的额外牵张刺激钳制时,左室MAPD90〔单相动作电位复极90%的时程(monophasicaction potential duration upstroke to the level of 90%)〕较正常分别延长15.4%、26.1%、44.4%(P<0.05),左室MAPD20、MAPD50无明显变化;牵张前后右室MAPD20、MAPD50及MAPD90均无明显变化。结论自行构建的心室压力钳方法能较准确地模拟生理、病理生理条件下心室内的负荷变化情况,并能灵活地对心脏施加机械刺激,为在器官水平上研究心脏机械电反馈(mechano-electricfeedback,MEF)提供了压力控制方法上的改进;左心室复极末期牵张刺激可引起其心肌细胞动作电位时程(action potential duration,APD)延长、复极减慢,右室则无明显改变,提示该刺激直接导致了左心室上内向电流的发生。

Objective To establish a ventricular pressure-clamping method for isolated-perfused hearts of small animals,observe the effect of mechanical stimuli on cardiac electrical activities and explore the phenomena and mechanisms of cardiac mechano-electric feedback. Methods Using the ventricular pressure-clamping method to stretch the left ventricle（LV） during the end of action potential,the effect on monophasic action potential duration（MAPD） of ventricles was observed. Results LVMAPD90 was lengthened by 15.4%,26.1%,44.4%（P0.05） comparing to the control when the left ventricle was clamped by extra stretch which was 130,140,150 mmHg,respectively,while LVMAPD20 and LVMAPD50 had no changes;There was no significant difference in RVMAPD20,RVMAPD50 and RVMAPD90 between before and after extra inflations were applied. Conclusion This ventricular pressure-clamping method developed by our lab can exactly mimic the changes of load in hearts under the physiological/pathophysiological conditions and can freely deliver mechanical stimuli to the ventricle,which improved the method of pressure-controlling on researching cardiac MEF at organ level;stretching the left ventricle during the end of the action potential could lengthen MAPD,slower repolarization,while the right ventricle had not the same changes,which suggested that the inflations caused a kind of inward current in the left ventricle.