摘要
实验采用家兔离体右室乳头肌标本,检测电场刺激对各向异性心肌组织的兴奋阈值.用玻璃微电极技术记录由不同强度的电场梯度刺激所引起的细胞跨膜动作电位.经大片电极给予的电场刺激,其梯度方向分别与心肌乳头肌长轴平行(纵向电场梯度)或垂直(横向电场梯度).实验结果表明,心肌细胞的纵向电扬梯度兴奋阈(0.60±0.31V/cm)显著低于横向电场梯度兴奋阅(1.02±0.67V/cm,P<0.01),纵横向电场梯度兴奋阈值之比为1∶1.73.本实验结果表明,心肌细胞兴奋对电场梯度的方向有依赖性,推测这种依赖性与心室电击除颤及纤维各向异性兴奋折返活动有关.
To investigate the potential gradient threshold in different directions to excite cardiac tissue, perfused rabbit papillary muscle was used and transmembrane potential was recorded when rectangular pulses were applied to the tissue. Electrical pulses were produced through large stimulating electrodes to create an even potential gradient field, the direction of which was parallel or perpendicular to the long axis of the papillary muscle. The thresholds for excitation were found to be 0.60±0.31 V/cm and 1.02± 0.67 of the potential gradient along and across the fiber orientation respectely, with a ratio of 1∶1.73 (P<0.01, n = 6). Thus, the dependence of cardiac tissue excitation threshold on the direction of the potential gradient has been clearly demonstrated, the relationship of which to the electrical ventricular defibrillation and the occurrence of anisotropic reentry have both been discussed.
基金
浙江省科学基金
关键词
乳头肌
生理学
电磁场
跨膜电位
兔
Papillary muscles/physiol
Electromagnetic fields
Membrane potentials
Rabbits
