心肌细胞兴奋与电场梯度方向的关系

The Relationship Between Cardiac Excitation and the Electrical Potential Gradient Directions

本实验采用玻璃微电极记录跨膜电位技术，探讨豚鼠心室肌兴奋对电场梯度方向的依赖性，电场梯度的方向分别与右室乳头肌长轴平行（纵向电场梯度）或垂直（横向电场梯度）．结果表明：心肌细胞纵向电场梯度兴奋阈显著低于横向电场梯度兴奋阈（０．６５±０．２６Ｖ／ｃｍＶＳ１．１３±０．４２Ｖ／ｃｍ，Ｐ＜０．０１）．提示心肌细胞兴奋对电场梯度方向有依赖性。

To investigate the dependence of cardiac excitation on the directions of potential gradient,perfused guineapig papillary muscles were used and transmembrane potentials were recorded by the glass microelectrode.The electrical pulses were given via large stimulation electrodes to create even potential gradient field,the direction of which was parallel or perpendicular to the papillary muscle,The threshold for excitation was found to be 0.65±0. 26 V/cm of potential gradient along the fiber orientation and 1.13±0.42 V/cm across the fiber orientation(P<0.01 compared along the fiber orientation,n=12).The ratio of potential gradient along the fiber orientation compared with across the fiber orientation was 1:1. 74.Thus,the cardiac tissue excitation depended on the direction of the potential gradient,which might be related to the electrical therapy for the malignant tachyarrhythmias and the occurence of electrically induced arrhythmias.