外源O对心肌线粒体跨膜电位和质子转位的作用

The effect of superoxide ainon on transmembrane potential and proton transfer of myocardial mitochondria

本实验利用铁氰化钾脉冲法和Ｒｈｏｄａｍｉｎｅ１２（Ｒｈ＿(１２３)）荧光染料流动透析法检测外源性黄嘌呤／黄嘌呤氧化酶系统产生对心肌线粒体跨膜电位及质子转位的作用，发现随－产生浓度的增加、能化后跨膜电位差逐渐减小，质子泵出速度降低及Ｈ￣＋／２ｅ￣－比值下降；随产生系统与线粒体共孵育时间的延长，能化后跨膜电位差逐渐减小，质子泵出速度降低，电子传递速度减小．Ｈ￣＋／２ｅ￣－比降低，即产生系统对Ｈ￣＋泵出及Ｈ￣＋／２ｅ￣－比的影响具有浓度依赖性和时间依赖性。丹参素对能化后膜电位差的下降有一定程度的恢复作用，推断对心肌线粒体膜的作用结果是使膜对质子的通透性增强，质子发生回漏，呼吸链电子传递酶系功能部分受损。

The preSent study was designai investigate the effed of superoxiue anion on protontranslocation and transmembrne potential to explor the mechanism of the link between oxidationand phosphorylation. Proton pump rate and H+/2e-determinations were carried out byK,Fe(CN)6 pulse method,but the fluorescent dye Rhodamine 123 was used to detect changesof the transmembrane potential.The results showed that when the level of introduced superoxideanions was increaed,energied transmembrane potential across the mitochondrial inner membrdne(ψ)(205.5±3.9mV)decreased(185.9±4.4mV);and both proton pump rate and H+/2e-decreadOn the other hand,with mitochondria incubated in superoxide anion genenating sys tem for alonger time,energed transmemblane potential decreased,proton pump rate fell down, electron trams-fer rate and H+/2e- decreased as well.It was found that the effects of superoxide anion on pro-ton pump and H+/2e-are time-dependent and level-dependent.It was suggested that superoxideradical may increase the proton permeability of the inner membrane of cardiac mitochondria,andcause the leak of proton.