Mitochondrial ATP-Sensitive K+ Channel in Heart

描述(申请人提供)：越来越多的证据表明，在心脏中开放线粒体ATP敏感性钾通道(MitoKATP)在缺血再灌注损伤中具有心脏保护作用。这项提案的长期目标是揭示mitoKATP发挥其心脏保护作用的机制。具体目标是：测试和推广mitoKATP是心脏保护部位的假设。为了验证线粒体K+流量微小变化对心肌细胞线粒体K+流量的影响这一假说。确定缺血前的mitoKATP开放如何作为心脏保护的“触发器”，以及mitoKATP开放如何增加活性氧的产生。以确定打开mitoKATP的内源性信号通路是否通过磷酸化该通道起作用。确定mitoKATP作为心脏保护终末效应器的作用和机制。这些目的背后的统一原则是，mitoKATP开放的结果强烈依赖于潜在的生物能量状态，特别是取决于线粒体膜电位(增量psi)在mitoKATP开放时是高还是低。这就解释了这一发现，即mitoKATP开放在心脏保护中扮演着两个截然不同的角色，既是预适应的触发者，也是最终效应者。在触发阶段，mitoKATP的开放导致活性氧物种的产生增加。在缺血和再灌流过程中，mitoKATP开放调节从线粒体到胞浆的能量转移。实验方法是从基础上研究这个问题--从通过纯化蛋白的K+流量的测量，到对线粒体和通透性纤维的生物能量学研究，再到对心肌细胞和灌流心脏的生理研究。

DESCRIPTION (provided by applicant): There is increasing evidence that opening the mitochondrial ATP-sensitive K+ channel (mitoKATP) in heart is cardioprotective in ischemia-reperfusion injury. The long-term goals of this proposal are to uncover the mechanisms by which mitoKATP exerts its cardioprotective effects. Specific aims are: To test and extend the hypothesis that mitoKATP is the site of cardioprotection. To test the hypothesis that the effects of mitoKATP opening/closing on cardiomyocytes are due to small changes in mitochondrial K+ flux. To determine how mitoKATP opening prior to ischemia acts as a "trigger" of cardioprotection and how mitoKATP opening increases generation of reactive oxygen species. To determine whether the endogenous signaling pathways that open mitoKATP act by phosphorylating the channel. To determine the role and mechanisms of mitoKATP as an end effector of cardioprotection. The unifying principle behind these aims is that the consequences of mitoKATP opening depend strongly on the underlying bioenergetic state, in particular, on whether mitochondrial membrane potential (delta psi) is high or low when mitoKATP is opened. This accounts for the finding that mitoKATP opening plays two distinct roles in cardioprotection as both a trigger and an end effector of preconditioning. In the trigger phase, mitoKATP opening causes increased generation of reactive oxygen species. During ischemia and reperfusion, mitoKATP opening regulates energy transfers from mitochondria to the cytosol. The experimental approach is to study the problem from the ground up - from measurements of K+ flux through the purified protein through bioenergetic studies on mitochondria and permeabilized fibers to physiological studies on the cardiomyocyte and perfused heart.