Mitochondrial ATP-Sensitive K+ Channel in Heart

描述（由申请人提供）：越来越多的证据表明，在心肌缺血再灌注损伤中，打开线粒体atp敏感的K+通道（mitoKATP）对心脏有保护作用。这项建议的长期目标是揭示mitoKATP发挥其心脏保护作用的机制。具体目的是：验证和扩展mitoKATP是心脏保护部位的假设。为了验证mitoKATP打开/关闭对心肌细胞的影响是由于线粒体K+通量的微小变化引起的假设。确定mitoKATP在缺血前打开如何作为心脏保护的“触发器”，以及mitoKATP打开如何增加活性氧的产生。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作为心脏保护末端效应物的作用和机制。这些目标背后的统一原则是，mitoKATP打开的后果在很大程度上取决于潜在的生物能量状态，特别是当mitoKATP打开时，线粒体膜电位（delta psi）是高还是低。这解释了发现mitoKATP打开在心脏保护中扮演两个不同的角色，作为预处理的触发和结束执行器。在触发阶段，mitoKATP的打开导致活性氧的产生增加。在缺血和再灌注过程中，mitoKATP的打开调节线粒体向细胞质的能量转移。实验方法是从头开始研究这个问题——从K+通量通过纯化蛋白的测量，到线粒体和渗透纤维的生物能量研究，再到心肌细胞和灌注心脏的生理研究。

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.