Mitochondrial ATP-Sensitive K+ Channel in Heart

描述（由申请人提供）：越来越多的证据表明，打开心脏中的线粒体ATP敏感性K+通道（mitoKATP）在缺血-再灌注损伤中具有心脏保护作用。该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：测试和扩展mitoKATP是心脏保护位点的假设。 为了验证线粒体KATP开放/关闭对心肌细胞的影响是由于线粒体K+流量的微小变化的假设。 确定缺血前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。 确定打开mitoKATP的内源性信号通路是否通过磷酸化通道起作用。 目的：探讨mitoKATP作为心肌保护终末效应物的作用和机制。这些目标背后的统一原则是，mitoKATP开放的后果强烈依赖于潜在的生物能量状态，特别是，在mitoKATP开放时，线粒体膜电位（Δ psi）是高还是低。这解释了发现mitoKATP开放在心脏保护中作为预处理的触发器和末端效应器起两种不同的作用。在触发阶段，mitoKATP开放导致活性氧产生增加。在缺血和再灌注期间，mitoKATP开放调节从线粒体到细胞质的能量转移。实验方法是从头开始研究这个问题-从测量通过纯化蛋白的K+通量，通过对线粒体和透性纤维的生物能量研究，到对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.