Exercise Training and Myocardial K-ATP Channel Function

描述（由申请人提供）：众所周知，耐力运动训练（Tr）使心脏对缺血和再灌注损伤更具抵抗力。到目前为止，这些适应的细胞基础还没有明确确定。在心脏中，ATP敏感性钾通道存在于肌膜（sI-KATP）和线粒体（mito-KATP）上，两者都参与保护心脏免受缺血性损伤。我们最近发现，Tr eleplasma显着减少的幅度缺氧诱导的，格列本脲敏感的外向钾电流（IK，ATP）在单个大鼠心室肌细胞。在特定目标1中，我们将使用电生理学（全细胞和切除的贴片）和免疫印迹技术来确定这一发现的细胞基础。我们将研究训练对（1）sI-KATP对ATP和ADP抑制的敏感性，（2）sI-KATP通道亚单位（Kit6.2和SUR 2A）的蛋白表达，以及（3）缺血应激时线粒体ATP产生的影响。我们还发现，严重的带状缺血引起的冠状动脉闭塞，然后再灌注，Tr产生的梗死保留和增强的机械功能，在离体灌注心脏。我们还观察到一个明显的TR诱导的充血，这是明显的整个缺血再灌注协议。在特定目标2中，我们将使用对sl-和mito-KATP通道具有选择性的KATP拮抗剂来鉴定这些特定通道在Tr诱导的梗死保留和机械功能保存中的参与。吲哚美辛和L-NAME将用于研究，以确定缺血后再灌注期间表现出的充血的细胞基础，以及TR诱导的充血对心肌梗死保护和心脏机械功能保护的程度。目标2中的实验包括LV功能、代谢物、生化和冠状动脉流量测量的综合电池。 运动训练被认为是有效的预防和治疗各种心脏病理条件。阐明这些积极适应的细胞变化可能在设计，开发和实施分子和药理学心脏病治疗和预防策略中特别重要。这一点尤其重要，因为心脏病比任何其他疾病都要夺去更多的北美人的生命。

DESCRIPTION (provided by applicant): It is well known that endurance exercise training (Tr) renders the heart more resistant to ischemia and reperfusion injury. To date, the cellular basis for these adaptations has not been clearly identified. In the heart, ATP-sensitive K channels exist on the sarcolemma (sI-KATP) and in mitochondria (mito-KATP) and both have been implicated in protecting the heart against ischemic injury. We recently found that Tr elicits a marked reduction in the magnitude of an anoxia-inducible, glibenclamide-sensitive outward K current (IK,ATP) in single rat ventricular cardiocytes. In Specific Aim 1, we will use electrophysiological (whole cell and excised patch) and immunoblotting techniques to determine the cellular basis for this finding. We will examine the effect of training on (1) the sensitivity of sI-KATP to inhibition by ATP and ADP, (2) the protein expression of sI-KATP channel subunits (Kit6.2 and SUR2A), and (3) mitochondrial ATP production in the face of ischemic stress. We also found that following severe zonal ischemia elicited by coronary artery occlusion and then reperfusion, Tr produced infarct sparing and augmented mechanical function in isolated perfused hearts. We also observed a marked Tr-induced hyperemia that was apparent throughout the ischemia reperfusion protocol. In Specific Aim 2, we will use KATP antagonists that are selective for sl- and mito-KATP channels to identify the involvement of these specific channels in Tr-induced infarct sparing and preservation of mechanical function. Indomethacin and L-NAME will be used in studies to determine the cellular basis for the hyperemia that was exhibited during post-ischemic reperfusion, and the extent to which the Tr-induced hyperemia contributed to infarct sparing and the preservation of mechanical function in the heart. The experiments in Aim 2 include a comprehensive battery of LV function, metabolite, biochemical, and coronary flow measurements. Exercise training is known to be effective in the prevention and treatment of a wide variety of cardiopathologic conditions. Elucidation of the cellular changes that underlie these positive adaptations may be of particular importance in the design, development, and implementation of molecular and pharmacological heart disease treatment and prevention strategies. This is particularly significant in view of the fact that heart disease claims more North American lives than any other disease.