Heat Shock Proteins, Nitric Oxide and Oxygen Consumption in the Heart

描述（由申请人提供）：已知缺血预处理（IPC）和高温（HT）可提供心脏保护，防止缺血性损伤，如心肌梗死。HT诱导热休克蛋白（HSP），其可作为分子伴侣预防心肌梗死，而IPC已知诱导一氧化氮（NO），其可介导心脏中的各种过程以最小化缺血性损伤。我们对离体心肌细胞的初步研究表明，热应激诱导的HSP 90可以激活NOS酶。因此，我们假设HT诱导的HSP 90可以激活热应激心脏中的NOS酶，因此HT和IPC在共同的途径中起作用以最小化缺血性损伤：即，在这两种情况下，NOS酶被激活以产生高丰度的NO。由于NO和氧对线粒体中的细胞色素c氧化酶位点具有高且相等的亲和力，因此预期在IPC和热应激心脏中心肌细胞的氧消耗和呼吸减少。然而，诱导型NO在IPC和热应激心肌耗氧中的作用尚未见报道。因此，本研究的主要目的是研究NO对热应激心脏氧耗的调节作用。我们建议使用电子顺磁共振（EPR）血氧饱和度与高灵敏度的酞菁锂微晶作为探针和专门设计的EPR仪器，直接测量正常，IPC和热应激心脏的耗氧量。本研究的主要目的有三：（1）缺血损伤心肌氧耗与功能恢复的直接关系;（2）研究缺血预处理产生的NO对心肌氧耗的影响;（3）研究热应激诱导的热休克蛋白对心肌氧耗的影响。利用其他支持性研究，可以证明在两种情况下（IPC和HT），NO介导的呼吸调节是心脏保护的关键机制之一。总的来说，本项目将确定在PC和HT心脏中NO和氧耗之间的关系，并提供对心脏保护的实际机制的见解。

DESCRIPTION (provided by applicant): Ischemic preconditioning (IPC) and hyperthermia (HT) are known to offer cardioprotection from ischemic injury such as myocardial infarction. While HT induces the heat shock proteins (HSP), which can act as chaperones in preventing myocardial infarction, IPC is known to induce nitric oxide (NO), which can mediate various processes in the heart to minimize ischemic injury. Our preliminary studies with isolated cardiomyocytes have indicated that the HSP90, induced through heat stress, can activate the NOS enzymes. Therefore we hypothesized in the present proposal that HSP90 induced by HT can activate the NOS enzymes in the heat stressed hearts and thus HT and IPC work in a common pathway to minimize the ischemic injury: i.e., in both cases the NOS enzymes are activated to produce high abundance of NO. Since the NO and oxygen have high and equal affinity to the cytochrome c oxidase site in the mitochondria, oxygen consumption and respiration of cardiomyocytes, is expected to be reduced in IPC and heat stressed hearts. However, the role of induced NO in the oxygen consumption in IPC subjected and heat stressed hearts has not been studied before. Thus the main goal of this proposal is to investigate the NO regulated oxygen consumption in PC subjected and heat stressed hearts. We propose to use electron paramagnetic resonance (EPR) oximetry with high sensitive LiPc microcrystals as probe and specially designed EPR instrumentation, to directly measure oxygen consumption in normal, IPC subjected and heat stressed hearts. The present proposal has three main aims: (1) Direct correlation of oxygen consumption and functional recovery in ischemically injured hearts; (2) To study the effect of NO generated during ischemic preconditioning on the myocardial oxygen consumption; (3) To study the role of heat shock proteins, induced by heat stress, on the myocardial oxygen consumption. Using other supporting studies, it would be proved that in both cases (IPC and HT) the NO mediated regulation of respiration is one of the key mechanisms of cardioprotection. Overall, this project will determine the relationship between the NO and the oxygen consumption in the hearts subjected to PC and HT and provide insight into the actual mechanism of cardioprotection.