MECHANISMS OF MYOCARDIAL ISCHEMIC INJURY IN DIABETES

描述：（申请书中的逐字记录）：本项目的长期目标 建议是确定是否损害心脏保护信号转导 和氧化应激增加是导致病情恶化的机制 糖尿病和高血糖症心肌缺血性损伤的研究， 综合细胞和生理学方法。冠状动脉疾病是 糖尿病患者死亡的主要原因，高血糖一直是 被描述为急性心肌梗死后死亡的最强预测因子之一 糖尿病和非糖尿病患者的心肌梗死。最近的调查结果来自 这个实验室已经证明，急性高血糖症消除了 缺血预处理早期提供的保护， 腺苷激活介导的内源性心脏保护机制 受体，蛋白激酶C（PKC）和三磷酸腺苷调节 钾（KATP）通道。为满足具体目标1而进行的实验将 提出急性高血糖（剂量依赖性）和急性（3 周）和慢性（6个月）糖尿病（四氧嘧啶/链脲佐菌素）加重 心肌缺血损伤，并取消早期提供的保护 和晚期缺血预适应。具体目标2将 解决高血糖症和糖尿病减弱的假设 通过抑制腺苷受体（A1）的心脏保护信号转导 和A3）、PKC和KATP通道激活。体内犬实验测量 响应于特异性激动剂的心肌梗死面积的减小将 并辅以体外实验。肌膜KATP通道活性将 使用膜片钳技术评估，线粒体KATP通道活性 用黄素蛋白荧光、间质腺苷浓度 用HPLC测定，并在对照组、高血糖组和 糖尿病狗氧源性自由基有助于 通过与腺苷和KATP通道的相互作用增强心肌损伤 将在具体目标3中进一步研究。实验wifi是 在用抗氧化剂tempol或 二甲基硫脲，以逆转增加的氧化剂的有害影响 应激对缺血再灌注损伤程度、间质腺苷 浓度和KATP通道活性诱导的糖尿病和高血糖。 糖尿病和高血糖症的持续时间和严重程度将具体 作为氧化应激程度的决定因素进行检查。因此，该提案将 阐明糖尿病不良后果的机制， 心肌缺血时高血糖症的综合干预方法 体内和细胞技术。

DESCRIPTION: (Verbatim from the application): The long term objective of this proposal is to determine if impairment of cardioprotective signal transduction and increased oxidative stress are mechanisms responsible for the exacerbation of myocardial ischemic injury in diabetes and hyperglycemia, using an integrated cellular and physiological approach. Coronary artery disease is the leading cause of death in diabetic patients, and hyperglycemia has been described as one of the strongest predictors of death after acute myocardial infarction in both diabetic and non-diabetic patients. Recent findings from this laboratory have demonstrated that acute hyperglycemia abolishes the protection afforded by the early phase of ischemic preconditioning, an endogenous cardioprotective mechanism mediated by activation of adenosine receptors, protein kinase C (PKC) and adenosine triphosphate-regulated potassium (KATP) channels. Experiments conducted to meet Specific Aim 1 will address the hypotheses that acute hyperglycemia (dosedependently) and acute (3 weeks) and chronic (6 months) diabetes (alloxan/streptozotocin) exacerbate myocardial injury during ischemia and abolish the protection afforded by early and late ischemic preconditioning in canine myocardium. Specific Aim 2 will address the hypotheses that hyperglycemia and diabetes attenuate cardioprotective signal transduction via inhibition of adenosine receptor (A1 and A3), PKC, and KATP channel activation. In vivo canine experiments measuring the reduction in myocardial infarct size in response to specific agonists will be complemented by in vitro experiments. Sarcolemmal KATP channel activity will be assessed using patch clamp techniques, mitochondrial KATP channel activity measured with flavoprotein fluorescence, interstitial adenosine concentrations determined with HPLC, and PKC isoforms quantified in control, hyperglycemic and diabetic dogs. The hypothesis that oxygen-derived free radicals contribute to enhanced myocardial injury via interactions with adenosine and KATP channels will be further investigated during Specific Aim 3. Experiments wifi be conducted in animals after chronic treatment with the antioxidants, tempol or dimethyithiourea, to reverse the deleterious effects of increased oxidant stress on the extent of ischemia and reperfusion injury, interstitial adenosine concentration and KATP channel activity induced by diabetes and hyperglycemia. The duration and severity of diabetes and hyperglycemia will be specifically examined as determinants of degree of oxidant stress. Thus, this proposal will delineate mechanisms responsible for the adverse consequences of diabetes and hyperglycemia during myocardial ischemia using an integrated approach of in vivo and cellular techniques.