MECHANISMS OF MYOCARDIAL ISCHEMIC INJURY IN DIABETES

描述：(来自应用程序的逐字)：此项目的长期目标 建议确定心脏保护性信号转导是否受损 和氧化应激增加是导致病情恶化的机制 糖尿病和高血糖患者心肌缺血损伤的研究 综合细胞和生理方法。冠状动脉疾病是 糖尿病患者的主要死因，高血糖一直是 被描述为急性心肌梗塞后死亡的最强预测因素之一 糖尿病患者和非糖尿病患者均存在脑梗塞。最新发现来自 本实验室已经证明，急性高血糖可以消除 缺血预适应早期阶段提供的保护，以及 腺苷激活介导的内源性心脏保护机制 蛋白激酶C(PKC)和三磷酸腺苷调节的受体 钾(KATP)通道。为实现具体目标1而进行的实验将 提出急性高血糖(剂量依赖)和急性高血糖(3 和慢性(6个月)糖尿病(四氧嘧啶/链脲佐菌素)加重 缺血时心肌损伤并取消早期对心肌的保护作用 犬心肌晚期缺血预适应。特定目标2将 提出高血糖和糖尿病可以缓解的假说 抑制腺苷受体(A1)的心肌保护信号转导 和A3)、PKC和KATP通道激活。犬活体实验测量 对特定激动剂的反应可减少心肌梗死面积 并辅之以体外实验。Sarcolemmal KATP通道活动将 使用膜片钳技术评估线粒体KATP通道活性 用黄素蛋白荧光、间质腺苷浓度测量 用高效液相色谱法测定，并定量测定对照组、高血糖组和高血糖组的PKC亚型。 患糖尿病的狗。氧衍生自由基对 腺苷和KATP通道相互作用增强心肌损伤 将在具体目标期间进行进一步调查3.实验将 在长期使用抗氧化剂、坦波尔或 二甲基硫脲，以逆转氧化剂增加的有害影响 应激对缺血再灌注损伤程度、间质腺苷的影响 糖尿病和高血糖诱导的血药浓度和KATP通道活性。 糖尿病和高血糖的持续时间和严重程度将特别 被检测为氧化应激程度的决定因素。因此，这项提议将 描述造成糖尿病不良后果的机制和 心肌缺血时高血糖的综合治疗方法 活体和细胞技术。

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.