RYANODINE RECEPTOR DYSFUNCTION IN DIABETIC RAT HEARTS

申请人摘要 2型ryanodine对肌浆网钙离子的释放 受体(RyR2)是导致一系列事件的不可或缺的一步 心肌收缩。研究表明，这个过程是 糖尿病大鼠心脏受损(Yu和McNeill，1991；Yu等人)。(1994年)。 我们最近发现，RyR2活性的下降源于 这种蛋白质的功能障碍，而不是它的表达减少(Bidasee et Al手稿#1)。到目前为止，RyR2功能障碍的分子基础 是未知的。我们的工作假说是“糖尿病改变了 RyR2上的钙外流途径。在这个项目中，我们想要表征 糖尿病引起的RyR2的变化及其对上述指标的影响 内源调节剂对RyR2调控的变化。同时， 我们想要调查胰岛素和维拉帕米的有益作用 治疗方法包括逆转糖尿病引起的RyR2蛋白变化。我们的 具体目标是：(1)鉴定和表征RyR2的分子变化 糖尿病诱导的蛋白质，(2)确定这些变化是否会改变 RyR2对Ca~(2+)、pH等内源调节剂的敏感性，(3) 确定长期糖尿病是否会导致RyR2的变化 用胰岛素逆转治疗，(4)确定维拉帕米治疗是否 可以保护和/或逆转糖尿病引起的RyR2变化，以及(5) 确定维拉帕米和胰岛素联合治疗是否具有相加作用 逆转糖尿病引起的RyR2的变化。实现这些目标 将极大地有助于理解 糖尿病患者RyR2蛋白(可能还有其他蛋白)活性降低 这可能导致对治疗策略的新见解 缓解糖尿病引起的心脏功能障碍。

Applicant's Abstract Release of calcium ions from the sarcoplasmic reticulum via type 2 ryanodine receptors (RyR2) is an integral step in the cascade of events leading to cardiac muscle contraction. Studies have shown that this process is compromised in heart of diabetic rats (Yu and McNeill 1991; Yu et al. 1994). We recently found that the decrease in activity of RyR2 stems from a dysfunction of this protein rather than a decrease its expression (Bidasee et al manuscript #1). To date, the molecular basis for the dysfunction of RyR2 is not known. Our working hypothesis is "diabetes alters the integrity of the calcium efflux pathway on RyR2." In this project we want to characterize changes in RyR2 induced by diabetes and to determine the effects of these changes on the regulation of RyR2 by endogenous modulators. At the same time, we want to investigate whether the beneficial effects of insulin and verapamil treatments include reversal of diabetes-induced changes to RyR2 protein. Our specific aims are: (1) to identify and characterize molecular changes to RyR2 protein induced by diabetes, (2) to ascertain whether these changes alter the sensitivity of RyR2 to endogenous modulators like Ca2+, pH etc., (3) to determine whether changes to RyR2 induced by long-term diabetes can be reversed with insulin treatment, (4) to determine whether verapamil treatment can protect and/or reverse diabetes-induced changes to RyR2, and (5) to establish if verapamil and insulin co-treatments have additive effects on reversing changes to RyR2 induced by diabetes. Accomplishment of these aims will contribute significantly to understanding the molecular basis for the decrease activity of RyR2 protein (and possibly other proteins) in diabetes and this could lead to newer insights into therapeutic strategies for alleviating diabetes-induced dysfunction of the heart.