Vascular Smooth Muscle Hyper-contractility/Hypertension

描述(申请人提供)：1600万美国人患有II型糖尿病，血管并发症是糖尿病患者发病和死亡的最常见原因。在糖尿病早期发现的血管收缩或扩张(血管运动)异常可导致血流失调和外周阻力增加，从而导致糖尿病并发症。我们和其他人发现db/db和高脂饮食诱导的II型糖尿病小鼠是高血压，从这些动物分离的血管平滑肌组织对刺激表现出显著增强的收缩反应。然而，其分子机制尚不清楚。在初步研究中，我们观察到从II型糖尿病小鼠分离的血管平滑肌组织中，钙离子对收缩的敏化作用显着增加。我们发现CPI-17、PKCbetall、RhoA和ROCK这四个钙敏化信号的关键分子在糖尿病动脉中显著上调/激活。此外，抑制PKC或ROCK可减弱db/db小鼠分离的血管平滑肌组织中钙离子对收缩的增敏作用。因此，我们推测，在II型糖尿病中，激活的PKCbetall和RhoA/ROCK激活了CPI-17，从而显著促进了II型糖尿病血管平滑肌的过度收缩和高血压。具体目的是：(1)验证CPI-17的激活与db/db和饮食诱导的II型糖尿病小鼠的钙敏感性和血管平滑肌超收缩力增强有关的假设。(2)验证在db/db和饮食诱导的II型糖尿病小鼠中，PKCbetall和RhoA/ROCK的激活是引起血管平滑肌高收缩所必需的假设。(3)用药理学和遗传学方法检测CPI-17在血管平滑肌收缩功能亢进和2型糖尿病合并高血压中的体内意义。将采用体外和体内两种方法。分离的肠系膜小动脉将被用来研究等长收缩、钙离子对收缩的敏感性、CPI-17、RhoA/ROCK和PKC的mRNA、蛋白和活性。此外，还将使用无线电遥测和颈动脉导管测量小鼠的血压。这项拟议的研究可能为了解II型糖尿病血管平滑肌功能障碍的分子机制和糖尿病相关高血压的发病机制提供新的见解。

DESCRIPTION (provided by applicant): Sixteen million Americans have type II diabetes, and vascular complications are the most common causes of morbidity and mortality in diabetic patients. Abnormalities in blood vessel constriction or dilatation (vasomotion) detected in early diabetes can result in blood flow dysregulation and increased peripheral resistance, thereby contributing to diabetic complications. We and others found that db/db and high fat diet-induced type II diabetic mice are hypertensive and vascular smooth muscle tissues isolated from these animals exhibit a significantly increased contractile response to stimuli. However, the molecular mechanisms are unknown. In preliminary studies we observed that Ca2+sensitization of contractions are significantly increased in vascular smooth muscle tissues isolated from type II diabetic mice. We found that CPI-17, PKCbetall, RhoA, and ROCK, four key players of Ca2+ sensitization signaling, are significantly up-regulated/ activated in diabetic arteries. Moreover, inhibiting PKC or ROCK diminished the enhanced Ca2+ sensitization of contractions in vascular smooth muscle tissue isolated from db/db mice. Therefore, we hypothesize that in type II diabetes, activated PKCbetall and RhoA/ROCK activate CPI-17 and thereby significantly contribute to type II diabetic vascular smooth muscle hyper-contractility and hypertension. Specific aims are: (1) To test the hypothesis that activation of CPI-17 is responsible for enhanced Ca2+ sensitization and vascular smooth muscle hyper-contractility in db/db and diet-induced type II diabetic mice. (2) To test the hypothesis that the activation of PKCbetall and RhoA/ROCK are required for vascular smooth muscle hyper-contractility in db/db and diet-induced type II diabetic mice. (3) To test the in vivo significance of the CPI-17 in vascular smooth muscle hyper-contractility and type II diabetes-associated hypertension by using pharmacological and genetic approaches. Both in vitro and in vivo methods will be employed. Isolated small mesenteric arteries will be used to investigating isometric contractions, Ca2+ sensitization of contractions, the mRNA, protein and activities of CPI-17, RhoA/ROCK and PKC. In addition, blood pressure will be measured in mice by using radiotelemetry and carotid artery catheter. The proposed study may provide new insight into the molecular mechanisms of vascular smooth muscle dysfunction in type II diabetes and into the pathogenesis of diabetes-associated hypertension.