Vascular Rho-kinase Signaling in Angiotensin II hyperten

高血压患者外周阻力的增加可能是由于促进血管内收缩蛋白激活的信号转导增强而导致的血管收缩。这一研究方案将扩大我们对高血压小鼠血管平滑肌中RhoA/Rho-Kinase信号系统的理解。这项研究将遵循这样的工作假设，即血管紧张素II诱导的高血压中血管反应性的增强是通过两步机制来增加RhoA/Rho-Kinase系统的功能活性：1)在血压升高的早期阶段， 血管紧张素II刺激超氧化物的产生，导致表皮生长因子受体(EGFR)的反式激活，随后刺激RhoA/Rho-Kinase引起血管收缩；2)在血压升高的既定阶段，血管紧张素II增加血浆和组织中的白介素6(IL-6)，导致JAK/STAT激活和RhoA/Rho-Kinase级联的组件表达增加，并维持血管收缩。这一工作假说将通过三个特定的目标来检验：1)检验该假说：在血管紧张素II诱导的高血压的早期阶段，八肽通过受体的超氧化物激活来刺激RhoA/Rho-Kinase信号 2)验证八肽和IL-6通过激活JAK/STAT增加RhoA/Rho-Kinase信号通路组成部分表达的假说；3)验证在Ang-II诱导的高血压中，RhoA/Rho-Kinase信号增强与血压本身无关的假说。通过注射血管紧张素II，小鼠将变得高血压，并将使用遥测技术测量血压。在高血压过程的启动和维持阶段，将处死小鼠，分离血管，并对RhoA/Rho-Kinase进行功能和生化分析 JAK/STAT信号转导通路。测定超氧阴离子和IL-6水平。用于评估信号通路贡献的技术包括：1)等长记录离体肠系膜和后肢动脉的收缩行为和升压活动的测量；2)药物干预以评估信号级联的组成部分；3)评估血管肌细胞(受保护的后肢)的压力依赖性激活；以及4)蛋白质表达的测量。在一个补充策略中，IL-6基因敲除小鼠将被用来评估这一作用 血管紧张素II信号转导中的细胞因子。我们预测，在血管心肌细胞中，血管紧张素II和IL-6将导致影响收缩活动的调节蛋白的活性增加。

Increased peripheral resistance in hypertension may be caused by a vasoconstriction resulting from enhanced transduction of signals promoting contractile protein activation within the vascular myocyte. This research proposal will extend our understanding of the RhoA/Rho-kinase signaling system in vascular smooth muscle from hypertensive mice. The research will be guided by the working hypothesis that augmented vascular reactivity in angiotensin II-induced hypertension occurs by a two-step mechanism to increase the functional activity of the RhoA/Rho-kinase system: 1) during the early phase of blood pressure elevation, angiotensin II stimulates superoxide production leading to transactivation of the epidermal growth factor receptor (EGFR) and subsequent stimulation of RhoA/Rho-kinase to cause vasoconstriction; and 2) during the established phase of blood pressure elevation, angiotensin II increases interleukin-6 (IL-6) in plasma and tissue leading to JAK/STAT activation and increased expression of components of the RhoA/Rho-kinase cascade and maintained vasoconstriction. This working hypothesis will be tested by three specific aims: 1) to test the hypothesis that during the early phase of blood pressure elevation in angiotensin II-induced hypertension, the octapeptide stimulates RhoA/Rho-kinase signaling via superoxide activation of the receptor for epidermal growth factor (EGFR); 2) to test the hypothesis that during the maintained phase of angiotensin II-induced hypertension, the octapeptide and IL-6 increase expression of components of the RhoA/Rho-kinase signaling pathway via activation of JAK/STAT; and 3) to test the hypothesis that augmented RhoA/Rho-kinase signaling is not related to blood pressure per se in angiotensin II-induce hypertension. Mice will be made hypertensive by infusion of angiotensin II and blood pressure will be measured using telemetry. During the initiation and maintenance phases of the hypertensive process, the mice will be killed and blood vessels will be isolated and subjected to functional and biochemical analyses of the RhoA/Rho-kinase and JAK/STAT signal transduction pathways. Superoxide anion and IL-6 levels will be measured. The techniques used to evaluate the contribution of the signaling pathways include: 1) isometric recording of contractile behavior of isolated arteries and measures of pressor activity in perfused mesentery and hindquarters; 2) pharmacological interventions to evaluate components of the signaling cascades; 3) evaluation of pressure-dependent activation of vascular myocytes (protected hindlimb); and 4) measures of protein expression. In a complementary strategy, IL-6 knock-out mice will be used to evaluate the role of this cytokine in the transduction of the angiotensin II signal. We predict that, in vascular myocytes, angiotensin II and IL-6 will lead to an increased activity of regulatory proteins that influence contractile activity.