ALTERED BLOOD VESSEL FUNCTION IN HYPERTENSION

高血压时血管功能的改变

• 批准号: 6241573
• 负责人: R Clinton Webb
• 金额: $ 15.7万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-07-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6241573
• 关键词: G protein; antihypertensive agents; biological signal transduction; calcium flux; cardiovascular function; cardiovascular pharmacology; fluorescent dye /probe; hormone regulation /control mechanism; hypertension; membrane transport proteins; nutrition related tag; phosphatidylinositols; sarcoplasmic reticulum; spontaneous hypertensive rat; vascular resistance; vascular smooth muscle; vasoconstriction

Current knowledge about hypertension suggests that an elevated peripheral resistance maintains high levels of arterial pressure. This increase in peripheral resistance may be caused by a vasoconstriction resulting from an alteration in vascular smooth muscle which makes it more sensitive to normal stimuli. Experimental observations suggest that this increased sensitivity reflects, at least in part, an abnormal regulation of intracellular calcium ion (Ca2+) by the phosphoinositide system. In this signal transduction system, activated receptors (i.e., alpha-adrenergic and serotonergic) act on a guanine nucleotide binding regulatory protein (G protein). Once activated, the G protein stimulates a phospholipase C that generates two second messengers: diacylglycerol (the physiological activator of protein kinase C) and inositol 1,4,5- trisphosphate (IP3), which activates a receptor-operated channel that releases Ca2+ from the sarcoplasmic reticulum. The activation of protein kinase C and other kinases contributes to the intracellular signal producing contraction. Previous work from this laboratory has demonstrated that components of this signal transduction pathway are increased in arteries of rats with genetic and experimental hypertension. This previous work used both pharmacological and biochemical assays and characterized the following: 1) receptor affinity and number; 2) inositol phosphate turnover and phospholipase C activity; 3) Ca2+ mobilization from the sarcoplasmic reticulum; and 4) protein kinase C activity. The goal of this research is to extend our understanding of the phosphoinositide signaling system in vascular smooth muscle from hypertensive rats. The research will be guided by the working hypothesis that augmented vascular reactivity in hypertension is due to an increase in the functional activity of a G protein (Gq) involved in agonist- promoted phosphoinositide hydrolysis. The research will focus on four aspects in rats with either genetic or experimentally-induced hypertension: 1) functional activity of G proteins and vascular reactivity; 2) regulation of G protein activity by nitric oxide- stimulated ribosylation; 3) antihypertensive therapy, blood pressure and G protein activity; and 4) genetic aspects of G protein coupling. The proposed experiments will be performed on isolated blood vessel segments (aorta, mesenteric arteries and arterioles, tail artery, femoral artery) from hypertensive and normotensive rats. The techniques used to evaluate functional characteristics of G protein activity include: 1) isometric recording of contractile behavior (intact and permeabilized preparations); 2) measurement of G protein levels using antibody techniques; 3) pharmacological characterization of G protein activity (agonists and antagonists of G protein activity coupled with antagonists of phospholipase C; 4) analysis of vascular traits in a genetic experiment; 5) analysis of vascular function in rats receiving antihypertensive therapy; 6) characterization of G protein function in arteries transplanted from hypertensive rats into normotensive rats (and vice versa) and 7) characterization of G protein function in blood vessels that are protected from elevated blood pressure by a ligation procedure. It is anticipated that this study will yield important information about functional determinants of vascular reactivity in hypertension.

目前关于高血压的知识表明，外周血中高血压的发生与高血压的发生有关。 阻力维持高水平的动脉压。 的这种增加 外周阻力可能是由血管收缩引起的， 血管平滑肌的改变，使其对 正常刺激。 实验观察表明，这增加了 敏感性至少部分地反映了一种异常调节， 细胞内钙离子（Ca 2+）的磷酸肌醇系统。 在这 信号转导系统，激活的受体（即，α肾上腺素能的 和多巴胺能）作用于鸟嘌呤核苷酸结合调节蛋白 （G蛋白）。 一旦被激活，G蛋白刺激磷脂酶 C产生两个第二信使：甘油二酯（ 蛋白激酶C的生理激活剂）和肌醇1，4，5- 三磷酸盐（IP 3），其激活受体操纵的通道， 从肌浆网释放Ca 2+。 激活蛋白 激酶C和其他激酶有助于细胞内信号 产生收缩。 这个实验室以前的工作 证明了这种信号转导途径的组成部分是 增加的动脉与遗传性和实验性高血压的大鼠。 这项先前的工作使用了药理学和生物化学测定， 特征如下：1）受体亲和力和数量; 2）肌醇 磷酸盐周转和磷脂酶C活性; 3）Ca 2+动员 从肌浆网;和4）蛋白激酶C活性。 的 这项研究的目的是扩大我们对 血管平滑肌中磷酸肌醇信号系统 高血压大鼠 这项研究将以工作假设为指导 高血压中血管反应性的增强是由于 参与激动剂的G蛋白（Gq）的功能活性- 促进磷酸肌醇水解。 研究将集中在四个方面 基因或实验诱导的大鼠 高血压：1）G蛋白和血管的功能活性 反应性; 2）通过一氧化氮调节G蛋白活性- 刺激核糖基化; 3）抗高血压治疗，血压和 G蛋白活性;和4）G蛋白偶联的遗传方面。 的 所提出的实验将在分离的血管段上进行 （主动脉、肠系膜动脉和小动脉、尾动脉、股动脉） 从高血压和血压正常的大鼠。 用于评估的技术 G蛋白活性的功能特征包括：1）等长的 记录收缩行为（完整和透化 制备）; 2）使用抗体测量G蛋白水平 G蛋白活性的药理学表征 （G蛋白活性的激动剂和拮抗剂与拮抗剂偶联 磷脂酶C; 4）分析血管性状的遗传 实验; 5）大鼠血管功能分析 抗高血压治疗; 6）G蛋白功能的表征， 从高血压大鼠移植到正常血压大鼠的动脉（和 反之亦然）和7）血液中G蛋白功能的表征 通过结扎保护血管免受血压升高的影响 procedure. 预计这项研究将产生重要的成果， 关于血管反应性的功能决定因素的信息， 高血压