ALTERED BLOOD VESSEL FUNCTION IN HYPERTENSION

目前对高血压的认识表明，外周血升高 阻力维持较高的动脉压水平。这一增长 外周阻力可能是由以下原因引起的血管收缩 血管平滑肌的一种改变，使其对 正常刺激。实验观察表明，这一点增加了 敏感性至少在一定程度上反映了对 细胞内钙离子(Ca~(2+))通过磷脂酰肌醇系统。在这 信号转导系统，激活的受体(即α-肾上腺素能 和5-羟色胺能)作用于鸟嘌呤核苷酸结合调节蛋白 (G蛋白)。一旦被激活，G蛋白就会刺激磷脂酶 C生成两个第二信使：二酰基甘油( 蛋白激酶C的生理激活剂)和肌醇1，4，5- 三磷酸(IP3)，它激活受体操作的通道， 从肌浆网释放钙离子。蛋白质的活化 激酶C和其他激酶对细胞内信号起作用 产生收缩。这个实验室以前的工作是 证明了该信号转导途径的组成部分是 遗传性高血压和实验性高血压大鼠动脉血流量增加。 这项先前的工作使用了药理和生化分析以及 特征如下：1)受体亲和力和数量；2)肌醇 磷酸盐周转与磷脂酶C活性；3)钙离子动员 来自肌浆网；4)蛋白激酶C活性。这个 这项研究的目的是扩大我们对 大鼠血管平滑肌肌醇磷脂信号系统的研究 高血压大鼠。这项研究将以工作假说为指导 高血压患者血管反应性的增强是由于 在参与激动剂的G蛋白(Gq)的功能活性中- 促进磷脂酰肌醇的水解。这项研究将集中在四个方面 遗传性或实验诱导性大鼠的Aspects 高血压：1)G蛋白的功能活性与血管 反应性；2)一氧化氮对G蛋白活性的调节 刺激核糖化；3)抗高血压治疗、血压和 G蛋白活性；4)G蛋白偶联的遗传方面。这个 拟议的实验将在分离的血管节段上进行 (主动脉、肠系膜动脉和小动脉、尾动脉、股动脉) 来自高血压和正常血压的大鼠。用于评估的技术 G蛋白活性的功能特征包括：1)等长 记录收缩行为(完整的和通透性的 准备)；2)使用抗体测量G蛋白水平 技术；3)G蛋白活性的药理学特性 G蛋白活性激动剂和拮抗剂与拮抗剂偶联 磷脂酶C；4)对一个遗传的维管束性状进行分析 实验；5)大鼠血管功能分析 抗高血压治疗；6)G蛋白功能的特征 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 程序。预计这项研究将产生重要的 血管反应性的功能决定因素的信息 高血压。

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.