INTESTINE IN CHRONIC PORTAL HYPERTENSION

描述：门静脉高压症，一种由肝硬化或 肝内肝病的特征在于门静脉压力升高， 门体分流，强烈的肠道血管扩张和减少 血管收缩反应性。以前的工作已经确定， 血浆胰高血糖素和一氧化氮（NO）有助于血管舒张， 通过直接作用和干扰血管收缩功能。现在 已经很清楚，在这一过程中的其他重要参与者包括cAMP 和cGMP，它们似乎通过改变Ca2+来放松血管平滑肌。 收缩机制的敏感性，即，肌动蛋白和肌球蛋白。后一 机制是本申请的重点。申请人提出了三种方法 这一过程可能发生的方式。首先，Gs信号通路的激活是 提出，导致cAMP增加，从而激活PKA。第二、 小GTP结合蛋白Rho A不能响应GI激活 和Gq偶联的血管收缩剂，因为这一事件会干扰 受体后信号转导，从而限制血管收缩作用的 一种特定的激动剂第三，肌球蛋白相关蛋白 影响MLCK的Ca2+敏感性的telokin可能被改变，导致 收缩效率降低。这些可能性将在四个 具体目标。这项工作将利用一种新的基因转移方法， 申请人的实验室。因此，申请人已证明有能力 通过电穿孔将cDNA构建体原位插入完整的血管中。 几天后收获血管并进行体外研究。使用这种方法， 申请者建议通过插入以下内容来研究拟议的机制： 几个关键参与者的显性消极或组成性积极结构 (e.g., G蛋白、PKA和Rho A）特异性地改变转导 细胞内的途径，而不施加外源性药理学 probes.

DESCRIPTION: Portal hypertension, a condition that results from cirrhosis or intrahepatic liver disease, is characterized by an elevated portal pressure, portosystemic shunting, an intense intestinal vasodilation and decreased vasoconstrictor responsiveness. Previous work has established that elevations in plasma glucagon and nitric oxide (NO) contribute to the vasodilation, both by a direct effect and by interfering with vasoconstrictor function. Now, it has become clear that other important participants in this process include cAMP and cGMP, which appear to relax vascular smooth muscle by altering the Ca2+ sensitivity of the contractile machinery, i.e., actin and myosin. This latter mechanism is the focus of this application. The applicant suggests three means by which this process might occur. First, activation of Gs signaling pathway is proposed, leading to an increase in cAMP and thus activation of PKA. Second, failure of the small GTP binding protein Rho A to activate in response to GI and Gq coupled vasoconstrictor is suggested, as this event would interfere with post-receptor signal transduction, thus limiting the vasoconstrictive effect of a specific agonist. Third, it is suggested that the myosin-associated protein telokin, which affects the Ca2+ sensitivity of MLCK, may be altered, leading to reduced contractile efficiency. These possibilities will be tested in four specific aims. The work will utilize a novel method of gene transfer developed in the applicant's laboratory. Thus, the applicant has demonstrated the ability to insert cDNA constructs into intact blood vessels in situ by electroporation. The vessels are harvested days later and studied in vitro. Using this method, the applicant proposes to study the proposed mechanisms by insertion of dominant negative or constitutively active constructs of several key players (e.g., G proteins, PKA and Rho A) to specifically alter the transduction pathways within the cells without the application of exogenous pharmacological probes.