INTESTINE IN CHRONIC PORTAL HYPERTENSION

描述：门静脉高压症，一种由肝硬变或 肝内肝病，以门脉压力升高为特征， 门体分流，强烈的肠道血管扩张和减少 血管收缩反应性。先前的研究已经确定了海拔高度 血浆中的胰高血糖素和一氧化氮(NO)都参与了血管扩张 通过直接作用和干扰血管收缩功能。现在，它 很明显，这一进程的其他重要参与者包括坎普 和cGMP，它们似乎通过改变钙离子来松弛血管平滑肌 收缩机械的敏感性，即肌动蛋白和肌球蛋白。后者 机制是本应用的重点。申请者建议三种方法 这一过程可能通过它来实现。首先，Gs信号通路的激活是 建议，导致cAMP增加，从而激活PKA。第二, GI诱导的小GTP结合蛋白Rho A不能激活 并建议使用GQ偶联血管收缩药，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 特定的激动剂。第三，有人认为肌球蛋白相关蛋白 影响MLCK钙敏感性的telokin可能发生改变，导致 降低了收缩效率。这些可能性将在四个月内进行测试 明确的目标。这项工作将利用开发的一种新的基因转移方法 在申请人的实验室里。因此，申请人已经证明了自己的能力 利用电穿孔技术将构建的基因插入完整的血管内。 几天后，这些血管被收获，并在体外进行研究。使用这种方法， 申请人建议研究拟议的机制，方法是插入 几个关键角色的主导的消极的或结构性的积极结构 (例如，G蛋白、PKA和Rho A)来特异性地改变转导 不使用外源药物的细胞内途径 探测器。

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.