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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK051430-11
Application #
6198402
Study Section
General Medicine A Subcommittee 2 (GMA)
Program Officer
Doo, Edward
Project Start
1991-02-01
Project End
2005-06-30
Budget Start
2000-09-01
Budget End
2001-06-30
Support Year
11
Fiscal Year
2000
Total Cost
$253,286
Indirect Cost
Name
University of South Alabama
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Mobile
State
AL
Country
United States
Zip Code
36688
Chen, Xuesong; Pavlish, Kristin; Benoit, Joseph N (2008) Myosin phosphorylation triggers actin polymerization in vascular smooth muscle. Am J Physiol Heart Circ Physiol 295:H2172-7
Chen, Xuesong; Pavlish, Kristin; Zhang, Hai-Ying et al. (2006) Effects of chronic portal hypertension on agonist-induced actin polymerization in small mesenteric arteries. Am J Physiol Heart Circ Physiol 290:H1915-21
Anderson, Cindy M; Lopez, Faye; Zimmer, Ashley et al. (2006) Placental insufficiency leads to developmental hypertension and mesenteric artery dysfunction in two generations of Sprague-Dawley rat offspring. Biol Reprod 74:538-44
Anderson, Cindy M; Lopez, Faye; Zhang, Hai-Ying et al. (2006) Mesenteric vascular responsiveness in a rat model of pregnancy-induced hypertension. Exp Biol Med (Maywood) 231:1398-402
Chen, Xuesong; Zhang, Hai-Ying; Pavlish, Kristin et al. (2005) Effects of chronic portal hypertension on small heat-shock proteins in mesenteric arteries. Am J Physiol Gastrointest Liver Physiol 288:G616-20
Anderson, Cindy M; Lopez, Faye; Zhang, Hai-Ying et al. (2005) Reduced uteroplacental perfusion alters uterine arcuate artery function in the pregnant Sprague-Dawley rat. Biol Reprod 72:762-6
Anderson, Cindy M; Lopez, Faye; Zhang, Hai-Ying et al. (2005) Characterization of changes in leptin and leptin receptors in a rat model of preeclampsia. Am J Obstet Gynecol 193:267-72
Zhang, Hai-Ying; Shirasawa, Yuichi; Chen, Xuesong et al. (2005) Impaired agonist-dependent myosin phosphorylation and decreased RhoA in rat portal hypertensive mesenteric vasculature. Am J Physiol Gastrointest Liver Physiol 288:G603-8
Payne, Michael C; Zhang, Hai-Ying; Shirasawa, Yuichi et al. (2004) Dynamic changes in expression of myosin phosphatase in a model of portal hypertension. Am J Physiol Heart Circ Physiol 286:H1801-10
Young, J L; Benoit, J N; Dean, D A (2003) Effect of a DNA nuclear targeting sequence on gene transfer and expression of plasmids in the intact vasculature. Gene Ther 10:1465-70

Showing the most recent 10 out of 22 publications