The magnitude of nitric oxide (NO) production by mammalian cells is dependent on numerous factors. Cells stimulated make inducible (inflammatory) NOS (iNOS) generate 100-to 1000-fold more NO than do cells containing distinct NOS isoforms present constitutively, and this high-output NO plays pathophysiological roles in inflammation and host defense. The principal objective of the proposed research is to elucidate the multiple mechanisms that are involved in the regulation or modulation of the high-output production of NO in vascular smooth muscle, endothelial cells and macrophages. The rationale for this objective is that in view of the widespread pathophysiological actions of iNOS-generated NO, it is essential to understand the mechanisms by which both iNOS and NO production are regulated. The central hypothesis that drives this proposal is that the production of both iNOS protein and NO is sensitive to regulation at various levels including NF-kappaB- mediated transcription, post-transcriptional stability of iNOS mRNA, post-translational stability of iNOS protein, and arginine availability as a substrate for iNOS.
Four specific aims are proposed to achieve the objective: (a) to elucidate the mechanism by which LPS causes downregulation and degradation of iNOS in vascular smooth muscle cells and macrophages, (b) to elucidate the mechanisms by which NO elicits positive and negative feedback modulation of NF-kappaB activation of iNOS induction in vascular cells and macrophages, (c) to determine how LPS-induced arginase plays a role in regulating high-output NO production by INOS in vascular cells and macrophages and (d) to ascertain the novel role of Ng- Hydroxyarginine as a distinct biological effector molecule in regulating intracellular arginine levels and high-output NO production in vascular cells and macrophages. The proposed research represents a continuing long-term effort to understand the regulation of NO production and action in vascular cells and macrophages.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL035014-12
Application #
6183490
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1985-08-01
Project End
2002-03-31
Budget Start
2000-04-01
Budget End
2002-03-31
Support Year
12
Fiscal Year
2000
Total Cost
$294,865
Indirect Cost
Name
University of California Los Angeles
Department
Pharmacology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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Garban, Hermes J; Buga, Georgette M; Ignarro, Louis J (2004) Estrogen receptor-mediated vascular responsiveness to nebivolol: a novel endothelium-related mechanism of therapeutic vasorelaxation. J Cardiovasc Pharmacol 43:638-44
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Bauer, P M; Buga, G M; Fukuto, J M et al. (2001) Nitric oxide inhibits ornithine decarboxylase via S-nitrosylation of cysteine 360 in the active site of the enzyme. J Biol Chem 276:34458-64
Wei, L H; Wu, G; Morris Jr, S M et al. (2001) Elevated arginase I expression in rat aortic smooth muscle cells increases cell proliferation. Proc Natl Acad Sci U S A 98:9260-4
Bauer, P M; Buga, G M; Ignarro, L J (2001) Role of p42/p44 mitogen-activated-protein kinase and p21waf1/cip1 in the regulation of vascular smooth muscle cell proliferation by nitric oxide. Proc Natl Acad Sci U S A 98:12802-7

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