© 2004 by European Society of Cardiology
Copyright © 2004, European Society of Cardiology
Gender differences in superoxide generation in microvessels of hypertensive rats: role of NAD(P)H-oxidase
Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, 05508-900, Av Prof Lineu Prestes, 1524, Room 217, Sao Paulo, SP, Brazil
* Corresponding author. Tel.: +55-11-3091-7433; fax: +55-11-3091-7237. mhcarval{at}icb.usp.br
Objective: This study is aimed to explore whether gender plays a role in the generation of nitric oxide (NO) and superoxide anion (O2–) in microvessels of hypertensive rats (SHR), as well as the potential mechanisms involved in these effects. Methods and results: NO generation in mesenteric arterioles was evaluated by measuring NO synthase (NOS) activity and protein expression. Oxidative stress was studied in vivo in mesenteric arterioles from male and female SHR by hydroethidine microfluorography. Although we did not observe any sex-related differences in NO generation, we found that hydroethitine oxidation is markedly increased (30.9±2.4%) in male compared to female (12.3±2.5%; p<0.05), demonstrating a gender difference in O2– production. The treatment of mesenteries with DPI (NAD(P)H-oxidase inhibitor) and treatment of SHR with losartan [Angiotensin-II type 1 (AT-1) receptor antagonist] markedly reduced O2– production in male, while produced a minor effect in female, suggesting that overexpression/activity of AT-1 receptor and NAD(P)H-oxidase contribute for the sexual dimorphism in superoxide generation. Immunoblot analyses provide evidences of overexpression of the NAD(P)H-oxidase components p22phox, gp91phox, p47phox and p67phox in arterioles from male in comparison to female. Losartan treatment inhibited the overexpression of these subunits in male, without affecting the responses in female. Conclusion: Taken together, our findings demonstrate that male SHR presents higher superoxide anion concentration under basal condition than does female. An AT-1-dependent overexpression of the NAD(P)H-oxidase components may account for the sexual dimorphism in oxidative stress, and may play an important role in the noted gender differences on incidence of cardiovascular disease.
KEYWORDS Oxygen radical; Nitric oxide; NAD(P)H-oxidase; Hypertension; Endothelial function; Angiotensin-II; Gender
Time for primary review 30 days
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