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Tetrahydrobiopterin improves endothelial dysfunction and vascular oxidative stress in microvessels of intrauterine undernourished rats
Author(s) -
Franco Maria do Carmo P.,
Fortes Zuleica B.,
Akamine Eliana H.,
Kawamoto Elisa M.,
Scavone Cristoforo,
De Britto Luiz Roberto Giorgetti,
Muscara Marcelo N.,
Teixeira Simone A.,
Tostes Rita C. A.,
Carvalho Maria Helena C.,
Nigro Dorothy
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.064055
Subject(s) - tetrahydrobiopterin , peroxynitrite , endocrinology , superoxide , medicine , enos , nitrotyrosine , chemistry , nitric oxide , nitric oxide synthase , endothelial nos , biopterin , oxidative stress , nitric oxide synthase type iii , endothelium , biochemistry , biology , enzyme
In the present study, we investigated the effects of the exogenous application of tetrahydrobiopterin on the endothelium‐dependent vasorelaxation and superoxide anion generation in the mesenteric microvessels of intrauterine undernourished rats. In addition, we investigated the presence of peroxynitrite in these rats by evaluation of nitrotyrosine‐containing proteins, a stable end‐product of peroxynitrite oxidation. For this, female pregnant Wistar rats were fed either normal or 50% of the normal intake diets during the whole gestational period. Male offspring (16 weeks of age) were studied to assess microvascular reactivity, superoxide production using a hydroethidine staining assay, nitric oxide synthase (NOS) activity and nitric oxide (NO) production. Western blot analysis was used to quantify nitrotyrosine‐containing proteins and relative multiplex RT‐PCR analysis for endothelial NOS (eNOS) mRNA expression. Superfusion with tetrahydrobiopterin significantly decreased superoxide generation and improved vascular function. Intrauterine malnutrition induced a decrement of NOS activity and NO production without affecting the gene expression of eNOS. However, incubation with tetrahydrobiopterin significantly improved NO production after stimulation with acetylcholine or bradykinin in intrauterine undernourished rats. The fact that the nitrotyrosine‐containing proteins were increased could, at first sight, suggest that the peroxynitrite is the mediator responsible for the excessive oxidation and depletion of tetrahydrobiopterin. Our study shows that exogenous application of tetrahydrobiopterin leads to a significant improvement of endothelium‐dependent vasodilatation, enhanced NO production and decreased superoxide generation in microvessels of intrauterine undernourished rats. Since we found a decrease in NOS activity without an alteration in the gene expression of eNOS, we suggest that impaired NOS‐dependent responses of mesenteric arterioles are related to the impairment of tetrahydrobiopterin pathways.