Tetrahydrobiopterin improves endothelial dysfunction and vascular oxidative stress in microvessels of intrauterine undernourished rats.
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.
Franco
Maria do Carmo P
Mdo C
Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Sciences, Universidade de São Paulo, São Paulo, Brazil. mdcfranco@yahoo.com
Fortes
Zuleica B
ZB
Akamine
Eliana H
EH
Kawamoto
Elisa M
EM
Scavone
Cristoforo
C
de Britto
Luiz Roberto Giorgetti
LR
Muscara
Marcelo N
MN
Teixeira
Simone A
SA
Tostes
Rita C A
RC
Carvalho
Maria Helena C
MH
Nigro
Dorothy
D
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001708:Biopterins / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015153:Blotting, Western; D031204:Caloric Restriction; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D048070:Fetal Nutrition Disorders / Q000188:drug therapy*; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress / Q000187:drug effects; D030421:Peroxynitrous Acid / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism; D014599:Uterus / Q000098:blood supply*; D014664:Vasodilation / Q000187:drug effects
D000975:Antioxidants; D012333:RNA, Messenger; D013481:Superoxides; D030421:Peroxynitrous Acid; D001708:Biopterins; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; C003402:sapropterin