title: Impaired nitric oxide production in coronary endothelial cells of the spontaneously diabetic BB rat is due to tetrahydrobiopterin deficiency.
abstract: Endothelial cells (EC) from diabetic BioBreeding (BB) rats have an impaired ability to produce NO. This deficiency is not due to a defect in the constitutive isoform of NO synthase in EC (ecNOS) or alterations in intracellular calcium, calmodulin, NADPH or arginine levels. Instead, ecNOS cannot produce sufficient NO because of a deficiency in tetrahydrobiopterin (BH(4)), a cofactor necessary for enzyme activity. EC from diabetic rats exhibited only 12% of the BH(4) levels found in EC from normal animals or diabetes-prone animals which did not develop disease. As a result, NO synthesis by EC of diabetic rats was only 18% of that for normal animals. Increasing BH(4) levels with sepiapterin increased NO production, suggesting that BH(4) deficiency is a metabolic basis for impaired endothelial NO synthesis in diabetic BB rats. This deficiency is due to decreased activity of GTP-cyclohydrolase I, the first and rate-limiting enzyme in the de novo biosynthesis of BH(4). GTP-cyclohydrolase activity was low because of a decreased expression of the protein in the diabetic cells.
authors.affiliation: Cardiovascular Research Institute and Department of Medical Physiology, The Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA. cjm@tamu.edu
authors.forename: C J
authors.initials: CJ
authors.lastname: Meininger
authors.forename: R S
authors.initials: RS
authors.lastname: Marinos
authors.forename: K
authors.initials: K
authors.lastname: Hatakeyama
authors.forename: R
authors.initials: R
authors.lastname: Martinez-Zaguilan
authors.forename: J D
authors.initials: JD
authors.lastname: Rojas
authors.forename: K A
authors.initials: KA
authors.lastname: Kelly
authors.forename: G
authors.initials: G
authors.lastname: Wu
mesh_terms: D000818:Animals; D001120:Arginine / Q000737:chemistry; D001708:Biopterins / Q000031:analogs & derivatives* / Q000172:deficiency* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003920:Diabetes Mellitus / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D006136:GTP Cyclohydrolase / Q000378:metabolism; D015151:Immunoblotting; D007700:Kinetics; D009249:NADP / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D020033:Protein Isoforms; D011621:Pteridines / Q000494:pharmacology; D011622:Pterins; D051381:Rats; D011922:Rats, Mutant Strains / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D020033:Protein Isoforms; D011621:Pteridines; D011622:Pterins; D001708:Biopterins; D009569:Nitric Oxide; D009249:NADP; D001120:Arginine; C016727:sepiapterin; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D006136:GTP Cyclohydrolase; C003402:sapropterin; D002118:Calcium