Impaired nitric oxide production in coronary endothelial cells of the spontaneously diabetic BB rat is due to tetrahydrobiopterin deficiency

Biochem J. 2000 Jul 1;349(Pt 1):353-6. doi: 10.1042/0264-6021:3490353.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arginine / chemistry
  • Biopterin / analogs & derivatives*
  • Biopterin / deficiency*
  • Biopterin / metabolism*
  • Calcium / metabolism
  • Calmodulin / metabolism
  • Chromatography, High Pressure Liquid
  • Diabetes Mellitus / metabolism*
  • Diabetes Mellitus / pathology
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / metabolism
  • GTP Cyclohydrolase / metabolism
  • Immunoblotting
  • Kinetics
  • NADP / metabolism
  • Nitric Oxide / biosynthesis*
  • Nitric Oxide Synthase / metabolism
  • Nitric Oxide Synthase Type III
  • Protein Isoforms
  • Pteridines / pharmacology
  • Pterins*
  • Rats
  • Rats, Mutant Strains / metabolism*

Substances

  • Calmodulin
  • Protein Isoforms
  • Pteridines
  • Pterins
  • Biopterin
  • Nitric Oxide
  • NADP
  • Arginine
  • sepiapterin
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type III
  • Nos3 protein, rat
  • GTP Cyclohydrolase
  • sapropterin
  • Calcium