High glucose inhibits expression of inducible and constitutive nitric oxide synthase in bovine aortic endothelial cells.
OBJECTIVE
To investigate the effects of high glucose on the expression of nitric-oxide synthase (NOS) in cultured bovine aortic endothelial cells (BAEC).


METHODS
BAEC were cultured and passaged in normal glucose (NG) 5.5 mmol.L-1, high glucose (HG) 25 mmol.L-1, or high osmolarity (glucose 5.5 mmol.L-1 + mannitol 19.5 mmol.L-1, Mann-BAEC), lipopolysaccharides (LPS)-induced nitric oxide (NO) production was assessed by Griess reaction. The expression of inducible NOS (iNOS) and constitutive NOS (ecNOS) was determined by Western blot.


RESULTS
At a concentration range from 0.5 to 2 mg.L-1, LPS stimulated NO production in NG-BAEC in a concentration-dependent manner. NO production reached the peak level at LPS 1 mg.L-1. HG inhibited NO production, when compared with NG- and Mann-BAEC (nitrite mumol.L-1: HG-BAEC 43 +/- 8, vs NG-BAEC 71 +/- 11, Mann-BAEC 70 +/- 9, n = 4 experiments, P < 0.01). iNOS expression was decreased by 39.9% and 39.3%, and ecNOS by 28% and 24% respectively in HG-BAEC, when compared with NG- or Mann-BAEC. However, no marked difference was observed in the LPS-induced NO production and the expression of iNOS and ecNOS between NG- and Mann-BAEC.


CONCLUSIONS
Inhibition of BAEC NO production by HG was mainly due to a decreased expression of NOS protein.
Guo
X
X
Laboratory of Molecular Pharmacology, Hu-nan Medical University, Changsha 410078, China.
Chen
L W
LW
Liu
W L
WL
Guo
Z G
ZG
D000818:Animals; D001011:Aorta; D002417:Cattle; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D005947:Glucose / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III
D008070:Lipopolysaccharides; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D005947:Glucose