Role of nitric oxide/cyclic guanosine monophosphate pathway in regulation of endothelial endostatin release under high-concentration glucose

Abstract

Objective To study the role of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway in regulation of endothelial endostatin release under high-concentration glucose. Methods Human umbilical vein endothelial cell (HUVEC) was cultured in DMEM media for 72 h with 5.6, 11.2, and 22.4 mmol/L glucose, respectively. The expression of endostatin protein was determined by Western blot and the level of NO in the supernatant of cell culture was measured by nitrate-reductase method. Those HUVECs incubated with 11.2 mmol/L glucose for 72 h were stimulated by NG-nitro-L-arginine methyl ester (L-NAME), sodium nitroprusside (SNP) and 1H-[1, 2, 4]-oxadiazole-[4, 3-a]-quinoxalin-1-one (ODQ), respectively. Western blot was used to determine endostatin protein expression in 4 groups. One-way analysis of variance and q test were used for data analysis. Results The level of endostatin protein expression and NO concentration in HUVECs were increased in a glucose-dependent manner. In comparison with the control group, endostatin protein expression was decreased in the L-NAME and ODQ group (33.5% and 43.7%; q values were -6.38 and -5.93, respectively; both P<0.01), although an increased level of endostatin protein expression was observed in the SNP group (129.0%; q=-3.89, P<0.05). Conclusions The endostatin protein expression was increased in a glucose-dependent manner. Nitric oxide/cGMP pathway may play a role in modulating endothelial endostatin release. Key words: Glucose; Endothelial cells; Endostatins; Nitric oxide