Investigation on the effects of diamide on NO production in vascular endothelial cells (VEC)

Nitric oxide (NO) controls several physiological functions of the cardiovascular system. The study on the effect of diamide (N₂H₄·H₂O) on NO production in vascular endothelial cells (VEC) may provide significant reference for VEC’s modeling in studying cardiovascular diseases. The objective of this study was to elucidate how high concentration diamide (V_diamide/V_{culture miedium}=5 ml/l) and low concentration diamide (V_diamide/V_{culture miedium}=0.5 ml/l) affect NO production in a human endothelial cell line (ECV304). After cells were incubated with diamide (5 or 0.5 ml/l) for 4, 6, 8 or 10 h, respectively, the amounts of NO metabolites released by the cells were quantitated and the degree of damage of VEC was observed using microscope. The results showed that NO production in VEC tended to decrease with the lapse of time in the 0.5 ml/l diamide group. In the 5 ml/l diamide group, on the contrary, NO production in VEC tended to increase with the lapse of time. At the same time, from the morphologic observation, the VEC were damaged severely after treated with 5ml/l diamide. So it could be concluded that the severe damage induced by high concentration diamide would have triggered the express of inducible nitric oxide synthases (iNOS). Just for the expresssion of iNOS, NO production in VEC treated with high concentration diamide occurred abnormally in contrast to the 0.5 ml/l group.