Evaluation of endothelial free radical release by vascular tension responses in insulin-resistant rat aorta.

Mechanical responses to superoxide anion scavengers and nitric oxide (NO) synthase inhibitors in aortic endothelial cells were compared in normal chow-fed rats and those made insulin-resistant by feeding of fructose. Cu(2+), Zn(2+)-superoxide dismutase-induced vascular relaxation and superoxide production, measured by the lucigenin-enhanced chemiluminescence method, were greater in aortas from fructose-fed rats than in those from normal chow-fed rats. N(G)-nitro-L-arginine-induced contractions due to suppression of NO synthase activity were smaller in aortas from fructose-fed rats. Vascular mechanical responses may reflect the generation of superoxide and NO by the endothelium. Thus, isometric tension studies may be a useful tool for evaluating the production of these radicals in blood vessels.