Insulin-induced peroxynitrite production in human platelet-rich plasma

Abstract

Recent data support the possible role of nitric oxide (NO*) in the development of insulin signalling. The aim of this study was to examine the effect of insulin on NO* production by platelets. The chemiluminescence of platelet-rich plasma prepared from the blood of healthy volunteers was measured in the presence of luminol. Indirect detection of NO* by luminol is possible in the form of peroxynitrite produced in the reaction of NO* with a superoxide free radical. Luminol oxidation induced by hydroxyl free radical and lipid peroxidation was prevented by 150 micromol/l of desferrioxamine mesylate. Insulin, in the range of 0.084-840 nmol/l, induced a concentration-dependent increase in chemiluminescence, which was inhibited both by the competitive antagonist of the NO* synthase enzyme. N(omega)-nitro-L-arginine methyl ester (at concentrations of 2.0-4.0 mmol/l, P<0.001), and by the elimination of superoxide free radicals using superoxide dismutase (72-144 IU/ml, P<0.001). In conclusion, we assume that the insulin-induced increase in chemiluminescence of platelet-rich plasma was due to increased production of NO* and superoxide free radicals forming peroxynitrite. The data are consistent with production of peroxynitrite from human platelets under insulin stimulation.

Insulin Generates Free Radicals by an NAD(P)H, Phosphatidylinositol 3′-Kinase-Dependent Mechanism in Human Skin Fibroblasts Ex Vivo

“…Kashiwagi et al (12) indirectly showed that insulin treatment increases superoxide in rats. Their findings also supported the hypothesis of Facchini et al (25), in which age-associated oxidative stress is determined by hyperinsulinemia, and the findings of Wittman et al (26), in which human platelets generate peroxynitrites under insulin stimulation.…”

Mechanisms involved in platelet hyperactivation and platelet-endothelium interrelationships in diabetes mellitus

“…Wittmann et al [16] reported that incubation of platelet-rich plasma with insulin induces an increase of peroxynitrite formation, due to the reaction between NO and superoxide anion. In platelets, peroxynitrite inhibits cyclooxygenase via nitration of tyrosine residues, resulting in inhibition of thromboxane generation [17••]; thus, the insulin-induced increase of peroxynitrite could play a role in the insulin-induced reduction of platelet aggregation.…”