[Platelet aggregation in modulation of the pathway L-arginine-NO in rats with cerebral ischemia]

Platelet aggregation in the plasma of rats with brain ischemia and modulation of L-arginine-NO pathway were studied in experiments (Born method using analyzer AP 21103AO SOLAR). We used L-arginine and inhibitors of NO-synthase: nonselective inhibitor Nomega-nitro-L-arginine methyl ester, selective inhibitors of neuronal NO-synthase-7-nitro-indazole and selective inhibitor of inducible NO-synthase-S-methylisothiourea. We found that an increase in platelet aggregation in rat plasma observed in both periods is mediated via NO: in an early period of brain ischemia it depends on neuronal NO-synthase and in a late period--on inducible NO-synthase. Moreover, a nonselective inhibitor of all isoforms of NO-synthase (including endothelial NO-synthase) Nomega-nitro-L-arginine methyl ester possesses proaggregant properties. On the other hand, L-arginine in combination with 7-nitro-indazole and S-methylisothiourea induces maximal antiaggregatory effect. These data allows us to suppose that endothelium-derived NO decreases platelet aggregation in brain ischemia-reperfusion in rats.