INHIBITION OF NITRIC-OXIDE SYNTHESIS INDUCES A SIGNIFICANT REDUCTION IN LOCAL CEREBRAL BLOOD-FLOW IN THE RAT

The effect of intravenous administration of N(G)-monomethyl-L-arginine (L-NMMA, 30 mg/kg), a specific inhibitor of nitric oxide synthesis, on local cerebral blood flow (lCBF) was examined in the rat using the [C-14]iodoantipyrine autoradiographic method. L-NMMA induced a statistically significant reduction in lCBF in the cerebral cortices as well as in various deep structures of the brain. This reduction in lCBF was accompanied by a clear increase in mean arterial blood pressure, suggesting that the cerebral resistance vessels constricted significantly beyond the autoregulatory response following L-NMMA administration. These findings indicate that the basal cerebral circulation may be closely related to nitric oxide production.