LACK OF EFFECTS OF INHIBITION OF NITRIC-OXIDE SYNTHESIS ON LOCAL GLUCOSE-UTILIZATION IN THE RAT-BRAIN

The effects of chronic treatment with N-G-nitro-L-arginine methyl este r, a potent inhibitor of nitric oxide synthase activity, on local cere bral glucose utilization were examined in conscious rats. Intraperiton eal injections of 50 mg/kg of the nitroarginine twice daily for 4 days have been found to result in almost complete inhibition of nitric oxi de synthase activity in brain. Local cerebral glucose utilization was determined by means of the quantitative autoradiographic [C-14]deoxygl ucose method in an experimental group (n = 7) of rats that were treate d with the nitroarginine according to this schedule and in a normal co ntrol group (n = 7) treated similarly with saline. The rats were consc ious but partially restrained during the determinations of local cereb ral glucose utilization. The nitroarginine treatment raised mean arter ial blood pressure statistically significantly to 147 +/- 3 mm Hg (mea n +/- SEM) from a level of 120 +/- 5 mm Hg in the saline controls (p < 0.001 by grouped t test), but there were no statistically significant effects on glucose utilization in any of 39 brain structures examined . It is concluded that nitric oxide normally exerts no significant inf luence on energy metabolism in the rat brain.