Actividad de la óxido nítrico sintasa mitocondrial de cerebro: efecto de la clorpromazina.

D´AMICO, G.; LORES ARNAIZ, S.; BUSTAMANTE, J. ; BOVERIS, A.

Los Cocos. Córdoba

Congreso; XVII Reunión Anual de la Sociedad Argentina de Neuroquímica; 2002

Sociedad Argentina de Neuroquímica

Nitric oxide (NO) is generated in mitochondria by mitochondria nitric oxide synthase (mtNOS), and exerts a regulatory function on mitochondrial respiration. The aim of this study was to determine enzymatic and functional brain mtNOS activity and to evaluate if modifications on NO metabolism could play a relevant role on pharmacological effect of the antipsychotic drug chlorpromazine (CPZ). Mice were injected with CPZ (10 mg/kg, i.p.) and after 1 hour we determined: NO and H2O2 production, oxygen consumption, and Western blot analysis in mitochondrial preparations. The in vitro effect was also determined. Brain mtNOS have a mtNOS (147 kDa) that reacts with anti nNOS antibodies and that shows an eznymatic activity of 0.48 nmol NO/min.mg protein. The activity has an optimal pH of 5.8. The direct supplementation of submitochondrial membranes with CPZ inhibited mtNOS (IC50 = 1 uM). Treated mice mitochondria showed an inhibition of 48% in mtNOS activity and an increase in metabolic state 3 respiration (30-40%). The oxygen consumption of mice brain mitochondria was decreased 6% by the addition of arginine and increased 30% by L-NNA, thus indicating the functional regulatory activity of mtNOS. The effects of arginine and L-NNA were less marked in mitochondria isolated from CPZ-treated animals (5-6%). Mitochondrial H2O2 production was not significantly affected by arginine but markedly (30%) decreased by L-NNA, this latter effect was absent in chlorpromazine-treated mice. Our results indicate that chlorpromazine is able to inhibit mtNOS activity and to modify the respiration and H2O2 mitochondrial production.