Brain mitochondrial nitric oxide synthase: in vitro and in vivo inhibition by chlorpromazine

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

ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS

ELSEVIER SCIENCE INC

Año: 2004 vol. 430 p. 170 - 177

0003-9861

Mouse brain mitochondria have a nitric oxide synthase (mtNOS) of 147kDa that reacts with anti-nNOS antibodies and that shows an enzymatic activity of 0.31–0.48nmol NO/minmg protein. Addition of chlorpromazine to brain submitochondrial membranes inhibited mtNOS activity (IC50 = 2.0 ± 0.1 lM). Brain mitochondria isolated from chlorpromazine-treated mice (10mg/kg, i.p.) show a marked (48%) inhibition of mtNOS activity and a markedly increased state 3 respiration (40 and 29% with malate–glutamate and succinate as substrates, respectively). Respiration of mitochondria isolated from control mice was 16% decreased by arginine and 56% increased by NNA (Nx-nitro-L-arginine) indicating a regulatory activity of mtNOS and NO on mitochondrial respiration. Similarly, mitochondrial H2O2 production was 55% decreased by NNA. The effect of NNA on mitochondrial respiration and H2O2 production was significantly lower in chlorpromazine-added mitochondria and absent in mitochondria isolated from chlorpromazine-treated mice. Results indicate that chlorpromazine inhibits brain mtNOS activity in vitro and can exert the same action in vivo.