Brain mitochondrial nitric oxide synthase: in vitro and in vivo inhibition by chlorpromazine.
Mouse brain mitochondria have a nitric oxide synthase (mtNOS) of 147 kDa that reacts with anti-nNOS antibodies and that shows an enzymatic activity of 0.31-0.48 nmol NO/min mg protein. Addition of chlorpromazine to brain submitochondrial membranes inhibited mtNOS activity (IC50 = 2.0 +/- 0.1 microM). Brain mitochondria isolated from chlorpromazine-treated mice (10 mg/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 (Nomega-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.
Lores-Arnaiz
Silvia
S
Laboratory of Free Radical Biology, School of Pharmacy and Biochemistry, University of Buenos Aires, Argentina. slarnaiz@ffyb.uba.ar
D'Amico
Gabriela
G
Czerniczyniec
Analía
A
Bustamante
Juanita
J
Boveris
Alberto
A
D000818:Animals; D001120:Arginine / Q000032:analysis; D001921:Brain / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002746:Chlorpromazine / Q000494:pharmacology*; D005260:Female; D006861:Hydrogen Peroxide / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology*; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D012119:Respiration / Q000187:drug effects
D009569:Nitric Oxide; D001120:Arginine; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D010100:Oxygen; D002746:Chlorpromazine