CARDIAC-ARREST INDUCES DECREASE OF NITRIC-OXIDE SYNTHASE ACTIVITY ANDINCREASE OF FREE-RADICAL GENERATION IN RAT-BRAIN REGIONS

Rats were subjected to 15 min cardiac arrest and sacrificed 1 h or 15- 20 days after resuscitation. Homogenates of brain regions were assayed for nitric oxide synthase (NOS) activity (by measuring the mononitros yl iron complex of NO with diethyl dithiocarbamate and endogenous brai n Fe2+ using electron spin resonance spectroscopy) and generation of f ree radicals (FRG; by measuring H2O2-induced, luminol-dependent chemil uminescence). Cardiac arrest induced marked decrease of NOS activity a nd the increase of FRG, most prominent in cerebellum and less marked i n cerebral cortex. Two groups of rats were revealed 15-20 days after c ardiac arrest: with NOS activity significantly lower than control and not different from control. Positive linear inter-regional cross-corre lations of both NOS activity and FRG (except of the group 1 h after re suscitation) as well as negative correlations between NOS and FRG were demonstrated. (C) 1996 Elsevier Science Ireland Ltd.