Time course of lung oxidative metabolism after exposure to ambient particles

MAGNANI, NATALIA; MARCHINI, TIMOTEO; TASAT, DEBORAH; ALVAREZ, SILVIA; EVELSON, PABLO

Santiago de Chile, Chile

Congreso; VI Meeting of the Society for Free Radical Biology and Medicine South American Group; 2009

Society for Free Radical Biology and Medicine South American Group

 Several studies suggest that oxidative stress may be involved in the mechanism of disease initiation and progression following the inhalation of ambient particles. The aim of this work was to study the time course of oxidative metabolism in lung mice after exposure to residual oil fly ash (ROFA). Swiss mice weighing 25 g, were intranasally instilled with a ROFA suspension (0.20 mg/kg). Measurements were made 1 and 3 h after the exposure. Instillation with ROFA increased oxygen consumption by tissue cubes by 77% in lung after 1 h (control value: 56 ± 2 ng-at O/min mg tissue, p< 0.005). NO production by lung homogenates was increased by 43% (control value: 0.74 ± 0.03 nmol NO/min.mg prot, p< 0.005) after 3 h of exposure. TBARS levels in lung homogenates showed a 29% increase after 1 h of exposure (control value: 249 ± 5 pmol/mg prot; p< 0.005), while a 30% increase in the carbonyl content was found after 3 h (control value: 2.3 ± 0.1 pmol/mg prot; p< 0.005). A 26% increase in superoxide dismutase activity was found in lung homogenates after 3 h of exposure (control group: 4.3 ± 0.2 U SOD/ mg prot, p< 0.005). The average TRAP values after 3 h of exposure decreased, by 40%, when compared with the control group (control value: 15 ± 1 ìM Trolox/mg prot; p< 0.005). Instillation with ROFA significantly increased mitochondrial oxygen consumption in state 3 (active respiration) and NADPH oxidase activity by 20%, after 1 h. Inhalation of ambient particles may induce oxidative and nitrosative stress, with macrophage activation and oxidative damage to macromolecules and consumption of low molecular weight antioxidants.