HYDROXYLATION OF SALICYLATE IN LUNGS OF FISCHER-344 RATS - EFFECTS OFAGING AND OZONE EXPOSURE

The formation of 2,3-dihydroxybenzoic acid (DHBA) from salicylate was measured in the lungs and plasma to assay for the . OH in juvenile (2 mo), adult (9 mo), and senescent (24 mo) Fischer 344 male rats exposed to clean air, 1 part/million (ppm) ozone, or 2 ppm ozone for 2 h. Sim ilar rates of distribution of salicylic acid in plasma and to the lung s were observed among air control animals of all age groups. Levels of 2,3-DHBA were about twice as high in the lungs of air control senesce nt rats compared with juvenile and adult rats (P < 0.05). Exposure to ozone resulted in 1.5- to 2-fold elevation of 2,3-DHBA in lungs and pl asma of all age groups (P < 0.05), whereas levels of 2,5-DHBA were not changed significantly. There was no effect of age on the magnitude of 2,3-DHBA increase in the lungs or plasma after ozone exposure. The po stulated source of OH is chemical reduction of H2O2, which could be ge nerated from increased age-dependent endogenous oxidant production or the age-independent reaction of ozone or macrophage-derived oxidants w ith the surfactant lining.