No abstract

Male, pathogen-free Fischer 344 rats aged 6 and 24 mo were exposed to 1.5 or 3.0 ppm for 8 h and recovery rates of diphosphonucleotides (NAD+ and NADH) and triphosphonucleotides (NADP+ and NADPH) were measured and compared to controls. Recovery after 0.5 ppm was not examined because no significant changes occurred in either age group after this lower exposure. At zero time (immediately after exposures) both concentrations are depressed in adults and aged animals except for NADH in aged animals at 3.0 ppm; NADP+ in adults at 1.5 and 3.0 ppm was decreased, but not significantly. For NAD+ and NADH, recovery of whole lung concentrations is complete by 24 h following an 8-h exposure to 1.5 or 3.0 ppm of ozone. Only after 3.0 ppm of ozone was the ratio of the reduced to oxidized form (NADH/NAD+) still elevated after 24 h; however, it also returned to control levels by 96 h. For the triphosphonucleotides, an 8-h exposure to 1.5 ppm of ozone resulted in a sustained depression of whole lung concentrations of NADPH throughout the 96-h recovery period. Also, only after the 1.5 ppm exposure was the reduced to oxidized ratio (NADPH/NADP+) significantly depressed throughout the 96-h recovery period. Unexpectedly, recovery of whole lung levels returned to normal within 24 h after the 8-h exposure to both the 1.5 and the 3.0 ppm concentrations. With the exception of the sustained effect on NADPH levels, these data indicate that di- and triphosphonucleotide concentrations rapidly return to normal in the lung after severe, acute oxidant injury. There were no differences in recovery rates between the adult and the aged groups.

Bioenergetics of isolated lung and heart mitochondria from adult and aged rats were examined in the presence of glutamate (NAD-linked substrate) or succinate + rotenone (FAD-linked substrate) following ozone exposure (3.0 ppm, 8 hr). In controls, several differences were observed between adults and aged in both organ preparations. Following exposure, all bioenergetic parameters were decreased significantly in lung preparations from both adult and aged rats. In heart mitochondria, the respiration rates in state 3 and in uncoupled state, and the ADP/O ratio were decreased significantly in both exposed age groups. The respiratory control ratio (RCR) was decreased significantly only in the aged exposed rats. These results suggest that acute exposure to high levels of ozone alters energy production in both lung and heart mitochondria of adult and aged rats.

No abstract

1. During investigation of microsomal xenobiotic N-demethylation in the presence of ascorbic acid, large increases in apparent enzymic activity were observed. 2. Examination of incubation components indicated that a non-enzymic interaction between ascorbic acid and Tris buffer, in the presence of acetylacetone and ammonium acetate (Nash reagent), was occurring. 3. The resulting chromophore had an absorption maximum at 412 nm that coincided with the absorption for the chromophore resulting from the interaction of the Nash reagent with the product (formaldehyde) of the enzymic reaction. 4. Strict controls of ascorbic acid potential chemical interaction with incubation components are required in enzymic studies.