Ozone interaction with rodent lung: effect on sulfhydryls and sulfhydryl-containing enzyme activities.

Abstract

Exposure of rats or rat lung homogenates to 2 ppM O/sub 3/ reduced total, protein, and non-protein sulfhydryl fractions in a dose-related fashion. The non-protein fraction was more susceptible to O/sub 3/ attack. Chronic O/sub 3/ exposure (0.8 ppM, 10 days) had no effect. Activities of SH-containing enzymes, glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD), in lung tissue decreased 10 to 15 and 30%, respectively, after 6 to 8 h exposure to 2 ppM O/sub 3/. In vitro exposure (2 to 3 ppM) led to reductions of 20 and 67%. Activities of cytochrome C reductases decreased 20% after acute exposure but increased 20% after chronic. Chronic exposure increased SH-generating enzyme, G6PD, activity in lung tissue 32% but had little effect on GR activity. Lipid peroxidation (as possible mechanism for SH oxidation) not affected by in vivo exposure but was increased almost 100% in vitro. G6PD activity signals hexose-monophosphate shunt pathway for NADPH production. This pathway is also active in various other diseases (e.g., toxic liver injury).