N-ACETYLCYSTEINE INCREASES THE GLUTATHIONE CONTENT AND PROTECTS RAT ALVEOLAR TYPE-II CELLS AGAINST PARAQUAT-INDUCED CYTOTOXICITY

A protective effect of N-acetylcysteine in oxidative lung damage was r eported by a number of workers; however, the mechanism underlying this effect was not thoroughly elucidated. The present research investigat es the protection by N-acetylcysteine against paraquat-induced cytotox icity to alveolar type II cells, which are known to be specific target s of paraquat toxicity in vivo. We found that addition of 1 mM N-acety lcysteine to alveolar type II cells incubated with 1 mM paraquat reduc ed the cytotoxic index from 17.4 +/- 1.3% to 9.3 +/- 1.5%. This effect could not be explained by the interference of N-acetylcysteine with t he active uptake of paraquat by type II cells. Incubation of these cel ls with N-acetylcysteine enhances their glutathione content, thus redu cing the paraquat-induced depletion of glutathione in these cells. The se results suggest that N-acetylcysteine exerts its protective effect by acting as a precursor for glutathione in alveolar type II cells.