N-ACETYLCYSTEINE PROTECTS CHINESE-HAMSTER OVARY (CHO) CELLS FROM LEAD-INDUCED OXIDATIVE STRESS

In vitro administration of lead acetate (PbA) to cultures of Chinese h amster ovary (CHO) cells had a concentration-dependent inhibitory effe ct on colony formation. Colony formation was returned to control level s in lead-treated cultures that were supplemented with 1 mM N-acetylcy steine (NAC), a well-documented synthetic antioxidant. In order to inv estigate the nature of NAC's protective effect, we measured L-gamma-gl utamyl-L-cysteinylglycine (GSH), oxidized glutathione (GSSG), malondia ldehyde (MDA) and catalase activity both in the presence and absence o f NAC in lead-exposed CHO cells. Increases in both MDA levels (P < 0.0 5) and catalase activity (P < 0.05) were observed in cultures that rec eived only PbA, but supplementation with NAC returned these measures t o pretreatment levels. The ratio of GSH to GSSG increased in lead-expo sed cells incubated in NAC-enhanced media, but declined in cultures tr eated with PbA only. Our results suggest that NAC can confer protectio n against lead-induced oxidative stress to CHO cells, possibly through the enhancement of the cell's own antioxidant defense mechanisms.