Glutathione S-transferase activities in placentas from smoking and non-smoking women.

1. Microsomal mono-oxygenase activity toward 7-ethoxyresoryfin, and cytosolic glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene were determined in 53 placentas obtained at delivery from smoking and non-smoking women. 2. Whereas mono-oxygenase activity was clearly stimulated in placentas from women who smoked, no parallel enhancement of glutathione S-transferase activity was evident. 3. This disparity in response could result in imbalance among placental detoxication systems following exposure to certain compounds.