Effect of phenobarbital on the expression of glutathione <i>S</i>‐transferase isoenzymes in cultured rat hepatocytes

Abstract

Cultured adult rat hepatocytes were treated daily with 3.2 mM phenobarbital (PB) in order to study its effect on the expression of cytosolic glutathione S-transferase isoenzymes. Glutathione S-transferase (GST) activities, using 1-chloro-2,4-dinitrobenzene and 1,2-dichloro-4-nitrobenzene as substrates, were increased when PB was present in the culture medium. After purification and separation of GST on glutathione Sepharose 6 B and reversed-phase HPLC, respectively, it was observed in vitro that PB caused an increase in the relative amounts of subunits 1, 3 and 7 compared to subunits 2 and 4. Using Northern blot technique, elevated levels of GST subunit 1/2 and 7 mRNA were measured, after addition of PB to the cultures.