Ontogenesis of rat liver microsomal glutathione transferase.

The ontogenesis of rat liver microsomal glutathione transferase was investigated by activity measurements and immunochemical methods. The activity rises from a very low level (3% of adults) at day 8 pre-partum to adult levels at days 50-150. Increases are associated with the neonatal and late-suckling clusters. Interestingly the capacity to become activated by N-ethylmaleimide is much lower in females early and late in life (days 35-100 and 300-550). After the initial increases (from 10% of adult levels at day 8 pre-partum), protein levels determined immunochemically remain constant throughout life with no apparent sex differences. The developmental pattern of microsomal glutathione transferase resembles those of other drug-metabolizing enzymes indicating that the function of the enzyme is required in adult life.