To the Editor.—Recently Krasner and Yaffe1 reported observations on the development of GSH aryl-transferase activity in mouse liver during the neonatal period. They also tried to enhance such enzymatic activity in the newborn mouse by injecting phenobarbital and substrate (sulfobromophthalein [BSP]) into the mother at the end of the pregnancy.
Although they did not obtain activation, they did not exclude the possibility that such a result might have been achieved by employing other drugs under different experimental conditions. This possibility has already been investigated by us experimentally. We were able to demonstrate2,3 in the newborn rat, an animal which shows a developmental pattern for this enzyme very similar to that of the newborn mouse, that 3, 4-benzpyrene (1 mg intraperitoneally on the first and second day of life) and to a lesser degree hydrosoluble prednisolone (150μg/rat/day for three to five days) induced a significantly increase of enzymatic