Lysosomal hydrolase activities in the developing rat liver.

The specific activity of three lysosomal proteinases (cathepsins B1, D, and L) as well as acid phosphatase and beta-galactosidase has been determined in the liver of both 7-10 day-old and young adult rats. Cathepsin B1 in suckling rats is markedly lower than in adults, while cathepsin D is only moderately lower and cathepsin L does not significantly differ. The activity of acid phosphatase is similar in the two groups of animals whereas that of beta-galactosidase in suckling rats is approx. twice as high as in adults. The activity of lysosomal hydrolases thus appears to be regulated individually during the development. Moreover it is suggested that the low activity of cathepsin B1 may be related to the low rate of cell protein catabolism characteristic of the developing liver (Conde and Scornik, 1977).