[Histochemical evidence of aminotransferases. VII. Quantitative histochemical and biochemical investigations of the amino-transferases of branched chain amino acids, glycine and serine in the rat organs during development (author's transl)].

Ontogenetic changes of the activity and isoenzymes of the aminotransferases of branched chain amino acids, glycine and serine in the rat organs have been studied by quantitative histochemical method and by electrophoresis. An increase of the enzymatic activity with the 3 branched chain amino acids has been observed up to the 7th day after birth. Thereafter the changes with leucine and isoleucine are rather similar. The intensity of the specific leucine aminotransferase isoenzymes in the liver and the brain gradually increase in the development. Despite this, the nonspecific isoenzymes are available only in the embryonic and early postnatal stages. Glycine- and serine aminotransferases show relatively similar pattern of activity and more prominent change between the 7th and 14th postnatal day. The variant pattern of the aminotransferase activity in the growing rats is discussed with regard to the metabolic, structural and hormonal changes in the development. The differences in the activity of one and the same aminotransferase or its isoenzymes in the organs are most probably related to the functional differentiation.