[Carboxylation intensity in the liver of birds of different ages]

Carboxylation intensity was studied in the liver of young and adult cocks, 14C-bi-carbonate was used as an indicator of the amino acids, proteins and lipids turnover. It is established that the amount of dry residue in the liver tissue of the adult cocks is 22% higher and that of pyruvate and dicarboxylic amino acids is twice as low. The relative weight of the liver changes with age: in the 18-month-old cocks it is 1.5%, in the one-month-old cocks, 2.75%. The maximum of 14C incorporation into the tissue, dicarboxylic compounds, proteins and lipids of young cocks in the in vivo experiments is at a shorter exposure of the isotope. 14C removal from these compounds in the young cocks occurs more quickly as well. A higher radioactivity of the compounds under study in the adult cocks liver with prolongation of the isotope exposure is due to the effect of factors which are not related to the synthesis. The experiments established that radioactivity of proteins and lipids in the young cock liver slices is 6 times as high at 60-minute exposure. The mentioned above evidences for a higher rate of carboxylation in young cocks as compared to adult ones. When interpreting the data of metabolism study by means of isotopes in animals of different age a corrections should be made for a change in the liver relative weight during the growth process.