THE RATE OF GLUCONEOGENESIS AND THE ACTIV ITY OF ITS KEY ENZYMES IN THE CHICK-EMBRYO KIDNEYS

The rate of glucose formation from lactate was studied in tubules isol ated from the kidneys of chick embryos of different age and for one- a nd two-day old chickens. Changes in the activity of the key enzymes of gluconeogenesis have also been followed in the chick embryo kidneys. The rate of gluconeogenesis markedly increased after hatching. Changes in the rate of gluconeogenesis during embryogenesis are correlated wi th those in the activity of key enzymes of this process: phospho(enol) pyruvate carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-ph osphatase. Glucose-6-phosphatase was shown to be polyfunctional in the kidneys of chick embryos and chickens: in addition to hydrolysis of g lucose-6-phosphate with formation of glucose, the enzyme is capable of phosphorylating glucose with the help of phosphate donors, carbamyl-p hosphate and pyrophosphate.