Kinetics of utilization in vivo of glucose carbon in the chick cerebral hemispheres during postnatal growth

Abstract

1. 1. The incorporation of glucose carbon in vivo into glucose, amino acids and carboxylic acids in the cerebral hemispheres was studied during post-hatching growth of the chick after subcutaneous injection of [U- 14C]glucose, the animals being decapitated at different times after the injection. 2. 2. The highest rate of incorporation of glucose carbon into the tissue free amino acids occurs between 10 hr and 4 days after hatching. 3. 3. At hatching time, glutamic acid as well as neutral amino acids account for 40% of the whole radioactivity in the amino acid fraction. On the 30th day of postnatal growth, the % of radioactivity in glutamic acid (56%) is higher than that in the neutral amino acids (23%), which is a characteristic of the metabolism in cerebral hemispheres of adult chicks. 4. 4. Studies of the evolution of cerebral glucose concentration during the postnatal growth show an increasing rate between 10 and 48 hr after hatching. 5. 5. On the 2nd, 4th and 30th days of postnatal growth aspartate and glutamate have approximately the same specific radioactivity. On the other hand, at 10 hr after hatching, the specific radioactivity of cerebral aspartate is always higher than that of glutamate. 6. 6. At 10 hr after hatching, the specific radioactivity of cerebral α-alanine is always considerably higher than that of other amino acids. On the 30th day of postnatal growth, and at 10 min after the injection of [U- 14C]glucose, the specific radioactivity of α-alanine is higher than that of other amino acids; afterwards, from 10 to 60 min after the injection of labelled glucose, the specific radioactivity of α-alanine decreases and its value tends towards zero.