PHOSPHORUS METABOLISM OF THE ADRENAL GLAND OF THE RAT: EFFECT OF EXPOSURE TO A COLD ENVIRONMENT FOR EIGHT DAYS ON THE AMOUNTS AND P32-LABELLING OF PHOSPHOLIPID AND RIBONUCLEIC ACID
The incorporation of inorganic phosphate labelled with P32 into the lipid P and ribonucleotide P of the adrenal glands of rats exposed to cold (3 ± 1 °C.) for eight days was measured 16 hr. after the P32 injection. In the cold-exposed animals, there was a decrease in the specific activity of both the lipid P and the ribonucleotide P and also a decrease in the specific activity of the lipid P and the ribonucleotide P relative to that of the inorganic P of the adrenal. The cold exposure caused an increase in the amounts of lipid P, ribonucleic acid (RNA), and desoxyribonucleic acid (DNA) per pair of adrenals. There was an increase in the ratio lipid P: DNA-P, but no change in the ratio RNA-P: DNA-P. Calculation showed that the cold exposure caused a decrease in the percentage renewal rate of both lipid P and ribonucleotide P, most of which could be attributed to the increased amounts of lipid P and ribonucleotide P present at the beginning of the isotope experiment. However, when allowance for this was made by calculating the renewal rates of the P of the phospholipid and RNA per pair of adrenals, the values remained slightly less in the cold-exposed animals.