The phosphorus metabolism of the brain

Abstract

Abstract The metabolism of the brain in vivo has been studied by measuring the rate of uptake of radioactive phosphorus into the different phosphorus-containing fractions of the mouse brain. By the use of specific-activity ratios referred to the acid-soluble fraction of the brain, satisfactorily constant values were obtained for the uptake into the nucleoprotein and phospholipid fractions in normal animals. The observed ratios indicated a relatively high metabolic activity for these fractions under normal conditions in vivo. The uptake of radioactive phosphorus into the nucleoprotein and phospholipid fractions of the brain was decreased in sodium pentobarbital anaesthesia; the effect was greater if the body temperature was also allowed to fall. Electrically induced convulsions and insulin hypoglycaemia caused a significant decrease in the uptake of radioactive phosphorus into the brain phospholipids without a corresponding change in the nucleoprotein fraction. A similar specific effect on the phospholipid metabolism was observed under normal physiological conditions in animals exposed for 3 hr. in a rotating drum. The effect was absent in animals which had previously been conditioned to the rotating drum. The results give evidence that the metabolism of the permanent or ‘structural’ elements of nervous tissue, as well as of the more labile metabolites, may vary in vivo with the state of functional activity of the brain.