Contributions to the Study of Brain Metabolism

Abstract

IN the course of some previous-experiments dealing with the carbohydrate metabolism of the brain [Holmes and Holmes, 1925, 1, 2], we observed that the lactic acid content of rabbits' brains showed little or no increase when the tissue was chopped and allowed to stand at room temperature, or was incubated, under anaerobic conditions. This appeared to be the case at PH 7-6, 8-2, 8-4 and 9 0. In similar circumstances, tissues such as muscle or liver might be expected to show a lactic acid production substantially above the "resting" value, with a corresponding diminution in lactic acid precursor. We further observed that there was no diminution in the " soluble carbohydrate " of brain after the organ had been allowed to stand for 24 hours at room temperature. Since brain tissue readily forms lactic acid from added glucose in these con- ditions, we deduced that the substances estimated in the extracts did not include glucose. We were subsequently able to show [1926] that the reducing substances which we estimated were largely, if not wholly, creatine and creatinine.