Studies on brain metabolism

Abstract

The properties of a specific succinic dehydrogenase preparation from ox heart were studied in detail; a-glycerophosphate dehydrogenase has only 1/10 of the activity of this enzyme and a glutamic acid deaminase which is also present attacks only the non-natural isomeride. Succinic dehydrogenase is inhibited by [alpha]-ketoglutaric acid, pvocyanine and phenosafranine. The formation of succinic acid from pyruvic and [alpha]-ketoglutaric acids is demonstrated anaerobically with brain slices and with minced brain. Aerobically, in experiments with minced brain poisoned with malonic acid, pyruvic, a-ketoglutaric and, in some cases, acetic acids were found to yield succinic acid. Under the same conditions the R. Q. of ketoglutaric oxidation is raised, indicating a specific inhibition of succinic dehydrogenase of roughly 50%. Malonic acid does not lead to succinic acid accumulation with brain slices, and with mince only if used in certain concentrations. Small amounts of a volatile acid, probably acetic acid, are formed from pyruvic acid by minced brain.