The glycolytic activity of brain

Abstract

I. The effects of various conditions and substances on the glycolytic activity of macerated rat brain were studied. The influence of rat age, tissue dilution, composition of suspending medium and pH of the medium is described. Small amts. of lactic acid are formed from glycogen and no lactic acid from hexosediphosphate. Adeno-sinetriphosphate is a coenzyme in brain glycolysis; activation by glutathione is irregular. No phosphoric ester formation could be demonstrated with intact brain cells. Incubation of brain pulp at 37[degree]C in N2 or O2 in the absence of glucose inactivates the brain prep. Activity is partially restored by addition of adenosinetriphosphate and glutathione. Brain tissue is unable to dephosphorylate phosphopyruvic acid. The mechanism of glucose breakdown by brain is very different from that of glycogen breakdown by muscle. [long dash]II. Brain tissue loses irreversibly its glycolytic power if ground with sand, if frozen and thawed or if suspended in water. Cytolyzed brain added to muscle extract inhibits the glycolytic activity of the latter. It also inhibits the fermentation of yeast extract. The inhibitor is not amylase. Glycolysis or fermentation of intact cells is not inhibited by cytolysed brain. The inhibitor is sensitive to heat, does not diffuse through collodion membranes and has a pH optimum.