Dehydrogenations by brain tissue. The effects of narcotics

Abstract

In brains of men, sheep, and ox the Michaelis constants were detd. for a number of substrates. Velocity-conc. curves all show maxima, above which increase of conc. leads to decreased reduction velocities. Grey matter was 3-4 times as active as white matter. Fresh brain tissue activated glucose, fructose, galactose, and mannitol as H donators. Na lactate, Na glycerophosphate, Na succinate and Na pyruvate were all more active than glucose or fructose. Storage of brain suspensions at 0[degree] or at 37[degree] resulted in a slow inactivation of the dehy-drogenases. When brain tissue was exposed to narcotics, there was an elimination of the activation of the sugars, while those of Na succinate and glycerophosphate were not markedly affected. The narcotic did not inactivate the lactic dehydrogenase irreversibly but its inhibiting action was dependent on the conc. of lactic acid present.