THE INFLUENCE OF DRUGS AND POTASSIUM ON RESPIRATION AND POTASSIUM ACCUMULATION BY BRAIN TISSUE

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Abstract
When brain cortex slices in which the potassium content has been reduced by cold-pretreatment are incubated aerobically at 38° in a potassium-free glucose-containing medium, addition to the medium of 3.6 mM potassium causes an increase of the oxygen uptake rate (15) accompanied by a reaccumulation of potassium in the tissue and an approximately equal extrusion of sodium. In the absence of added substrate or in a sodium-free medium, little potassium is reaccumulated in the tissue and no increase of the oxygen uptake rate is observed. Malonate (1 mM), pentobarbital (0.5 mM), and protamine (100 μg per ml), which decrease the potassium uptake, and phenobarbital (0.5 mM), chlorpromazine (0.01 mM), atropine (1 mM), and procaine (0.1 mM), which have no effect on potassium uptake, suppress the stimulatory action of 3.6 mM potassium on respiration and markedly reduce the large stimulatory effect of 60 mM potassium. Protoveratrine (0.001 mM) and 2,4-dinitrophenol (0.05 mM) also exert little or no effect on the non-stimulated respiration, but when they are added with potassium (3.6 mM) the respiration is increased more than by potassium alone. When protoveratrine is added before potassium, it depresses the potassium uptake and suppresses the stimulatory action of potassium on respiration. Interrelations of the actions of drugs and potassium are discussed and the similarities between the biochemical actions of diverse agents are noted.