Glutamate, calcium ion-chelating agents and the sodium and potassium ion contents of tissues from the brain

摘要

p1. Salts of l-glutamate added to cerebral tissues maintained in glucose–saline–bicarbonate solutions cause the Nasup+/sup content of the tissues to increase rapidly and Ksup+/sup to be lost. Entry of sup22/supNasup+/sup also is accelerated by l-glutamate and this acceleration is inhibited by low concentrations of tetrodotoxin. 2. Tissue Nasup+/sup content and its rate of increase after the addition of l-glutamate are affected by the Casup2+/sup of incubation media. 3. Very rapid and extensive entry of Nasup+/sup to the tissue is caused by EDTA, and a moderate entry by citrate and ATP. Calculations of the concentration of free Casup2+/sup in media after these additions indicate that Nasup+/sup entry is sometimes associated with low Casup2+/sup concentration, but that other substances, especially l-glutamate, act without greatly diminishing Casup2+/sup concentration. 4. Experiments with 2,4-dinitrophenol and valinomycin are also reported and aspects of the Nasup+/sup entry formulated and discussed./p