Glutamate, calcium ion-chelating agents and the sodium and potassium ion contents of tissues from the brain.
1. Salts of l-glutamate added to cerebral tissues maintained in glucose-saline-bicarbonate solutions cause the Na(+) content of the tissues to increase rapidly and K(+) to be lost. Entry of (22)Na(+) also is accelerated by l-glutamate and this acceleration is inhibited by low concentrations of tetrodotoxin. 2. Tissue Na(+) content and its rate of increase after the addition of l-glutamate are affected by the Ca(2+) of incubation media. 3. Very rapid and extensive entry of Na(+) to the tissue is caused by EDTA, and a moderate entry by citrate and ATP. Calculations of the concentration of free Ca(2+) in media after these additions indicate that Na(+) entry is sometimes associated with low Ca(2+) concentration, but that other substances, especially l-glutamate, act without greatly diminishing Ca(2+) concentration. 4. Experiments with 2,4-dinitrophenol and valinomycin are also reported and aspects of the Na(+) entry formulated and discussed.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001923:Brain Chemistry / Q000187:drug effects*; D002118:Calcium; D002614:Chelating Agents / Q000494:pharmacology*; D002951:Citrates / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D011188:Potassium / Q000032:analysis*; D012964:Sodium / Q000032:analysis*; D013779:Tetrodotoxin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002614:Chelating Agents; D002951:Citrates; D004140:Dinitrophenols; D005971:Glutamates; D013779:Tetrodotoxin; D000255:Adenosine Triphosphate; D004492:Edetic Acid; D012964:Sodium; D011188:Potassium; D002118:Calcium