L-Glutamate effects on electrical potentials of synaptic plasma membrane vesicles.
The electrogenic nature of the L-glutamate-stimulated Na+ flux was examined by measuring the distribution of the lipophilic anion [35S]thiocyanate (SCN-) into synaptic membrane vesicles that were incubated in a NaCl medium. Concentrations of L-glutamate from 10(-7) to 10(-4) M added to the incubation medium caused an enhanced intravesicular accumulation of SCN-. Based on the SCN- distribution in synaptic membrane vesicles it was calculated that 10 microM L-glutamate induced an average change in the membrane potential of + 13 mV. L-Glutamate enhanced both the Na+ and K+ conductance of these membranes as determined by increases in SCN- influx. Other neuroexcitatory amino acids and amino acid analogs (D-glutamate, L-aspartate, L-cysteine sulfinate, kainate, ibotenate, quisqualate, N-methyl-D-aspartate, and DL-homocysteate) also increased SCN- accumulation in synaptic membrane vesicles. These observations are indicative of the activation by L-glutamate and some of its analogs of excitatory amino acid receptor ion channel complexes in synaptic membranes.
D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D005971:Glutamates / Q000378:metabolism / Q000494:pharmacology*; D018698:Glutamic Acid; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013861:Thiocyanates / Q000378:metabolism
D005971:Glutamates; D013861:Thiocyanates; D018698:Glutamic Acid