The potassium-dependence of excitatory amino acid transport: resolution of a paradox.

Schwartz and Tachibana have claimed that the uptake of excitatory amino acids (EAAs) into glia is independent of intracellular potassium, in contradiction to the results of our previous studies. We show here that failure to observe the potassium-dependence of uptake resulted from the use of small whole-cell pipettes, which fail to dialyze properly the cell interior, and the use of D-aspartate instead of L-glutamate as the transported EAA, the uptake of D-aspartate being maintained down to lower levels of intracellular potassium than is the uptake of L-glutamate.