Kainate-induced uptake of calcium by synaptosomes from rat brain.

Kainic acid induces a rapid increase in 45Ca2+ uptake by crude synaptosomal fractions isolated from rat brain. This enhanced Ca2+ permeability occurs with a half-time of approx. 1 s, similar to the fast phase of depolarization-induced calcium uptake. The depolarization-induced uptake of calcium is inhibited 85% by 3 mM CoCl2, 80% by 100 microM quinacrine and 50% by 15 microM trifluoperazine while these agents had little effect on the kainate-induced uptake. It is proposed that kainate induces receptor-mediated opening of a class of calcium channels with properties different from those of the voltage-dependent channels.