On the mechanism of enhanced release of [14C]glutamate in hippocampal long-term potentiation.

K+-induced release of [14C]glutamate was studied in slices of dentate gyrus prepared from control rats and rats in which long-term potentiation (LTP) had been induced in vivo. At all concentrations of Ca2+ studied, release from potentiated slices was greater than from control slices. In the same preparations both Ruthenium Red and caffeine enhanced basal release but in potentiated tissue the Ruthenium Red-induced release was significantly greater than in control tissue. These results are discussed in the light of our recent finding that enhanced transmitter release is associated with LTP.