Enhancement of long-term potentiation by the calcium channel agonist Bayer K8644 in CA1 of the rat hippocampus in vitro

The effect of the Ca agonist BAY K8644 was studied on long-term potentiation (LTP) of extracellular excitatory postsynaptic potentials in the stratum radiatum of CA₁ of the hippocampus in vitro. LTP was evoked by brief trains of high-frequency stimulation applied to the stratum radiatum of CA₁. 0.5% Ethanol, the vehicle used to dissolve BAY K8644, reduced LTP from 43% to 15%. An amount of 15 μM BAY K8644, in 0.5% ethanol, enhanced LTP from 13% in the ethanol control to 57%. The Ca channel antagonist verapamil did not alter control LTP, but did inhibit the potentiating action of BAY K8644 on LTP. It is postulated that the enhancement of LTP by BAY K8644 may occur through enhancement of Ca influx through voltage-dependent Ca channels.