Inhibition of apamin-sensitive calcium dependent potassium channels facilitate the induction of long-term potentiation in the CA1 region of rat hippocampus in vitro

Using field potential recording in the CA1-region of rat hippocampal slices we investigated the effect of apamin; a specific antagonist of small conductive calcium activated potassium channels on long-term potentiation (LTP). The experiments revealed that LTP of excitatory postsynaptic potentials induced by a single 100 Hz tetanization was intensified by extracellular application of apamin in a concentration range of 1-200 nM. No effects of apamin on LTP induced by triple 100 Hz tetanization were seen. We conclude that the positive modulation of LTP by apamin is effective in a nanomolar concentration range and dependent upon the employed tetanization. Because it has been shown that apamin-binding sites are affected by learning disorders including Alzheimer's disease, our finding suggests that changes in the sensitivity to apamin may result in memory disorders. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.