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.