INHIBITION OF APAMIN-SENSITIVE CALCIUM-DEPENDENT POTASSIUM CHANNELS FACILITATE THE INDUCTION OF LONG-TERM POTENTIATION IN THE CA1 REGION OFRAT HIPPOCAMPUS IN-VITRO

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