Purinergic Modulation of Hippocampal Acetylcholine Release Involves α-Dendrotoxin-Sensitive Potassium Channels |
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Authors: | Christina G Benishin |
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Institution: | Department of Physiology, Faculty of Medicine, University of Alberta, Edmonton, Canada. |
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Abstract: | Modulation of acetylcholine (ACh) release from superfused hippocampal slices was examined when the release of ACh was stimulated by exposure of slices to elevated K+ concentration. Evoked release was not sensitive to inhibition by 0.1 microM tetrodotoxin, but it could be inhibited in a dose-dependent manner by a muscarinic agonist (10-100 nM oxotremorine) and a purinergic agonist (10-100 nM 2-chloroadenosine). The alpha-dendrotoxin (100 nM), which selectively blocks voltage-gated inactivating K+ channels in nerve endings, did not affect the release of ACh under resting or depolarized conditions. However, alpha-dendrotoxin reduced the 2-chloroadenosine-induced inhibition of release, but did not alter the oxotremorine-induced inhibition. These results suggest that an alpha-dendrotoxin-sensitive K+ channel may be activated as an obligatory step in the modulation of ACh release by presynaptic purinergic receptor activation, but not in the modulation by presynaptic muscarinic receptors. |
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Keywords: | Acetylcholine Hippocampus Potassium channel α-Dendrotoxin 2-Chloroadenosine Oxotremorine |
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