Purinergic modulation of hippocampal acetylcholine release involves alpha-dendrotoxin-sensitive potassium channels.
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.
Benishin
C G
CG
Department of Physiology, Faculty of Medicine, University of Alberta, Edmonton, Canada.
D015762:2-Chloroadenosine / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D004546:Elapid Venoms / Q000494:pharmacology*; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology; D010095:Oxotremorine / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D011687:Purines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology
D004546:Elapid Venoms; D009498:Neurotoxins; D015221:Potassium Channels; D011687:Purines; D015762:2-Chloroadenosine; D013779:Tetrodotoxin; D010095:Oxotremorine; C020273:dendrotoxin; D000109:Acetylcholine