Presynaptic muscarinic receptors modulate acetylcholine release from rat antral mucosal/submucosal nerves.
The purpose of the present studies was to determine whether autoinhibition of acetylcholine release could be demonstrated in vitro from mucosal/submucosal neurons in rat antrum. Rat antral mucosal/submucosal tissues preloaded with [3H]choline were perifused and [3H]acetylcholine release measured under basal and stimulated conditions. Carbachol inhibited both spontaneous and evoked (electrical field stimulation, KCl) acetylcholine release from rat antral tissues: 1 x 10(-5) M carbachol inhibited basal [3H]ACh release maximally to -38.2 +/- 3.1% (P < 0.001 vs control). The nonselective muscarinic antagonist atropine enhanced both basal and stimulated acetylcholine release and abolished carbachol-induced inhibition of acetylcholine release. Pirenzepine, a muscarinic M1 receptor antagonist, inhibited acetylcholine release and did not alter carbachol-induced inhibition of acetylcholine release. In conclusion, acetylcholine release from rat antral mucosal/submucosal neurons is regulated negatively by a presynaptic feedback mechanism involving M2 and/or M3 receptors, while presynaptic M1 receptors facilitate release of neurotransmitter.
Ren
J
J
Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City 73126.
Harty
R F
RF
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005753:Gastric Mucosa / Q000294:innervation*; D066298:In Vitro Techniques; D008297:Male; D010890:Pirenzepine / Q000494:pharmacology; D011706:Pyloric Antrum / Q000294:innervation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000502:physiology*; D017661:Receptors, Presynaptic / Q000502:physiology*
D011976:Receptors, Muscarinic; D017661:Receptors, Presynaptic; D010890:Pirenzepine; D001285:Atropine; D002217:Carbachol; D000109:Acetylcholine