Choline is an inhibitory modulator of cholinergic nerve function in guinea-pig colon.
Using the novel smooth muscle-myenteric plexus (smmp) preparation from the guinea-pig colon, it has been possible to measure acetylcholine (ACh) overflow by a radiolabelling technique. The possibility that choline may be a modulator of cholinergic nerve activity in this preparation was investigated by observing its effects on electrically-evoked overflow of [3H]acetylcholine. Choline (72, 144 microM), in concentrations that did not contract the smmp preparation, caused a depression of electrically-evoked [3H]ACh overflow. This effect was unlikely to be due to actions on cholinesterase enzymes by end product inhibition. Choline also produced substantial non-muscarinic elevation of spontaneous [3H]overflow. It is concluded that inhibitory modulation of enteric cholinergic nerve activity by presynaptic muscarinic receptors may not be exclusively mediated by the actions of acetylcholine.
Trout
S J
SJ
Department of Pharmacology, London Hospital Medical College, UK.
Burleigh
D E
DE
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002794:Choline / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects / Q000294:innervation*; D004558:Electric Stimulation; D006168:Guinea Pigs; D066298:In Vitro Techniques; D010275:Parasympathetic Nervous System / Q000187:drug effects*
D001285:Atropine; D002794:Choline; D000109:Acetylcholine