Calcium-dependent stimulation of acetylcholine release by substance P and vasoactive intestinal polypeptide

In the guinea-pig myenteric plexus-longitudinal muscle preparation from the small intestine, the release of acetylcholine evoked by substance P and vasoactive intestinal polypeptide was examined in vitro. Both neuropeptides stimulated efflux of [3H]acetylcholine from myenteric neurons in a calcium-dependent manner. This observation is consistent with the view that neurotransmitter release elicited by neuropeptides requires the presence of extracellular calcium ions.