Facilitation and Inhibition by 5-Hydroxytryptamine and R 51 619 of Acetylcholine Release from Guinea Pig Myenteric Neurones
Electrophysiological (North et al., 1980) and neurochemical (Kilbinger and Pfeuffer-Friederich, 1982; Pfeuffer-Friederich and Kilbinger, 1983) experiments have shown that the cholinergic nerves of the guinea pig myenteric plexus are endowed with two types of 5-hydroxytryptamine (5-HT) receptors: 1. Exitatory receptors whose stimulation leads to an increased release of acetylcholine (ACh). This receptor is stimulated by 5-HT and by metoclopramide. It has been suggested that the increase by metoclopramide of smooth muscle contraction of the guinea pig ileum is related to the release of ACh (Kilbinger et al., 1982). 2. Inhibitory receptors whose activation by 5-HT or by LSD causes an inhibition of ACh release evoked by electrical stimulation of the myenteric plexus. The inhibitory receptor can be specifically blocked by methysergide and by methiothepine (Kilbinger and Pfeuffer-Friederich, 1982; Pfeuffer-Freiderich and Kilbinger, 1983).
KeywordsGastrointestinal Motility Myenteric Plexus Acetylcholine Release Field Stimulation Cholinergic Nerve
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