[The role of the chemosensory systems in the inhibitory regulation of cholinergic transmission in the small intestine].

The double bath method has been used to study reflex inhibition of cholinergic transmission in the guinea-pig ileum segment. It is shown that adenosine, noradrenaline, 5-methylfurmethide as well as acute hypoxia, which affect the oral part of the intestine are able to evoke two kinds of effects in its anal part firstly, the depression of cholinergic transmission, and secondly, the stimulation of non-adrenergic, non-cholinergic contractions. A preliminary treatment with capsaicin and with hexamethonium on the oral part of the gut prevents these effects, and the chymotrypsin abolishes these effects. A mechanism of this reflex descending inhibition of cholinergic transmission is realised apparently through the stimulation of the chemoreceptors in afferent capsaicin-sensitive nerves with participation of cholinergic interneurons and activation of the inhibitory, most probably vasoactive intestinal peptidergic (VIP) neurons in the enteric plexuses.