Gastric relaxatory response to feeding before and after vagotomy

Experiments were performed on 4 non-anaesthetized dogs with chronic gastric fistulae. Gastric tonus was studied by volume and inflow rate recording at low pressure heads. Gastric tonus was not affected by propranolol or phentolamine. It was markedly reduced by atropine, presumably by blocking excitatory cholinergic nervous activity. Guanethidine induced a marked increase of gastric tonus, presumably by inhibiting sympathetic modulating activity on intramural cholinergic ganglia. Feeding was accompanied by a marked gastric relaxation which was not blocked by any of the drugs mentioned. Vagotomy, however, entirely abolished the gastric relaxatory response to feeding. The findings suggest that gastric receptive relaxation accompanying feeding is mediated via specific relaxatory vagal nerve fibres, which are non-adrenergic and non-cholinergic.