Reflex suppression of gastric motility during laparotomy and gastroduodenal nociceptive stimulation

The effects on gastric motility of laparotomy or of nociceptive stimuli directed to the antro-duodenal area were studied in anaesthetized cats. A diathermic lesion of the duodenal or gastric antral wall induced pronounced gastric relaxation, which could either fade off within 0.5--1.5 h or persist for several hours. This gastric relaxatory response persisted after administration of antiadrenergic and anticholinergic drugs but was eliminated by vagotomy or cold blockade of the vagi. Vagotomy performed during the relaxed gastric state after diathermy immediately resulted in a more or less complete recovery of gastric tone. Blunt mechanical stimulation of the duodenum also caused a prompt gastric relaxation, which showed the same characteristics as the response to diathermy as regards the effects of nerve-blocking drugs and vagotomy. The laparotomy incision per se caused temporary inhibition of rhythmic gastric contraction, but this effect was largely abolished if atropine or guanethidine had been given. It is concluded that nociceptive stimuli against the gastric or duodenal wall induce, besides a sympathoadrenergic reflex inhibition of gastric motility, a profound long-lasting gastric relaxation via a reflex activation of the vagal nonadrenergic inhibitory fibres. This vagally mediated relaxation of the stomach is likely to contribute to the suppression of gastric motility seen in 'paralytic ileus'.