The effect of duodenal distension upon antro-pyloric motility and liquid gastric emptying in pigs.

BACKGROUND

This study has investigated first the role of the antrum and pylorus in the retardation of gastric emptying during distension of the duodenum, and second whether ascending duodenal intramural nerves contribute to control of both antro-pyloric motility and liquid gastric emptying in response to distension of the duodenum.

METHODS

Studies were performed on 18 pigs. In six the duodenum was transected 1-2 cm distal to the pylorus, to interrupt intramural nerves, in six the pylorus was excised and a further six pigs without any transection or resection acted as controls. Motility of the antrum, pylorus and duodenum was recorded by a sleeve/side hole manometric catheter. Gastric emptying was measured by drainage of the duodenum through a cannula.

RESULTS

In control animals distension of the duodenum inhibited antro-pyloric pressure waves (APPW), from 1.52 waves/min at minimum distension to 0.25/min at maximum distension (P=0.0007), stimulated isolated pyloric pressure waves (IPPW), from 0.56/min to 1.80/min (P=0.034) and slowed emptying of a 1000 mL load of 5% dextrose over 30 min from 788 mL to 251 mL (P=0.0001). Duodenum transected animals did not show the duodenal distension-induced stimulations of IPPW (maximum distension: 0.93/min), but both the distension-induced inhibition of APPW (maximum distension: 0.85/min) and slowing of emptying (maximum distension: 52 mL emptied) were unaltered. Similarly in pylorus-excised animals, duodenal distension inhibited APPW (maximum distension: 0.47/min) and slowed liquid emptying (maximum distension: 267 mL), effects which did not differ from control animals. Retardation of gastric emptying by duodenal distension may be due in part to inhibition of antral contractions.

CONCLUSIONS

Under the conditions of this experiment, increased pyloric resistance to flow does not play a major role in the slowing of emptying by duodenal distension, but the stimulation of the pylorus by duodenal distension depends on duodenal intramural neural pathways. Duodenal distension-induced feedback control of emptying is mediated primarily via pathways other than ascending intraduodenal nerves.