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 a nd 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 gastr ic emptying in response to distension of the duodenum. Methods: Studie s 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 pyl orus was excised and a further six pigs without any transection or res ection acted as controls. Motility of the antrum, pylorus and duodenum was recorded by a sleeve/side hole manometric catheter. Gastric empty ing was measured by drainage of the duodenum through a cannula. Result s: In control animals distension of the duodenum inhibited antro-pylor ic pressure waves (APPW), from 1.52 waves/min at minimum distension to 0.25/min at maximum distension (P = 0.0007), stimulated isolated pylo ric pressure waves (IPPW), from 0.56/min to 1.80/min (P = 0.034) and s lowed emptying of a 1000 mt load of 5% dextrose over 30 min from 788 m t to 251 mt (P = 0.0001). Duodenum transected animals did nor show the duodenal distension-induced stimulation 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 mt emptied) were unaltered. Similarly in pylorus-excised animals, duo denal distension inhibited APPW (maximum distension: 0.47/min) and slo wed liquid emptying (maximum distension: 267 mt), effects which did no t differ from control animals. Retardation of gastric emptying by duod enal distension may be due in part to inhibition of antral contraction s. Conclusions: Under the conditions of this experiment, increased pyl oric resistance to flow does not play a major role in the slowing of e mptying by duodenal distension, but the stimulation of the pylorus by duodenal distension depends on duodenal intramural neural pathways. Du odenal distension-induced feedback control of emptying is mediated pri marily via pathways other than ascending intraduodenal nerves.