ROLE OF ANTRAL INTRAMURAL NEURAL PATHWAYS IN CONTROL OF GASTRIC-EMPTYING IN THE PIG

1. The role of antral intramural pathways in the control of antropylor ic motility and gastric emptying was evaluated in five conscious pigs equipped with chronic gastric and duodenal cannulae. Neural pathways w ere divided by transection and re-anastomosis of the antrum 2 cm proxi mal to the pylorus. Concurrent measurements of gastric emptying, trans pyloric flow and antropyloric motility were performed before and 6 wee ks after surgery. 2. Antral transection retarded gastric emptying, onl y 36% of 1000 mi saline being emptied in 30 min compared with 62% befo re transection. Transection did not alter the number of transpyloric f low pulses (22.0 +/- 4.0 cf. 24.4 +/- 3.2 pre-transection), but reduce d (P < 0.01)the volume of flow pulses substantially (8.6 +/- 0.4 cf. 1 8.7 +/- 1.5 ml pre-transection). 3. Antral transection was associated with a reduction in the rate of distal antral pressure waves (P < 0.05 ), but no alteration in the rate of phasic low level pressurization of the entire gastric content by gastric contractions (gastric common ca vity pressure waves). However, transection was associated with a signi ficant (P < 0.05) shortening of the interval between the onset of gast ric common cavity pressure waves, and the onset of lumen-occlusive pyl oric pressure waves generated by the same contraction sequence (3.2 +/ - 0.3 cf. 7.9 +/- 0.6 s). 4. Transection did not alter the inhibition of antral pressure waves, stimulation of localized pyloric pressure wa ves, and retardation of gastric emptying produced by infusion of 25% d extrose into the duodenum. 5. These studies suggest that antral intram ural nerves regulate the emptying of liquids from the stomach by modul ating the timing of pyloric closure in relation to phasic gastric antr al and corpus contractions. 6. Distal antral intramural neural pathway s do not appear to play a major role in the suppression of antral moto r activity produced by duodenal glucoreceptors.