Effect of oleic acid on canine gastroduodenal motility, pyloric diameter and gastric emptying.

The motility of the antrum, duodenum and pylorus was recorded with strain gauge transducers and induction coils in conscious beagle dogs. The effect of oleic acid on gastroduodenal motility and on the pyloric diameter was studied in the interdigestive state and during emptying of a mashed potato meal. The flow of digesta was observed fluoroscopically. Gastric emptying was measured by planimetry of the radiopaque gastric silhouette. The intraduodenal injection of oleic acid reduced the diameter of the pylorus in the empty stomach. In the digestive state oleic acid diminished gastric emptying of the potato meal. The antral motility was significantly diminished (amplitudes from 100 +/- 39.2 to 93 +/- 41.2 mV, contractile frequency from 4.3 +/- 0.6 to 3.8 +/- 1.5 min-1, motility index from 435 +/- 197 to 345 +/- 213 V, n = 3400-4700 contractions), whereas the duodenal motility was enhanced (amplitudes from 100 +/- 49.6 to 106 +/- 58.6 mV, motility index from 548 +/- 296 to 567 +/- 377 V, n = 5800-6400 contractions). The diameter of the pyloric opening during the phase of relaxation was about 25% less in comparison to the control meal. The weaker antral contractions and the less opening of the pylorus diminished gastric evacuation and enhanced retropulsion of the gastric chyme. A higher incidence of segmental duodenal contractions produced a slower transfer of digesta. Results demonstrated that gastric emptying was regulated by several co-operating factors. The pylorus was involved by producing different resistances to flow during its phase of relaxation.