To-and-fro movements across the canine pylorus

A two marker technique was used to measure gastric emptying, duodenogastric reflux, and gastric volume secretion after intragastric instillation of a 300 ml liquid lipid meal in 11 dogs. The dogs either had an intact pylorus (n = 5), a Heineke -Mikulicz pyloroplasty (n = 3), or an extramucosal circular pylorectomy (n = 3). The mean gastric emptying rates in the three groups of dogs were 4.9 ml/min +/- 0.3 SEM, 5.7 +/- 0.2 (p less than 0.05), and 8.6 +/- 1.8 (p less than 0.01) respectively. The duodenogastric reflux rates were 0.7 ml/min +/- 0.2 SEM, 1.8 +/- 0.2 (p less than 0.05), and 3.2 +/- 1.0 (p less than 0.05), respectively. The gastric volume secretion did not significantly differ. Although emptying rates were higher in the dogs with surgically destroyed pylorus than in dogs with intact pylorus, the rate of disappearance of the test meal from the stomach was nearly identical in the three groups. This is due to the different degrees to-and-fro movements across the gastroduodenal junction. They amounted to 2.3 percent of the test meal +/- 1.0 SEM in dogs with intact pylorus, to 7.7 +/- 1.0 in dogs with pyloroplasty (p less than 0.05), and to 15.5 +/- 2.4 in dogs with pylorectomy (p less than 0.01). It is concluded that pyloroplasty and pylorectomy increase both gastric emptying and duodenogastric reflux rate. Simple assessment of the disappearance of a test meal from the stomach without measurement of to-and-fro movements cannot detect this effect on emptying rate. The pylorus keeps to-and-fro movements across the gastroduodenal junction at a low level.