Duodenogastric reflux in the fasting dog: role of pylorus and duodenal motility.

A two-marker technique was used to determine duodenogastric reflux in fasting dogs with normal or surgically modified gastroduodenal junctions. All nine dogs had an esophagostomy for gastric marker perfusion. The duodenal marker was given via a duodenal fistula. In two dogs a Heineke-Mikulicz pyloroplasty was performed, and in four dogs extramucosal circular pylorectomy was performed in addition. The mean fasting duodenogastric reflux rate in dogs with a normal pylorus was 1.1 +/- 0.5 (SE) ml/10 min; after pyloroplasty it was 1.6 +/- 0.3 ml/10 min (P greater than 0.1), and after pylorectomy it was 1.5 +/- 0.4 ml/10 min (P greater than 0.1). Simultaneous intraduodenal manometry revealed no relation between the interdigestive myoelectric complex and reflux. The marker technique for the measurement of reflux was validated by pharmacologically induced reflux. Subcutaneous injection of 0.1 mg of apomorphine increased the reflux rate tenfold. A transpyloric tube increased reflux rate fivefold. It is concluded that, in the fasting dog, phenomena such as retropulsive peristalsis are determinants of duodenogastric reflux and not the presence or absence of the pylorus and normal interdigestive motility.