Duodenal control of gastric emptying in the milk-fed calf.

1. It has been ascertained experimentally that an open duodenal cannula does not cause any marked variation in emptying of the abomasum when compared to the rate of emptying of the normal viscus or when the cannulae are closed. 2. Duodenal re-entrant cannulae provide a preparation whereby it is possible to infuse the duodenum via the distal cannula and to collect simultaneously the effluent fluid of the abomasum from the proximal arm of the cannula (Fig. 1). 3. With this preparation the duodenal infusate is not contaminated by the gastric effluent and thus the duodenal stimulus can be restricted to the single non-varying effect of the infusate. 4. In the milk-fed calf using this preparation the following facts have been established. (a) On infusion into the duodenum, hypotonic and isotonic solutions of sodium chloride and sodium bicarbonate increase abomasal emptying; bicarbonate being the more effective stimulus. (b) Potassium chloride, calcium chloride, glucose and hydrochloric acid inhibit gastric emptying when infused into the duodenum. (c) Ammonium chloride, urea, lactose and acetic acid have little effect. (d) Hypertonic solutions of all substances tested were inhibitory to gastric emptying when infused into the duodenum. 5. It has been demonstrated unequivocally that it is the effect of the infusate in the duodenum which controls gastric emptying for when the stomach is isolated from the duodenum, gastric emptying can be manipulated from the duodenum whatever the stomach contents may be. 6. Our results bring firm experimental confirmation of the views discussed by Hunt & Knox (1968) that gastric outflow is regulated by mechanisms initiated from receptors situated in the duodenum.