Gastric emptying of organic acids in the dog.

Test meals of 300 ml. of six different organic acids were instilled into the stomach of six healthy mongrel dogs. Citric, acetic, propionic, lactic, tartaric and succinic acid were given in 50, 100, 150, and 200 mN concentrations. 2. During the emptying process, the gastric contents were aspirated and immediately re-instilled at 10 min intervals, and the following parameters were recorded: volume, concentration of the organic anion, pH, hydrogen ion concentration and osmolarity. 3. By multiple stepwise regression analysis, the combination of parameters which most effectively determines gastric emptying rate was found to be: concentration of the organic anion, followed by intragastric volume and number of previous test meals given on the same day. These three parameters appear in the equation for gastric emptying rate in which the individual characteristic of each acid is expressed by a constant. 4. Among the various acids, inhibition of emptying rate increases with rising number of carboxylic groups of the acid and its molecular weight. 5. After proximal gastric vagotomy, emptying rate of organic acids is independent of volume, and emptying approaches an exponential pattern. 6. A model for gastric emptying of organic acids with at least three different receptors is proposed: one for the structure of the organic acid, one for concentration and one for intragastric volume.