A new technique for the analysis of phasic gastric acid responses in the unanesthetized rat.

A chronically indwelling gastric fistula was implanted into rats. To collect gastric acid, a collection system was coupled to the fistula. This system operated by infusing physiological saline directly into the stomach of unanesthetized rats; the acid content of the perfusate was immediately determined by automatic titration machinery. Using this technique, a value of 3.25 uEq H+/2 minutes was obtained as the basal gastric secretion. For a sham-fed test meal of 2 ml of 36% sucrose, the stimulated phase of gastric acid secretion consisted of a dynamic response (peak 200% of basal) with a brief latency (< 2 minutes) and short duration (< 24 minutes). Results indicated that this response to sham feeding was a cephalic response, since direct infusion of a similar test meal into the stomach did not alter basal gastric acid output. Experience with the perfusion-collection technique indicated that the procedure was a sensitive nondisruptive method for chronic gastric acid collection from unanesthetized animals.