Response of the Chronic Gastric Fistula Rat to Histamine

Abstract

The preparation of chronic gastric fistula rats, their care and how they may be used for physiological and pharmacological studies on gastric secretion is described. The rat has a large interdigestive secretion and secretes free acid (pH 4.5) after 48–72 hours of fasting. For controlled studies this requires the replacement of fluid and chlorides. Statistically significant differences between the control output of acid and the response to 1 mg of histamine diphosphate were obtained. The threshold dose of the diphosphate is approximately 0.1 for a 350-gm rat. The least amount of histamine diphosphate to yield an average maximum output of acid (10 mg/hr.) is 0.5 mg subcutaneously every 15 minutes. The body dose of histamine required to stimulate gastric secretion is about the same in man, dog, cat and the rat. On the basis of body weight, the amount of histamine base required to yield a maximum output of acid in the rat is 34.6 µg/kg/min. as compared with 1.6 µg/kg/min. in the dog.