DOSES OF HISTAMINE PRODUCING MINIMAL AND MAXIMAL GASTRIC SECRETORY RESPONSES IN DOG AND MAN

Abstract

The histamine doses which produced minimal and maximal gastric secretory responses in the dog were established, and the threshold value was obtained in the human. The minimal doses were similar in intact and in vagotomized total pouch dogs, whether histamine was admd. by periodic subcut. or continuous intraven. injn. Maximal doses were also similar in pouch and intact dogs by either method of injn. These results indicate that va-gotomy does not alter the gastric secretory response to histamine in the dog, and that after subcut. injn. no histamine is inactivated during its absorption from the subcut. tissues into the blood. The max. secretory response that could be elicited by histamine was very similar in intact dogs and in dogs with vagally denervated pouches of the entire stomach. It amounted, on the avg., to 80 ml. per hr. with a total acid concn. of 140 m.Eq. per liter. Humans are much more sensitive to histamine than dogs; acid responses were obtained with an avg. dose of 0.004 micrograms of base per kg/min., or about 10% of the dose necessary to produce a minimal response in the dog. The parietal cell appears to be the most sensitive to histamine of any in the intact body, although it is possible that this sensitivity may be equalled at times by that of the cerebral vessels. The characteristics of the gastric response to histamine, the possible mode of action by the drug to cause gastric secretion, and the evidence bearing upon the possible role of histamine as a physiol. stimulant of gastric secretion are discussed.