HISTAMINE has been a standard stimulant of gastric secretion for the past four decades, but its effect on the output of gastric pepsin is still controversial. Babkin1 concluded that histamine stimulates only the parietal cells whose secretions then serve to wash out preformed pepsin. Other studies have given evidence that histamine is either a true stimulant of pepsin secretion,2,3 or that it inhibits pepsin output,4 or that it does neither.1,5,6 Hirschowitz7 has suggested that the main confusion is caused by species differences: men, monkeys, frogs, and mice secrete pepsin following histamine, but cats and dogs do not.8 Hirschowitz has stated that the administration of histamine to dogs does not stimulate9 and may inhibit8 the secretion of pepsin.
In a study of the responses of various denervated canine gastric pouches to graded stimuli, we were surprised to find that histamine-stimulated pepsin secretion at the