The gastrin-like pentapeptide I.C.I. 50 123 was found to be a more effective stimulant of gastric secretion in man than histamine and to produce a maximal acid output in humans at 1.2 µg./kg./hr. by constant intravenous infusion or 6 µg./kg. by subcutaneous injection.
Atropine administration or vagotomy with pyloroplasty reduced the response to pentapeptide about twice as much as it did the response to histamine, suggesting that cholinergic innervation plays an important role in the effect of pentapeptide on gastric secretion.
The gastric secretory test with pentapeptide has an obvious advantage over all previously used secretory methods insofar as it provides a reproducible, safe, and physiological stimulant to examine the capacity of the human stomach to secrete acid.
The author is indebted to Dr. J. D. Fitzgerald for the gift of pentapeptide (I.C.I. 50 123).