During gastric secretory studies in dogs designed to test the effect of cross-transfusion of a proposed antral chalone, we noted inhibition of gastric secretion following intravenous administration of heparin(1).The following experiments were designed to study the effect of this inhibition on gastric secretion stimulated by food (antral phase) and by histamine.Materials and methods. Thirteen adult female mongrel dogs weighing approximately 20 kg were used in this study. Denervated pouches of the gastric fundus (Heidenhain) were prepared in the usual fashion, and a stainless steel cannula was used to drain the pouch to the outside. During the 30 or more days which elapsed between the operation and onset of testing, the dogs were trained in the Pavlov stand. The animals were fasted for 18 or more hours prior to testing. In all studies, gastric pouch secretion was measured every 30 minutes and the acidity determined by using Topfer's reagent, titrating with N/10 NaOH. Specimens of less than 1 cc were discard...