SUMMARY This study confirms previous reports that satisfactory gastric acid secretory responses to intravenous administration of histamine, carbachol, and gastrin can be obtained.Bilateral castration of the male rats significantly reduced acid gastric secretory responses to carbachol but not to histamine.Ovariectomized rats treated with 1 7B-oestradiol (short-term treatment) showed a statistically significant reduction in gastric acid secretion induced with all the secretagogues, but the results when rats were treated with testosterone were inconsistent. In animals given gastrin or histamine gastric acid secretion was reduced and was of statistical significance with gastrin (0.02 < p < 0(05) but not with histamine (0.05 < p > 0.1).It is concluded that a high oestrogen blood level is capable of inhibiting effectively acid gastric secretion in both sexes except that a higher level of blood oestrogen is required in the male. Tite results showed further that of all the sex hormones used, only oestrogen had a significant effect on gastric acid secretion.It has long been recognized that peptic ulceration rarely occurs in human pregnancy. This has naturally focused attention on gastric secretory activ,ity during this period, and there have been reports of diminished secretion of pepsin and hydrochloric acid during pregnancy (

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Summary1. The amounts of crude gastrin extract and the gastrin activities of extracts from antral mucosa of several mammalian species have been determined. 2. The yield of crude gastrin powder per gramme wet weight of antral mucosa was greater in goats and rabbits than in cat, dog, man or pig. 3. Statistical differences do not appear to exist between the potencies of gastrin from the various species. The potencies of the powders were within the ranges 1X2-1 8 ,ug porcine gastrin 1I/mg with the exception of the extract from frozen dog antra (08 ug/mg). 4. During prolonged freezing of animal antra and consequent thawing before extraction, significant losses in gastrin activity occurred in the dog. 5. The amounts of gastrin activity per gramme wet weight of antral mucosa from herbivores (goat, rabbit and cattle) were greater than those from nonherbivores (cat, dog, man and pig). IntroductionThe isolation of the hormone gastrin, the elucidation of its structure and the more comprehensive characterization of its activities have now placed the endocrine function of some cells of the gastric antrum beyond doubt. The work in the Pavlovian School reported by Babkin (1928) and investigations of other workers have shown that meat extracts and some other constituents of food, stimulate the release of the antral hormone, thus the gastrin content of the antral mucosa may reflect the dietary habit of the animal. The present paper is concerned with a comparative study of the gastrin activity extracted from the antral mucosa of various mammals including carnivores (dog and cat), herbivores (cattle, rabbit and goat) and omnivores (hog and man).

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The log dose‐response curves for graded doses of the secretagogues porcine gastrin (a partially purified sample; the crude and its gastrin II equivalent), histamine, and a gastrin pentapeptide (pentagastrin) on the perfused stomachs of urethanized rats are parallel. On weight basis, pentagastrin is 60 times and histamine four times more active than the crude porcine gastrin preparation. The partially purified porcine gastrin sample is six times more potent than histamine but half as potent as pentagastrin. On molar basis gastrin (as the pure porcine gastrin II) has 3000 times the activity of histamine dihydrochloride and 5000 times that of the histamine base. Gastrin is 50 times more potent than pentagastrin. Gastrin and pentagastrin are more potent and have less undesirable side‐effects than histamine.