Secretory behaviour and histamine formation in the rat Heidenhain pouch following antrectomy.

1. In conscious rats provided with a Heidenhain pouch, the changes in the secretion of acid and pepsin following antrectomy were investigated in the interdigestive state and in response to graded doses of intravenous hog gastrin II and methacholine. The change in mucosal histamine formation (histamine-forming capacity, HFC, i.e. histidine decarboxylase activity) was determined in the fasting state in the Heidenhain pouch following antrectomy.2. Antrectomy was followed by a substantial reduction in the interdigestive secretion of acid.3. Methacholine infusion when the antrum was intact evoked a maximal acid secretory response that exceeded twice the response obtained with gastrin.4. After resection of the antrum the acid response to graded doses of methacholine and to gastrin at maximal but not at submaximal dose levels was significantly reduced.5. After antrectomy, threshold or submaximal infusion of gastrin accentuated the acid secretory responses to methacholine, but did not restore the maximal secretory response to methacholine obtained before antrectomy.6. The changes in pepsin secretion following antrectomy were similar to those in acid secretion but smaller.7. Mucosal HFC of the pouch was significantly lowered following antrectomy.8. After antrectomy gastrin failed to accelerate histamine formation in the mucosa in the usual way.