Gastric acid and pepsin hypersecretion in conscious rabbits

In conscious, gastric fistula rabbits, gastric acid and pepsin secretion averaged 4.5 +/- 0.1 mmol/h (1.3 mmol.kg-1.h-1) and 4.9 +/- 0.3 IU/h (1.6 IU.kg-1.h-1), respectively; these values represent approximately 40-50% of maximal output. Basal serum gastrin concentrations averaged 24 +/- 4 pg/ml and did not correlate with basal acid secretion. Atropine and vagotomy incompletely inhibited basal acid secretion (by 84 and 50%, respectively) and completely inhibited 2-deoxy-D-glucose-stimulated gastric acid secretion. Atropine and vagotomy similarly inhibited basal pepsin secretion by 50 and 40%, respectively. Ranitidine decreased acid and pepsin secretion, but as with atropine, inhibition was not complete (73 and 37%, respectively). Although omeprazole did not affect pepsin secretion, omeprazole completely inhibited basal acid secretion and elevated postprandial intragastric pH above 5.0. Conscious, gastric fistula rabbits have the highest basal acid and pepsin output among species commonly studied. Both vagal-cholinergic pathways and histamine drive basal acid and pepsin secretion in the rabbit.