The Effect of Pentagastrin on the Gastric Secretion by the Totally Isolated Vascularly Perfused Rat Stomach

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Abstract
Gastric acid and pepsin secretion by the totally isolated vascularly perfused rat stomach was studied. Rat stomachs were vascularly perfused with Krebs-Ringer buffer gassed with 96% O2-4% CO2 and containing 5 mM glucose, 5 mM pyruvate, 4% bovine serum albumin, 10% ovine erythrocytes, and various concentrations of pentagastrin. The gastric lumen was perfused with distilled water gassed with 100% 02. To remove preformed juice and to enable preformed pepsin to be washed out, the initial 20-min gastric juice was discarded. The gastric effluent was then collected continuously for six 10-min periods, and the H+ concentration was determined by titration and the pepsin concentration estimated by a hemoglobin digestion method. Inclusion of pentagastrin in the perfusion buffer increased the acid output dose-dependently from 2.3 ± 0.4 μeq/h during the control perfusion to a maximum of 12.7 ± 2.1 μeq/h (p < 0.01). With the higher doses of pentagastrin and concomitant high acid secretion, gastric acid secretion faded during the collection period. In contrast, gastric pepsin secretion was virtually unaffected by pentagastrin. The present model should be useful for studying the regulation of gastric acid and pepsin secretion.