INCREASED HISTAMINE‐OUTPUT FROM THE ISOLATED GASTRIC MUCOSA OF THE RAT IN RESPONSE TO PENTAGASTRIN AND METHACHOLINE

Abstract

A rat isolated gastric mucosal preparation was used to monitor histamine output and acid secretion during stimulation by different secretagogues. In non‐stimulated preparations, spontaneous histamine output decreased over 450 min. Stimulation of secretion with 4(5)‐methylhistamine or dibutyryl cyclic adenosine 3′,5′‐monophosphate (db cyclic AMP) and theophylline did not influence histamine output. Pentagastrin, gastrin and methacholine increased both acid secretion and histamine output. Pentagastrin and gastrin mobilized six times more histamine in relation to acid secretion than did methacholine. Spontaneous histamine output and secretagogue‐induced increases were unaffected by changes in external Ca 2+ (0.0 to 7.2 m m ) or Mg 2+ (1.2 to 4.8 m m ). These results support the hypothesis that mucosal histamine plays a more important role in the action of gastrin than of cholinomimetics on the parietal cell.