Cimetidine increases the pancreatic response to histamine.

The effects of histamine alone and histamine plus cimetidine on basal pancreatic exocrine secretion were determined in anaesthetized rabbits with an acute pancreatic cannula. Intravenous histamine administration (0.2-0.8 n mol/kg/min) increased pancreatic enzyme secretion. A much greater stimulative effect on pancreatic secretion was observed when histamine was administered against a constant background of H2 antagonist (cimetidine 4 mumol/kg/min). The results indicate that in the rabbit pancreas the stimulatory effect of histamine is mediated by H1 receptors.