Histamine stimulation of digestive enzyme secretion by in vitro rabbit pancreas

Histamine (10(-3) M) was found to stimulate pancreatic enzyme secretion from in vitro isolated rabbit pancreas preparations. Histamine produced a peak and then a sustained stimulated secretory rate. Secretion of amylase, lipase, trypsinogen, chymotrypsinogen, and total radio active protein were all found to be stimulated. Although fluid output was slightly increased by histamine, enzyme concentrations in secretion were elevated. This, along with the observed sustained release rate, rules out washout effects. Histamine produced a significant response at 10(-5) M with ED50 being about 3 x 10(-5) M and maximal responses produced by 10(-3) M. Histamine stimulation can be blocked with mepyramine (10(-4) or 10(-5) M) or mepyramine in combination with cimetidine. The observed behavior of the pancreas suggests a similarity with pepsinogen secretion in the stomach.