The role of histamine receptors in the pathophysiology of gastric mucosal damage.

In four canine Heidenhain pouches the net fluxes of H+ and Na+ have been examined before, during, and after instillation of sodium taurocholate into the pouch. These experiments were conducted in animals given H1 (mepyramine maleate) and H2 (metiamide) histamine antagonists, alone and in combination. Control experiments without antagonists were also conducted. In control experiments, as well as in those using the histamine antagonists separately, the usual sequence of events followed exposure to taurocholate-that is, a gain in the volume of the solution in the pouch and an increase in the fluxes of Na+ and H+ across the mucosa. In experiments in which H1 and H2 histamine antagonists were used in combination, taurocholate had very little effect on the ionic fluxes of H+ and Na+, suggesting that changes in the ionic permeability of the gastric mucosal barrier are mediated by histamine through both H1 and H2 receptor sites.