Influence of cholinergic stimulation on gastric secretory response to histamine in ex vivo isolated canine stomach

Totally isolated canine stomach, included into a perfusion system containing a living “supporting” dog, serving as an oxygenator, is able to secrete juice rich in H⁺ for several hours. Blood circulating in this system is homologous blood and the stomach may be stimulated by intraarterial continuous infusion of a secretion stimulant. The ex vivo preparation was used for the study of secretion stimulated by histamine and/or bethanechol chloride, a stable cholinergic drug. All combinations of histamine plus bethanechol chloride used in this study gave higher outputs of HCl and pepsin than could be accounted for on the basis of summation of stimulatory effects. Outputs of HCl and pepsin were higher when two agents were given together than the maximal output of either HCl or pepsin during stimulation by one agent. Potentiation with regard to acid and pepsin secretion was evident when a cholinergic drug, in various doses, was superimposed on histamine stimulation.