COMPARATIVE-STUDY OF THE CONTROL OF BASAL ACID OUTPUT FROM RODENT ISOLATED STOMACHS

1 Isolated, lumen-perfused, whole stomach preparations from mouse and immature rat produced a stable basal acid output which. although not b locked by histamine H-2-, acetylcholine M- or CCK(B)/gastrin receptor antagonists, was almostly completely blocked by the H+/K+-ATPase inhib itor, omeprazole, and the metabolic inhibitor, sodium thiocyanate (NaS CN). 2 Fully-defined concentration-effect curves could be obtained on both assays with the phosphodiesterase inhibitor, isobutyl methylxanth ine (IBMX) and with dibutyryl cyclic AMP. 3 On the rat stomach assay, histamine H-2-receptor blockade had no effect on the IBMX curve. In co ntrast, the IBMX response in the mouse was abolished by histamine H-2- receptor blockade. On both assays responses to dibutyryl cyclic AMP we re resistant to H-2-receptor blockade. 4 In the absence of suprathresh old endogenous histamine, it is argued that H+/K+-ATPase mediated basa l acid secretion from the mouse stomach assay is regulated by somethin g other than cyclic AMP.