A HISTOCHEMICAL STUDY OF ADENOSINE TRIPHOSPHATASE IN THE TOAD (BUFO SPINULOSUS) GASTRIC MUCOSA

Adenosine triphosphatase (ATPase) activity was studied by histochemical methods in the gastric mucosa of Bufo spinulosus. Two types of activity were established. One is activated by Mg ++ , and is localized mainly at the intercellular boundaries and the basal zone of the oxyntic-peptic cells; the reaction products are found only on the outer side of the cells. The other is activated by HCO 3 – and is mainly localized at the microvilli at the apical zone of the oxyntic-peptic cells. The intensity and/or distribution of the reactions are influenced by histamine stimulation. Control experiments demonstrated that: the microsomal fraction of gastric mucosa contained a Mg ++ -requiring ATPase activity which was enhanced by addition of HCO 3 – ; 25% of the ATPase activity of fresh tissue was maintained after fixation and incubation in presence of lead ion; the medium employed in the histochemical studies did not enhance the lead-catalyzed, nonenzymatic hydrolysis of ATP by more than 20% when compared with spontaneous ATP hydrolysis; and incubation in media with different ATP-Pb ratios did not significantly alter the location of the staining.