Aims: Pharmacological inhibition of phosphoinositol 3 kinase (PI3K) and partial deficiency of phosphoinositide dependent kinase PDK1 have previously been shown to enhance basal gastric acid secretion. PI3K/PDK1 dependent signaling involves activation of protein kinase B/AKT, which may thus be similarly involved in the regulation of gastric acid secretion. The present study explored the involvement of PKB/Akt2 in the regulation of gastric acid secretion. Methods: BCECF fluorescence has been employed to determine Na⁺ independent pH recovery from an ammonium pulse, a measure of K⁺/H⁺ activity. Experiments were performed in isolated glands from gene targeted mice lacking functional Akt2 (akt2^-/-) or from their wild type littermates (akt2^+/+). Results: Cytosolic pH in isolated gastric glands was similar in akt2^-/- and akt2^+/+ mice. Na⁺-independent pH recovery (DpH/min) following an ammonium pulse, a measure of H⁺/K⁺ ATPase activity, was, however, significantly faster in akt2^-/- than in akt2^+/+ mice. In both genotypes, DpH/min was virtually abolished by H⁺/K⁺ ATPase inhibitor omeprazole (100 mM). Increase of extracellular K⁺ concentrations to 35 mM (replacing Na⁺) significantly increased DpH/min to a larger extent in akt2^+/+ than in akt2^-/- mice and dissipated the differences between the genotypes. Similarly, treatment with 5mM forskolin enhanced DpH/min significantly only in akt2^+/+ mice and abolished the differences between the genotypes. Conversely, protein kinase A inhibitor H89 (50 nM) decreased DpH/min to similarly low values in both genotypes. Conclusion: Akt2 suppresses gastric acid secretion and contributes to or even accounts for the inhibition of gastric acid secretion by PI3K.