Function of K+–Cl− Cotransporters in the Acid Secretory Mechanism of Gastric Parietal Cells

Gastric proton pump (H+, K+-ATPase) secretes H+ of acid (HCl) via the luminal membrane of parietal cells. For the HCl secretion, Cl−- and K+-transporting proteins are required. Recent our studies have demonstrated that K+–Cl− cotransporters (KCC3a and KCC4) are expressed in gastric parietal cells. KCC3a is associated with Na+, K+-ATPase in the basolateral membrane, and KCC4 is associated with H+, K+-ATPase in the apical canalicular membrane. This paper summarizes the functional association between KCCs and P-type ATPases and the contribution of these complexes to acid secretion in gastric parietal cells.