Figure 2.
Schematic of acid secretion. A: Classically defined pathway of acid secretion: Gastrin released from the G cell binds to receptors on the ECL cell causing histamine release from the ECL cell. The histamine binds to receptors on the parietal cell and stimulates proton efflux; B: Modified model of acid secretion involving a functional CaSR on the basolateral membrane of both the G cell and parietal cell. Acid secretion can be activated directly by the CaSR on the parietal cell or via the G cell pathway.