THE MEMBRANE-RECRUITMENT-AND-RECYCLING HYPOTHESIS OF GASTRIC HCL SECRETION

In the unstimulated oxyntic (or parietal) cell, the primary pump for g astric HCl secretion, the H+/K+-ATPase, is retained within the cytopla sm in a membranous compartment of tubulovesicles. Neural or hormonal s timulation of acid secretion induces extensive membrane transformation s consistent with a fusion and recruitment of tubulovesicles to the ap ical plasma membrane. The consequent placement of H+/K+-ATPase in para llel with K+ and Cl- channels provides the necessary ionic flow and AT P-driven exchange for Met HCl secretion. Current evidence is consisten t with a recruitment and recycling of membrane transporters, such as H +/K+-ATPase, through docking/fusion machinery analogous to that in man y other systems.