Localization of ClC-2Cl(-) channels in rabbit gastric mucosa

HCl secretion across the parietal cell apical secretory membrane involves t he H+-K+-ATPase, the ClC-2 Cl- channel, and a K+ channel. In the present st udy, the cellular and subcellular distribution of ClC-2 mRNA and protein wa s determined in the rabbit gastric mucosa and in isolated gastric glands. C lC-2 mRNA was localized to parietal cells by in situ hybridization and by d irect in situ RT-PCR. By immunoperoxidase microscopy, ClC-2 protein was con centrated in parietal cells. Immunofluorescent confocal microscopy suggeste d that the ClC-2 was localized to the secretory canalicular membrane of sti mulated parietal cells and to intracellular structures of resting parietal cells. Immunogold electron microscopy confirmed that ClC-2 is in the secret ory canalicular membrane of stimulated cells and in tubulovesicles of resti ng parietal cells. These findings, together with previous functional charac terization of the native and recombinant channel, strongly indicate that Cl C-2 is the Cl- channel, which together with the H+-K+-ATPase and a K+ chann el, results in HCl secretion across the parietal cell secretory membrane.