Gap junctional channels regulate acid secretion in the mammalian gastric gland

Gap junction channels are regarded as a primary pathway for intercellular message transfer, including calcium wave propagation. Our study identified two gap junctional proteins, connexin26 and connexin32, in rat gastric glands by RT-PCR, Western blot analysis, and immunofluorescence. We demonstrated a potential physiological role of the gap junctional channels in the acid secretory process using the calcium indicator fluo-3, and microinjection of Lucifer Yellow. Application of gastrin (10^-7 M) to the basolateral membrane resulted in the induction of uniphasic calcium signals in adjacent parietal cells. In addition, single parietal cell microinjections in intact glands with the cell-impermeant dye Lucifer Yellow resulted in a transfer of dye from the injected cell to the adjacent parietal cell following gastrin stimulation, demonstrating gastrin-induced cell-to-cell communication. Both calcium wave propagation and Lucifer Yellow transfer were blocked by the gap junction inhibitor 18α-glycyrrhetinic acid. Our studies demonstrate that functional gap junction channels in gastric glands provide an effective means for rapid cell-to-cell communication and allow for the rapid onset of acid secretion.