Gap junctional coupling modulates secretion of exocrine pancreas.

Dispersed pancreatic acini were studied to assess the function of junctional coupling between adult secretory cells. Nonstimulated control cells were extensively coupled to their neighbors throughout each acinus. Addition of heptanol caused their uncoupling and increased their basal amylase release. Neurotensin, secretin, and vasoactive intestinal peptide (VIP) stimulated amylase secretion without uncoupling acinar cells. Heptanol rapidly and markedly uncoupled the neurotensin-, secretin-, and VIP-stimulated acinar cells and increased their amylase secretion in an additive manner. By contrast, the secretory response to carbamoylcholine (carbachol), a secretagogue that, alone, uncoupled acinar cells, was not affected by heptanol. Basal as well as neurotensin-, secretin-, and VIP-stimulated output returned to the lower control values following removal of heptanol and recovery of normal coupling. The data provide evidence that blockage of gap junctional coupling increases the basal secretion of exocrine pancreas as well as the response of the gland to a variety of secretagogues.