Blockage of cell-to-cell communication within pancreatic acini is associated with increased basal release of amylase

To assess whether junctional coupling is involved in the secretory activity of pancreatic acinar cells, dispersed rat acini were incubated for 30 min in the presence of either heptanol (3.5 mM) or octanol (1.0 mM). Exposure to either alkanol caused a marked uncoupling of the acinar cells which, in control acini, were extensively coupled. Uncoupling was associated with an increased basal release of amylase that was at least twice that of controls. By contrast, carbamylcholine (10(-5) M)-induced maximal amylase secretion, cytosolic pH, and free Ca2+, as well as the structure of gap junctions joining the acinar cells, were unaffected. Both uncoupling and the alteration of basal secretion were already observed after only 5 min of exposure to heptanol, they both persisted throughout the 30-min exposure to the alkanols, and were reversible after removal of either heptanol or octanol. Since neither of the two uncouplers appeared to alter unspecifically the secretory machinery and the nonjunctional membrane of acinar cells, the data are consistent with the view that junctional coupling participates in the control of the basal secretion of acinar cells.