A G‐protein mediates secretagogue‐induced gap junctional channel closure in pancreatic acinar cells

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Abstract
Using the double whole‐cell patch‐clamp technique, we determined that dialysis of cell pairs by GTP[S] potentiated electrical uncoupling induced by extracellular addition of carbamylcholine (CCh). An inhibitor of diglyceride lipase, RHC 80267, further potentiated CCh/GTP[S]‐induced junctional channel closure, probably by accumulation of diacylglycerol. Moreover, the protein kinase C inhibitor polymyxin B completely blocked uncoupling elicited by CCh/GTP[S]. These results provide the first evidence suggesting that gap junction channel closure by cholinergic stimulation is mediated by a G‐protein, which acts by increasing phosphatidylinositol biphosphate breakdown and protein kinase C activity.