Electrical coupling and dye transfer between acinar cells in rat salivary glands

1. Adjacent acinar cells in isolated rat parotid and submaxillary glands were found to be electrically coupled in greater than 90% of the pairs tested. 2. Cells injected with fluorescein or procion yellow showed transfer of the dyes to their coupled neighbours. While not all coupled cells exchanged dye, exchange occurred only between coupled cells. 3. In experiments using three micro-electrodes, coupled acinar cells from parotid gland were found to have a mean coupling coefficient of 0.69 +/- 0.04. This value is higher than those reported for most other vertebrate epithelial systems. 4. Membrane damage sufficient to reduce the occurrence of coupling between cells by 97% lowered the transmembrane potential by only 13%. This would indicate that in this system membrane potential may not be the most sensitive indicator of cell damage. 5. The significance of the presence of electrical coupling and cell-to-cell transfer of small tracer molecules is discussed in relation to salivary gland structure and possible functional consequences.