Utility of intensely fluorescent cyanine dyes (Cy3) for assay of gap junctional communication by dye-transfer.

Utilization of a class of fluorescent cyanine dyes (Cy3) for the assay of gap junctional communication by the dye transfer method was examined. When compared with Lucifer Yellow (LY), a commonly used tracer, microinjected Cy3 dye was found to yield similar degrees of cell coupling. Blockade of the transfer of both tracers by 12-O-tetradecanoylphorbol-13 acetate (TPA), which is known to cause closure of communicating channels, confirmed gap junctional mediation of dye movement. The fixability of a microinjected amine derivative of Cy3 dye demonstrated its compatibility with immunostaining protocols involving fluorescein isothiocyanate (FITC)-conjugated reagents. These results together with the brilliant fluorescence of Cy3 dyes suggest the potential of Cy3 reagents as additional tools to study gap junction function.