Vasoactive intestinal peptide (VIP), adenosine and epinephrine effects on basal levels of inter-TEC GJIC. Co-cultures of the mouse TEC line were either treated or not (Ct- 6 hrs) with increasing concentrations of VIP (1 - 1000 nM, panels C to F), and the degree of cell coupling, ascertained by cytofluorometry, did not change as compared to the 6 hours untreated control (B), in relation to both percentages of coupled cells and calcein mean fluorescence. Values are shown at the upper right corner of each panel, representing the percentage of double positive cells (above) and the calcein geometric mean fluorescence intensity (below) of these populations. Panel A depicts the flow cytometry profiles of TEC that were not co-cultured. Panel G shows that adenosine does not alter inter-TEC GJIC as well, as revealed by the percentages of coupled cells seen after treatment of various doses of the nucleotide. Panel H shows that epinephrine (1 nM to 10 μM) increased the percentage of dye coupling between TEC in a dose-dependent fashion. Data are shown as mean ± standard deviation, being representative of 2 independent experiments performed in triplicate.