Inhibitory effects of 12-O-tetradecanoylphorbol-13-acetate on dye leakage from single Novikoff cells and on dye transfer between reaggregated cell pairs.

The inhibitory effects of 12-O-tetradeconylphorbol-13-acetate (TPA) on the Lucifer Yellow leakage in single (nondissociated and dissociated) Novikoff cells in the presence of ethyleneglycotetraacetic acid (EGTA) and transfer between reaggregated cell pairs were investigated. Under treatment with TPA, single Novikoff cells showed inhibition of the dye leakage in the presence of EGTA, especially after 60-min treatment. There were only slight differences between nondissociated and dissociated cells in these experiments. The dye transfer in reaggregated cell pairs were significantly inhibited after 30-min treatment with TPA. In pretreatment with TPA during the recovery period of reaggregation the dye transfer in cell pairs was completely blocked. It was suggested that TPA blocks the assembly of gap junction, while it had no remarkable effect on gating mechanism of the hemichannels.