Effects of ultraviolet radiation on intercellular communication in V79 Chinese hamster fibroblasts

The effects of ultraviolet (UV) radiation on gap junctionalintercellular communication (GJIC) in V79 Chinese hamster fibroblastswere studied by means of a dye transfer assay. Intercellularcommunication was shown to be altered by UVB (297/302 nm) andUVA (365 nm) radiation, the effect depending on the wavelengthof exposure and time between irradiation and microinjectionof the dye in the dye transfer assay. Exposure to 297/302 nmradiation induced a reduction in intercellular communication6 min after exposure. Incubation of the cells post-irradiationreversed the inhibition of GJIC. From 2 to 24 h after exposurean increase in GJIC over the control cells was seen, with amaximum at 8 h post-irradiation. UVA (365 nm) radiation, onthe other hand, induced an increase in the intercellular communication6 min after irradiation. Incubation of the cells post-irradiationled to a decrease in the number of communicating cells, witha minimum seen 4 h after exposure. The reduction in communicationobserved after exposure to UVB and UVA was not correlated withsimilar modifications in the gap junction protein connexin43as found when exposing the cells to the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate. For the higher fluences of UVA, a decrease in immunorecognizableconnexin43 was seen, concomitant with a markedly increased backgroundof higher mol. wt compounds. This may be due to UVA-inducedcrosslinking of connexin43. No correlation was found betweenchanges in communication induced by UV radiation and levelsof cyclic AMP.