The effects of NiSO4, K2CrO4, PbAc2, CrCl3 and CdAc2 on gap junctional intercellular communication (GJIC) were studied. Two exposure procedures were used — A: an established monolayer of cells was exposed to the compound, and B: the compound was mixed with the cells before seeding. The apparent inhibition of GJIC by CrCl3 and CdAc2 could be accounted for by cytotoxicity, i.e. disruption of physical contacts between cells. PbAc2 had no effect on GJIC. The effects of NiSO4 and K2CrO4 depended on the exposure procedure and cell type studied. Specifically, K2CrO4 induced a significant increase in GJIC in BPNi cells by procedure A, and a decrease by procedure B. The cytotoxic effects of NiSO4 were examined in more detail. The toxic concentrations varied widely between the methods used. The results indicate that the effect of compounds on GJIC may vary with different exposure procedures, and that inhibition of GJIC is not due to general cytotoxic effects.
