SUMMARY

We examined the gap-junctional communication properties of a communication-defective cell line R5/3 and its communication-competent revertant H2T12. For these studies, we carried out microelectrode impalements to monitor ionic coupling and dye coupling. Our dye-injection experi-ments revealed that the H2T12 cells are much more efficient in dye coupling than the R5/3 cells. This latter observation is in agreement with the previous finding that the H2T12 cells are much better metabolically coupled than the R5/3 cells. With ionic coupling measurements, however, both cell lines exhibited similar levels of cell-cell coupling. The R5/3 cells demonstrated an ionic coupling coefficient of 0-19 ±0-011 (S.E.M.) and H2T12 a coupling coefficient of 0-25 ± 0-009 (S.E.M.). These results in conjunction with observations from other studies indicate that the dif-ferent experimental approaches for monitoring gap-junctional communication may have different levels of sensitivity for detecting as opposed to measuring the level of cell-cell coupling