A new reporter-based assay for the evaluation of gap junctional intercellular communication (GJIC) is presented. This assay was applied to the study of endogenous GJIC as well as to the evaluation of cell-to-cell communication exogenously induced in non-coupling cells by transfection with connexin 32. The results obtained with 18-alpha -glycyrrhetinic acid indicate that this assay system can be used to monitor the GJIC induced by transport of cAMP induced by activation of the dopamine 1 receptor cascade.