DETERMINATION OF GAP JUNCTIONAL INTERCELLULAR COMMUNICATION BY CAPACITANCE MEASUREMENTS

Electrical coupling between cells is usually measured using the double patch-clamp technique with cell pairs. Here, a single patch-clamp tec hnique that is not limited to cell pairs is described to determine ele ctrical coupling between cells. Capacitance measurements in clusters o f normal rat kidney (NRK) fibroblasts were used to study intercellular communication. In the whole-cell patch-clamp configuration capacitive transients were evoked by applying small voltage pulses. Total membra ne capacitance was calculated from these capacitive transients after d etermination of access resistance, membrane conductance, and the decay constant of the transients, or alternatively by integrating the curre nt transient. We found that in clusters of one to ten cells, membrane capacitance increased linearly with cell number; showing that the cell s are electrically coupled. Membrane conductance of the cluster of cel ls also increased, as expected for cells that are well coupled. in sub confluent and confluent cultures, high membrane conductances together with large capacitive transients were observed, indicative of electric al coupling. Capacitance could only be determined qualitatively under these conditions, due to space clamp problems. In the presence of the gap junctional inhibitors halothane, heptanol or octanol, capacitance of all clusters of cells fell to single-cell levels, showing a complet e uncoupling of the cells. The tumour promoter 12-O-tetradecanoylphorb ol-13-acetate (TPA) also uncoupled the cells completely, within 10 min . We conclude that capacitance measurements can provide a useful tool to study changes in intercellular communication in clusters of cells.