Electrical coupling between ventricular paired cells isolated from guinea-pig heart.

Guinea-pig hearts were digested enzymatically, resulting in aggregates of cells, cell pairs and single cells. Pairs of cells were chosen for measurement of coupling resistance (rj). Current was injected into one cell of a cell pair. The ratio of the resulting voltage change of the other cell to that of the injected cell was more than 0.8 in most cells (tight electrical coupling) or near 0 in a few cells (functional isolation). rj was affected neither by the transjunctional current, nor by the membrane potential itself. On the other hand, either a reduction of external Na+ concentration (15-60 mM), or an application of ouabain or strophanthidin (10(-5) M) produced a significant increase in rj. It is concluded that low-resistance cell-to-cell junctions are functionally preserved in pairs of dissociated ventricular cells, that the junctional membrane shows no detectable rectification and that intracellular Ca2+ reduces the junctional conductance.