FURTHER-STUDIES ON THE INFLUENCE OF CAMP-DEPENDENT PROTEIN-KINASE ON JUNCTIONAL CONDUCTANCE IN ISOLATED HEART CELL PAIRS

The influence of the catalytic subunit (20 μg/ml) of cAMP-dependent protein kinase on junctional conductance (gj) of isolated rat ventricular cell pairs was investigated. It was found that gj was increased by 90% within 4 to 5 min when the subunit was dialysed into both cells. The dialysis of the catalytic subunit into just one cell of the pair increased gj and generated rectification of junctional membrane. The regulatory subunit (20 μg/ml) of cAMP-dependent protein kinase reduced gj by about 17% when dialysed into both cells of pairs. These results might indicate that the symmetric phosphorylation of junctional proteins in the two hemichannels increases gj without rectification while asymmetric phosphorylation generates rectification of junctional membrane. © 1991.