MODULATION OF GAP-JUNCTIONAL INTERCELLULAR COMMUNICATION THROUGH THE ACTION OF CYCLIC GMP-DEPENDENT PROTEIN-KINASE IN RETINAL HORIZONTAL CELLS

The status of intercellular coupling among retinal horizontal cells wa s examined with Lucifer yellow CH, to determine whether the blocking e ffect of cGMP on the gap junctions was through the activation of G-kin ase, independent of the well-known dopamine/cAMP pathway. Dye-coupling was observed when a mixture of cGMP and G-kinase inhibitor was inject ed into the horizontal cell, while dye-coupling was blocked when a mix ture of cGMP and A-kinase inhibitor was injected. These findings sugge st that the ability of cGMP to block the spread of dye between horizon tal cells is modulated through the action of G-kinase, and that this a ction is independent of the dopamine/cAMP pathway.