ARACHIDONIC-ACID BLOCKS GAP-JUNCTIONS BETWEEN RETINAL HORIZONTAL CELLS

HORIZONTAL cells in turtle retinae are electrically coupled via gap ju nctions, and the input resistances of the cells are too low to be meas ured. However, intracellular injection of arachidonic acid into horizo ntal cells caused great increases in the input resistances of the cell s, and the cells could be easily polarized by intracellular current in jection. The injection of arachidonic acid also caused decrease in lig ht responses of horizontal cells to surround illumination, and blocked dye-couplings with Lucifer Yellow CH. On the other hand, injection of a lipoxygenase inhibitor or a guanylate cyclase inhibitor into horizo ntal cells suppressed the decoupling effect of arachidonic acid. These findings suggest that lipoxygenase metabolites of arachidonic acid bl ock gap junctions by activating guanylate cyclase.