RETINAL GANGLION-CELLS EXPRESS A CGMP-GATED CATION CONDUCTANCE ACTIVATABLE BY NITRIC-OXIDE DONORS

We have identified a putative cGMP-gated cation conductance in rat ret inal ganglion cells. Both in situ hybridization and polymerase chain r eaction amplification detected transcripts in ganglion cells that were highly homologous to the cGMP-gated cation channel expressed in rod p hotoreceptors. Whole-cell patch-clamp recordings detected a current st imulated by cGMP due to activation of nonselective cation channels. Th is current had a reversal potential near 0 mV, showed some outward rec tification, and could be blocked by Cd2+. The current could also be ac tivated by a phosphodiesterase inhibitor and the nitric oxide donors s odium nitroprusside and S-nitrosocysteine. We propose that nitric oxid e released from an identified subpopulation of amacrine cells may acti vate this channel to modulate ganglion cell activity.