THE ERG AND LIGHT-INDUCED EXTRACELLULAR POTASSIUM CHANGES OF THE ISOLATED SUPERFUSED RCS RAT RETINA

1. ERG and light-induced extracellular potassium changes were measured in the isolated superfused retina of the normal rat and the RCS rat a s a model for degenerative retinal disease. 2. In the retinae from nor mal rats the ERG, the light-induced potassium increase in the proximal retina and the potassium decrease around the receptors were similar t o those described in other species. Up to day 18-21 the ERG and the po tassium decrease around receptors was normal in RCS rats. Thereafter t he potassium decrease diminished and was unmeasurable at day 33. Never theless, at day 33 a small cornea-negative potential in the electroret inogram remained which rapidly returned to the baseline. Despite the c learly reduced b-wave at day 33 the potassium increase in the proximal retina seemed to be not much affected. 3. When the superfusion of ret inae from RCS rats with reduced b-wave was maintained for 45 min the b -wave increased to 220 +/- 45%, which indicated that the functioning o f the abnormal isolated retina may be improved if nutrients are suppli ed directly to the tissue in vitro.