Fig. 2.

Electrophysiological identification of rod and cone photoreceptors in flat-mounted rd mouse retina. Current responses to voltage steps in a representative rod (A) and cone (B). The potential was stepped from a holding potential of −70 mV to potentials ranging from −120 to +40 mV in 20 mV increments. C,Averaged current–voltage curves of rod and cone response to voltage steps (cones, n = 20; rods, n = 5; ±SEM). Cones typically exhibited a large outward current at potential superior to −30 mV, whereas rods showed an inward current activated at the most negative potentials. D, Rod and cone photoreceptor responses to a GABA puff application (1 mm, 1 sec). GABA elicited a large current in cones but not in rods.