Effects of dopamine D1 receptor blockade on the intensity-response function of ERG b- and d-waves under different conditions of light adaptation

Abstract The effect of dopamine D 1 receptor blockade by SCH 23390 on the V –log  I function of the ERG b- and d-waves was investigated in dark and light adapted frog eyes. We obtained that the blocker enhanced the amplitude of the b- and d-waves in both conditions of adaptation. The enhancing effect of the blocker was more pronounced on the rod- than cone-dominated responses for the both ERG waves. The absolute sensitivity of the b-wave was not altered, but that of the d-wave was significantly increased. The intensity-response function of the b-wave, but not that of the d-wave, was shifted to the left along the intensity axis. The b-wave V –log  I function had steeper slope and narrower dynamic range in both dark and light adapted eyes after the D 1 receptor blockade. The results obtained indicate that the endogenous dopamine, acting through D 1 receptors, does not play a crucial role in the process of retinal adaptation, although it changes in a specific manner the intensity-response function of both the ERG b- and d-waves.