[Effects of retinal intrinsic dopamine on the in in vivo electroretinogram of rabbits].

The effects of intravitreal injection of nomifensine, a potent dopamine uptake blocker, on the electroretinogram (ERG) were investigated in rabbit. Nomifensine enhanced the amplitude of the oscillatory potentials at 100 microM (intravitreal concentration) and 300 microM (p < 0.05), but it attenuated the oscillatory potentials at 1,000 microM (p < 0.01). Nomifensine attenuated the amplitude of the scotopic b-wave at 100 microM and 1,000 microM (p < 0.05), leaving the peak latency of the scotopic b-wave unaltered at all concentrations tested (30, 100, 300, 500 and 1,000 microM). Neither the amplitude nor the peak latency of the dark-adapted a- and b-waves elicited by bright stimuli was altered at any nomifensine concentration tested. 1 microM dopamine and 30 microM nomifensine together, each of which is insufficient to alter either of the scotopic b-wave or the oscillatory potentials when applied alone, reduced the scotopic b-wave and enhanced the oscillatory potentials. These results suggest that intrinsic dopamine release in the retina is large enough to alter the ERG.