The effect of fluphenazine on rod-mediated retinal responses

The effect of various concentrations of the dopamine antagonist fluphenazine on ocular field potentials, recorded under scotopic conditions from isolated, arterially perfused cat eyes, was studied. Responses from outer (isolated PIII-component of the electroretinogram, ERG), middle (b-wave), and inner (optic nerve response, ONR) retinal layers were separated. Neither the fast or slow PIII-amplitude nor the temporal characteristics of the response were influenced by any of the drug concentrations tested. In contrast, fluphenazine reversibly increased the rod b-wave amplitude over a large range of concentrations. Only very high drug concentrations led to an irreversible loss of the b-wave. In the ONR the initial transient on-response increased during drug injection, whereas the sustained on-response and off-response decreased. In summary, the dopamine antagonist fluphenazine affects mainly the signal processing of the rod pathway in the inner retinal layers, while responses from outer retinal layers are not influenced. On- and off-responses of the ONR are affected differently.