Dopaminergic regulation of horizontal cell gap junction particle density in goldfish retina

Light- or dark-adapted goldfish (Carassius auratus) retinas were treated with dopamine, which is believed to uncouple horizontal cells via D1 receptors, or with the dopamine antagonist haloperidol. Aldehyde-fixed retinas were freeze-fractured and the replicas examined by electron microscopy to identify horizontal gap junctions. The density (number per micron2) of intra-membrane particles of horizontal cell soma gap junctions was significantly …