LIGHT-STIMULATED RELEASE OF DOPAMINE FROM THE PRIMATE RETINA IS BLOCKED BY L-2-AMINO-4-PHOSPHONOBUTYRIC ACID (APB)

Macaca mulatta retinas were superfused, in vitro, to measure the efflu x of dopamine. Steady light, in the low photopic range, stimulated dop amine release slightly. Flashing light (3 Hz) superimposed over the st eady background increased dopamine efflux significantly. This increase was completely blocked by the addition of d,l-2-amino-4-phosphonobuty ric acid (d,l-APB, 10-100 mu M) to the superfusion medium, but not by the addition of the inactive enantiomer d-APB (10 mu M). The results s uggest that ON bipolar cells provide the excitatory drive to dopaminer gic amacrine cells in primates, as in other species.