Nitric oxide inhibits depolarization-induced release of endogenous dopamine in the rabbit retina.

Abstract The effect of nitric oxide donor compounds (sodium nitroprusside, hydroxylamine and S -nitroso- N -acetyl- d,l -penicillamine) on depolarization-induced release of endogenous dopamine in the light-adapted, isolated retina of the rabbit was studied by HPLC. All three compounds had the same effect, reducing the amount of dopamine released by up to 90%. The effect was concentration dependent, saturating at 300 μM; it was blocked by the nitric oxide scavenger, mannitol (50 mM), which by itself had no effect on the basal release of dopamine. GABA A receptors were not involved. Possible cellular mechanisms underlying the findings are discussed. It is suggested that the inhibitory interaction between dopamine and nitric oxide could represent a higher order function in the light adaptation process in the retina.