title: Effects of dopamine receptor blockade on the intensity-response function of electroretinographic b- and d-waves in light-adapted eyes.
abstract: The effects of dopamine receptor blockade by sulpiride (D2-class antagonist) and sulpiride plus SCH 23390 (D1-class antagonist) on the V - log I function of the electroretinographic (ERG) b- and d-waves were investigated in light-adapted frog eyes. Sulpiride significantly decreased the absolute sensitivity of the b- and d-waves. The amplitude of the both waves was diminished over the whole intensity range studied. A similar effect on the b-, but not d-wave amplitude was seen during the perfusion with sulpiride plus SCH 23390. The effect on the d-wave amplitude depended on stimulus intensity. The threshold of the d-wave was not significantly altered. The suprathreshold d-wave amplitude was enhanced at the lower stimulus intensities and remained unchanged at the higher ones. The results obtained indicate that the action of endogenous dopamine on the photopic ERG shows clear ON-OFF asymmetry. Participation of different classes of dopamine receptors is probably responsible for this difference.
authors.affiliation: Department of Physiology, Medical Faculty, Medical University, 1431, Sofia, Bulgaria, epopova@abv.bg.
authors.forename: E
authors.initials: E
authors.lastname: Popova
mesh_terms: D000221:Adaptation, Ocular; D000818:Animals; D001001:Anura; D001552:Benzazepines / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004596:Electroretinography / Q000187:drug effects; D005071:Evoked Potentials / Q000187:drug effects*; D005123:Eye / Q000187:drug effects*; D066298:In Vitro Techniques; D009799:Ocular Physiological Phenomena / Q000187:drug effects*; D010775:Photic Stimulation; D013469:Sulpiride / Q000494:pharmacology*; D014795:Visual Pathways / Q000187:drug effects
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; C534628:SCH 23390; D013469:Sulpiride