Light-adaptation attenuates the effects of phosphodiesterase blackade by Zaprinast in the isolated rat retina.
The effect of the type V/VI-selective phosphodiesterase inhibitor, Zaprinast, (200 microM) on the light-evoked extracellular field potential (EFP) in the isolated rat retina was tested under dark- and light-adapted conditions at two different temperatures. Peak enhancement EFP in dark- (344 +/- 70%; mean +/- SEM) and light-adapted (182 +/- 31%) retina at 37 degrees C was reached within 3 min of treatment with Zaprinast (200 microM) followed by a slower decrease to a level of 85 +/- 14 and 26 +/- 7% in dark- and light-adapted retina, respectively. The effect of Zaprinast (20 microM) on the pharmacologically-isolated photoreceptor component of the EFP was lost with increasing levels of background light. This may suggest that there is a slow time scale (minutes) shift in the steady state level of cGMP during light-adaptation.
Barabás
Péter
P
Department of Neurochemistry, Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H 1025 Budapest, Hungary. barabas@chemres.hu
Antal
Károly
K
Kardos
Julianna
J
D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D003623:Dark Adaptation; D003624:Darkness; D004307:Dose-Response Relationship, Radiation; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000528:radiation effects; D066298:In Vitro Techniques; D008027:Light; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D010775:Photic Stimulation; D011688:Purinones / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors
D010726:Phosphodiesterase Inhibitors; D011688:Purinones; D010727:Phosphoric Diester Hydrolases; C011145:zaprinast