L-dopa mediated accumulation of cyclic AMP in isolated rabbit retinae in vitro. Effects of light and/or pharmacological factors.
The ability of L-dopa to stimulate the formation of cyclic AMP in pieces of intact rabbit retina in vitro has been studied and compared with that of dopamine and of other dopamine-mimetic drugs. Dose-dependent effects were measured in response to 5 microM up to 100 microM L-dopa with a maximal stimulation after 20 min of incubation at 35 degrees C. The L-dopa precursor, tyrosine, was totally ineffective. The L-dopa mediated response was detectable only in pieces of intact tissues (and not in homogenates) and is presumably due to the formation of newly formed dopamine, since it was completely inhibited by a decarboxylase inhibitor (benserazide). The biochemical response (cyclic AMP increase) was facilitated by ambient light, this effect being potentiated by 56 mM K+ or fully inhibited by 1 mM gamma-butyrolactone (GBL). The data suggest that the measurement of cyclic AMP levels in pieces of rabbit retina may provide a useful neurochemical model for the study of physiological and/or pharmacological agents able to interact at pre- and/or post-synaptic dopaminergic sites.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D004298:Dopamine / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D007980:Levodopa / Q000494:pharmacology*; D008027:Light; D008297:Male; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012160:Retina / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
D007980:Levodopa; D000242:Cyclic AMP; D001058:Apomorphine; D011188:Potassium; D004298:Dopamine