Dopaminergic mechanisms in the teleost retina. I. Dopamine-sensitive adenylate cyclase in homogenates of carp retina; effects of agonists, antagonists, and ergots.
A specific dopamine-sensitive adenylate cyclase has been identified in homogenates of the teleost (carp) retina. Maximal stimulation by 100 microM-dopamine resulted in a 5--10-fold increase in adenylate cyclase activity with half-maximal stimulation occurring at a concentration of 1 microM. l-Noradrenaline and l-adrenaline were some 10 times less potent than dopamine whilst the alpha- and beta-adrenoreceptor agonists, l-phenylephrine and dl-isoprenaline were inactive. Apomorphine elicited a partial stimulation of adenylate cyclase activity whilst various ergot alkaloids produced mixed agonist/antagonist responses. Dopamine-stimulated adenylate cyclase activity was potently antagonised by various neuroleptic drugs including fluphenazine, alpha-flupenthixol and alpha-piflutixol, and to a lesser extent by the butyrophenone derivatives haloperidol and spiperone. The benzamide derivatives, metoclopramide and sulpiride, together with the alpha- and beta-adrenoreceptor blocking agents, phentolamine and propranolol respectively were essentially inactive at blocking dopamine-stimulated adenylate cyclase activity. These data suggest the presence of a highly specific dopamine-sensitive adenylate cyclase in homogenates of teleost retina possessing similar pharmacological properties to the dopamine-sensitive adenylate cyclase observed in the mammalian central nervous system.
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001058:Apomorphine / Q000494:pharmacology; D002347:Carps; D004298:Dopamine / Q000494:pharmacology*; D018492:Dopamine Antagonists; D004789:Enzyme Activation; D004837:Epinephrine / Q000494:pharmacology*; D004876:Ergot Alkaloids / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D009638:Norepinephrine / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D012160:Retina / Q000201:enzymology*
D014150:Antipsychotic Agents; D018492:Dopamine Antagonists; D004876:Ergot Alkaloids; D010656:Phenylephrine; D000262:Adenylyl Cyclases; D007545:Isoproterenol; D001058:Apomorphine; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine