title: The action of psychotropic drugs on adenylate cyclases and phosphodiesterases in the rat retina.
abstract: In this overview we demonstrate differences in the mode of action of DA and NA on cAMP-synthesizing systems by using psychotropic compounds such as fluphenazine and haloperidol. Evidence exists that this catecholamine induced cAMP-synthesis occurs in post-synaptic receptor-coupled adenylate cyclases. Our results reveal the expected inhibitory action of the psychotropic drugs on the DA- and NA-stimulated adenylate cyclases. We present, however, also evidence for a drug-induced inhibition of the phosphodiesterase activity involved in the NA-induced cAMP synthesis. This drug-induced inhibition of P.D.-ases was not found in the DA-governed enzymatic process. We also measured the DA- and NA-responses at various low potassium-ion concentrations (0-6 mM). Our data on this point suggest a specific membrane conformation modulated by potassium ions, which change the readiness of DA- and NA-receptors to accept the catecholamines involved. An elevation of the potassium-ion concentration up till 15 mM produced a relatively high cAMP-formation, which was suppressed by various amounts of psychotropic compounds. Our results point to different cell types in the rat retina, all containing the structure for cAMP-synthesis and cAMP-breakdown.
authors.affiliation: Dept. of Neurophysiology; University of Groningen, Bloemsingel 10; 9712 KZ Groningen; The Netherlands.
authors.forename: J S
authors.initials: JS
authors.lastname: Wassenaar
authors.forename: H
authors.initials: H
authors.lastname: Roelse