title: The handling of five amines by the extraneuronal deaminating system of the rat heart.
abstract: The handling of five amines by the extraneuronal deaminating system was studied in perfused hearts of rats (pretreated with reserpine; COMT and neuronal uptake inhibited). Hearts were perfused with 50 nmol/l 3H-noradrenaline for 30 min, in the presence of increasing concentrations of unlabelled (-)-adrenaline, (-)-noradrenaline, dopamine, tyramine and 5-HT. IC50's were determined as those concentrations of unlabelled amines which halved the steady-state rate of deamination of 3H-noradrenaline. After correction for changes in the tissue/medium ratio for 3H-noradrenaline, "half-saturating outside concentrations" were obtained. They increased in the order (-)-adrenaline (15 mumol/l) - tyramine - dopamine - noradrenaline - 5-HT (53 mumol/l). The Vmax for extraneuronal deamination was determined for 3H-(-)-adrenaline, 3H-(-)-noradrenaline and 3H-dopamine, as well as (by HPLC and electrochemical detection) for tyramine and 5-HT. It was low for (-)-adrenaline, intermediate for (-)-noradrenaline, dopamine and 5-HT, high for tyramine. For the three catecholamines the half-saturating outside concentrations of the extraneuronal deaminating system clearly exceeded those for the extraneuronal O-methylating system of the same organ (see Grohmann and Trendelenburg 1985), although the two enzymes appear to co-exist in the same cells, so that the same transport system is involved.
authors: Institut für Pharmakologie und Toxikologie der Universität, Würzburg, Federal Republic of Germany.
authors: M
authors: M
authors: Grohmann
authors: U
authors: U
authors: Trendelenburg
mesh_terms: D000818:Animals; D001679:Biogenic Amines / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism; D066298:In Vitro Techniques; D008995:Monoamine Oxidase / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism; D014439:Tyramine / Q000378:metabolism
chemical_list: D001679:Biogenic Amines; D012701:Serotonin; D008995:Monoamine Oxidase; D004298:Dopamine; D009638:Norepinephrine; D014439:Tyramine; D004837:Epinephrine