title: Reversible and irreversible components of [(3)H]-N-propylnorapomorphine interaction with rat striatal membranes.
abstract: The kinetics of L-(-)-[N-propyl-(3)H(N)]-norapomorphine ([(3)H]NPA) interactions with rat striatal membranes were studied. The analysis revealed that in addition to specific dopaminergic binding a substantial part of the radioligand was bound irreversibly to heterogeneous populations of non-specific binding sites of these membranes. The specific binding of [(3)H]NPA with dopamine receptors, determined from the differences of kinetic curves of total and non-specific binding, was fast, reversible, and revealed high affinity. The irreversible component was heterogeneous and seems to be related to oxidative degradation of the radioligand, as the rate of this process was substantially reduced by antioxidants like ascorbic acid and dithiothreitol.
authors.affiliation: Institute of Organic and Bioorganic Chemistry, University of Tartu, Jakobi Str. 2, EE-51014, Tartu, Estonia.
authors.forename: Martin
authors.initials: M
authors.lastname: Lepiku
authors.forename: Jaak
authors.initials: J
authors.lastname: Järv
authors.forename: Kjell
authors.initials: K
authors.lastname: Fuxe
authors.forename: Ago
authors.initials: A
authors.lastname: Rinken
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001058:Apomorphine / Q000031:analogs & derivatives* / Q000378:metabolism*; D001205:Ascorbic Acid / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D007700:Kinetics; D017072:Neostriatum / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D011849:Radioactive Tracers; D051381:Rats; D011954:Receptors, Dopamine / Q000378:metabolism; D014316:Tritium
chemical_list: D000975:Antioxidants; D011849:Radioactive Tracers; D011954:Receptors, Dopamine; D014316:Tritium; C009074:N-n-propylnorapomorphine; D001058:Apomorphine; D001205:Ascorbic Acid; D004229:Dithiothreitol; D004298:Dopamine