Modulation of [(35)S]GTPgammaS binding to chinese hamster ovary cell membranes by D(2(short)) dopamine receptors.
Rat dopamine D(2short) expressed in Chinese hamster ovary (CHO) cells were characterized by means of activation of [(35)S]-guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding and inhibition of [(3)H]raclopride binding. Among 18 dopaminergic ligands studied dopamine, NPA, apomorphine and quinpirole were full agonists in activation of [(35)S]GTPgammaS binding, while seven ligands were partial agonists with efficacies from 16 to 69% of the effect of dopamine and seven ligands were antagonists having no effect on the basal level of [(35)S]GTPgammaS binding, but inhibited dopamine-dependent activation in a dose-response manner. Despite the different efficacies, the potencies of all 18 ligands to modulate [(35)S]GTPgammaS binding revealed a good correlation with their potencies to inhibit [(3)H]raclopride binding in the CHO cell membranes. This indicates that the binding of the ligand to the receptor determines its potency, but has no direct correlation with its intrinsic activity.
Terasmaa
A
A
Institute of Chemical Physics, University of Tartu, Jakobi Str. 2, EE-51014, Tartu, Estonia.
Finnman
U B
UB
Owman
C
C
Ferré
S
S
Fuxe
K
K
Rinken
A
A
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002069:Butaclamol / Q000494:pharmacology; D016466:CHO Cells; D006224:Cricetinae; D004298:Dopamine / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D008566:Membranes / Q000187:drug effects / Q000378:metabolism*; D020891:Raclopride / Q000378:metabolism / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000502:physiology*; D013134:Spiperone / Q000031:analogs & derivatives / Q000494:pharmacology; D013462:Sulfur Radioisotopes; D014316:Tritium
D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D013462:Sulfur Radioisotopes; D014316:Tritium; C068824:N-(4-isothiocyanatophenethyl)spiperone; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D020891:Raclopride; D013134:Spiperone; D002069:Butaclamol; D004298:Dopamine