Actions of 8-hydroxy-2-(N-dipropylamino) tetralin (8-OH-DPAT) at alpha 2-adrenoceptors.
1 We have examined the actions of the 5-HT1A-receptor ligand 8-OH-DPAT at alpha 2-adrenoceptor ligand binding sites in human platelet and rat kidney membranes and at functional pre- and postjunctional alpha 2-adrenoceptors in rat atrium and human saphenous vein, respectively. 2 8-OH-DPAT had low affinity for the alpha 2A ligand binding site of human platelet but showed 10 times higher affinity for the alpha 2B ligand binding site of rat kidney (K1 of 6.41, -log M). 3 In functional studies, 8-OH-DPAT had low potency as an antagonist of noradrenaline-induced contractions in human saphenous vein, with a KB of 5.40 (-log M). 4 In rat atria preincubated with [3H]-noradrenaline, 8-OH-DPAT potentiated stimulation-evoked overflow of tritium with an EC30 (concentration producing 30% increase in the stimulation-evoked overflow) of 6.37 (-log M). 5 It is concluded that 8-OH-DPAT shows selectively for the alpha 4B ligand binding site of rat kidney and for the functional prejunctional alpha 2-adrenoceptor of rat atrium, which resembles the alpha 2B ligand binding site.
Borton
M
M
Department of Clinical Pharmacology, Royal College of Surgeons in Ireland, Dublin.
Connaughton
S
S
Docherty
J R
JR
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000328:Adult; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D012501:Saphenous Vein / Q000187:drug effects; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
D011942:Receptors, Adrenergic, alpha; D013764:Tetrahydronaphthalenes; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin