[3H]idazoxan binding at non-alpha 2-adrenoceptors in rabbit adipocyte membranes.
The imidazoline ligand, [3H]idazoxan, labels a large population of high-affinity binding sites in rabbit fat cell membranes (Bmax = 1370 +/- 91 fmol/mg protein; KD = 1.6 +/- 0.6 nM) when imidazoline derivatives are used for definition of non-specific binding. [3H]Idazoxan sites are not alpha 2-adrenoceptors as assessed by competition studies which showed that epinephrine, norepinephrine and yohimbine do not inhibit [3H]idazoxan binding. Naphazoline, tramazoline and the Na+/H+ exchange inhibitor, amiloride, completely inhibited [3H]idazoxan binding. The Ki values were 9, 27 and 48 nM, respectively.
Langin
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D
INSERM U.317, Institut de Physiologie, Université Paul Sabatier, Toulouse, France.
Lafontan
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M
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D004146:Dioxanes / Q000378:metabolism*; D004147:Dioxins / Q000378:metabolism*; D019329:Idazoxan; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D015016:Yohimbine / Q000378:metabolism
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D004147:Dioxins; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D019329:Idazoxan