Characterization of imidazoline binding protein(s) solubilized from human brainstem: studies with [3H]idazoxan and [3H]clonidine.
Imidazoline binding sites from the human brainstem were solubilized with 3-[(3-cholamido-propyl)-dimethylammonio]-1-propane-sulfonate (CHAPS). [3H]idazoxan and [3H]clonidine were used as ligands to characterize the solubilized binding sites. In both the soluble and membrane fractions, [3H]idazoxan binding was saturable, stereoselective, sensitive to imidazolines and insensitive to (-)norepinephrine and to amiloride. The affinities of [3H]idazoxan for the soluble and membrane sites were similar (KD = 25 +/- 11 nM and 20 +/- 3 nM). In both soluble and membrane fractions, the alpha 2-adrenoceptor binding being masked with (-)norepinephrine, [3H]clonidine bound to a low affinity site which was insensitive to (-)norepinephrine and which exhibited the same selectivity for various drugs as the [3H]idazoxan binding site. alpha 2-adrenoceptor binding was present in the membrane and the soluble fractions although it was difficult to detect in the soluble fraction because of inhibition of [3H]rauwolscine binding by the CHAPS detergent.
Greney
H
H
Laboratoire de Pharmacologie Cardiovasculaire et Rénale, CNRS URA 589, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
Bricca
G
G
Dontenwill
M
M
Stutzmann
J
J
Bousquet
P
P
Belcourt
A
A
D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism; D002793:Cholic Acids; D002850:Chromatography, Gel; D003000:Clonidine / Q000378:metabolism*; D004146:Dioxanes / Q000378:metabolism*; D006801:Humans; D019329:Idazoxan; D007093:Imidazoles / Q000378:metabolism*; D054755:Imidazoline Receptors; D009638:Norepinephrine / Q000494:pharmacology; D011955:Receptors, Drug / Q000302:isolation & purification / Q000378:metabolism*; D012995:Solubility; D014316:Tritium; D015016:Yohimbine / Q000378:metabolism
D002793:Cholic Acids; D004146:Dioxanes; D007093:Imidazoles; D054755:Imidazoline Receptors; D011955:Receptors, Drug; D014316:Tritium; D015016:Yohimbine; D003000:Clonidine; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate; D009638:Norepinephrine; D019329:Idazoxan