title: alpha 2-Adrenergic receptors in human polymorphonuclear leukocyte membranes.
abstract: Human polymorphonuclear cell membranes contain alpha 2-adrenergic receptors which are measured by binding of the alpha 2-adrenergic antagonist [3H]yohimbine. The alpha 1-adrenergic antagonist [3H]prazosin showed no specific binding. High and low affinity sites were detected which had Kd values of 2.38 +/- 0.4 and 139 +/- 12 nM, respectively, and which bound maximally 4.82 +/- 0.9 and 81 +/- 9 fmoles of [3H]yohimbine/mg membrane protein. The high and low affinity sites were also detected by competition studies with phentolamine, epinephrine and norepinephrine and by dissociation kinetics of bound [3H]yohimbine. [3H]Yohimbine binding was stereospecifically inhibited by (-)- and (+)-epinephrine and norepinephrine. [3H]Yohimbine binding to intact cells showed about 500 high affinity sites per cell (Kd 0.5 nM) and approximately 4000 lower affinity sites per cell (Kd 3-4 nM). Yohimbine enhanced the (-)-norepinephrine stimulation of cAMP production in intact cells.
mesh_terms: D000527:Alprostadil; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009504:Neutrophils / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011458:Prostaglandins E / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013268:Stimulation, Chemical; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D011458:Prostaglandins E; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D000242:Cyclic AMP; D000527:Alprostadil; D009638:Norepinephrine; D011224:Prazosin; D010646:Phentolamine