Detail of "83498-72-0"

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Classification of b-adrenergic subtypes in immature rabbit bone marrow erythroblasts

Classification of b-adrenergic subtypes in immature rabbit bone marrow erythroblasts. Sechenska, M.; Bonanou-Tzedaki, Sophia A.; Arnstein, Henry R. V. (Cent. Lab. Biophys., Sofia 1113, Bulg.). Biochem. Pharmacol., 35(21), 3679-84 (English) 1986. CODEN: BCPCA6. ISSN: 0006-2952. DOCUMENT TYPE: Journal CA Section: 2 (Mammalian Hormones) The b-adrenergic receptors of immature rabbit bone marrow erythroid cells (proerythroblasts and basophilic erythroblasts) were identified. 125I-labeled iodocyanopindolol [83498-72-0] bound to membrane prepns. derived from these erythroblasts in a rapid, reversible, and saturable manner. Scatchard anal. of binding data revealed a single class of binding sites (Hill coeff. of 0.954) with an apparent equil. dissocn. const. (Kd) of 8 pM, and a d. of binding sites (Bmax) of 1.53 pM/106 cells, corresponding to 920 receptors per cell. The binding of [125I]iodocyanopindolol was inhibited stereospecifically by concns. of (-)-propranolol [4199-09-1] 2 orders of magnitude lower than by the (+)-isomer [105612-49-5]. Only the b2-adrenergic specific l-isoprenaline [51-31-0] and l-adrenaline [51-43-4] activated the adenylate cyclase [9012-42-4] of immature rabbit erythroblasts, whereas the b1-agonist noradrenaline [51-41-2] was inactive. The order of potency of different agonists for displacement of bound [125I]iodocyanopindolol was: isoprenaline > adrenaline > noradrenaline with resp. EC50 (concn. required for half maximal inhibition of binding) of 7.9 ′ 10-7, 1.5 ′ 10-5, and 7.9 ′ 10-5 M. This agonist potency series did not change with differentiation of rabbit bone marrow erythroblasts. The inhibition of specific [125I]iodocyanopindolol binding to immature cells by b1- and b2-selective drugs (noradrenaline, practolol [6673-35-4], procaterol [72332-33-3], and butoxamine [1937-89-9]) resulted in linear Hofstee plots. The inhibition curves obtained with procaterol and butoxamine, with apparent Kd values of 3.1 ′ 10-9 and 4.9 ′ 10-9 M, resp., provide further evidence that the high-affinity binding sites correspond to a homogeneous b2-receptor subtype.