Alpha/sub 2/-adrenergic receptors on a platelet precursor cell line, HEL
The authors have identified ..cap alpha../sub 2/-adrenergic receptors on human erythroleukemia HEL cells, a suspension-growing, bone-marrow-derived cell line related to human platelets. Intact HEL cells were studied using radioligand binding and cAMP accumulation assays. The authors identified saturable specific binding of the ..cap alpha../sub 2/-antagonist (/sup 3/H)yohimbine (yoh) in cells incubated at 37/sup 0/C for 1 hr (B/sub max/ 5900 +/- 2100 sites/cell, K/sub d/ 3.6 +/- 0.9 nM, n = 7). Competition for (/sup 3/H)yoh binding sites with antagonists confirmed that these sites were similar to human ..cap alpha../sub 2/-adrenoceptors from platelets and other resources, as typified by their high affinity for WY-26392, yohimbine and idazoxan, and very low affinity for prazosin. Studies at 37/sup 0/C revealed a low affinity of these sites for catecholamines (K/sub i/ for (-)-epinephrine, 21 ..mu..M; (-)-norepinephrine, 45 ..mu..M, (+)-epinephrine, 80 ..mu..M). When experiments were conducted at 4 /sup 0/C, (-)-epinephrine was able to compete for only 50-60% of the sites specifically labelled by (/sup 3/H)yoh at 37/sup 0/, but (-)-epinephrine had an approximately 10-fold greater affinity for these sites (K/sub i/ at 4 /sup 0/C = 2.4 ..mu..M). In addition, epinephrine inhibited cAMP accumulation stimulated by forskolin and PGE/sub 1/ in HEL cells; this response was inhibited by pertussis toxin. The authors conclude that HEL cells possess ..cap alpha../sub 2/-adrenergic receptors linked to G/sub i/ and thus should serve as a useful model to explore metabolism and regulation of these receptors in human cells.
- Research Organization:
- Univ. of California San Diego, La Jolla
- OSTI ID:
- 5451238
- Report Number(s):
- CONF-8604222-; TRN: 86-028326
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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SYMPATHOMIMETICS
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RECEPTORS
ADRENALINE
AFFINITY
AMP
BIOLOGICAL MODELS
BLOOD PLATELETS
CATECHOLAMINES
LEUKEMIA
LIGANDS
NORADRENALINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
TUMOR CELLS
ADRENAL HORMONES
AMINES
ANIMAL CELLS
AROMATICS
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARDIOTONICS
CARDIOVASCULAR AGENTS
DISEASES
DRUGS
HEMIC DISEASES
HORMONES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
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NEOPLASMS
NEUROREGULATORS
NUCLEOTIDES
ORGANIC COMPOUNDS
PHENOLS
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REACTION KINETICS
STEROID HORMONES
550201* - Biochemistry- Tracer Techniques