title: Characterization of the rat mast cell beta-adrenergic receptor in resting and stimulated cells by radioligand binding.
abstract: Rat serosal mast cell beta-adrenergic receptors were characterized both functionally by assessing changes in histamine release and cyclic 3',5' adenosine monophosphate (cAMP) levels and directly by radioligand binding studies using [3H]dihydroalprenolol ([3H]DHA), a beta-adrenergic antagonist. Mast cells were obtained by lavage of the pleural and peritoneal cavities of Sprague-Dawley rats and were purified on metrizamide gradients to greater than 95% purity. Resting mast cells stimulated with beta-adrenergic agonists demonstrate a marked rise in cAMP levels after a 15-sec incubation. However, the same concentrations of these agonists have no effect on IgE-mediated mast cell histamine release. [3H]DHA binding to intact mast cells is rapid, reversible, saturable, and stereoselective. The cells possess 40,000 +/- 14,000 beta-adrenergic receptors/cell and demonstrate a binding affinity of 1.58 +/- 0.56 nM for [3H]DHA. Competition studies reveal that 83.5% of the receptors are of the beta 2 subtype and 16.5% are beta 1. Neither sensitization with anti-DNP-BSA IgE nor subsequent challenge with specific antigen alters mast cell beta-adrenergic receptor characteristics. Rat mast cells possesses large numbers of high affinity beta-adrenergic receptors, primarily of the beta 2 subtype, coupled to adenylate cyclase, but the role of these receptors in mast cell secretory events is not yet established.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D000242:Cyclic AMP / Q000032:analysis; D004082:Dihydroalprenolol / Q000378:metabolism; D004136:Dinitrobenzenes / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology; D007545:Isoproterenol / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism*; D011433:Propranolol / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000032:analysis*; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D012710:Serum Albumin, Bovine / Q000276:immunology; D013237:Stereoisomerism
chemical_list: D000318:Adrenergic beta-Agonists; D004136:Dinitrobenzenes; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D012710:Serum Albumin, Bovine; D007073:Immunoglobulin E; D004082:Dihydroalprenolol; D011433:Propranolol; D000242:Cyclic AMP; D007545:Isoproterenol