title: Beta-adrenergic receptors of human lymphocytes in physically active and immobilized subjects: characterization by a polyethylene glycol precipitation assay.
abstract: To investigate the role of physical conditioning in the regulation of cellular beta-adrenergic responsiveness in man, a simple and accurate method for the determination of lymphocytic beta-adrenergic receptors was developed and subsequently utilized for the characterization of these receptors in subjects with varying degrees of physical fitness. This method combines the advantages of the use of [125I]iodocyanopindolol as the radioligand and polyethylene glycol (PEG) precipitation for the separation of bound and unbound radioligand. The assay is quick and easy to perform and allows several samples to be processed simultaneously. The concentration of beta-adrenergic receptors in lymphocytic membrane particulates in 16 healthy subjects was 58 +/- 4 fmol/mg protein (mean +/- SEM) and the Kd of the interaction between [125I]iodocyanopindolol and the receptor was 4 X 10(-11) mol/l. The receptor level was similar in both sexes. As compared with the controls, the cellular concentration of beta-adrenergic receptors was higher in eight regularly competing long-distance runners (73 +/- 4 fmol/mg protein; p less than 0.025), whereas the corresponding receptor level in six sprinters (62 +/- 9 fmol/mg protein) did not differ from that of controls. The concentration of lymphocyte beta-adrenergic receptors in seven patients undergoing supine immobilization for weeks because of neck fracture or dislocation showed a wide range from 44 to 155 fmol/mg protein.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000293:Adolescent; D000328:Adult; D011232:Chemical Precipitation; D000242:Cyclic AMP / Q000032:analysis; D005260:Female; D006801:Humans; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D008214:Lymphocytes / Q000032:analysis*; D008297:Male; D008722:Methods; D008875:Middle Aged; D010809:Physical Fitness; D010869:Pindolol / Q000031:analogs & derivatives; D011092:Polyethylene Glycols; D011943:Receptors, Adrenergic, beta / Q000032:analysis*; D012146:Rest
chemical_list: D011943:Receptors, Adrenergic, beta; D011092:Polyethylene Glycols; D020120:Iodocyanopindolol; D010869:Pindolol; D000242:Cyclic AMP; D007545:Isoproterenol