Beta-adrenergic receptors and cyclic adenosine monophosphate generation in human fetal lung

Pediatric Research
D J DavisJ M Roberts

Abstract

We designed experiments to determine whether beta-adrenergic receptors are present and functional in human fetal lung during the 2nd trimester of gestation. To determine the presence of beta receptors, characterize their binding sites, and assess changes in receptor with gestational age, we performed radioligand binding assays with the specific, high-affinity beta antagonist, 125I-iodocyanopindolol, in membrane particulates from the lungs of 2nd trimester abortuses (15-23 wk). Binding of 125I-iodocyanopindolol was saturable and of high affinity (dissociation constant = 40 pM). Binding was stereoselective as determined by competition studies with (-) and (+) stereoisomers of propranolol. Agonist affinities (isoproterenol greater than epinephrine much greater than norepinephrine) were consistent with a predominance of beta-2 receptors; this predominance was confirmed by competition studies with the specific beta-2 receptor antagonist ICI 118-551 (75% beta-2, 25% beta-1). The concentration of beta-adrenergic receptors increased with gestational age. To assess the functional coupling of the beta receptors, we tested the ability of receptor occupancy to activate adenylate cyclase. For this assay, we incubated minced human fetal lung...Continue Reading

Citations

Dec 1, 1988·Proceedings of the National Academy of Sciences of the United States of America·H G LileyP L Ballard
Nov 11, 2008·Pediatric Critical Care Medicine : a Journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies·Brian Wu, Dennis W Nielson
Sep 18, 2002·Journal of Applied Physiology·Edward D Crandall, Richard M Effros

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