title: Alpha 1-adrenergic receptors in the adult, neonatal, and fetal canine heart.
abstract: Using the radioligand, iodo-2-[beta-(4-hydroxyphenyl)ethylaminomethyl]tetralone ([125I]-IBE 2254), alpha 1-adrenergic receptors were identified in membranes isolated from fetal, neonatal, and adult canine ventricular myocardium. Binding of the radioligand to alpha 1-adrenergic sites in adult canine heart was rapid, reversible, stereoselective and saturable. Computer analysis of binding data indicated 2 classes of receptors; one with very high affinity and limited capacity (Kd = 13 +/- 9 pM, Bmax = 25 +/- 15 fmol/mg, n = 5) and a second site with lower affinity and greater capacity (Kd = 1.20 +/- 0.43 nM, Bmax = 510 +/- 165 fmol/mg). Two sites were also identified in membranes isolated from fetal and neonatal canine ventricular myocardium. At the higher affinity site, all the age groups displayed similar capacities and affinities. At the lower affinity site, however both fetal and neonatal membranes displayed greater capacity than that of the adult.
mesh_terms: D000317:Adrenergic alpha-Antagonists; D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D004285:Dogs; D005260:Female; D005333:Fetus / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D010627:Phenethylamines; D011247:Pregnancy; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D044024:Tetralones
chemical_list: D000317:Adrenergic alpha-Antagonists; D010627:Phenethylamines; D011942:Receptors, Adrenergic, alpha; D044024:Tetralones; C010652:BE 2254