title: Characteristics of beta-adrenergic receptors in isolated cells and in crude membranes of brown adipose tissue.
abstract: In relation to decreased metabolic sensitivity to catecholamines observed, in vitro, in brown fat of cold-acclimated rats, beta-adrenergic receptors were studied in isolated cells and in a crude membrane preparation from rat interscapular brown adipose tissue. [3H] dihydroalprenolol binding had the same characteristics in both types of preparation; competition studies of [3H] dihydroalprenolol binding led to the characterization of beta 1 subtype adrenergic receptors with a lower affinity of beta-adrenergic agonists for [3H] dihydroalprenolol binding sites in membranes than that found in isolated cells. Cold acclimation produced, in isolated cells only, a decrease of 41% in the [3H] dihydroalprenolol binding sites and a beta-adrenergic agonist affinity increase. It is concluded that beta-adrenergic receptor decrease could be a factor, at the hormone receptor interaction level, in the regulation of the transmission of biological action responsible for the cold-induced decrease in catecholamine responsiveness in brown adipose tissue. For a study of the desensitization process in brown fat, isolated cells seem to offer certain advantages over a crude membrane preparation.
mesh_terms: D000222:Adaptation, Physiological; D002001:Adipose Tissue, Brown / Q000166:cytology*; D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000032:analysis; D003080:Cold Temperature; D004082:Dihydroalprenolol / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
chemical_list: D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol