Evidence of functional alpha 2-adrenergic receptors in adult-rat adipocytes by using the agonist UK 14304.
The aim of this study was to re-assess whether alpha 2-adrenergic receptors were present in rat adipocytes, by using UK 14304, a new and very selective alpha 2-agonist. The following observations demonstrate the presence of functional alpha 2-adrenoceptors in rat adipocytes. (1) Adipocyte lipolysis was dose-dependently inhibited by UK 14304 (maximal effect 80% at 1 microM-UK 14304, 45% at 10 microM-UK 14304, under basal or theophylline-stimulated conditions respectively). (2) UK 14304 bound specifically to purified plasma membranes, with Bmax. = 744 fmol/mg of protein and KD = 9 nM. (3) The effect of UK 14304 was suppressed by alpha 2-antagonists. (4) Adrenaline inhibited lipolysis upon beta-adrenergic blockade (propranolol). (5) The anti-lipolytic effect of UK 14304 was modulated by the age of the rats.
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000367:Age Factors; D000818:Animals; D000068438:Brimonidine Tartrate; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003000:Clonidine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D008066:Lipolysis / Q000187:drug effects; D008297:Male; D011810:Quinoxalines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011924:Rats, Zucker; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D011810:Quinoxalines; D011942:Receptors, Adrenergic, alpha; D000068438:Brimonidine Tartrate; D013806:Theophylline; D003000:Clonidine; D004837:Epinephrine