title: Inhibition of the lipolytic action of beta-adrenergic agonists in human adipocytes by alpha-adrenergic agonists.
abstract: The aim of this study was to define the role of the alpha-adrenergic receptor in the regulation of lipolysis by human adipocytes. Glycerol production by isolated human adipocytes was stimulated by the pure beta-adrenergic agonist isoproterenol in a dose-dependent fashion. This stimulation of lipolysis was inhibited by the alpha-adrenergic agonists methoxamine, phenylephrine, and clonidine. Epinephrine-stimulated lipolysis was potentiated by the alpha-adrenergic antagonists, dihydroergocryptine, phentolamine, phenoxybenzamine, and yohimbine. Whereas the attenuation of beta-adrenergic agonist-stimulated lipolysis by alpha-adrenergic agonists was reversed completely by the alpha 2-adrenergic antagonist yohimbine, the alpha 1-antagonist prazosin did not reverse such attenuation. It is concluded that alpha-adrenergic agonists act as antilipolytic agents in human adipocytes and that this action may result from the interaction of these compounds with a population of alpha 2-adrenergic receptors.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008053:Lipid Mobilization / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology
chemical_list: D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D011942:Receptors, Adrenergic, alpha; D007545:Isoproterenol; D003000:Clonidine; D004837:Epinephrine