title: Comparative effects of RX 781094, mianserin, yohimbine, rauwolscine and prazosin in reversing clonidine inhibition of MIX-stimulated lipolysis in hamster isolated white fat cells.
abstract: Different alpha-adrenergic receptor antagonists: RX 781094, yohimbine and rauwolscine (selective alpha 2-adrenergic antagonists); mianserin (tetracyclic anti-depressant, antagonist at alpha 2-presynaptic autoreceptors) and prazosin (selective alpha 1-adrenergic antagonist) were used at concentrations ranging from 10(-7) to 10(-4) M, to reverse clonidine inhibition of MIX-stimulated lipolysis in the hamster fat cell. In this adipose tissue (like human but unlike rat) there co-exist prolipolytic beta-adrenoceptors and antilipolytic alpha-adrenoceptors. Although no effects were observed with prazosin, RX 781094 was ten times more potent than yohimbine or its isomer rauwolscine in reversing clonidine inhibition of the MIX-stimulated lipolysis. Mianserin was an effective blocker only from a concentration of 10(-4) M, consistent with its relative lack of specificity for alpha 2-adrenoceptors cited elsewhere. Overall these results confirm the utility of this model for testing compounds presumed to act at alpha 2-adrenoceptors.
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology*; D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000037:antagonists & inhibitors*; D006224:Cricetinae; D004146:Dioxanes / Q000494:pharmacology; D004822:Epididymis; D019329:Idazoxan; D066298:In Vitro Techniques; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D008803:Mianserin / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D013806:Theophylline / Q000031:analogs & derivatives*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D008803:Mianserin; D015016:Yohimbine; D013806:Theophylline; D003000:Clonidine; D015056:1-Methyl-3-isobutylxanthine; D011224:Prazosin; D019329:Idazoxan