Functional alpha 2-adrenoceptors in rat adipocytes: inhibition of cyclic AMP accumulation.
Alpha 2-adrenoceptor activation inhibits cyclic AMP accumulation in fat cells from many species. However, the presence of alpha 2-adrenoceptors in rat adipocytes has been difficult to demonstrate. We observed that alpha 2-adrenergic activation inhibits forskolin-stimulated cyclic AMP accumulation both in rat and hamster adipocytes; UK 14304, p-amino clonidine and clonidine were the agents with higher efficacy. The effect of UK 14304 was blocked by yohimbine but not by prazosin demonstrating the involvement of alpha 2-adrenoceptors. Pertussis toxin blocked the alpha 2-adrenergic effect. Our results demonstrate the presence in rat fat cells of alpha 2-adrenoceptors coupled to adenylate cyclase via "Gi".
García-Sáinz
J A
JA
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F.
Martínez
O M
OM
D037361:Adenylate Cyclase Toxin; D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000068438:Brimonidine Tartrate; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism*; D008297:Male; D037342:Pertussis Toxin; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D011810:Quinoxalines; D011942:Receptors, Adrenergic, alpha; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D000068438:Brimonidine Tartrate; C016986:apraclonidine; D000242:Cyclic AMP; D037342:Pertussis Toxin; D003000:Clonidine