Some characteristics of the beta-adrenergic system in rat adipocyte membranes after the chronic administrations of isoproterenol.
The effects of chronic administrations of isoproterenol (IPR) on adipocyte beta-adrenergic system were investigated. A 21-days in vivo administration of IPR (2.5 mg/kg BW/day) reduced (-)-IPR- and 5'-guanylylimidodiphosphate-stimulated adenylate cyclase activities. Moreover, the number of beta-adrenergic receptors (beta-AR) and (-)-IPR-stimulated [3H]GDP release from adipocyte membranes were significantly depressed in the treated rats compared to controls. These results suggest that the desensitized response of adenylate cyclase to beta-agonists, induced by chronic in vivo administrations of IPR, may result from impaired coupling efficiency between beta-AR and adenylate cyclase with the significant loss of the number of beta-AR and possible change(s) of guanine nucleotide regulatory proteins.
Izawa
T
T
Laboratory for Exercise and Applied Physiology, Tokyo College of Pharmacy, Japan.
Komabayashi
T
T
Suda
K
K
Kunisada
Y
Y
Shinoda
S
S
Tsuboi
M
M
D000262:Adenylyl Cyclases / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D000818:Animals; D006153:Guanosine Diphosphate / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
D011943:Receptors, Adrenergic, beta; D006153:Guanosine Diphosphate; D000262:Adenylyl Cyclases; D007545:Isoproterenol