![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
BE Levin and AC Sullivan
A new in vitro radioligand binding assay is described for brown adipose tissue using the beta adrenergic antagonist [3H]CGP 12177 (4-(3-t- butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazol-2-one). Binding was saturable and stereoselectively inhibited by propranolol. There was 60 to 80% specific binding using either 30 microM l-isoproterenol or 10 microM l-propranolol to define nonsaturable binding. [3H]CGP 12177 was bound to partially purified membranes from collagenase-separated brown adipocytes with a Kd of 0.84 nM, as determined from kinetic studies, and 1.24 +/- 0.13 nM as found by equilibrium binding studies; maximum binding was 14.2 +/- 0.9 fmol/mg of protein. Membranes from whole-pad homogenates had a similar Kd of 1.17 +/- 0.14 nM but twice the maximum number of binding sites (28.5 +/- 4.4 fmol/mg of protein). Intact brown adipocytes had a Kd of 0.55 nM and a maximum binding of 29.4 +/- 1.5 fmol X 10(-6)/cell or 17,700 sites per cell. Competitive binding studies showed about 80% of the binding sites to be of the beta-1 and 20% of the beta-2 subtype. The pA2 values derived from inhibition of isoproterenol-stimulated in vitro oxygen consumption in intact brown adipocytes by the beta-1 selective antagonist metoprolol and beta-2 selective lCl 118551 were in close agreement with their respective K1 values at the beta-1 receptor as derived from competitive binding studies. These data strongly suggest that the beta-1 adrenoreceptor on brown adipose tissue is primarily responsible for the initiation of thermogenesis in this tissue.
This article has been cited by other articles:
|
|
 |
|
  B. CANNON and J. NEDERGAARD Brown Adipose Tissue: Function and Physiological Significance Physiol Rev, January 1, 2004; 84(1): 277 - 359. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Chernogubova, B. Cannon, and T. Bengtsson Norepinephrine Increases Glucose Transport in Brown Adipocytes via {beta}3-Adrenoceptors through a cAMP, PKA, and PI3-Kinase-Dependent Pathway Stimulating Conventional and Novel PKCs Endocrinology, January 1, 2004; 145(1): 269 - 280. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Farias-Silva, D. M. Grassi-Kassisse, V. Wolf-Nunes, and R. C. Spadari-Bratfisch Stress-induced alteration in the lipolytic response to {beta}-adrenoceptor agonists in rat white adipocytes J. Lipid Res., September 1, 1999; 40(9): 1719 - 1727. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. Zhao, B. Cannon, and J. Nedergaard Thermogenesis is beta 3- but not beta 1-adrenergically mediated in rat brown fat cells, even after cold acclimation Am J Physiol Regulatory Integrative Comp Physiol, December 1, 1998; 275(6): R2002 - R2011. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Bengtsson, K. Redegren, A. D. Strosberg, J. Nedergaard, and B. Cannon Down-regulation of beta 3 Adrenoreceptor Gene Expression in Brown Fat Cells Is Transient and Recovery Is Dependent upon a Short-lived Protein Factor J. Biol. Chem., December 27, 1996; 271(52): 33366 - 33375. [Abstract] [Full Text] [PDF]
|
|
 |
 |
 |
|
 |
 |
 |
