Quantitative characterization of beta-adrenergic receptor subtypes in porcine adipocytes.
1. Two populations of beta-adrenergic receptor (beta AR) subtypes and their proportions were characterized in adipocytes isolated from subcutaneous adipose tissue of castrated male crossbred pigs (60-85 kg). 2. Specific binding of the radioligand 125I-iodopindolol (IPIN) to crude plasma membranes (70-90% of total binding) reached equilibrium conditions in 30 min (38 degrees C), was tissue concentration-dependent, stereospecific and saturable (bmax = 168 +/- 5.8 fmol/mg protein). 3. Displacement curves by ICI 89,406 were best-fit by a two site model (P less than 0.01) that indicated the presence of two receptor populations and selectivity of IPIN for the beta 2AR subtype. 4. Forty-five percent of the receptors had a high affinity for ICI 89,406, Ki = 2.27 +/- 0.68 nM and were classified as beta 1AR.
Coutinho
L L
LL
Department of Animal Science, Michigan State University, E. Lansing 48824.
Bergen
W G
WG
Merkel
R A
RA
Smith
C K
CK
D000273:Adipose Tissue / Q000737:chemistry* / Q000166:cytology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000187:drug effects; D013552:Swine / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta