Determination of beta-adrenoceptor subtypes in human pulmonary artery and thoracic aorta by radioligand binding.
The beta-adrenoceptors of human pulmonary artery (PA) and thoracic aorta (TA) were studied by the use of a high specific activity radioligand [125I]pindolol (Pin). To identify the subtypes of beta-adrenoceptors in the 2 blood vessels, the competitive inhibition curves of [125I]Pin by beta 1-antagonist atenolol and beta 2-agonist salbutamol were analyzed using a computer program LIGAND of a mathematical model of the ligand-binding system. The Bmax (15.3 +/- 1.2 fmol/mg protein) and the dissociation constant Kd (44 +/- 4 pmol.L-1) for PA were similar to those for TA (Bmax, 12.8 +/- 1.2 fmol/mg protein, Kd, 45 +/- 4 pmol.L-1). Competitive inhibition analysis showed that the beta 1- and beta 2-adrenoceptor subtypes coexisted in human PA and TA, with beta 1 adrenoceptor dominant. The ratios of beta 1:beta 2 in PA and TA were 2.9:1.0 and 2.1:1.0, respectively.
Peng
H L
HL
Department of Pharmacology, School of Pharmacy, Shanghai Medical University, China.
Jiang
M H
MH
Yang
Z C
ZC
D000420:Albuterol / Q000494:pharmacology*; D001011:Aorta / Q000378:metabolism*; D001262:Atenolol / Q000494:pharmacology*; D001667:Binding, Competitive; D006801:Humans; D010869:Pindolol / Q000378:metabolism*; D011651:Pulmonary Artery / Q000378:metabolism*; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000145:classification / Q000378:metabolism*
D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D010869:Pindolol; D000420:Albuterol