THE COMPARSION OF AFFINITY BETWEEN BUNITROLOL AND PROPRANOLOL TO MYOCARDIAL B-ADRENERGIC RECE- PTORS / 中国药理学通报

The maximum specific binding(Bmax)and the dissociation constants(K D) of 8H -dihydroalprenolol in rat myocardial membrane are 104.1 +4. 7 fmol/mg protein and 10.1+2.7nM, respectively, and the Hill coeffici-ent(nn) is equal to 1.007+0.002. The half inhibition concentration concentration ( IC50) of bunitrolol and propranolol on 3H - dihydroal- prcnolol binding to myocardial B-adrenergic receptors are 3.30+ 0. 74 x 10- 8M ,and 3. 87+0.66 x 10-7M , the apparant dissociation constants (Kl) are 2.2+0.48x10-8M and 2.58+0.44x10-7M, respectively. The affinity of bunitrolol to myocardial B-adrener-gic receptors is 11.7 times as potent as propra'nolol.