however , the number of beta-adrenergic receptors measured by binding of [ 125i ] iodocyanopindolol , a potent beta-adrenergic antagonist , was very low in purified plasma membranes of freshly isolated cells ( 20 fmol/mg of protein ) , and the number increased about 6-fold without change in the dissociation constant ( kd = 132 pm ) when the cells were cultured for 7 h .
C0034785
beta-adrenergic receptors
C0007603
plasma membranes