Fig. 5. Comparison of muscarinic cholinergic receptor density and affinity in propofol-treated tracheal smooth muscle cells. The cells were incubated in the absence (control, circles ) or presence of 100 μM ( triangles ) or 300 μM ( diamonds ) propofol for 30 min. ( A ) Binding assays were performed in triplicate with concentration of [3H]NMS ranging from 20 to 1,600 pM. Each curve represents one experiment. ( B ) Scachard plot of specific [3H]NMS binding data in ( A ). X-intercept of least-squares fit to Scachard plot is a measure of maximal receptor density (Bmax) and negative reciprocal of slope is the dissociation constant (KD). Data are from one of five experiments.