Association and dissociation kinetics of [3H]44 (A,B) and [3H]64 (C,D) determined at CHO-hM2R cell homogenates at 23 °C.
(A) Association of [3H]44 (c = 2 nM) with the M2R. Inset: ln[B(eq)/(B(eq) – B(t))] vs time. (B) Dissociation of [3H]44 (preincubation: 4 nM, 1 h) from the M2R determined in
the presence of 6 (1000-fold excess), showing complete
monophasic exponential decline. Inset: ln[B(t)/B(0)] vs time. (C)
Association of [3H]64 (c =
0.6 nM) with the M2R. Inset: ln[B(eq)/(B(eq) – B(t))] vs time. (D) Dissociation of [3H]64 (preincubation: 0.6 nM, 1 h) from the M2R determined in the presence of 6 (1000-fold
excess), showing incomplete monophasic exponential decline. Inset:
ln[(B(t) – B(plateau)/B(0)]
versus time. For kon and koff values, see Table 2. Data represent mean ± SEM from three (A,B,D)
or two (C) independent experiments (each performed in triplicate).