Fig. 3.

The mechanism of 5-HT₃ receptor inhibition by scopolamine. (A) Concentration-response curves were performed in the absence or presence of the indicated concentrations of scopolamine. The curves showed parallel dextral shifts with maximal currents restored by increasing concentrations of 5-HT. Parameters derived from these curves can be seen in Table 1. (B) A Schild plot was created from the dose ratios of the curves shown in 3A and fitted with Eq. (3) to yield a slope of 1.06 ± 0.10 (R² = 0.97) and a pA₂ of 5.03 ± 0.43 (K_b, 9.33 μM).