Fig. 2.

Menthol does not compete for the nAChR agonist binding site labeled by [³H]epibatidine. Membranes from human embryonic kidney cells expressing α3β4 nAChRs were incubated for 2 hours with ∼0.5 nM [³H]EB in the absence or presence of increasing concentrations of menthol or nicotine. The membranes were then filtered and counted. Data were analyzed by nonlinear least-squares regression analysis. The K_i of nicotine in these studies was 256 nM. Menthol at concentrations up to 1 mM did not compete for these receptors. Data shown are the mean ± S.E.M. of five independent assays.