Fig. 5.
Menthol inhibits α3β4 nAChRs in a voltage- and use-independent manner and without affecting single-channel conductance. (A) Current voltage relationship for peak response to ACh (30 μM) and after 20-second application of menthol (100 μM). The background current in the absence of ACh is subtracted. The inset shows the fraction of the menthol versus control current at indicated potentials. (B) Responses to repeated, 5-second stimulation with ACh (30 μM) under control conditions (upper trace) or in the presence of 200 μM menthol (lower trace). Scale bars, 1 nA and 20 seconds. (C) Mean peak responses to ACh from experiments depicted in (B) (n = 3). (D) Representative single-channel currents from a cell-attached patch (VM, –110 mV, 10 μM ACh in pipette) under control conditions (upper trace) and in the presence of 200 μM menthol. (E) All-points histograms constructed from 2 seconds of continuous data. The smooth lines represent best-fits to Gaussian functions yielding similar conductances (G) of 30.9 and 30.3 pS respectively. (F) Mean open time measured from data in (E) (measured from >50 events).