Fig. 2.

Effects of cocaine on nicotine-induced currents mediated by α₃β₄ nAChRs in SH-SY5Y cells. Typical traces of responses to the indicated concentrations of nicotine in the absence of cocaine (a, indicated by horizontal black bar) or with 30 s cocaine pretreatment (b, indicated by open horizontal bar). The traces from (a) and (b) were recorded from the same cell. c Statistical comparison of the inhibitory rate of cocaine against nicotine-induced current. All symbols were normalized to the peak amplitude of 1000 µM nicotine-induced current, to form the concentration-response curves for responses to the indicated concentrations of nicotine either alone (open symbols) or coapplied with 1.5 µM cocaine (filled symbols). The data are represented as the mean ± SEM. d Bar graph shows that cocaine equally inhibited different concentrations of nicotine-induced inward currents (**P < 0.01)