Fig. 4.
The time course and extent of desensitization are concentration-dependent. A, Plot of the peak amplitudes of the currents induced by ACh test pulses (100 μm) with respect to time before and during continuous perfusion with 1 μm (open squares), 10 μm(filled circles), or 30 μm(open circles) nicotine in oocytes expressing α3β4 receptors. τd is the time constant for a single exponential fit to the time course of desensitization. Thearrowheads represent near-equilibrium conditions at which the magnitude of desensitization was estimated (see Fig. 5).B, Representative traces of currents induced by ACh test pulses before (control) and at the indicated times during incubation with either 1 μm (top traces) or 10 μm (bottom traces) nicotine. All data were obtained in calcium-free media.