Figure 4.

Influence of nAChR intracellular domain upon the kinetics of desensitization. α7 loop (a) and α10 loop (b) are shown as examples of chimaeras with slow and fast desensitization, respectively. Subunits chimaeras were expressed in tsA201 cells whole-cell responses obtained by 20 s applications of 50 μM DMPP. These were inverted and fitted with one or the sum of two exponential functions of the form I=I_ss+I_max*e^(−t/τ), where I_ss is the steady state current, I_max the peak steady-state current, τ, the time constant. The insets show, on an expanded timescale, the fit to the initial part of the response. Traces are representative examples of n=8–21 responses from 3–12 cells. DMPP, 1,1-dimethyl-4-phenylpiperazinium iodide; nAChR, nicotinic acetylcholine receptor.