Fig. 6.
Single-channel properties of recombinant α1 and α1P250T receptor channels. A, Thetop trace shows single-channel currents of homomeric wild-type channels recorded from an outside-out patch in the presence of 100 μm glycine. The bottom trace shows an experiment with a patch containing multiple homomeric mutant receptor channels, with the arrow indicating the application of 1 mm glycine. In the continued presence of glycine, the baseline (dotted line) was reached within 1 sec. Note the increase in noise after the application of glycine. The holding potential was −100 mV. For display, data were refiltered at fc = 1 kHz. B, Nonstationary variance analysis of outside-out patches. The top panel shows 10 superimposed traces with the mean current printed ingray. The bottom panel shows the mean variance plotted versus time. C, Plot of the mean variance obtained from a total of 30 responses in this patch as a function of the mean current. The data were fitted with Equation 3 (see Materials and Methods), the obtained parameters are:i = 1.6 pS; popen = 0.01; N = 42.