Figure 2. NR1/2D receptor single-channel properties in 0 Mg²⁺_o.

A, examples of NR1/2D receptor single-channel current traces recorded at −105 mV. B, open period (left) and closed-duration (right) histograms. Same patch as in A. The open period histogram was fitted by two exponentials with time constants of 60 μs (22.8%) and 655 μs (77.2%). The closed-duration histogram was fitted by four exponentials with time constants of 138 μs (15.2%), 11.7 ms (16%), 15.5 ms (2%) and 92.5 ms (66.8%). C, lack of voltage-dependence of the open period (left) and closed-duration (right) components that were observed in all patches. Time constants averaged across all voltages are: open period, 668 ± 30 μs; closed-duration, 94 ± 11 μs, 17.6 ± 3.6 ms and 124 ± 23 ms. D, example of amplitude histogram at −105 mV. Two Gaussian components were fitted to data with peaks at −2.44 pA (area, 40.4%) and at −4.73 pA. E, mean single-channel current plotted as a function of voltage. Unconstrained regression fits gave slope conductances of 19.5 and 37.4 pS and reversal potentials −1.6 and −5.5 mV, respectively.