Fig. 3.
Extrasynaptic NMDA channels in outside-out patches. A, Single-channel records from an outside-out patch taken from the soma of a P12 granule cell (Vcmd = −80, −60, and −40 mV). Inward currents in response to bath application of 1 μmglutamate and 3 μm glycine indicate the opening of1 or 2 channels from the closed level (C). B, Histogram of cursor-fit channel amplitudes at −60 mV. The data are fit by two Gaussian distributions (solid line) with the current levels of −2.86 ± 0.13 (88.7%) and −2.27 ± 0.13 pA (mean ± SD). For a reversal potential of −6.4 mV (see C), this corresponds to single-channel chord conductances of 53.3 and 42.3 pS.C, Current–voltage relationship for channel openings from the same cell as A and B (all-point amplitude measurements). The solid line is a linear regression through the data, yielding a slope conductance of 49.7 pS and an extrapolated reversal potential of −6.4 mV.