Fig. 1.

NMDA-gated single-channel currents in outside-out patches excised from cerebellar granule cells of wild-type and ε1 subunit-ablated mutant mice. Single-channel currents were activated by 50 μm NMDA in patches excised from cerebellar granule cells at −70 mV holding potential in nominally Mg²⁺-free solution containing 1 mm Ca²⁺, 10 μm glycine, 0.3 μmtetrodotoxin, and 1.0 μm strychnine. Channel openings in a patch from P9 (A) and P21 (B) wild-type (+/+) mice and P9 (C) and P21 (D) ε1 mutant (−/−) mice are shown. In D, the currents recorded from the patch with only low-conductance channels are illustrated.Dashed lines in sample records (upper panel) indicate the mean current amplitudes derived from the corresponding single-channel amplitude distribution (histograms in lower panels). Main levels and sublevels of high-conductance channels were 49.2 ± 1.1 pS and 40.2 ± 1.1 pS (n = 5) at P9 wild-type, 51.8 ± 1.4 pS and 42.3 ± 2.1 pS (n = 6) at P21 wild-type, and 50.0 ± 0.60 pS and 40.3 ± 0.59 pS (n = 7) at P9 ε1 mutant (−/−). Main levels and sublevels of low-conductance channels were 36.4 ± 0.64 and 19.5 ± 1.7 pS (n = 4) at P21 wild-type and 33.7 ± 1.4 pS and 18.2 ± 0.52 pS (n = 6) at P21 ε1 mutant (−/−). For illustration, records were filtered at 1 kHz (−3 dB).