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. 2007 Feb 1;579(Pt 3):671–677. doi: 10.1113/jphysiol.2007.127977

Figure 1.

Figure 1

Functional characterization of WT and mutant AChRs in GH4C1 cells A, typical cell-attached recordings of channel openings evoked by ACh (200 nm) in cells transfected with WT or mutant AChRs, as indicated, revealing prolonged burst duration in εV259F and εT264P mutant AChRs. Traces were filtered at 1 kHz for display (5 kHz for analysis). Unitary conductance was: 49.8 pS (WT), 46.0 pS (εV259F) and 46.6 pS (εT264P). B, distribution of burst durations for the same recordings as in A, best fitted with the sum of two or three exponential components (dotted lines). Time constants (weight) of the fitting distributions in these three cells (at −100 mV membrane potential) were: for WT-AChR, τb1= 0.46 ms (42%), τb2= 2.9 ms (58%), critical τ= 4 ms; for εV259F, τb1= 0.17 ms (41%), τb2= 2.7 ms (14%), τb3= 78 ms (45%), critical τ= 4 ms; for εT264P, τb1= 0.24 ms (34%), τb2= 7.9 ms (18%), τb3= 63 ms (48%), critical τ= 1 ms. C, typical whole-cell responses to repetitive ACh (100 μm for 0.5 s) applications (black bars) in cells transfected as indicated. Dotted lines represent the exponential fit of the current peaks with the parameters given on each panel, showing the enhanced run-down of mutant AChRs. Holding potential, −60 mV. Open bars indicate superfusion with standard solution.