Table 1.

Electrophysiological features of cells expressing εL269F-AChRs

FeatureMouse muscleaOocytebHuman musclec
εL269FControlεL269FControlεL269FControl
Channel open times
 τ00.520.314.210.750.190.12
 τ113.23.8519.953.632.923.04
 τ2NDdND 45.44ND16.67ND
Channel conductancee76.575.1
Muscle action potentials per nerve stimulusf2–3 1
Decremental responseg13.63.0
MEPC amplitudeh2.02.9
MEPC decay phasesi
 τs7.891.44
 τ10.810.12
 τ226.63.47
  • SE and p values included in Results.

  • aDuration (msec) of brief (τ1) and long (τ2) duration channel events recorded from acutely dissociated muscle fibers at −50 mV in presence of 400 nmACh.

  • bDuration of channel events (in msec, fitted to three exponentials, τ0, τ1, and τ2) recorded in oocytes at 100 mV and 18°C in presence of 4 μm ACh after injection with mRNA corresponding to εL269F or wild-type ε subunits and wild type α, β, and δ subunits.

  • cDuration (msec) of channel burst events recorded in acutely dissociated muscle fibers at −80 mV and 22°C in presence of 1 μm ACh in patient who expressed εL269F-AChRs (Engel et al., 1996).

  • dThird component not detected.

  • eSingle-channel conductance (in pA) as determined from the current–voltage relationship.

  • fNumber of compound muscle action potentials (CMAP) recorded over mouse gastrocnemius evoked by single nerve stimulus.

  • gThe percent decrease in amplitude of the 10th CMAP recorded over intrinsic muscles of the mouse hindpaw during repetitive-nerve stimulation at 5 Hz.

  • hMiniature endplate current (MEPC) amplitude (nA) recorded in excised diaphragm.

  • iTime constant (msec) of decay phases (τs) of diaphragm MEPCs fitted to a single exponent. Time constant of first (τ1) and second (τ2) exponential of the MEPCs having biexponential decay phase.