Table 1.

Fractional magnitudes of time constants for L689I ionic current, gating current, and fluorescence during the onset of SI

Channel variant (measured parameter)AFAIASCn
L689I (I)0.10 ± 0.010.06 ± 0.02a0.54 ± 0.040.30 ± 0.057
L689I (Q) (2 µM TTX)0.11 ± 0.040.05 ± 0.020.20 ± 0.050.63 ± 0.045
L689I DI (F)0.15 ± 0.02a0.12 ± 0.050.29 ± 0.060.45 ± 0.03a7
L689I DII (F)0.12 ± 0.050.06 ± 0.03a0.21 ± 0.030.61 ± 0.05a4
L689I DIII (F)0.26 ± 0.070.15 ± 0.060.31 ± 0.040.28 ± 0.098
L689I DIV (F)0.28 ± 0.080.04 ± 0.020.26 ± 0.130.42 ± 0.126
  • First, SI of ionic current at +45 mV was fit using three exponentials with time constants for fast, intermediate, and slow components: τF = 1.8 ± 0.2 s, τI = 13.1 ± 1.1 s, and τS = 195 ± 33 s. Because the three time constants span the time domains of our protocol, they can be held constant and used to describe data from ionic, gating, and fluorescence measurements by varying the fractional magnitude of each component. The table shows the fractional magnitude of each component for all studies in this paper. n, the number of cells studied; I, current assessed after subtraction of Q; F indicates a fit to fluorescence; DI, DII, DIII, and DIV indicate L689I channels that also carry the single site changes DI-S216C, DII-S660C, DIII-L115C, and DIV-S1436C, respectively.

  • a Parameter is significantly different from WT.