Table 1.

The effect of SMase D on hNaV inactivation kinetics in Xenopus oocytesa

Parameters hNaV1.4α hNaV1.4α + β1 hNaV1.5α hNaV1.5α + β1 muthNaV1.4αb 
Control      
τ 7.8 ± 0.2 msc 1.0 ± 0.1 msc 1.1 ± 0.04 msc 1.3 ± 0.02 msc 2.2 ± 0.1 msc 
SMase D      
τ 9.5 ± 0.2 msc    7.0 ± 0.2 msc 
τ1  0.7 ± 0.2 msd 0.5 ± 0.2 msd 0.6 ± 0.1 msd  
τ2  7.0 ± 0.2 msd 3.8 ± 0.2 msd 5.6 ± 0.2 msd  
A1/(A1 + A2)  0.32 ± 0.01d 0.34 ± 0.01d 0.47 ± 0.02d  
A2/(A1 + A2)  0.68 ± 0.01d 0.66 ± 0.01d 0.53 ± 0.02d  
Parameters hNaV1.4α hNaV1.4α + β1 hNaV1.5α hNaV1.5α + β1 muthNaV1.4αb 
Control      
τ 7.8 ± 0.2 msc 1.0 ± 0.1 msc 1.1 ± 0.04 msc 1.3 ± 0.02 msc 2.2 ± 0.1 msc 
SMase D      
τ 9.5 ± 0.2 msc    7.0 ± 0.2 msc 
τ1  0.7 ± 0.2 msd 0.5 ± 0.2 msd 0.6 ± 0.1 msd  
τ2  7.0 ± 0.2 msd 3.8 ± 0.2 msd 5.6 ± 0.2 msd  
A1/(A1 + A2)  0.32 ± 0.01d 0.34 ± 0.01d 0.47 ± 0.02d  
A2/(A1 + A2)  0.68 ± 0.01d 0.66 ± 0.01d 0.53 ± 0.02d  
a

Data is presented as mean ± SEM (n = 4 – 8).

b

Contains the S5–S6 linkers of hNaV1.5.

c

Inactivation time courses were fit to I(t)=Aet/τ.

d

Inactivation time courses were fit to I(t)=A1et/τ1+A2et/τ2.

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