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. Author manuscript; available in PMC: 2020 Feb 15.
Published in final edited form as: Circ Res. 2019 Feb 15;124(4):539–552. doi: 10.1161/CIRCRESAHA.118.314050

Figure 4: Voltage dependence of DIII-VSD activation strongly correlates with tonic block by mexiletine.

Figure 4:

A. Locations along the primary sequence and channel topology of 15 LQT3 variants tested.

B. Relationship between the voltage dependence of DIII-VSD activation (V1/2 of DIII F-V) and normalized tonic block by mexiletine. The mean ± SEM is reported for groups of 3 to 4 cells. The data were fitted with a Boltzmann function and the correlation calculated. A strong correlation (R2=0.9) between these two parameters were observed when fitted with a Boltzmann function.

C. Relationship between the SSI (V1/2 of SSI) and normalized tonic block by mexiletine. The mean ± SEM is reported for groups of 3 to 4 cells. The two parameters are not well-correlated, suggesting that channel inactivation is not a good predictor of mexiletine tonic block.