Figure 1.

RPR260243 (RPR) slows deactivation kinetics in WT and R56Q LQTS2-associated mutant channels in a concentration-dependent manner. (A and B) Typical current traces recorded in response to the voltage protocol shown at 21°C from Xenopus oocytes (A), and at 37°C from whole-cell patch-clamp of HEK cells (B) during control conditions (C) and in response to application of RPR260243 at the indicated concentration. Recordings from WT channels are shown in black, and from R56Q mutant channels in blue. (C and D) Plots of mean deactivation time constants (left) and their relative amplitude (right) derived from double exponential fits of current decay during deactivation at 21°C (C; n = 5 for WT, n = 6 for R56Q) and 37°C (D; n = 5). Relative amplitudes are represented as the fast phase amplitude relative to the amplitude of total current decay (see Materials and methods, as well as Table 1). *, significant difference from control value; **, significant difference from WT control value.