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. 2002 Sep 3;99(19):12461–12466. doi: 10.1073/pnas.192367299

Fig 2.

Fig 2.

Effect of repositioning S6 aromatic residues in HERG on biophysical properties and sensitivity to bock by cisapride. (a) Voltage pulse protocol and endogenous currents in an uninjected oocyte. (b) Block of wt HERG channel current by 30 nM, 100 nM, and 0.3 μM cisapride. (c and d) HERG/Y-up and HERG/F-down channels are only partially blocked by 10 μM cisapride. Note that HERG/F-down channel current is time-independent. (e) Effect of 0.3, 1, and 3 μM cisapride on HERG/F-up channel current. (f) Concentration–effect relationship for block of wt (▪), Y-up (•), F-down (▾), and F-up (▴) HERG channels by cisapride. The IC50 was 0.102 ± 0.001 μM and 1.60 ± 0.11 μM for wt HERG and HERG/Y-up (n = 4). (g) Voltage dependence of channel availability for wt HERG and HERG/F-up channels, determined with a triple pulse protocol. Data were fitted with a Boltzmann function (curve) to estimate one-half point (V1/2) and slope factor (k): wt-HERG (▪, V1/2 = −81.2 ± 1.4 mV, k = 25.0 ± 1.3 mV, n = 7) and HERG/F-up (▴, V1/2 = −85.3 ± 1.3 mV, k = 21.5 ± 1.2 mV, n = 8).