Figure 2.

Electrophysiological characterization of ReaChR photocurrents and membrane response in ventricular cardiomyocytes derived from TAC and sham-operated animals. In all voltage- and current-clamp experiments, ReaChR was activated by 470-nm light (1 s, 10 mW/mm²). (A) Representative whole-cell voltage clamp recording of ReaChR photocurrents from an isolated TAC cardiomyocyte. The membrane potential was clamped at −90 mV. I_peak: maximal current amplitude, I_plateau: current amplitude at the end of the illumination period, time-to-peak: the length of the time interval between the beginning of illumination and the appearance of I_peak, τ_inact: half-decay time of current decay from I_peak to I_plateau, τ_off: half-decay time of current decay from I_plateau to zero current. (B) ReaChR I_plateau amplitudes observed at a range of holding potentials between −110 and 50 mV. (C) Time-to-peak values of ReaChR current representing activation kinetics of ReaChR. (D) τ_inact values of ReaChR current representing ReaChR inactivation kinetics. (E) τ_off time constant representing ReaChR closing kinetics. (F and G) ReaChR I_peak (F) and I_plateau (G) amplitudes measured at −90 mV holding potentials. (H) Representative membrane potential response to 470 nm illumination (blue bar) recorded under current-clamp conditions in a cardiomyocyte isolated from a TAC animal. (I) Resting membrane potentials (V_rest) observed before illumination. (J) Plateau potentials (V_plateau) measured at the end of the 1 s light pulse. Each dot represents the results of an individual cell. For (C–H), n = 8 cells from four hearts in the TAC group and n = 7 cells from two hearts in the sham group. For (I) and (J), n = 7 cells from four hearts in the TAC group and n = 5 cells from two hearts in the sham group. Numerical data are represented as mean ± SEM, all P-values were calculated by the Student’s t-test.