Effects of Wenxin Keli (WK) on L-type calcium channel current (ICa). A: Representative current traces in the presence and the absence of 5g/L WK. B: Normalized averaged I-V relationship for ICa at different concentrations of WK (n=4–9). C: Averaged steady-state activation plot for ICa at different concentrations of WK. The normalized conductance vs. voltage plots where fit with a single Boltzmann function (n=9, 5 and 4 for control, 5g/L and 10 g/L WK, respectively). D: Representative example of the inhibitory effects of WK on unloaded cell shortening in field stimulated isolated myocytes. WK (1 g/L, 5g/L, 10g/L) was added sequentially to the bath solution for 120 seconds each during continuous field stimulation at 0.5 Hz.