Fig. 1.

Effect of ginsenoside Rd (GSRd) on peak I_Ca,L in adult rat ventricular myocytes. Myocytes were voltage-clamped at −40 mV, and I_Ca,L was repetitively elicited by a single voltage pulse to 0 mV. (A) Consecutive exposure to different concentration GSRd (10 μmol/L, 30 μmol/L, and 100 μmol/L) resulted in consecutive further suppression of peak I_Ca,L. Upon washout of GSRd, I_Ca,L partially recovered. (B) Initial superimposed current traces of control and GSRd at times (a–d) indicated in A. (C) The concentration–response curve. Data fitted cell by cell to the following equation: IR = IR_max/[1 + ([C]/IC₅₀)^b], where IR is the inhibitory rate [(I_Ca-Cont − I_Ca-GSRd)/I_Ca-Cont × 100%]. [C], concentration of GSRd; IC₅₀, half-maximum inhibition; b = Hill index. IC₅₀ of GSRd was 32.4 ± 7.1 μmol/L, with a Hill coefficient of 1.71 (n = 21 cells).