Changes in cytoplasmic [Ca2+] induced by actin-acting drugs. [Ca2+]c was assessed based on the fluorescence of Calcium green-1, as described in the Methods section. All data were representative of at least four independent experiments. F0 represented the fluorescence intensity value of Calcium green-1 before treatments, and F represented the fluorescence intensity value in same root hair after treatments. (A) and (B) Changes in [Ca2+]c after the application of actin drugs at different concentrations in testing medium over a 10 min period. The intersections of the horizontal dashed line and the two vertical dashed lines indicated when [Ca2+]c decreased to a level lower than that of before treatment. (C) The effect of 100 μM La3+ on the Lat-B-induced [Ca2+]c increase as indicated by Calcium green-1 fluorescence intensity. The intersection of the horizontal and vertical dashed lines indicated when [Ca2+]c decreased to a level lower than that of before treatment. (D) Ca2+ release from internal Ca2+ stores due to the inhibition of the ER by 2 μM thapsigargin, after which Lat-B elicited a long lasting [Ca2+]c increase attributable to the opening of the mPTP. The drugs were applied for the durations indicated by the horizontal bars. The dashed line showed the start time of the Lat-B treatment.