FIG 4.

Effect of dronedarone (Droned) on the [Ca²⁺]_i of L. mexicana promastigotes. Promastigotes were loaded as described under Materials and Methods. (A) Effect of 2.5 μM dronedarone (arrow) on the parasite cytoplasmic Ca²⁺ concentration in the presence of 2 mM external Ca²⁺. (B) Effect of 2.5 μM dronedarone (arrow) on fura 2-loaded promastigotes in the absence of external Ca²⁺ (EGTA). (C) Effect of 0.65 nM dronedarone (arrow) on the parasite cytoplasmic Ca²⁺ concentration in the presence of 2 mM external Ca²⁺. The figures shown are representative of at least three independent experiments. (D) Initial slopes (300 s) of the curves obtained in the presence of 2 mM external Ca²⁺. The first and second slopes were taken from at least three independent experiments similar to that shown in panel A. The slope named IC₅₀ was taken from at least three independent experiments similar to that shown in panel C. Each point represents the mean ± SD. *, significant difference (measured using Student's t test, P < 0.01); nd, not determined.