Figure 10.

Absence of ABCB1-like activity after ATP depletion in epimastigote forms and after treatment with transport modulators in trypomastigote forms of the T. cruzi Y strain. ABCB1-like activity was evaluated by the Rhodamine 123 (Rho 123) efflux assay. (A,B) 10⁶ epimastigotes were preincubated for 60 min at 27°C with 40 mM sodium azide or 1 mM iodoacetic acid (C₂H₃IO₂) in PBS. Parasites were then centrifuged and suspended in PBS containing 100 nM Rho 123. After 30 min, parasites were centrifuged and incubated in PBS for another 30 min. (C,D) 10⁶ trypomastigotes were incubated in medium containing 100 nM Rho 123 in the presence or absence of 2 μM cyclosporin A (CsA) or 10 μM of either verapamil (VP) or trifluoperazine (TFP) for 30 min. Parasites were then centrifuged and incubated in medium in the presence or absence of the modulators for another 30 min. After incubation, parasites were centrifuged, suspended in PBS and maintained on ice for acquisition by flow cytometry. Graphs in (A,C) represent the median fluorescence intensity (MFI) for Rho 123 and in (B,D) the percentages of Rho 123+ parasites at 37°C. The Friedman statistical test was used with n = 8 independent experiments. Lines represent the median for each group and the significance values were represented by ^**p < 0.01 and ^***p < 0.001.