FIG 2.

(a) Uptake of [¹⁴C]2DOG by isolated P. falciparum trophozoites in the presence of lopinavir (100 μM), compound 3361 (200 μM), or vehicle. The parasites were suspended in HEPES-buffered saline containing 200 μM glucose. (b) Uptake of [¹⁴C]2DOG by isolated P. falciparum trophozoites at increasing concentrations of lopinavir. The uptake was quenched after 2 min. IC₅₀s were calculated using nonlinear regression analysis. Uptake data are expressed as means ± SEM. A 30-s or 1-min time point would have been a more accurate measurement of initial rates; however, we chose the longer time point to enhance the uptake signal, as the degree of nonlinearity will probably not greatly affect the calculated IC₅₀ value.