FIG. 1.

Uptake of sitamaquine in L. donovani parasites. (A) Effect of temperature on [¹⁴C]sitamaquine uptake. Cells were incubated with 5 μM [¹⁴C]sitamaquine for 15 min at 4°C and 28°C, with (+) and without (−) subsequent washing with 100 μM nonradioactive sitamaquine. No significant differences were observed in sitamaquine accumulation at 4°C and 28°C (P > 0.05). (B) Effect of nonradioactive sitamaquine on [¹⁴C]sitamaquine uptake. Cells were incubated with 5 μM [¹⁴C]sitamaquine and at the same time with increasing concentrations of nonradioactive sitamaquine at 28°C. After 15 min, cells were washed with 100 μM sitamaquine. (C) Effect of extracellular pH on [¹⁴C]sitamaquine uptake. Cells were incubated with [¹⁴C]sitamaquine in HBS at several pHs and processed as described above. Results are means ± standard deviations of three independent experiments. SQ, sitamaquine.