TABLE 1

Comparison of [3H]pentamidine transport parameters in bloodstream and procyclic T. brucei brucei

High-affinity transport of [3H]pentamidine was measured at concentrations of 25 to 40 nM radiolabel or 12.5 nM for the determination of Km values; low-affinity transport was assayed at 1 μM [3H]pentamidine. Data given are the average of at least three independent experiments, each performed in triplicate ± S.E. Bloodstream forms were isolated from the blood of infected rats, whereas procyclics were cultured in standard SDM79 medium. Some of the values have been reported previously (de Koning, 2001).

Bloodstream FormsProcyclic Forms
High-Affinity Transport
    Pentamidine Km (μM)0.035 ± 0.0050.030 ± 0.003
    Pentamidine Vmax (pmol · 107 cells−1 · s−1)0.0028 ± 0.00060.031 ± 0.07
    Propamidine Ki (μM)4.6 ± 0.73.7 ± 0.4
    Diminazene Ki (μM)63 ± 354 ± 16
    DB820 Ki (μM)43 ± 1045 ± 18
    CPD0801 Ki (μM)40 ± 816 ± 4
Low-Affinity Transport
    Pentamidine Km (μM)56 ± 833 ± 10
    Pentamidine Vmax(pmol · 107 cells−1 · s−1)0.75 ± 0.150.78 ± 0.12
    Propamidine Ki (μM)316 ± 3429 ± 180
    Diminazene Ki (μM)160 ± 50180 ± 20