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 Forms | Procyclic Forms | |
|---|---|---|
| High-Affinity Transport | ||
| Pentamidine Km (μM) | 0.035 ± 0.005 | 0.030 ± 0.003 |
| Pentamidine Vmax (pmol · 107 cells−1 · s−1) | 0.0028 ± 0.0006 | 0.031 ± 0.07 |
| Propamidine Ki (μM) | 4.6 ± 0.7 | 3.7 ± 0.4 |
| Diminazene Ki (μM) | 63 ± 3 | 54 ± 16 |
| DB820 Ki (μM) | 43 ± 10 | 45 ± 18 |
| CPD0801 Ki (μM) | 40 ± 8 | 16 ± 4 |
| Low-Affinity Transport | ||
| Pentamidine Km (μM) | 56 ± 8 | 33 ± 10 |
| Pentamidine Vmax(pmol · 107 cells−1 · s−1) | 0.75 ± 0.15 | 0.78 ± 0.12 |
| Propamidine Ki (μM) | 316 ± 3 | 429 ± 180 |
| Diminazene Ki (μM) | 160 ± 50 | 180 ± 20 |