Inhibition by analogs of adenine and adenosine on uridine transport by TLCT1 and ARAC/D2 stable transfectants
Transport of 10 μM [3H]uridine into TLCT1 and ARAC/D2 transfectants was measured in sodium-containing transport buffer in the absence or presence of 1 mM test compound as described under Materials and Methods. Initial rates of uptake were obtained from 180-s uptake time courses. The results are the means ± S.D. of triplicate determinations. The ratios of transport rates were determined by dividing rates in the presence of test compound by rates obtained in their absence.
| Test Compounds | (hCNT1) | ARAC/D2 (hCNT2) | ||
|---|---|---|---|---|
| Transport Ratesa | Ratio | Transport Ratesa | Ratio | |
| pmol / μl cell water / s | pmol / μl cell water / s | |||
| No additive | 0.290 ± 0.004 | 1 | 0.105 ± 0.002 | 1 |
| Uridine | 0.005 ± 0.002 | 0.02 | 0.002 ± 0.003 | 0.02 |
| Adenosine | 0.005 ± 0.004 | 0.02 | 0.002 ± 0.004 | 0.02 |
| 2′-Deoxyadenosine | 0.003 ± 0.003 | 0.01 | 0.002 ± 0.001 | 0.02 |
| 5′-Deoxyadenosine | 0.037 ± 0.002 | 0.13 | 0.023 ± 0.003 | 0.22 |
| 2′-3′-Dideoxyadenosine | 0.281 ± 0.003 | 0.97 | 0.092 ± 0.003 | 0.88 |
| 2-Chloroadenosine | 0.032 ± 0.004 | 0.11 | 0.016 ± 0.004 | 0.15 |
| 8-Chloroadenosine | 0.191 ± 0.002 | 0.66 | 0.064 ± 0.002 | 0.61 |
| N6-(p-aminobenzyl)adenosine | 0.004 ± 0.003 | 0.01 | 0.003 ± 0.001 | 0.03 |
| Adenine | 0.289 ± 0.004 | 0.99 | 0.098 ± 0.003 | 0.93 |
| Caffeine | 0.003 ± 0.005 | 0.01 | 0.003 ± 0.001 | 0.03 |
| erythro-9-(2-Hydroxy-3-nonyl)adenine | 0.276 ± 0.004 | 0.95 | 0.052 ± 0.004 | 0.49 |
| Nicotine | 0.002 ± 0.006 | 0.01 | 0.025 ± 0.002 | 0.24 |
↵ a Uridine transport rates, mean ± S.D.