Table 2.
Assay conditions and observed increase of AQP facilitated lactate transport.
| Ext. pH | Lactate gradient (mmol l-1) | Neutral acid fraction (%) | Lactate transport via membrane (pmol min-1 oocyte-1) | Lactate transport via AQP (pmol min-1 oocyte-1) | Ratio of transport AQP/membrane | |
|---|---|---|---|---|---|---|
| AQP9 | 7.4 | 1 | 0.03 | 9.8 | 13.1 | 1.3 |
| 5.5 | 1 | 2.45 | ? | 51.1 | ? | |
| NIP2;1 | 7.6 | 20 | 0.02 | 27.0 | 26.0 | 1.0 |
| 6.0 | 20 | 0.79 | 43.0 | 43.0 | 1.0 | |
| 5.0 | 20 | 7.36 | 27.0 | 35.0 | 1.3 | |
| 4.5 | 20 | 20.08 | 76.0 | 108.0 | 1.6 | |
| 4.0 | 20 | 44.27 | 85.0 | 227.0 | 2.7 | |
| 3.5 | 20 | 71.53 | 139.0 | 521.0 | 3.7 | |
| LpGlpF1 | 7.0 | 80 | 0.08 | 45.3 | 62.2 | 1.4 |
| LpGlpF4 | 7.0 | 80 | 0.08 | 45.3 | 91.5 | 2.0 |
| SmAQP | 7.4 | 1 | 0.03 | 7.2 | 25.2 | 3.5 |
| 6.3 | 1 | 0.36 | ? | 54.3 | ? | |
Compared are transport rates via the Xenopus laevis oocyte plasma membrane and via AQP9 (Tsukaguchi et al., 1998), NIP2;1 (Choi and Roberts, 2007), LpGlpF1/LpGlpF4 (Bienert et al., 2013), and SmAQP (Faghiri et al., 2010). Bold numbers indicate AQP/membrane transport ratios ≥ 2 at neutral pH.