Table 4.
Model predictions at macula densa under ex vivo conditions
| Conditions | [Na+]i | [K+]i | [Cl−]i | Vbl | pHi | JNKCC2 | JNHE |
|---|---|---|---|---|---|---|---|
| Lumen [NaCl] = 25 mM (reference) | 21.7 | 152.3 | 7.6 | −79.0 | 6.87 | −20.6 | 54.6 |
| Lumen [NaCl] = 145 mM | 61.2 | 112.9 | 27.7 | −51.6 | 6.89 | 121.7 | 48.0 |
| Bath [NaCl] = 25 mM | 27.2 | 146.8 | 6.5 | −54.2 | 6.84 | 52.8 | 52.1 |
| Lumen and bath [NH4Cl] = 0.1 mM | 22.4 | 151.1 | 7.5 | −79.2 | 6.85 | −20.6 | 57.6 |
| Lumen and bath [NH4Cl] = 1.0 mM | 31.4 | 135.9 | 7.0 | −81.2 | 6.70 | −21.2 | 93.9 |
| NKCC2 × 2.0 | 21.6 | 152.3 | 7.5 | −79.2 | 6.87 | −21.1 | 54.9 |
| NKCC2 × 0.5 | 21.8 | 152.2 | 7.7 | −78.7 | 6.87 | −19.6 | 54.3 |
| NHE × 2.0 | 23.8 | 151.3 | 7.3 | −79.3 | 6.96 | −27.7 | 72.2 |
| NHE × 0.5 | 19.9 | 152.9 | 7.9 | −78.7 | 6.78 | −14.4 | 39.3 |
Reference luminal and peritubular concentrations under ex vivo conditions are given in mathematical model. JNKCC2 and JNHE, respectively, represent the Na+ fluxes across NKCC2 and apical Na+/H+ exchanger (NHE). Fluxes are given in pmol·min−1·mm−1, concentrations are in mM, and the basolateral membrane potential (Vbl) is in mV. The last 4 rows correspond to a twofold increase or decrease in the density of NKCC2 or NHE, respectively.