Table 1.
mTAL inflow and peritubular concentrations
| mTAL Inflow (Lumen) | OM-IM (Peritubular) | C-M (Peritubular) | MD (Peritubular) | |
|---|---|---|---|---|
| Na+ | 250 | 284 | 144 | 144 |
| K+ | 10 | 10 | 5 | 5 |
| Cl− | 232.54 | 270.94 | 123.88 | 122.88 |
| HCO3− | 25 | 25 | 25 | 25 |
| H2CO3 | 4.41 × 10−3 | 4.41 × 10−3 | 4.41 × 10−3 | 4.41 × 10−3 |
| CO2 | 1.5 | 1.5 | 1.5 | 1.5 |
| HPO4− | 6 | 3 | 2 | 2 |
| H2PO4− | 1.8 | 0.9 | 0.6 | 0.6 |
| Urea | 10 | 20 | 5 | 5 |
| NH3 | 57.3 × 10−3 | 57.3 × 10−3 | 29.4 × 10−3 | 14.7 × 10−3 |
| NH4+ | 3.84 | 3.84 | 1.97 | 0.99 |
| Ca2+ | 3.75 | 2.50 | 1.25 | 1.25 |
Concentrations are in mM. mTAL, medullary thick ascending limb; OM-IM, outer-inner medullary junction; C-M, cortico-medullary junction; MD, macula densa. Peritubular concentrations are taken to vary linearly between the OM-IM and C-M junctions; peritubular [NH4+] and [Cl−] also vary linearly between the C-M junction and the MD.