Table 2. Na+ transport kinetic constants for NHE1 in Amphiuma RBCs stimulated to steady-state in isosmotic solution with 500 nM CLA, or mildly hyperosmotic (1.2×IR) solution ± CLA.
Treatment | Km(mM Na+) | Jmax (mmoles Na+/Kg dcs minute |
Isosmotic (1×IR) | NA | 0.02±0.01* |
Isosmotic (1×IR) + CLA | 44.3±7.7 | 10.4±1.4 |
Hyperosmotic (1.2×IR) | 43.3±36.8 | 3.4±1.4 |
Hyperosmotic (1.2×IR) + CLA | 44.4±11.8 | 19.8±2.5 |
Kinetic constants are expressed as Km or Jmax ± SEM. Values for Km are similar in all 3 conditions, while Jmax is increased by CLA treatment relative to hyperosmotic medium alone. Estimated* (by hyperbolic curve-fit) Jmax activity in the unstimulated isosmotic condition is also shown.