Is the Second Sodium Pump Electrogenic?

Figure 2

Short-Circuit current (𝐼_sc) in permeabilized MDCK cells: Na⁺-free media. A typical record is shown to demonstrate the experimental protocol. After equilibration in Na⁺-free medium, amphotericin B (10 μM) was added to the apical solution, to permeabilize the apical plasma membrane to small cations. This maneuver allows measuring basolateral pump currents. Then, Na⁺-free media was replaced by Na⁺-containing medium (50 mM) and the effects of ouabain (0.25 and 0.5 mM) was evaluated.