Figure 6.

External K⁺ speeds the closure of Na/K pump-channels opened by palytoxin. The axon was internally dialyzed with 94 mM Na⁺ and held at 0 mV throughout the measurements of (A) ²²Na⁺ efflux and (B) net membrane current. A detailed description of the experiment is given in the text. Blue lines indicate the extrapolated baselines for ²²Na⁺ efflux and net current. The red trace represents the measured efflux data transformed by Eqs. 1 and 2 using the best-fit n' value of 0.96 and least-squares delay obtained as described in Fig. 5. After a saturating concentration of ouabain partially reverses palytoxin action, replacement of all external Na⁺ with K⁺ fully restores baseline current and ²²Na⁺ efflux levels in ∼10 min.