Fig 4. Estimated transition times of (a) Na⁺ binding (from extracellular to bound states, in ns), (b) Na⁺ dissociation (from bound to extracellular states, in μs), and (c) Na⁺ egress (from bound to intracellular states, in s) as a function of extracellular Na⁺ concentration.

The Na⁺ concentration in the cytoplasm is assumed to be constant. Transition times are calculated as the median of the mean first passage times calculated from individual bootstrap samples and the full sample. Confidence intervals were estimated as the differences from the 1^st and 3^rd quartiles.