Fig. 6.

All-or-none mechanism of fast water conductance: inhibition of fast water transport by K⁺. G was equivalent to ≈20,000 open channels. At 10 and 100 mM KCl, the channels mediated a water permeability P_f,c of ≈30 μm/s (black solid and dashed lines). At 0.3 and 0.4 M K⁺, P_f,c was immeasurably small (Inset), indicating inhibition of the fast transport mode (gray solid and dashed lines). At the intermediate 0.2 M K⁺ concentration (dark gray), part of the channels showed high water permeability.