Internal cesium alters sodium inactivation in Myxicola.

When Myxicola giant axons are internally dialyzed with Cs+ as the sole cation, the time-course of prepulse inactivation is selectively accelerated compared to its rate with K+ dialysis in the same axons. This decrease in tauph occurs without any change in the magnitude or time-course of INa during step depolarizations and results in tauph/taush ratios near unity over most of the potential range in Cs+ dialyzed axons.