Figure 5.

Effects of calcium removal. Following a record in 100Ca 100Na, the fiber was washed with 0Ca 100Na for approximately 30 s (15 chamber volumes). Forty-one seconds after beginning the wash, I_Na is increased both during the activating pulse (to 0 mV) and during deactivation (at −80 mV) because of decreased channel block by calcium. The tail time constant (τ) is approximately doubled at 41 s, and it increases progressively to 1224 μs at 68 s. At this time I_Na is very small. It recovers completely in 100Ca 100Na: the bracketing traces in this solution superimpose almost perfectly. Temperature: 8°C.