Use-dependent inhibition rate of sodium current at −20 and 0 mV
| Group of rats | N/n | Rate at −20 mV | N/n | Rate at 0 mV |
|---|---|---|---|---|
| Young-adult | 4 /5 | −0.03 ± 0.16 | 6 /7 | −1.89 ± 0.55* |
| Control aged | 6 /7 | −0.02 ± 0.06 | 7 /8 | −1.88 ± 0.24** |
| GH-treated aged | 3 /3 | −0.01 ± 0.09 | 2 /3 | −2.04 ± 0.33*** |
| Hex-treated aged | 5 /7 | +0.08 ± 0.24 | 2 /3 | −1.65 ± 0.29*** |
The use-dependent inhibition rate of sodium currents recorded in inside-out patches was calculated by linear regression of the normalized peak current on the number of pulse as illustrated in figure1 and is given as mean ± S.E.M. per 1000 pulses. N/n: number of rats/number of fibers. For a given potential, no significant difference was found among fiber types, but the rate observed at 0 mV is significantly higher than the rate observed at −20 mV (*P < .05; **P < .01; ***P < .005).