Table 1.

Postnatal maturation of action potential properties

PropertyAge (days postnatal)
P11P15P25–P29
AP threshold (mV)−39.5 ± 0.94 (5)−44.8 ± 0.95 (9)*−45.4 ± 0.77 (19)*
Relative AP threshold (mV above Vm)24.0 ± 0.81 (5)21.7 ± 1.4 (9)24.1 ± 1.0 (19)
AP amplitude (mV above threshold)75.7 ± 3.0 (5)82.1 ± 1.8 (9)84.8 ± 1.4 (19)*
AP rise time 10–90% (ms)0.246 ± 0.014 (5)0.214 ± 0.0083 (9)0.194 ± 0.0065 (19)**
AP half-width (ms)1.18 ± 0.082 (5)0.786 ± 0.020 (9)0.680 ± 0.020 (19)***,#
Peak AP derivative (Vs − 1)314 ± 29 (5)419 ± 27 (9)475 ± 17 (21)**
Slow AHP amplitude (mV)−13.0 ± 0.83 (5)−8.74 ± 1.5 (9)**−8.91 ± 0.46 (17)*
  • All results are shown as mean ± SEM (n). Significance was determined by nonparametric Kruskal–Wallis test followed by Dunn's multiple comparison post-tests. Overall differences were statistically significant (p < 0.05) for all variables except for relative AP threshold (p = 0.374). Action potential and afterhyperpolarizing potential (AHP) amplitudes are expressed relative to AP threshold (Vt).

  • *p < 0.05;

  • **p < 0.01;

  • ***p < 0.001 (significantly different from P11 level);

  • #p < 0.05 (significantly different from P15 level).