Table 1.
Postnatal maturation of action potential properties
| Property | Age (days postnatal) |
||
|---|---|---|---|
| P11 | P15 | P25–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).