Table 1.
Properties of action potential and diastolic depolarization in Cav1.2DHP−/− SANC.
| Firing Cav1.2DHP−/− SANC (n = 21) | Responder Dormant Cav1.2DHP−/− SANC (n = 12) | |||||
|---|---|---|---|---|---|---|
| Baseline | ISO | ISO + Nife | Baseline | ISO | ISO + Nife | |
| Frequency (AP·min−1) | 197 ± 22 | 401 ± 15 **** | 176 ± 30 $$$$ | NA | 320 ± 46 | 49 ± 31 |
| MDP (mV) |
−59.8 ± 1.5 | −60.3 ± 1.4 | −61.7 ± 1.6 | NA | −53.4 ± 2 | −59.9 ± 3.3 |
| Linear slope (mV·ms−1) |
0.042 ± 0.005 | 0.092 ± 0.009 *** | 0.053 ± 0.004 $$$ | NA | 0.080 ± 0.008 | 0.079 ± 0.005 |
| Expo slope (mV·ms−1) |
0.317 ± 0.019 | 0.596 ± 0.042 **** | 0.340 ± 0.018 $$$$ | NA | 0.452 ± 0.046 | 0.411 ± 0.012 |
| AP threshold (mV) |
−43.7 ± 1.5 | −42.2 ± 1.5 * | −41.7 ± 1.7 | NA | −30.1 ± 2.5 | −34.9 ± 2.8 |
| Upstroke (mV·ms−1) |
13.9 ± 2.8 | 13.3 ± 2.6 | 13.4 ± 2.8 | NA | 6.1 ± 2.9 | 5.4 ± 0.3 |
| AP amplitude (mV) |
82.3 ± 2.9 | 85.9 ± 3.3 | 89.1 ± 4 | NA | 68.3 ± 4 | 84.1 ± 7.1 |
| AP duration (ms) |
133.6 ± 4.4 | 108.9 ± 3.5 **** | 111.4 ± 4.3 | NA | 117.1 ± 9.1 | 105.2 ± 15.1 |
| Coefficient of variation |
0.42 ± 0.12 | 0.06 ± 0.01 **** | 0.47 ± 0.15 $$$ | NA | 0.43 ± 0.22 | 1.11 ± 0.67 |
Data are expressed as mean ± SEM; MDP, maximum diastolic potential; NA, not applicable. * p < 0.05, *** p < 0.001, **** p < 0.0001 vs. firing SANC at baseline control by one-way ANOVA (parametric) or Friedman test (non-parametric). $$$ p < 0.001, $$$$ p < 0.0001 vs. firing SANC under ISO perfusion by one-way ANOVA (parametric) or Friedman test (non-parametric). Only n = 3 dormant SANC did not stop under ISO + Nife condition, hence no statistical analysis was performed.