Table I. Heart rate and dysrhythmia in HCN2-deficient mice.
| Parameter | Genotype | Rest | Active | Isoproterenol | Atropine | Methoxamine |
|---|---|---|---|---|---|---|
| Heart rate (per min) | HCN2+/+ | 531 ± 17 | 673 ± 6 | 727 ± 8 | 723 ± 12 | 311 ± 25 |
| HCN2–/– | 510 ± 9 | 677 ± 17 | 708 ± 15 | 692 ± 4 | 377 ± 28 | |
| SDRR (ms) | HCN2+/+ | 7 ± 1 | 5 ± 2 | 4 ± 1 | 3 ± 1 | 46 ± 18 |
| HCN2–/– | 17 ± 1a | 5 ± 7 | 3 ± 1 | 1 ± 0 | 34 ± 8 |
aSignificant difference (P < 0.001) between corresponding values from wild-type and HCN2-deficient mice. SDRR, standard deviation of RR intervals representing a measure of dysrhythmia. Each group included six animals.