Table 1.
Age-associated changes of the physical characteristics and the SAN function
| Characteristics | Young | Adult | Senescent |
|---|---|---|---|
| BW (g) | 50 ± 1.2 | 350 ± 1.5* | 500 ± 4.7# |
| HW (mg) | 292 ± 14 | 1236 ± 11* | 1797 ± 15# |
| HBWR (mg/g) | 5.91 ± 0.04 | 3.36 ± 0.03* | 3.52 ± 0.03 |
| RHR (bpm) | 530 ± 7 | 382 ± 5* | 331 ± 4# |
| IHR (bpm) | 430 ± 4 | 310 ± 2* | 255 ± 5# |
| SACT (ms) | 12.5 ± 0.6 | 17.7 ± 0.2* | 22. 5 ± 0.4# |
| CSNRTmax (ms) | 33.9 ± 1.0 | 50.7 ± 3.0* | 78.1 ± 4.9# |
BW: body weight; CSNRTmax: rate-corrected maximal sinoatrial node recovery time; HBWR: heart-to-body weight ratio; HW: heart weight; IHR: intrinsic heart rate; RHR: resting heart rate; SACT: sinoatrial conduction time.
Mean ± SEM, n = 16, *P < 0.05 versus young group; #P < 0.05 versus adult group.