Table 1.
Values are illustrative/approximated based on literature averages and our laboratory experiences.
| Parameter | Human | Mouse | Difference (mouse vs. human) |
|---|---|---|---|
| Anatomical/Systemic | |||
| Myocyte size (μm) | 140×20×15 | 140×20×15 | not different |
| Sarcomere length (μm) | 2.0–2.2 | 2.0–2.2 | not different |
| Force per myocyte (μN) | 10–15 | 10–15 | not different |
| Systolic pressure (mmHg) | 110 | 110 | not different |
|
| |||
| EC-coupling | |||
| Non-SR Ca2+ cycling per beat (% total) | 30 | 3 | ~10-fold lower |
| APD 90% (ms) | 300 | 30 | ~10-fold faster |
| Myosin isoform$ | human β (MYH7) | mouse α (MYH6) | >5-fold faster |
|
| |||
| Baseline Kinetics (at rest) | |||
| Resting Heart Rate (bpm) | 50–70 | 500–700 | ~10-fold higher |
| dP/dtmax (mmHg/s) | 1500 | 15000 | ~10-fold higher |
| TTP (ms) | 185 | 35 | >5-fold faster |
| RT50% (ms) | 130 | 20 | >5-fold faster |
|
| |||
| Kinetic Reserve | |||
| Increase in HR (% rest) | 100–200 | 10–50 | >5-fold less |
| Acceleration of TTP (% rest) | 35 | 5 | >5-fold less |
| Acceleration of RT50% (% rest) | 40 | 5 | >5-fold less |
ADP: Action potential duration to 90% repolarization.
$
Quantitative myosin isoform difference reflects the combined difference in species and isoform.
TTP: Time to peak tension in an isometrically contracting myocardial muscle preparation. RT50%: Time from peak tension to 50% relaxation in an isometrically contracting myocardial muscle preparation. Kinetic reserve values reflect differences at maximal heart rate compared to the species’ resting rate.