Table 2.
Function of working heart preparations from cTnT-ND transgenic and wild type mice
| 55 mmHg afterload | 90 mmHg afterload | |||
|---|---|---|---|---|
| WT (n = 5) | cTnT-ND (n = 4) | WT (n = 5) | cTnT-ND (n = 4) | |
| Heart weight/body weight (mg g−1) | 5.89 ± 0.46 | 5.82 ± 0.38 | — | — |
| Heart rate (beats min−1) | 480 | 480 | 480 | 480 |
| LVPmax (mmHg) | 72.48 ± 1.78 | 73.02 ± 1.21 | 103.12 ± 1.27‡ | 105.21 ± 1.91‡ |
| LVPmin (mmHg) | 2.02 ± 0.56 | 1.87 ± 0.46 | 1.78 ± 0.84 | 2.04 ± 0.82 |
| +dP/dtmax (mmHg s−1) | 3847 ± 128 | 3479 ± 104* | 5024 ± 224‡ | 4796 ± 281‡ |
| –dP/dtmax (mmHg s−1) | 3311 ± 151 | 3331 ± 122 | 5268 ± 231‡ | 5123 ± 376‡ |
| TP50 (ms) | 19.5 ± 0.9 | 20.1 ± 0.8 | 20.6 ± 0.6 | 21 ± 0.4 |
| TP (ms) | 43.3 ± 4.6 | 43.8 ± 2.9 | 38.5 ± 1.0 | 42 ± 2.6 |
| TR75 (ms) | 44.5 ± 3.5 | 44.2 ± 1.7 | 50 ± 0.2 | 47 ± 1.4 |
| Stroke volume (μl mg−1) | 0.096 ± 0.010 | 0.107 ± 0.006 | 0.074 ± 0.010‡ | 0.102 ± 0.007† |
The functional measurements show that cTnT-ND hearts decreased +dP/dtmax at 55 mmHg afterload in comparison with the wild type (WT) hearts. When afterload increased from 55 mmHg to 90 mmHg, LVPmax and ±dP/dtmax increased in both WT and cTnT-ND hearts. Whereas stroke volume decreased significantly in WT hearts when the afterload was increased, cTnT-ND hearts sustained the stroke volume, demonstrating a tolerance to pressure overload.
*
P < 0.05 versus WT control;
†
P < 0.05 versus WT control at 90 mmHg afterload by one-tailed t test;
‡
P < 0.01 versus that at 55 mmHg afterload by paired Student's t test.