TABLE 1.
Echocardiographic parameters for wild-type, heterozygous Irx4Δex2/+ mice, and homozygous Irx4Δex2/Δex2 micea
| Mouse age (wks) | Genotype (n) | HR (min−1) | LVAW (mm) | LVPW (mm) | LVEDD (mm) | LVESD (mm) | LVFS (%) | VcF (circumferences/s) |
|---|---|---|---|---|---|---|---|---|
| 6 | Wild type (6) | 559 ± 41 | 0.78 ± 0.02 | 0.78 ± 0.02 | 3.20 ± 0.06 | 1.51 ± 0.12 | 53 ± 3 | ND |
| Irx4Δex2/+ (4) | 551 ± 17 | 0.87 ± 0.01 | 0.86 ± 0.01 | 3.00 ± 0.11 | 1.33 ± 0.05 | 55 ± 2 | ND | |
| Irx4Δex2/Δex2 (6) | 566 ± 22 | 0.90 ± 0.06 | 0.90 ± 0.06 | 3.22 ± 0.09 | 1.65 ± 0.15 | 48 ± 3 | ND | |
| 24–30 | Wild type (6) | 547 ± 41 | 0.85 ± 0.04 | 0.85 ± 0.04 | 3.37 ± 0.17 | 1.51 ± 0.20 | 55 ± 5 | 10.7 ± 1.2 |
| Irx4Δex2/+ (5) | 525 ± 27 | 1.00 ± 0.04∗ | 1.00 ± 0.04∗ | 3.20 ± 0.20 | 1.46 ± 0.14 | 55 ± 2 | 9.4 ± 0.4 | |
| Irx4Δex2/Δex2 (7) | 453 ± 24 | 1.06 ± 0.03∗ | 1.06 ± 0.03∗ | 3.65 ± 0.15 | 2.22 ± 0.22∗# | 40 ± 4∗# | 7.1 ± 0.6∗ |
a
∗, significant difference (P < 0.05) compared with wild-type mice; #, significant difference (P < 0.05) compared with Irx4Δex2/+ mice. HR, heart rate; LVAW, LV anterior wall thickness; LVEDD, LV end-diastolic diameter; LVFS, LV fractional shortening; LVPW, LV posterior wall thickness; LVESD, LV systolic diameter; VcF, velocity of fiber shortening; ND, not determined.