Table 5.
Capillary, muscle and heart phenotypes in wild-type and myoglobin knockout mice following ∼13 wk feeding of a high-fat diet (45% of calories)
| Genotype |
Sex |
Genotype × Sex |
|||
|---|---|---|---|---|---|
| WT | Mb−/− | P Value | P value | P Value | |
| C:F (#capillaries/#fibers) | |||||
| Heart | na | na | |||
| GA-d | 1.60 ± 0.06 | 1.84 ± 0.05*† | <0.01 | <0.05 | ns |
| GA-s | 1.33 ± 0.05 | 1.39 ± 0.06† | ns | <0.001 | ns |
| SOL | 1.92 ± 0.07 | 2.16 ± 0.05* | <0.01 | ns (0.10) | ns |
| EDL | 1.45 ± 0.06 | 1.46 ± 0.05 | ns | <0.05 | ns |
| PLT | 2.07 ± 0.07 | 1.97 ± 0.07 | ns | ns | ns (0.06) |
| Capillary density (#/mm2) | |||||
| Heart | 2,423 ± 62 | 2,408 ± 66‡ | ns | ns (0.08) | <0.01 |
| GA-d | 740 ± 27 | 872 ± 38* | <0.01 | ns | ns |
| GA-s | 463 ± 17 | 475 ± 12† | ns | <0.001 | ns (0.072) |
| SOL | 920 ± 30 | 1,078 ± 36*† | <0.001 | <0.05 | ns |
| EDL | 764 ± 23 | 797 ± 34 | ns | ns (0.06) | ns |
| PLT | 925 ± 27 | 866 ± 45 | ns | ns | ns |
| Mean fiber area (μm2) | |||||
| Heart | na | na | |||
| GA-d | 2,051 ± 48 | 2,103 ± 84 | ns | ns | ns |
| GA-s | 2,472 ± 49 | 2,460 ± 70 | ns | ns | ns (0.072) |
| SOL | 2,029 ± 68 | 2,041 ± 68 | ns | ns | ns |
| EDL | 1,900 ± 77 | 1,782 ± 49 | ns | ns | ns |
| PLT | 2,228 ± 102 | 2,295 ± 140 | ns | ns | ns |
| Type 1 fibers (%) | |||||
| Heart | na | na | |||
| GA-d | 32.2 ± 0.01 | 34.7 ± 0.01 | ns (0.057) | ns | ns |
| GA-s | 0.3 ± 0.1 | 0.3 ± 0.1 | ns | ns | ns |
| SOL | 48.3 ± 1.3 | 49.6 ± 2.3† | ns | <0.01 | ns |
| EDL | 14.9 ± 0.9 | 14.4 ± 0.07† | ns | <0.05 | ns (0.069) |
| PLT | 40.6 ± 1.3 | 37.1 ± 1.3 | ns (0.068) | ns | ns |
| Type 2 fibers (%) | |||||
| Heart | na | na | |||
| GA-d | 67.6 ± 0.1 | 65.3 ± 0.1 | ns (0.067) | ns | ns |
| GA-s | 99.7 ± 0.1 | 99.8 ± 0.3 | ns | ns | ns |
| SOL | 52.2 ± 1.3 | 50.7 ± 2.3† | ns | <0.01 | ns |
| EDL | 85.1 ± 0.1 | 85.5 ± 0.1† | ns | <0.05 | ns (0.053) |
| PLT | 59.4 ± 1.3 | 62.9 ± 1.3 | ns (0.068) | ns | ns |
Means ± SE. na, not analyzed. Significant difference by *genotype, †sex, ‡genotype × sex interaction; ns, not statistically significant (trends at P < 0.1 in parentheses); n = 16–20/genotype. EDL, extensor digitorum longus; GA-d, gastrocnemius muscle deep; GA-s, gastrocnemius muscle superficial; Mb−/−, myoglobin knockout; PLT, plantaris; SOL, soleus; WT, wild type.