Table 4.
Physiological and anatomical characteristics of wild type, Bax KO, and MyoGDNF medial gastrocnemius muscle
| Wild type | Bax KO | MyoGDNF | |
|---|---|---|---|
| Twitch force (mN) | 540 ± 140 (15) | 590 ± 140 (11) | 200 ± 60 (6)* |
| Twitch rise time (ms) | 23 ± 3 (11) | 22 ± 3 (9) | 24 ± 2 (6) |
| Twitch half-width (ms) | 21 ± 2 (11) | 21 ± 2 (9) | 22 ± 3 (6) |
| Tetanus force (N) | 2.2 ± 0.4 (7) | 3.0 ± 0.4 (6)* | 1.3 ± 0.3 (6)* |
| Tetanus 50% fatigue (s) | 1.1 ± 0.3 (7) | 0.9 ± 0.4 (6) | 2.7 ± 1.2 (6)* |
| Tetanus/twitch | 4.9 ± 1.2 (7) | 5.4 ± 1.3 (6) | 6.6 ± 1.4 (6) |
| Fixed muscle mass (g) | 0.17 ± 0.03(21) | 0.18 ± 0.02(11) | 0.08 ± 0.01(13)* |
| Neuromuscular junctions | 4931 ± 342(3) | 5134 ± 449(3) | 4341 ± 465(3) |
| Fibers/mm2 (head) | 1370 ± 30 (3) | 1340 ± 70 (3) | 2680 ± 520 (3)* |
| Fibers/mm2 (insertion) | 880 ± 90 (3) | 760 ± 100 (3) | 2620 ± 220 (3)* |
| Fiber size μ m2 (head) | 83 ± 29 (3) | 90 ± 27 (3) | 41 ± 00 (3)* |
| Fiber size μ m2 (insertion) | 138 ± 41 (3) | 151 ± 47 (3) | 37 ± 8 (3)* |
Values shown are mean ± SD (number of animals is in parentheses). Fiber density (medial gastrocnemius) was estimated from a 400 × 400 μm2 area and fiber size (cross-section area) from 50 fibers per group.
*Significant difference from wild type (p < 0.05, t test).