Table 1.
Contractile and Morphometric Properties of the Extensor Digitorum Longus Muscle Following sActRIIB Therapy in the mdx Mouse Model of Duchenne Muscular Dystrophy
| Variable | 1.0 mg/kg−1 Treatment⁎ |
10.0 mg/kg−1 Treatment⁎ |
||||
|---|---|---|---|---|---|---|
| Control mdx | Treated mdx | P value | Control mdx | Treated mdx | P value | |
| Contraction time (ms) | 34.0 ± 1.6 | 37.5 ± 1.6 | 0.1545 | 41.0 ± 2.3 | 38.0 ± 1.3 | 0.2790 |
| ½ Relaxation time (ms) | 37.5 ± 1.3 | 38.6 ± 2.1 | 0.6583 | 47.0 ± 2.5 | 44.5 ± 1.4 | 0.3924 |
| ECC force drop (%) | 22.8 ± 5.6 | 15.5 ± 1.4 | 0.2438 | 27.9 ± 2.4 | 33.3 ± 4.7 | 0.2938 |
| Total fibers (no.) | 769.7 ± 38.6 | 633.3 ± 46.0 | 0.0638 | 742.0 ± 28.1 | 842.4 ± 71.4 | 0.1910 |
| CN fibers (%) | 52.3 ± 4.6 | 62.3 ± 5.9 | 0.2079 | 52.2 ± 5.6 | 43.2 ± 6.0 | 0.3066 |
| PO-positive fibers (%) | 6.9 ± 2.1 | 8.7 ± 3.8 | 0.6754 | 11.9 ± 2.3 | 11.1 ± 1.1 | 0.7544 |
CN, centrally nucleated; ECC, eccentric contraction; ms, milliseconds; PO, Procion Orange.
⁎
Treatment: Inhibition of activin receptor type IIB (ActRIIB) signaling was achieved using a fusion protein comprised of a form of the extracellular domain of ActRIIB linked to the Fc portion of murine IgG (RAP-031; Acceleron Pharma, Cambridge, MA).