Figure 7.

Effect of recombinant macrophage-colony stimulating factor (M-CSF) delivery to aged mice following hindlimb unloading. A: sections of soleus muscles from aged mice that received vehicle or M-CSF injections were measured for the abundance of cells positive for Dapi, CD68, and CD163. B: representative image of soleus cross sections. C–H: ex vivo force production of soleus muscles from aged mice during early recovery following hindlimb unloading that received intramuscular injections of M-CSF or PBS (Vehicle) into contralateral hindlimbs. C–F: muscles were subjected to a single pulse stimulation to induce a twitch contraction for the measurement of specific force (C), rate of contraction (D), or rate of relaxation (E). F: raw force tracings from a single-pulse stimulation that induced a twitch contraction. G: the specific force was measured across a range of stimulation frequencies from 10 to 200 Hz. H: raw force tracings from a 100 Hz stimulation. A and C–E: individual data points are shown and connected with respective contralateral limbs and the mean is represented as a bar and relative to Vehicle. G: data points are shown as means ± SE. Paired t tests (A, and C–E) or a two-way ANOVA with Sidak’s multiple-comparisons test (G) was used. C–E, and G: n = 6/group or n = 4/group (A).