Figure 5.

Triceps surae muscle macrophages (A and B) and extracellular matrix (D, G, and J) via immunofluorescence of male C57BL/6 mice exposed to physical inactivity (PIA) as hindlimb unloading (HU) or as early life ambulatory controls (CON) in the early postnatal period (days P28–42) examined in early adulthood (∼5 mo/P150) as ambulatory controls (AMB) or mice exposed to HU or HU + 7 days of reloading (RL7). The triceps surae muscle macrophage content for ambulatory controls and reload experiments (B). The relationship between triceps surae muscle macrophages and maximum grip force with all samples or ambulatory only (HU excluded; C). Wheat germ agglutinin (WGA) % area as a marker for the extracellular matrix (D) with correlations with all samples or ambulatory only (HU excluded) against macrophages (E) and maximum grip force (F). Collagen IV (COL-IV) % area (G) with correlations with all samples or ambulatory only (HU excluded) against macrophages (H) and maximum grip force (I). Degraded collagen (B-CHIP; J) with correlations with all samples or ambulatory only (HU excluded) against macrophages (K) and maximum grip force (L) Data are means ± SE. Different letters within each experimental group (CON, PIA) indicate differences (P < 0.05) across adult experimental conditions (AMB, HU, RL7). #P < 0.05 vs. CON in that condition.