Fig 1.
The foot was placed at 0° of dorsal flexion. Surface electrodes were placed on the front and back surface of lower leg and plantar flexor muscles were stimulated supramaximally (45 V) for 2 s given every 6 s (A). ECC contractions comprised forced dorsiflexion from 0° to 40° at 20°/s during electrical stimulation. Typical torque traces of plantar flexion and ankle angle of dorsal flexion during eccentric contractions (B).
Table 1.
Effects of tumor-bearing and/or eccentric training on body and muscle mass in control and colon 26 mice.
Fig 2.
ECC-ES training activates protein synthesis and the mTORC1 signaling in gastrocnemius muscles from C-26 mice.
(A) Representative western blots for puromycin, total and phosphorylated p70S6K Thr389 (p-p70S6K) and rpS6 Ser240/244 (p-rpS6) in control (CNT) and C-26 mice at 6 hours after one bout of ECC-ES. The expression levels of puromycin was normalized to the whole proteins in stain-free images (B). The levels of p-p70S6K (C) and p-rpS6 (D) were normalized to total p70S6K and rpS6 content, respectively. Data show mean ± SEM for 5–7 muscles per group. Statistical significance was set at P < 0.05: main effect of *C-26 and #ECC; difference versus aCNT-untrained and bC-26-untrained.
Fig 3.
ECC training inhibits increases in E3 ubiquitin ligase MuRF1 mRNA in gastrocnemius muscles from C-26 bearing mice.
Expression levels of regulated in development and DNA damage responses (REDD) 1 (A), forkhead box O (FoxO) 1 (B), atrogin-1 (C), and muscle ring finger protein 1 (MuRF-1) (D) mRNA in gastrocnemius muscles from control (CNT) and C-26 mice with or without ECC training. Data show mean ± SEM for 5 muscles per group. Statistical significance was set at P < 0.05: main effect of *C-26 and #ECC; difference versus aCNT-untrained, bC-26-untrained, and cCNT-ECC.
Fig 4.
Increase in autophagy-related protein in gastrocnemius muscles from C-26 bearing mice.
Representative western blots for microtube-associated protein 1 light chain 3B (LC3B), Beclin-1, and p62 expression in gastrocnemius muscles from control (CNT) and C-26 mice with or without ECC training (A). The LC3B-II/LC3B-I ratio (B) and the expression levels of Beclin-1 (C) and p62 (D) normalized to GAPDH content. Data show mean ± SEM for 5 muscles per group. Statistical significance was set at P < 0.05: main effect of *C-26 and #ECC; difference versus aCNT-untrained and cCNT-ECC.
Fig 5.
The expression levels of myofibrillar proteins are not altered in gastrocnemius muscles from C-26 bearing mice.
Stain free images of myosin heavy chain (MyHC) and representative western blots for actin, tropomyosin (Tm), total troponin I (TnI), fast type troponin T (fTnT), and desmin expression of gastrocnemius muscles in control (CNT) and C-26 mice with or without eccentric (ECC) training (A). The expression levels of MyHC (B), actin (C), Tm (D), TnI (E), fTnT (F), and desmin (G) normalized to GAPDH content. Data show mean ± SEM for 5 muscles per group.