Animals ; Diet, High-Fat ; Glucagon ; blood ; Glucose ; metabolism ; Hormones ; blood ; Insulin ; blood ; Leptin ; blood ; Lipid Metabolism ; Male ; Rats ; Rats, Sprague-Dawley

Objective To investigate the influence of mechanical stretch at different frequencies on proliferation and aerobic capacity of mice myoblast cells C2C12. Methods C2C12 cells cultured in vivo were exposed to mechanical strain with the magnitude of 15% at the frequency of 1 and 2 Hz, respectively, for 2 hours per day over a period of 4 days by using Flexercell Cell Tension System, while in control group C2C12 cells were cultured statically. The C2C12 cells were observed by inverted phase contrast microscope. CCK-8 Cell Counting Kit was used to estimate the proliferation of cells. After the experiment, the cells were obtained by trypsin digestion. MitoXpress-Xtra system with oxygen sensitive probe was induced to detect the extracellular oxygen consumption level. Results The morphology of C2C12 cells presented a typical long spindle under the microscope following the mechanical stretch stimulation. The cells were arranged in a certain direction, parallel to the direction of tension stimulation and growing in good condition. Compare with the control group, the cell numbers in 1 Hz group and 2 Hz group were significantly increased (P<0.05). At the 3rd and 4th day, number of cells in 1Hz group was significantly increased than that in 2 Hz group. However, the oxygen consumption capacity increased in both 1 Hz group and 2 Hz group, but no significant difference was found between experiment groups (P>0.05). Conclusions Cyclic mechanical stretch stimulation can effectively induce proliferation of C2C12 cells, which is related to the frequency of mechanical stretch, with the frequency of 1 Hz being optimum. But stretch stimulation has no significant impact on the aerobic ability of C2C12 cells.

OBJECTIVETo illustrate the molecular mechanism of skeletal muscle growth by examining the effect of swimming training on skeletal muscle growth and p70s6k, rpS6 protein expression.

METHODSTwenty four male SD rats were used to establish swimming training models with a 15% body mass load. The training protocol adopted interval swimming training (every other day with 8 weeks). The gastrocnemius and soleus muscle were collected and weighed after training, and the protein expression of p70s6k, rpS6 and their phosphorylated forms were examined.

RESULTSAfter 8 weeks treatment, no significant change was observed in skeletal muscle mass between training group (T) and control group (C) (P > 0.05), but muscle mass in training rapamycin (TR) group has a significantly decrease compared with that in T and C groups (P < 0.05). Soleus and gastrocnemius muscle mass index in T group increased significantly compared with C group (P < 0.05). Compared with the C group, the ratio of P-p70s6k/p70s6k in T group increased with significant difference (P < 0.05), but the ratio in TR group was significantly reduced (P < 0.05). The ratio of P-rpS6/rpS6 had a significant difference between TR and T group (P < 0.05).

CONCLUSIONThese results suggest that the interval training protocol is helpful to increase the relative muscle hypertrophy, and has a role in promoting the expression of p70s6k and rpS6.

Animals ; Male ; Muscle, Skeletal ; growth & development ; metabolism ; physiology ; Physical Conditioning, Animal ; Rats ; Rats, Sprague-Dawley ; Ribosomal Protein S6 Kinases, 70-kDa ; metabolism ; Swimming

OBJECTIVE: To investigate the effects of 650 nm laser irradiation on cell oxygen consumption rate in CC myoblasts following different doses. METHODS: CC cells were irradiated with 650 nm laser(λ=650 nm, p=5 mW) with energy densities of 0, 0.4, and 0.8 J/cm. Cell oxidative function was measured by oxygen consumption rate kit. Protein expression of myogenic determination factor (MyoD), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), mammalian target of rapamycin (mTOR) and its phosphorylation were detected by Western blot. RESULTS: Compared to the control group, the expression levels of MyoD, PGC-1α protein were increased and cell oxygen consumption rate was promoted in the low dose group(<0.05). MyoD and PGC-1α protein expressions were also increased(<0.05), the ratio of mTOR and its phosphorylationwere decreased significantly in the high dose group(<0.05). CONCLUSIONS 650 nm laser irradiation that dose is 0.4 J/cm enhances cell oxidative function, it related to that proper dose laser irradiation promoted the expression of PGC-1a protein.
Animals ; Cell Line ; Mice ; Myoblasts ; Oxidation-Reduction ; Oxygen Consumption ; Transcription Factors