Electromyostimulation with Blood Flow Restriction Enhances Activation of mTOR and MAPK Signalling Pathways in Rat Gastrocnemius Muscles

Abstract

AimNeuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) can induce muscle hypertrophy. However, cellular mechanisms underlying the muscle hypertrophy induced by NMES combined with BFR remain unclear. Thus, the purpose of this study was to elucidate the signalling pathways involved in NMES with BFR induced muscle hypertrophy.MethodsAge‐matched male Wistar rats (6 months old, n=7 per group) were assigned randomly into control, BFR alone (BFR), NMES alone (NMES) and NMES combined with BFR (NMES/BFR) groups. NMES induced 25 isometric contractions lasting 8 s with a 4 s resting period between each contraction in the gastrocnemius muscle. Four sets in total were performed, with 1‐min intervals between each set. Latex cuff was placed on the proximal portion of hind limb and BFR was conducted in four sets (each set 5 min) with 1‐min rest intervals in between at 200 mmHg. Venous blood was collected from the lateral tail vein to determine pH, H+, lactic acid concentration before and immediately after the treatments. Expression levels of proteins related to muscle hypertrophy were determined by western blot analysis.ResultsThe application of NMES combined with BFR encouraged muscle fatigue more than NMES alone. NMES/BFR induced greater changes in accumulation of metabolites and increase in the weight of gastrocnemius muscle. The phosphorylation of mTOR and MAPK signalling related proteins also enhanced following NMES combined with BFR, compared with other conditions.ConclusionsWe elucidated that NMES enhanced the activation of mTOR and MAPK signalling pathways when combined with BFR.Support or Funding InformationThis work was supported by Japan Society for Promotion of Science (JSPS) KAKENHI Grant No. 16K16564 (T. Natsume) and Grant No. 17K01765 (T. Yoshihara). Grants from the MEXT‐Supported Program for Strategic Research Foundation at Private Universities also supported this research.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.