Abstract
Background and AimsPhysical exercise leads to substantial adaptive responses in skeletal muscles and plays a central role in a healthy life style. Since exercise induces major systemic responses, underlying cellular mechanisms are difficult to study in vivo. It was therefore desirable to develop an in vitro model that would resemble training in cultured human myotubes.MethodsElectrical pulse stimulation (EPS) was applied to adherent human myotubes. Cellular contents of ATP, phosphocreatine (PCr) and lactate were determined. Glucose and oleic acid metabolism were studied using radio-labeled substrates, and gene expression was analyzed using real-time RT-PCR. Mitochondrial content and function were measured by live imaging and determination of citrate synthase activity, respectively. Protein expression was assessed by electrophoresis and immunoblotting.ResultsHigh-frequency, acute EPS increased deoxyglucose uptake and lactate production, while cell contents of both ATP and PCr decreased. Chronic, low-frequency EPS increased oxidative capacity of cultured myotubes by increasing glucose metabolism (uptake and oxidation) and complete fatty acid oxidation. mRNA expression level of pyruvate dehydrogenase complex 4 (PDK4) was significantly increased in EPS-treated cells, while mRNA expressions of interleukin 6 (IL-6), cytochrome C and carnitin palmitoyl transferase b (CPT1b) also tended to increase. Intensity of MitoTracker®Red FM was doubled after 48 h of chronic, low-frequency EPS. Protein expression of a slow fiber type marker (MHCI) was increased in EPS-treated cells.ConclusionsOur results imply that in vitro EPS (acute, high-frequent as well as chronic, low-frequent) of human myotubes may be used to study effects of exercise.
Highlights
Physical training leads to extensive adaptations in skeletal muscles [1,2,3,4]
BSA (Bovine Serum Albumin), L-carnitine, and Dulbecco’s phosphatebuffered saline (DPBS; with Mg2+ and Ca2+), oleic acid, extracellular matrix (ECM) gel and HEPES were obtained from Sigma (St Louis, MO)
To verify that electrical stimulation of cultured human myotubes leads to expected metabolic changes, the myotubes were exposed to acute, high-frequency electrical pulse stimulation (EPS), and deoxyglucose uptake and cellular contents of ATP, PCr and lactate were examined
Summary
Physical training leads to extensive adaptations in skeletal muscles [1,2,3,4]. Regular physical activity plays central role in both prevention and improvement of many chronic diseases, improvement of life-style and increased life expectancy [2]. Molecular mechanisms underlying these adaptations are still poorly understood, emphasizing the requirement for a cell culture model resembling training ex vivo. Motor neuron activation of muscle fibres can be replaced by electrical pulse stimulation (EPS) of differentiated skeletal muscle cells (myotubes) in culture [5,6]. Physical exercise leads to substantial adaptive responses in skeletal muscles and plays a central role in a healthy life style. It was desirable to develop an in vitro model that would resemble training in cultured human myotubes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
