Distinct Adaptations of Mitochondrial Dynamics to Electrical Pulse Stimulation in Lean and Severely Obese Primary Myotubes

BACKGROUNDSkeletal muscle from lean and obese subjects elicit differential adaptations in response to exercise/muscle contractions. In order to determine whether obesity alters the adaptations in mitochondrial dynamics in response to exercise/muscle contractions and whether any of these distinct adaptations are linked to alterations in insulin sensitivity, we compared the effects of electrical pulse stimulation (EPS) on mitochondrial network structure and regulatory proteins in mitochondrial dynamics in myotubes from lean humans and humans with severe obesity and evaluated the correlations between these regulatory proteins and insulin signaling. METHODSMyotubes from human skeletal muscle cells obtained from lean humans (BMI 23.8 ± 1.67 kg/m) and humans with severer obesity (45.5 ± 2.26 kg/m) (n=8/group) were electrically stimulated for 24 hours. Four-hours after EPS, mitochondrial network structure, protein markers of insulin signaling and mitochondrial dynamics were assessed. RESULTSEPS enhanced insulin-stimulated Akt phosphorylation, reduced the number of non-networked individual mitochondria and increased the mitochondrial network size in both groups (P