High Intensity Interval Training (HIIT) Induces Specific Changes in Respiration and Electron Leakage in the Mitochondria of Different Rat Skeletal Muscles

Abstract

High intensity interval training (HIIT) is characterized by vigorous exercise with short rest intervals. Hydrogen peroxide (H2O2) plays a key role in muscle adaptation. This study aimed to evaluate whether HIIT promotes similar H2O2 formation via O2 consumption (electron leakage) in three skeletal muscles with different twitch characteristics. Rats were assigned to two groups: sedentary (n=10) and HIIT (n=10, swimming training). We collected the tibialis anterior (TA-fast), gastrocnemius (GAST-fast/slow) and soleus (SOL-slow) muscles. The fibers were analyzed for mitochondrial respiration, H2O2 production and citrate synthase (CS) activity. A multi-substrate (glycerol phosphate (G3P), pyruvate, malate, glutamate and succinate) approach was used to analyze the mitochondria in permeabilized fibers. Compared to the control group, oxygen flow coupled to ATP synthesis, complex I and complex II was higher in the TA of the HIIT group by 1.5-, 3.0- and 2.7-fold, respectively. In contrast, oxygen consumed by mitochondrial glycerol phosphate dehydrogenase (mGPdH) was 30% lower. Surprisingly, the oxygen flow coupled to ATP synthesis was 42% lower after HIIT in the SOL. Moreover, oxygen flow coupled to ATP synthesis and complex II was higher by 1.4- and 2.7-fold in the GAST of the HIIT group. After HIIT, CS activity increased 1.3-fold in the TA, and H2O2 production was 1.3-fold higher in the TA at sites containing mGPdH. No significant differences in H2O2 production were detected in the SOL. Surprisingly, HIIT increased H2O2 production in the GAST via complex II, phosphorylation, oligomycin and antimycin by 1.6-, 1.8-, 2.2-, and 2.2-fold, respectively. Electron leakage was 3.3-fold higher in the TA with G3P and 1.8-fold higher in the GAST with multiple substrates. Unexpectedly, the HIIT protocol induced different respiration and electron leakage responses in different types of muscle.

Preservation of skeletal muscle mitochondrial content in older adults: relationship between mitochondria, fibre type and high‐intensity exercise training

“…In rats, intense exercise increased mitochondrial respiration in tibialis anterior compared to soleus (Ramos‐Filho et al . ). The specific upregulation of NDUFA9 in type II fibres may be related to the exercise employed which may recruit more type II fibres (Kristensen et al .…”

Decrement in resting and insulin‐stimulated soleus muscle mitochondrial respiration is an early event in diet‐induced obesity in mice

“…The specific rate of H 2 O 2 production was determined using a linear regression curve fitted with Origin v.8.0 (OriginLab, Northampton, MA, USA). Hydrogen peroxide emission is expressed as picomoles per minute per milligram (Ramos‐Filho et al., ).…”

Moderate dependence of reactive oxygen species production on membrane potential in avian muscle mitochondria oxidizing glycerol 3-phosphate

“…Given that mGPDH and GP are components that interlink cytosolic and mitochondrial energy transduction pathways, some physiological stimuli that could activate this pathway might also induce mGPDH/GPmediated superoxide production. A few studies have reported that high-intensity training altered mitochondrial functions in skeletal muscle [25,26], and the training augmented GP-supported mitochondrial superoxide production [26]. We recently found that hyperthermia induced GP-supported superoxide production in avian muscle mitochondria [27].…”