The Effect of 20-Hydroxyecdysone on the Functioning of Isolated Mouse Skeletal Muscle Mitochondria

In this work we have studied the effect of the phytoecdysteroid 20-hydroxyecdysone (20E) on the functioning of mouse skeletal muscle mitochondria. It is shown that 20E at a concentration of 100 µM or more suppresses mitochondrial respiration fueled by glutamate and malate (substrates of complex I of the respiratory chain) or succinate (substrate of complex II of the respiratory chain). This effect of 20E is accompanied by a decrease in the mitochondrial membrane potential and is associated with inhibition of the activity of complex III, the total activity of complexes I + III and II + III of the mitochondrial respiratory chain. We have noted a prooxidant effect of 20E, which manifests itself in an increase in the production of hydrogen peroxide by skeletal muscle mitochondria. In addition, 20E reduces the ability of mitochondria to accumulate calcium ions in the matrix. We discuss the mechanisms of the possible toxic effect of 20E on the functioning of skeletal muscle mitochondria.