Sensitivity of Ca²⁺ Transport of Mitochondria to Reactive Oxygen Species Available to Purchase

The relationship between Ca²⁺ transport and energy transduction of myocardial mitochondria in the presence of reactive oxygen species was investigated. Following treatment with oxygen free radicals [superoxide(O₂^•) or hydroxyl radical (^•)OH], lipid free radicals in myocardial mitochondrial membrane could be detected by using the method of EPR spin trap. Simultaneously there were obvious alterations in the free Ca²⁺ ([Ca²⁺]_m) in the mitochondrial matrix; the physical state of membrane lipid; the efficiency of oxidative phosphorylation (ADP/O); the value of the respiratory control ratio (RCR); and the membrane potential of the inner membrane of myocardial mitochondria. If the concentrations of reactive oxygen species were reduced by about 30%, the alterations in the physical state of the membrane lipid and energy transduction of myocardial mitochondria were not observed, but the changes in Ca²⁺ homeostasis remained. We conclude that Ca²⁺ transport by myocardial mitochondria is more sensitive to agents such as (O₂^•) or ^•OH, etc. than are oxidation phosphorylation and the respiratory chain.