SENSITIVITY OF CA2+ TRANSPORT OF MITOCHONDRIA TO REACTIVE OXYGEN SPECIES

The relationship between Ca2+ transport and energy transduction of myo cardial mitochondria in the presence of reactive oxygen species was in vestigated. Following treatment with oxygen free radicals [superoxide( O-2(.-)) or hydroxyl radical ((OH)-O-.)], lipid free radicals in myoca rdial mitochondrial membrane could be detected by using the method of EPR spin trap. Simultaneously there were obvious alterations in the fr ee 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 pot ential of the inner membrane of myocardial mitochondria. If the concen trations of reactive oxygen species were reduced by about 30%, the alt erations in the physical state of the membrane lipid and energy transd uction of myocardial mitochondria were not observed, but the changes i n Ca2+ homeostasis remained. We conclude that Ca2+ transport by myocar dial mitochondria is more sensitive to agents such as O-2(.-) or (OH)- O-., etc. than are oxidation phosphorylation and the respiratory chain .