[Formation of superoxide radicals in isolated cardiac mitochondria: effect of low oxygen concentration].

The formation of superoxide radical in isolated rat heart mitochondria under conditions of variable oxygen concentration has been studied by the spin trapping technique and EPR oximetry. Lithium phthalocyanine and TEMPONE-D-15 N16 were used to determine the oxygen concentration. TIRON was used as a spin trap. By varying the oxygen content in reaction medium, it was shown that isolated heart mitochondria can produce superoxide even at an oxygen partial pressure of 17.5 mmHg. However, the rate of superoxide generation was considerably lower than in control. It was found that increasing the oxygen concentration leads to an increase in the rate of superoxide generation.