O2-. spin trapping on cardiac submitochondrial particles isolated from ischemic and non-ischemic myocardium.

An electron spin resonance (ESR) spin trapping technique was applied to determine the generation of superoxide anions in submitochondrial particles prepared from the ischemic heart. Ischemia was produced in the dog heart by occlusion of the circumflex coronary artery for 60 min. Mitochondria were prepared from ischemic and non-ischemic regions of myocardial tissue. To avoid the influence of superoxide dismutase located in the mitochondrial matrix, submitochondrial particles were utilized instead of whole mitochondria. Using the spin trap 5,5'-dimethyl-1-pyrroline-N-oxide (DMPO), the kind of active oxygen species generated from the mitochondrial electron transport system was determined from ESR spectrum. The relative signal intensity of the DMPO-superoxide anion adduct was found to be high in submitochondrial particles prepared from subsarcolemmal mitochondria obtained from the ischemic region, as compared with those from the non-ischemic region.