Free radical metabolites in myocardium during ischemia and reperfusion.
Low-temperature electron paramagnetic resonance (EPR) spectroscopy and spin traps were used to measure paramagnetic species generation in rat hearts and isolated mitochondria. The hearts were freeze-clamped at 77 K during control perfusion by the Langendorff procedure, after 20-30 min of normothermic ischemia or 10-30 s of reperfusion with oxygenated perfusate. All EPR spectra measured at 4.5-50 K exhibited signals of both mitochondrial free radical centers and FeS proteins. The analysis of spectral parameters measured at 243 K showed that free radicals in heart tissue were semiquinones of coenzyme Q10 and flavins. The appearance of a typical "doublet" signal at g = 1.99 in low-temperature spectra indicated that a part of ubisemiquinones formed a complex with a high potential FeS protein of succinate dehydrogenase. Ischemia decreased the free radical species in myocardium approximately 50%; the initiation of reflow of perfusate resulted in quick increase of the EPR signal. Mitochondria isolated from hearts during control perfusion and after 20-30 min of ischemia were able to produce superoxide radicals in both the NADH-coenzyme Q10 reductase and the bc1 segments of the respiratory chain. The rate of oxyradical generation was significantly higher in mitochondria isolated from ischemic heart.
Ruuge
E K
EK
Institute of Experimental Cardiology, USSR Cardiology Research Center, Moscow.
Ledenev
A N
AN
Lakomkin
V L
VL
Konstantinov
A A
AA
Ksenzenko MYu
D000818:Animals; D003327:Coronary Disease / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D005420:Flavoproteins / Q000378:metabolism*; D005609:Free Radicals; D066298:In Vitro Techniques; D008297:Male; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013481:Superoxides / Q000378:metabolism*; D014216:Triacetoneamine-N-Oxyl / Q000378:metabolism; D014451:Ubiquinone / Q000378:metabolism*
D005420:Flavoproteins; D005609:Free Radicals; D009589:Nitrogen Oxides; D013481:Superoxides; D014451:Ubiquinone; D014216:Triacetoneamine-N-Oxyl; C039900:nitroxyl