MYOCARDIAL RESPONSE TO REGIONAL ISCHEMIA AND REPERFUSION IN-VIVO IN RAT-HEART

Ischemia-reperfusion-induced myocardial oxidative changes were investi gated in open-chest hearts of anesthetized rats. Surgical occlusion of the left anterior descending coronary artery for 30 min followed by 1 5 min reperfusion resulted in a significant decrease of reduced glutat hione, an increase in glutathione disulfide, and an enhanced lipid per oxidation in rapidly frozen left ventricular tissues. Direct electron paramagnetic resonance spectroscopy revealed an increase in free radic al concentration in ischemic cardiac tissues reperfused for 45 s, but the increase diminished at 15 min. These alterations were associated w ith decreased activities of myocardial glutathione peroxidase, glutath ione reductase, and catalase. Ischemia resulted in a significant reduc tion of high-energy phosphate compounds and an accumulation of nucleot ide degradation products, particularly adenosine, in the myocardium. D eterioration of cardiovascular function in reperfused animals was also evident. It is concluded that regional ischemia followed by reperfusi on in situ can produce biochemical and physiological alterations consi stent with free radical injury in rat hearts, and that an increased pu rine nucleotide degradation and a decreased antioxidant defense may be responsible for the observed changes.