Myocardial response to regional ischemia and reperfusion in vivo in rat heart

Ischemia-reperfusion-induced myocardial oxidative changes were investigated in open-chest hearts of anesthetized rats. Surgical occlusion of the left anterior descending coronary artery for 30 min followed by 15 min reperfusion resulted in a significant decrease of reduced glutathione, an increase in glutathione disulfide, and an enhanced lipid peroxidation in rapidly frozen left ventricular tissues. Direct electron paramagnetic resonance spectroscopy revealed an increase in free radical concentration in ischemic cardiac tissues reperfused for 45 s, but the increase diminished at 15 min. These alterations were associated with decreased activities of myocardial glutathione peroxidase, glutathione reductase, and catalase. Ischemia resulted in a significant reduction of high-energy phosphate compounds and an accumulation of nucleotide degradation products, particularly adenosine, in the myocardium. Deterioration of cardiovascular function in reperfused animals was also evident. It is concluded that regional ischemia followed by reperfusion in situ can produce biochemical and physiological alterations consistent with free radical injury in rat hearts, and that an increased purine nucleotide degradation and a decreased antioxidant defense may be responsible for the observed changes.