Myocardial damage caused by free radicals in experimentally induced myonephropathic metabolic syndrome in dogs.

Myocardial damage was studied in the dog heart with experimentally induced myonephropathic metabolic syndrome (MNMS). The animals underwent a ligation of the infrarenal arteries with a re-establishment of arterial flow 5 hours after the operation (group 1) and all showed the typical phenomena of MNMS and revealed basophilic changes in the myocardial cells fixed with 4 per cent formalin in 2 per cent calcium acetate. These degenerated cells were distributed in either the left or right ventricle, or even in both as several foci composed of a considerable number of the myocardial cells. Most of these cells showed a significantly enhanced expression of immunoreactive copper-zinc superoxide dismutase in their sarcoplasm. With luxol fast blue staining, the basophilic myocardial cells appeared to be deep blue in color which indicated an accumulation of phospholipid. Such basophilic cells in the animals undergoing a sham operation (group 2) were only sporadically observed in the myocardium fixed with the same fixative. The present study including morphological procedures indicates that dog MNMS causes severe myocardial damage with superoxidation due to an excessive production of free radicals after the re-establishment of arterial flow.