Immunoreactive copper-zinc superoxide dismutase in damaged human myocardium

The myocardium in 50 autopsy cases was studied using immunostaining for copper-zinc superoxide dismutase (CuZn-SOD) and standard histochemical procedures. Mucinous degeneration observed in 42 cases showed moderately enhanced expression of immunoreactive CuZn-SOD in lesions which were stained strongly by periodic acid-Schiff but negative with Heidenhain iron-hematoxylin (HIH), von Kossa and luxol fast blue (LFB) stains, whereas coagulation necrosis in 4 cases revealed almost identical immunostaining for CuZn-SOD and HIH to that of contraction band necrosis, i.e. strongly positive HIH staining but negative immunostaining. Basophilic alteration of the myocardial cells in sections fixed with 4% formalin in 2% calcium acetate was seen in 29 cases, being identified frequently in isolated cells as well as in several foci varying considerably in size. This type of alteration demonstrated significantly enhanced expression of immunoreactive CuZn-SOD and was strongly positive with von Kossa and LFB stains. The present study indicates that the myocardium can be affected by free radicals produced in any organ of the body, and that subsequently, insoluble phospholipids react with calcium ions in the fixative and accumulate in the basophilic sarcoplasm.