Correlations of antimyosin accumulation and histological manifestation of myocyte necrosis at different stages of idiopathic cardiomyopathy.

Abstract

Although antimyosin uptake has been demonstrated in idiopathic cardiomyopathy, discrepancies between antimyosin positivity and histological examinations using biopsy speciments have been found. In order to investigate the correlations between antimyosin localization and histopathological alterations, the magnitude and distribution of antimyosin uptake were quantitatively assessed in aged-matched control (F1b) and hereditary idiopathic cardiomyopathy (Bio 14.6) hamsters at three different ages. In these studies, gamma counting and macroautoradiography were compared with histological alterations. Myocardial activities and percent areas of antimyosin uptake were significantly (P<0.05) greater in 10-, 20-, and 30-week old Bio groups than in their respective control groups. Autoradiograms showed that antimyosin antibody was relatively localized, massive, and scattered in 10-week-old, 20-week-old and 30-week-old Bio hamsters, respectively. Histopathology demonstrated antimyosin positivity not only in necrotic myocytes and accompanying calcium deposits but also in tissues showing inflammatory reactions but no histologically identifiable myocyte necrosis. In conclusion, antimyosin uptake seen in tissues with age-related disease processes did not necessarily correspond to histologically verified myocyte necrosis in the cardiomyopathy hearts, suggesting that antimyosin positivity reflects myocytes which show impaired sarcolemmal integrity but have not yet undergone myolysis.