IMMUNOCYTOCHEMICAL DETECTION OF ENHANCED EXPRESSION OF C-MYC PROTEIN IN THE HEART OF CARDIOMYOPATHIC HAMSTER

An immunocytochemical study was performed to examine the expression of cellular c-myc protein in the heart of 30-, 120-and 180-day-old cardi omyopathic Syrian UM-X7.1 hamsters. The heart of age- and sex-matched BIO-RB hamster was used as normal control. In paraffin sections, an im munostaining for c-myc was markedly increased in cytoplasm of cells fr om the UM-X7.1 heart as compared with that of the BIO-RB heart which s howed a weak staining. However, c-myc was localized in nuclei of cells in frozen sections of the heart. Specific cell types of the heart wer e differentiated with anti-vimentin, and we found that the increased e xpression of c-myc was present in nuclei of muscle cells of the UM-X7. 1 myocardium. A quantitative study of c-myc-positive nuclei of muscle and nonmuscle cells was carried out by a video micrometer. The mean nu mber of c-myc-positive nuclei of muscle cells was significantly higher in the cardiomyopathic heart than in the control heart from hamsters of all ages studied. These results suggest that the increase of c-myc protein may relate to the pathological state or pathogenesis of the he reditary cardiomyopathy.