Comparison of adriamycin-induced nucleolar segregation in skeletal muscle, cardiac muscle, and liver cells.

Male Sprague-Dawley rats were treated with either 2.5, 3.5, or 5.0 mg/kg of adriamycin by iv injection. After 1 or 3 hours of treatment, samples of liver, cardiac muscle, and skeletal muscle cells were examined by electron microscopy. The changes in ultrastructure observed in these tissues after the first hour included nucleolar segregation and altered distribution of the perinucleolar chromatin. However, no alterations in the ultrastructure of either the nucleus or cytoplasm were observed in tissues examined 3 hours after a 5-mg/kg dose of adriamycin. The doses at which nucleolar alterations occurred varied between tissues. In skeletal and cardiac muscle cells, marked alterations in nucleolar ultrastructure were observed at doses of 3.5 and 5.0 mg/kg of adriamycin. Liver cell nucleoli, however, exhibited few structural aberrations at these doses. The similarities in response of skeletal and cardiac muscle suggest that ultrastructural analysis of skeletal muscle biopsies may be useful in evaluating adriamycin cardiotoxicity.