Myocardial subcellular fractionation studies on cardiomyopathic Syrian hamsters

Myocardial homogenates from control animals and from hamsters with hereditary cardiomyopathy were subjected to analytical subcellular fractionation and enzymic microanalysis. Animals without ventricular hypertrophy or overt heart failure were used in this study. The principal subcellular organelles were characterised by density gradient centrifugation. Apart from evidence of enhanced lysosomal and peroxisomal fragility, probably secondary to the intracellular oedema, the intracellular organelles investigated in this study were unaffected by the myopathic process. Highly significant increases in 5'-nucleotidase activity, a marker for the sarcolemma, and an increased equilibrium density of this organelle were found in the myopathic tissue. Ultrastructural studies revealed patchy myocytolysis associated with lysosomes and with more extensive invaginations of the sarcolemma. It is suggested that a primary defect in membrane composition, leading to increased cation permeability, is the underlying abnormality in the myopathic hamster.