Analytical subcellular fractionation of human heart: a comparison of left and right ventricle with hypertrophic obstructive myopathic tissue

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Abstract
Enzymic microanalysis in combination with analytical subcellular fractionation by density gradient centrifugation has been used to compare left ventricular myocardium (papillary muscle from patients with rheumatic mitral valve disease) and right ventricular myocardium (infundibulum resected from patients with Tetralogy of Fallot). In addition the subcellular pathology of left ventricular out-flow tract tissue from patients with hypertrophic obstructive cardiomyopathy was investigated. In the non-cardiomyopathic tissue the principal organelles have been characterised by their enzymic content. Increased activities of sarcolemma enzymes (5'-nucleotidase, Na+, K+-activated Mg2+-dependent ATPase) and of lysosomal enzymes (N-acetyl-β-glucosaminidase) were found in the right ventricular infundibular myocardium compared with left ventricle papillary muscle. Increased lysosomal integrity was noted in right ventricular extracts. Density gradient centrifugation experiments indicated that the density of the lysosomes and sarcoplasmic reticulum was greater in the right ventricle. In hypertrophic obstructive myopathic tissue, compared with non-myopathic left ventricular papillary muscle, increased activities of certain mitochondrial enzymes (Mg2+-dependent ATPase, monoamine oxidase), sarcolemma, lysosomal, and sarcoplasmic reticulum enzymes were noted. Subcellular fractionation studies showed a small increase in median density of the sarcolemma. By analogy with the hereditary cardiomyopathic hamster it is suggested that the primary lesion in human hypertrophic obstructive cardiomyopathy may reside in the sarcolemma. Changes in the other organelles could be secondary to the sarcolemmal changes.