The Content of Cytochrome c in Human Heart and Skeletal Muscle

Activities of key enzymes in the energy metabolism of human myocardial and skeletal muscle

Activities of total creatine kinase (CK), its isoenzyme MB (CK-MB), total lactate dehydrogenase (LD) and its isoenzyme LD1, phosphofructokinase (PFK), aspartate aminotransferase (ASAT) and citrate synthase (CS) were determined in skeletal muscle biopsies obtained from physically trained and untrained men and in myocardial biopsies from patients subjected to open heart surgery because of valve disease. The LD1, ASAT and CS activities were higher in trained than in untrained skeletal muscle and still higher in heart muscle than in either trained or untrained skeletal muscle. The CK-MB activity was higher in trained than untrained skeletal muscle and the myocardial CK-MB activity was similar to that in trained skeletal muscle. Total CK activity was slightly lower in trained than in untrained skeletal muscle and the myocardial CK activity was approximately one third of the skeletal muscle CK. Both the PFK and the total LD activity was of similar magnitude in the different muscle types. In conclusion, as estimated by enzyme activities, the oxidative capacity is 2-3 times larger in myocardial than in skeletal muscle, while the glycolytic capacity as estimated by PFK appears to be the same.

Enzymatic analysis and collagen content in endomyocardial biopsy samples of patients with congestive cardiomyopathy of unknown etiology

Endomyocardial biopsy samples from patients suffering from congestive cardiomyopathy of unknown etiology (COCM) were analyzed for lactate dehydrogenase (LDH) isoenzyme distribution by microisoelectric focusing. In addition, the concentration of collagen in the biopsy samples was estimated by determination of hydroxyproline and proline. The results were correlated with the clinical and hemodynamic data of the patients. Increased activities of total LDH and LDH5--the worse the hemodynamic parameters, the higher the concentration of LDH5--indicate an enhanced anaerobic glycolysis in the myocardium of COCM patients. The close correlation between the hemodynamic data and the LDH isoenzyme pattern suggests an association between severity of COCM and impairment of aerobic metabolism. The results of the alteration in the LDH isoenzyme pattern were not influenced by the collagen content in the myocardial biopsy samples. Varying isoenzyme patterns in the different parts and wall layers of the normal heart show the necessity of analyzing biopsy samples only from comparable localizations.