Key enzymes of myocardial energy metabolism in papillary muscle of patients with mitral valve disease--relation to left ventricular function.

Metabolic adaptations were studied in papillary muscle from 18 patients undergoing open-heart surgery for mitral valve disease. Analyses were made of myoglobin (MG), the enzymes lactate dehydrogenase (LD) with its isoenzymes, glyceraldehyde phosphate dehydrogenase (GAPDH), phosphofructokinase (PFK), citrate synthase (CS) and creatine kinase (CK) with its isoenzymes MB (CK-MB) and mitochondrial CK (CK-MIT). Myocardial function was assessed with left ventricular angiography. Positive and significant correlations were found between enzymes of oxidative metabolism, i.e. CS on the one hand and MG (r = 0.76), LD1 (r = 0.68), CK-MIT (r = 0.86) and CK-MB (r = 0.65) on the other. Indicators of glycolysis--PFK, GAPDH and LD3--varied independently of CS. LD3% was directly related to GAPDH (r = 0.66). In a sub-group of 12 patients with isolated mitral regurgitation due to myxomatous valve degeneration, LD3% rose (r = 0.72) with increasing myocardial derangement which, however, showed no relationship with any other marker. Thus the capacities of oxidative and glycolytic pathways did not co-vary. Volume load appeared not to affect oxidative capacity, while the anaerobic fraction of glycolysis was increased.