Enzyme pattern in hypoxic skeletal muscle

Abstract

Key enzymes representing constant proportion groups within the metabolic systems of glycolysis and fat metabolism were determined in muscle samples taken from various striated muscles of the extremities in patients with obliterative artery disease. Ratios of key enzymes were calculated, allowing the possibility of quantitating the enzyme capacity of one metabolic system to another. In all patients there was found a preponderance of lipid metabolic activity over that of the glycolytic activity. This finding was the more pronounced the higher the degree of obstruction, culminating in patients where exacerbation of the conditions occurred due to embolism or thrombosis. The changes, furthermore, increased significantly from the proximal to the distal part of the extremities. Pronounced elevations were found in the activity of the hexose-monophosphate shunt by which the production of ribose-5-phosphate required for nucleic acid synthesis is secured. The LDH activity, generally, was found normal, elevated in a few instances but relatively increased compared to the diminished glycolytic activity. In severely hypoxic feet, caused by obliterative arterial disease, the intracellular concentration of FFA was significantly increased. This is explained by an insufficient supply of glycerophosphate, due to the diminished glycolytic activity, for the synthesis of triglycerides, resulting in a storage of FFA within the cells.