DECREASED GLYCOLYTIC ENZYME ACTIVITY IN EPIPHYSEAL CARTILAGE OF CORTISONE-TREATED RATS

Procedures are described for highly reproducible assays of protein content and the activity of hexokinase, phosphofructokinase, aldolase, pyruvate kinase, lactate dehydrogenase, NAD-linked glycerophosphate dehydrogenase, and glucose-6-phos-phate dehydrogenase in epiphyseal cartilage from rat tibiae. Glucokinase is not present. With cortisone treatment the four glycolytic enzymes, phosphofructokinase, aldolase, pyruvate kinase, and lactate dehydrogenase, exhibit a closely coordinated decrease in activity of over 50% per cell, or an average decrease of 34% in specific activity (Enzyme Units/milligram protein). Glycerophosphate dehydrogenase follows a generally similar pattern. Hexokinase and glucose-6-phosphate dehydrogenase are also decreased per cell, but only to the same extent as total protein so that there is little change in specific activity. Starvation brings about changes in the enzyme activity pattern similar to those of cortisone-treatment. © 1969.