Human skeletal muscle enolase and factors influencing its activity

Enolase activity was determined in human skeletal muscle extracts using two procedures to measure the phosphoenolpyruvate formed. The results closely agreed, as did double determinations on bipartite muscle pieces. Activities in m. vastus lateralis quadricipitis did not differ significantly in adult males, females and 11- to 14-year-old girls. M. vastus medialis and deltoideus exhibited significantly higher activities than vastus lateralis. Endurance-trained athletes had lower enolase activities when compared to untrained subjects. The effects of changes in temperature, pH and K+ concentration in the medium were investigated and the possible physiological implications discussed.