Clinical Chemistry, Vol 20, 1331-1336, Copyright © 1974 by the American Association for Clinical Chemistry

Effect of Energy-Rich Compounds on Release of Intracellular Enzymes from Human Leukocytes and Rat Lymphocytes

¹ Department of Chemical Pathology, Charing Cross Hospital Medical School, Fulham Palace Road, London W6 8RF, U. K.

Experiments have been performed to determine some of the factors affecting the release of intracellular enzymes, in the hope of improving our understanding of the mechanisms whereby tissue enzymes reach the circulation in disease processes. The discharge of intracellular enzymes into the medium during prolonged incubation of human leukocytes and rat lymphocytes has been shown to be inversely related to their ATP contents. Incorporation of ATP into the medium has a marked protective effect against enzyme loss. Other high-energy phosphates, such as uridine triphosphate and phosphoenolpyruvate, which can readily be converted into ATP, also exert a protective effect, but creatine phosphate, which cannot be so converted owing to the low activity of creatine kinase in the cells, exhibits no such action. Glucose and certain intermediates of the glycolytic pathway also reduce the leakage of intracellular enzymes, an effect which parallels their concentrations in the media. ATP also protects rat lymphocytes against enzyme loss provoked by high potassium concentrations. It is suggested that the integrity of the cell membrane, as assessed by its ability to prevent the leakage of enzymes, depends on the energy content of the cell, a decrease of which may be a common factor in clinical situations associated with elevated enzyme activities in the serum.