Changes in elemental concentrations are associated with early stages of apoptosis in human monocyte-macrophages exposed to oxidized low-density lipoprotein: An X-ray microanalytical study

This study examines ion homeostasis in monocyte-macrophages committed to de ath by apoptosis. S-ray microanalysis has been used to demonstrate that int racellular concentrations of potassium decreased whilst those of sodium inc reased following 3 h of exposure to 100 mu g/ml of oxidized low-density Lip oprotein (LDL) in vitro. In contrast, the maximal incidence of cell death, as determined by the inability to exclude trypan blue, was not seen until 2 4 h of exposure. At 12 h, less than 1 per cent of cells were stained using terminal transferase-mediated DNA nick-end labelling, which is generally ac cepted as a marker of late stages in the apoptotic pathway. This is the fir st demonstration of early perturbations of ion homeostasis in monocyte-macr ophages exposed to concentrations of oxidized LDL known to cause apoptosis, Copyright (C) 1999 John Wiley & Sons, Ltd.