Real‐time measurement of cytosolic free calcium concentration in HL‐60 cells during static magnetic field exposure and activation by ATP

Calcium ions are involved in a number of important signal transduction pathways in cells. Cytosolic calcium concentration ([Ca 2+ ] c ) can be affected by the activation of Ca 2+ channels through the action of ligands such as ATP. The response of [Ca 2+ ] c to ligands may be affected by external factors like magnetic fields. The purpose of this study was to determine if exposure to a static magnetic field (SMF) for 800 s altered the [Ca 2+ ] c response to ATP in undifferentiated HL‐60 cells. We sham exposed or field exposed fura‐2 loaded HL‐60 cells to a SMF of 1, 10, and 100 mT. Cells were activated with ATP 300 s into the exposure. The level of [Ca 2+ ] c was followed before, during, and after field or sham exposure with a ratiometric fluorescence spectroscopy system. It was found that high concentrations of ATP resulted in greater [Ca 2+ ] c responses, but faster recovery to near basal levels. The application of 1, 10, or 100 mT SMF did not affect the [Ca 2+ ] c response to ATP. Future work could examine the effect of a longer SMF exposure on the [Ca 2+ ] c response to ATP. Longer exposures might provide sufficient time for morphological changes in the plasma membrane to occur. Bioelectromagnetics 29:439–446, 2008. © 2008 Wiley‐Liss, Inc.