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.