Immunoglobulin E Receptor Cross-Linking Induces Oscillations in Intracellular Free Ionized Calcium in Individual Tumor Mast Cells.

摘要

Fura-2 fluorescence in single rat basophilic leukemia cells was monitored to study the rise in intracellular free ionized calcium ((Ca2+)i) produced by aggregation of immunoglobulin E receptors. Repetitive transient increases in (Ca2+)i were induced by antigen stimulation and were measured using digital video imaging microscopy at high time resolution. The (Ca2+)i oscillations were not dependent upon changes in the membrane potential of the cells and were observed in cells stimulated with antigen either with or without extracellular Ca2+. Transient oscillations in (Ca2+)i were also observed when calcium influx was blocked with La3+. These results suggested that during antigen stimulation of cells under normal physiological conditions, release of Ca2+ from intracellular stores makes an important contribution to the initial increase in (Ca2+)i. Oscillations in (Ca2+)i are not induced by elevating (Ca2+)i with the calcium ionophore ionomycin. Mitochondrial calcium buffering is not required for (Ca2+)i oscillations to occur. (JES)