Secretagogue-induced calcium wave shows higher and prolonged transients of nuclear calcium concentration in mast cells

Abstract To clarify the mechanism of secretagogue (compound 48 80 )-induced calcium signaling in rat peritoneal mast cells, we analyzed serial confocal calcium images with high spatial and temporal resolution using different Ca 2+ -probes. The Ca 2+ -wave began at the periphery of the cytoplasm, and then spread to the center of the nucleus. Nuclear [Ca 2+ ] i was clearly higher than cytoplasmic [Ca 2+ ] i . The heterogeneity of [Ca 2+ ] i continued until about 2 min after degranulation. These results suggest the existence of an intranuclear Ca 2+ -store which possesses a Ca 2+ -releasing mechanism similar to that in the cytoplasm.