THAPSIGARGIN-INDUCED NUCLEAR CALCIUM SIGNALS IN RAT BASOPHILIC LEUKEMIA-CELLS

By a confocal fluorescence microscope with an argon-ion laser (488 nm) and a He-Cd laser (325 nm) we have studied thapsigargin-induced calci um signals in individual rat basophilic leukaemia (RBL-2H3) cells. In the presence or absence of external calcium ions, thapsigargin-induced calcium signals were transferred to the nucleus as well as to the cyt oplasm of RBL-2H3 cells. The calcium signals were generally much stron ger in the nucleus than in the cytoplasm. However, some of the RBL-2H3 cells had apparently reduced nuclear calcium signals. They had a baso phil-like bilobed (multilobed) nucleus, although most RBL-2H3 cells ha d a mast-cell-like monolobed nucleus. In the cells with a bilobed nucl eus, IgE-receptor-mediated calcium signals were neither transferred to the nucleus nor to the cytoplasm. The results gave a new insight into the understanding of the mechanism of the nuclear calcium signals in RBL-2H3 cells.