BRADYKININ INDUCES RISE OF FREE CALCIUM IN NUCLEI OF NEUROBLASTOMA X GLIOMA HYBRID NG-108-15 CELLS

Confocal fluorescence microscopy was used to study the bradykinin-indu ced calcium signals in the neuroblastoma x glioma cell line NG 108-15. We found that bradykinin induced a rise in free calcium, not only in the cytoplasm but also in the nucleus, The nuclear and cytosolic calci um concentrations were not significantly different and rose to about 1 .2 mu M. The signal was mediated by the B-2-receptor subtype as confir med using the specific antagonist Hoe 140. Both the onset and the inte nsity of the calcium signals were concentration-dependent. The rise of nuclear calcium level was independent of extracellular calcium and su ppressed by thapsigargin which is known to deplete inositol 1,4,5-tris phosphate-sensitive calcium stores, Bradykinin-induced calcium increas e desensitizes rapidly, This desensitization was shown not to involve activation of protein kinase C. (c) 1995 Wiley-Liss, Inc.