IMAGING [CA-2+]I DYNAMICS DURING SIGNAL TRANSDUCTION

The elevation of free intracellular Ca2+ activity ([Ca2+]i) is widely recognised as a central event in many signal transduction processes in cellular physiology. Recent advances in optical techniques for measuring [Ca2+]i as well as developments in quantitative low light level fluorescence microscopy have led to the application of these methods to the study of subcellular [Ca2+]i in many biological systems. In the following paper we describe some techniques in our laboratory to provide quantitative high spatio-temporal resolution measurements of [Ca2+]i in individual living cells during the signal transduction of cell surface receptor ligand interactions. In particular, we are studying the changes in [Ca2+]i induced by the micro-aggregation of immunoglobulin E (IgE) receptor complexes on the surface of rat basophilic leukemia (RBL) cells (a tumor mast cell line) by multivalent antigen [1]. We seek to understand the mechanisms which are involved in the detection of these cell surface events which lead to changes in [Ca2+]i as well as the interactions between the various subcellular components which impart the delicate control of [Ca2+]i during cellular stimulation. The limitations and properties of the technology used for these studies will be discussed, and some illustrative examples of the type of [Ca2+]i changes found in this biological system will be given. © 1990.