Mapping Of IP3-Mediated Ca2+ Signals In Single Human Neuroblastoma SH-SY5Y Cells : Cell Volume Shaping The Ca2+ Signal. K. Van Acker, B. Bautmans, G. Bultynck, K. Maes, A. F. Weidema, P. De Smet, J.B. Parys, H. De Smedt, L. Missiaen and G. Callewaert. Laboratory of Physiology, K.U. Leuven, Campus Gasthuisberg O/N, B-3000 Leuven, Belgium.
APStracts 6:0534N, 1999.
Fast confocal laser-scanning microscopy was used to study spatiotemporal properties of IP3-mediated Ca2+ release signals in human SH-SY5Y neuroblastoma cells. [Ca2+]i increases were not affected by ryanodine (30 µM) or caffeine (10 mM) and largely insensitive to removal of external Ca2+, indicating predominance of IP3-induced Ca2+ release. Ca2+ signals evoked by high concentration (10 (M) of the muscarinic agonist carbachol appeared as self-propagating waves initiating in cell processes. At low carbachol concentrations (500 nM) Ca2+ changes in most cells displayed striking spatiotemporal heterogeneity. The Ca2+ response in the cell body was delayed, had a smaller amplitude and a slower rise time than that in processes. Ca2+ changes in processes either occurred in a homogeneous manner throughout the whole process or were sometimes confined to hot spots. Regional differences in surface-to-volume ratio appear to be critical clues that determine the spatiotemporal pattern of intracellular Ca2+ release signals.
Received 29 July 1999; accepted in final form 19 October 1999.
APS Manuscript Number J636-9.
Article publication pending Journal of Neurophysiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 21 December 1999