Temporal and spatial heterogeneities of Ca2+ signaling: mechanisms and physiological roles
Toescu, E.C.
American Journal of Physiology 269(2 Pt 1): G173-G185
1995
ISSN/ISBN: 0002-9513 PMID: 7653557 Document Number: 440251
In the cells of the gastrointestinal tract, as in most other types of cells, many of the fundamental cellular functions are mediated by increases of intracellular Ca-2+. These increases are mediated primarily by elevations of inositol 1,4,5-trisphosphate (IP-3), which, in turn, are a consequence of the activation of specific plasma membrane receptors. Extensive investigations of these intracellular processes in the last few years have revealed the complexities of Ca-2+ signaling. The extreme heterogeneity of Ca-2+ signaling, which is manifest by variations in both the time course and the spatial distribution of these signals, forms the central theme of this review. On the basis of the available information, the various intracellular mechanisms that allow the manifestation of this heterogeneity are discussed. It is argued that these variations in Ca-2+ response are the result not only of the existence of multiple, complex mechanisms participating in the generation and maintenance of the agonist-evoked Ca-2+ signal but also of the existence of various isoforms for almost every one of the main molecules involved in signaling and the concomitant participation of many intracellular modulators.