Calcium signaling in restricted diffusion spaces.
One- and two-dimensional models of Ca2+ diffusion and regulation were developed and used to study the magnitudes and the spatial and temporal characteristics of the Ca2+ transients that are likely to develop in smooth muscle cells in restricted diffusion spaces between the plasma membrane and intracellular organelles. Simulations with the models showed that high [Ca2+] (on the order of several microM) can develop in such spaces and persist for 100-200 ms. These Ca2+ transients could: 1) facilitate the coupling of Ca2+ influx to intracellular Ca2+ release; 2) provide a mechanism for the regulation of stored Ca2+ that does not affect the contractile state of smooth muscle; 3) locally activate specific signal transduction pathways, before, or without activating other Ca2+ dependent pathways in the central cytoplasm of the cell. The latter possibility suggests that independent enzymatic processes in cells could be differentially regulated by the same intracellular second messenger.
Kargacin
G J
GJ
Department of Medical Physiology, University of Calgary, Canada.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004058:Diffusion; D007700:Kinetics; D008433:Mathematics; D008954:Models, Biological; D009130:Muscle, Smooth / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D015398:Signal Transduction; D012984:Software; D013997:Time Factors
D002118:Calcium