Elementary and global aspects of calcium signalling.
TLDR
Using Ca2+ imaging techniques, the opening of individual channels has now been visualized and models have been proposed to explain how these elementary events are coordinated to generate the global Ca 2+ signals that regulate cellular activity.Abstract:
Calcium is a ubiquitous second messenger used to regulate a wide range of cellular processes. This role in signalling has to be conducted against the rigid homeostatic mechanisms that ensure that the resting level of Ca2+ is kept low (i.e. between 20 and 100 nmol l-1) in order to avoid the cytotoxic effects of a prolonged elevation of [Ca2+]. Cells have evolved a sophisticated signalling system based on the generation of brief pulses of Ca2+ which enables this ion to be used as a messenger, thus avoiding its toxic effects. Such Ca2+ spikes usually result from the coordinated release of Ca2+ from internal stores using either inositol 1,4,5-trisphosphate or ryanodine receptors. Using Ca2+ imaging techniques, the opening of individual channels has now been visualized and models have been proposed to explain how these elementary events are coordinated to generate the global Ca2+ signals that regulate cellular activity.read more
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References
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Inositol trisphosphate and calcium signalling
TL;DR: Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle.
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A model for receptor-regulated calcium entry
TL;DR: A capacitative model is proposed for the mechanism by which activation of surface membrane receptors causes sustained Ca2+ entry into cells from the extracellular space, which allows forCa2+ release and Ca2-mobilization to be controlled by a single messenger, inositol (1,4,5) trisphosphate.
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TL;DR: It is reported here that micromolar concentrations of Ins1,4,5P3 release Ca2+ from a nonmitochondrial intracellular Ca2- store in pancreatic acinar cells, and the results strongly suggest that this is the same Ca1+ store that is released by acetylcholine.
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Calcium sparks: elementary events underlying excitation-contraction coupling in heart muscle
TL;DR: The calcium spark is the consequence of elementary events underlying excitation-contraction coupling and provides an explanation for both spontaneous and triggered changes in the intracellular calcium concentration in the mammalian heart.