Calcium Wave Propagation Triggered by Local Mechanical Stimulation as a Method for Studying Gap Junctions and Hemichannels

We here describe intercellular calcium waves as a novel form of cellular communication among thymic epithelial cells. We first characterized the mechanical induction of intercellular calcium waves in different thymic epithelial cell preparations: cortical 1-4C18 and medullary 3-10 thymic epithelial cell lines and primary cultures of thymic “nurse” cells. All thymic epithelial preparations responded with intercellular calcium wave propagation after mechanical stimulation. In general, the propagation efficacy of intercellular calcium waves in these cells was high, reaching 80-100% of the cells within a given confocal microscopic field, with a mean velocity of 6-10 μm/s and mean amplitude of 1.4- to 1.7-fold the basal calcium level. As evaluated by heptanol and suramin treatment, our results suggest the participation of both gap junctions and P2 receptors in the propagation of intercellular calcium waves in thymic nurse cells and the more prominent participation of gap junctions in thymic epithelial cell lines. Finally, in cocultures, the transmission of intercellular calcium wave was not observed between the mechanically stimulated thymic epithelial cell and adherent thymocytes, suggesting that intercellular calcium wave propagation is limited to thymic epithelial cells and does not affect the neighboring thymocytes. In conclusion, these data describe for the first time intercellular calcium waves in thymic epithelial cells and the participation of both gap junctions and P2 receptors in their propagation.

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Intercellular calcium wave propagation in linear and circuit-like bone cell networks

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2009.0221 ◽

2010 ◽

Vol 368 (1912) ◽

pp. 617-633 ◽

Cited By ~ 20

Author(s):

Bo Huo ◽

Xin L. Lu ◽

X. Edward Guo

Keyword(s):

Wave Propagation ◽

Gap Junctions ◽

Calcium Release ◽

Bone Cells ◽

Molecular Transport ◽

Bone Cell ◽

Calcium Wave ◽

Contact Printing ◽

Inhibition Studies ◽

Cell Networks

In the present study, the mechanism of intercellular calcium wave propagation in bone cell networks was identified. By using micro-contact printing and self-assembled monolayer technologies, two types of in vitro bone cell networks were constructed: open-ended linear chains and looped hexagonal networks with precisely controlled intercellular distances. Intracellular calcium responses of the cells were recorded and analysed when a single cell in the network was mechanically stimulated by nano-indentation. The looped cell network was shown to be more efficient than the linear pattern in transferring calcium signals from cell to cell. This phenomenon was further examined by pathway-inhibition studies. Intercellular calcium wave propagation was significantly impeded when extracellular adenosine triphosphate (ATP) in the medium was hydrolysed. Chemical uncoupling of gap junctions, however, did not significantly decrease the transferred distance of the calcium wave in the cell networks. Thus, it is extracellular ATP diffusion, rather than molecular transport through gap junctions, that dominantly mediates the transmission of mechanically elicited intercellular calcium waves in bone cells. The inhibition studies also demonstrated that the mechanical stimulation-induced calcium responses required extracellular calcium influx, whereas the ATP-elicited calcium wave relied on calcium release from the calcium store of the endoplasmic reticulum.

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Intercellular Communication in Spinal Cord Astrocytes: Fine Tuning between Gap Junctions and P2 Nucleotide Receptors in Calcium Wave Propagation

Journal of Neuroscience ◽

10.1523/jneurosci.20-04-01435.2000 ◽

2000 ◽

Vol 20 (4) ◽

pp. 1435-1445 ◽

Cited By ~ 134

Author(s):

Eliana Scemes ◽

Sylvia O. Suadicani ◽

David C. Spray

Keyword(s):

Spinal Cord ◽

Wave Propagation ◽

Gap Junctions ◽

Intercellular Communication ◽

Fine Tuning ◽

Calcium Wave ◽

Nucleotide Receptors ◽

P2 Nucleotide Receptors

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Vesicular ATP Is the Predominant Cause of Intercellular Calcium Waves in Astrocytes

The Journal of General Physiology ◽

10.1085/jgp.200709780 ◽

2007 ◽

Vol 129 (6) ◽

pp. 485-491 ◽

Cited By ~ 137

Author(s):

David N. Bowser ◽

Baljit S. Khakh

Keyword(s):

Wave Propagation ◽

Gap Junctions ◽

Glutamate Receptors ◽

Extracellular Space ◽

Metabotropic Glutamate Receptors ◽

Calcium Wave ◽

Calcium Waves ◽

Metabotropic Glutamate ◽

Spatiotemporal Scales ◽

Hippocampal Astrocytes

Brain astrocytes signal to each other and neurons. They use changes in their intracellular calcium levels to trigger release of transmitters into the extracellular space. These can then activate receptors on other nearby astrocytes and trigger a propagated calcium wave that can travel several hundred micrometers over a timescale of seconds. A role for endogenous ATP in calcium wave propagation in hippocampal astrocytes has been suggested, but the mechanisms remain incompletely understood. Here we explored how calcium waves arise and directly tested whether endogenously released ATP contributes to astrocyte calcium wave propagation in hippocampal astrocytes. We find that vesicular ATP is the major, if not the sole, determinant of astrocyte calcium wave propagation over distances between ∼100 and 250 μm, and ∼15 s from the point of wave initiation. These actions of ATP are mediated by P2Y1 receptors. In contrast, metabotropic glutamate receptors and gap junctions do not contribute significantly to calcium wave propagation. Our data suggest that endogenous extracellular astrocytic ATP can signal over broad spatiotemporal scales.

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