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Ionic changes accompanying astrocytic intercellular calcium waves triggered by mechanical cell damaging stimulation.
1Department of Physiology and Pathophysiology, University of Ghent, De Pintelaan 185 (Blok B), B-9000, Ghent, Belgium.
Brain Research
|March 4, 2000
Summary
Mechanical damage to astrocytes triggers intercellular calcium waves and associated ion changes. These changes, particularly in intracellular sodium, may signal neurons to boost energy metabolism for survival.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Confluent astrocyte cultures exhibit intercellular calcium (Ca(2+)) waves upon mechanical stimulation.
- The association of these waves with other ion changes is not fully understood.
Purpose of the Study:
- To investigate spatiotemporal changes in intracellular calcium (Ca(i)2+), sodium (Na(i)+), and protons (H(i)+), as well as extracellular potassium (K(e)+) during intercellular calcium waves in astrocytes.
- To elucidate the role of these ion changes in the propagation of intercellular calcium waves.
Main Methods:
- Primary cultures of rat cortical astrocytes were used.
- Microfluorescence imaging with fura-2, SBFI, and BCECF was employed to monitor Ca(i)2+, Na(i)+, and H(i)+.
- Extracellular K(e)+ changes were measured using K(+)-sensitive microelectrodes.
Main Results:
- Mechanical damage initiated intercellular Ca(2+) waves propagating up to 160 microm.
- Na(i)+ increases were observed 2-3 cell diameters away, H(i)+ changes 1-2 cell diameters away, and K(e)+ increases up to 75 microm.
- Kinetic analysis indicated Na(i)+ and H(i)+ changes were secondary to Ca(i)2+ changes, while K(e)+ changes were rapid and preceded Ca(i)2+ changes.
Conclusions:
- Intercellular calcium waves in astrocytes are accompanied by changes in intracellular sodium and protons, and extracellular potassium.
- Astrocytic intracellular sodium changes may act as a signal to activate glycolysis, potentially enhancing neuronal energy metabolism and survival following damage.