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Calcium influx and release in isolated rat osteoclasts
V S Shankar1, C L Huang, O A Adebanjo
1Bone Research Unit, St George's Hospital Medical School, London.
Experimental Physiology
|July 1, 1994
Summary
Osteoclasts utilize both intracellular calcium stores and extracellular calcium influx for cytosolic calcium regulation. This study identifies a refillable intracellular calcium source crucial for osteoclast function.
Area of Science:
- Cell Biology
- Physiology
- Biochemistry
Background:
- Cytosolic calcium (Ca2+) transients are critical for cellular regulation.
- Osteoclasts play a key role in bone remodeling and resorption.
Purpose of the Study:
- To investigate the sources of cytosolic Ca2+ elevation in isolated rat osteoclasts.
- To differentiate between intracellular and extracellular Ca2+ contributions to cytosolic Ca2+ levels.
Main Methods:
- Utilized fura-2 fluorescence imaging to measure cytosolic Ca2+.
- Applied the Ca2+ ionophore ionomycin in Ca2+-containing and Ca2+-free solutions.
- Manipulated extracellular potassium to alter membrane potential and depleted intracellular Ca2+ stores.
Main Results:
- Cytosolic Ca2+ transients persisted in Ca2+-free solutions, indicating intracellular Ca2+ release.
- Sustained Ca2+ responses in Ca2+-containing solutions demonstrated extracellular Ca2+ entry.
- Capacitative Ca2+ entry was observed upon restoration of extracellular Ca2+ after store depletion.
Conclusions:
- Osteoclasts possess a refillable intracellular Ca2+ store.
- Both intracellular and extracellular Ca2+ sources contribute to cytosolic Ca2+ regulation in osteoclasts.
- Intracellular Ca2+ stores are vital for osteoclast-mediated processes.