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Calcium metabolism in the rat: a temporal self-organized model
J F Staub1, P Tracqui, P Brezillon
1UA 163, Centre National de la Recherche Scientifique, CHU Saint Antoine, Paris, France.
The American Journal of Physiology
|January 1, 1988
Summary
This study models rat calcium metabolism as a self-organizing system, revealing circadian rhythms in calcium dynamics. The model distinguishes between bone calcium pools, crucial for understanding calcium regulation.
Area of Science:
- Biophysics
- Physiology
- Systems Biology
Background:
- Calcium (Ca) metabolism is complex and exhibits daily rhythms.
- Understanding these circadian behaviors is key to comprehending Ca regulation.
- Previous models have not fully captured the self-organized nature of Ca metabolism.
Purpose of the Study:
- To analyze the circadian behavior of rat calcium metabolism.
- To present a self-oscillatory model (M) for rat calcium metabolism.
- To explore the implications of a self-regulated system on Ca homeostasis.
Main Methods:
- Utilized rat plasma Ca and 45Ca concentrations.
- Developed a compartmental model (M) with a second-order autocatalytic process.
- Differentiated Ca compartments within bone, including those involved in growth, maturation, and mature bone.
Main Results:
- The model M describes Ca in eight compartments, distinguishing between bone growth/maturation and mature bone pools.
- Identified two self-oscillating compartments in mature bone, potentially linked to Ca-P interfaces and osteoblast-osteocyte control.
- Characterized mature bone Ca as large, less available hydroxyapatite (HA) crystals and smaller, more available HA crystals.
Conclusions:
- Rat calcium metabolism functions as a self-organized, self-oscillating system with circadian rhythms.
- Bone Ca influx and efflux are critical for extracellular fluid regulation but distinct from accretion/resorption.
- The model provides insights into Ca deficiency and the conceptual framework of Ca metabolism as a self-regulated process.