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Proton-induced physicochemical calcium release from ceramic apatite disks
D A Bushinsky1, N E Sessler, R E Glena
1Nephrology Unit, University of Rochester School of Medicine and Dentistry, New York.
Summary
Acidic conditions cause calcium to leave bone mineral and protons to enter it. This study used synthetic bone mineral to show acid medium directly drives this mineral dissolution, independent of cells.
Area of Science:
- Biomineralization
- Bone Physiology
- Materials Science
Background:
- Bone is a dynamic tissue susceptible to changes in its chemical environment.
- Acidic conditions are known to influence bone resorption, but the direct effects on mineral dissolution are complex.
- Understanding physicochemical dissolution is crucial for comprehending bone loss pathologies.
Purpose of the Study:
- To isolate and investigate the independent effect of acidic medium on physicochemical bone mineral dissolution.
- To quantify calcium efflux and proton influx in response to acid exposure using a cell-free model.
Main Methods:
- Utilized cell-free synthetic ceramic apatite (CAP) disks, chemically similar to bone mineral.
- Incubated CAP disks and neonatal mouse calvariae in control (pH ~7.44) or acidic (Met, pH ~7.11) media for 48 hours.
- Analyzed medium at 3, 24, and 48 hours to measure calcium efflux (JCa) and proton influx (JH).
Main Results:
- Acidic medium significantly increased JCa from both CAP disks and calvariae compared to control.
- Over 48 hours, JCa progressively increased more in CAP disks than calvariae exposed to acidic medium.
- Acidic medium significantly increased JH into both CAP disks and calvariae, with greater influx into CAP disks.
Conclusions:
- Acidic medium directly induces physicochemical calcium efflux from bone mineral.
- Proton influx into bone mineral is also enhanced by acidic conditions, independent of cellular activity.
- Synthetic bone mineral models effectively demonstrate the direct impact of acid on mineral dissolution processes.