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Effects of aluminum on bone surface ion composition
D A Bushinsky1, S M Sprague, P Hallegot
1Nephrology Unit, University of Rochester, New York 14642, USA.
Summary
Aluminum exposure causes significant calcium loss from bone by altering surface ion composition. This suggests aluminum promotes bone removal through a combination of cell-mediated resorption and physicochemical dissolution.
Area of Science:
- Biochemistry
- Bone Biology
- Toxicology
Background:
- Aluminum exposure is linked to bone alterations.
- The precise mechanism of aluminum's effect on bone ion composition and resorption is not fully understood.
Purpose of the Study:
- To investigate how aluminum affects the ion composition of bone surfaces.
- To determine if aluminum-induced changes are consistent with cell-mediated resorption, physicochemical dissolution, or both.
Main Methods:
- Cultured neonatal mouse calvariae were treated with or without aluminum (10(-7) M) for 24 hours.
- Secondary ion mass spectroscopy (SIMS) was used to analyze surface and subsurface ion concentrations (Na, Al, K, Ca).
- Net calcium efflux from bone was quantified.
Main Results:
- Aluminum incorporation into bone significantly depleted surface sodium (Na) and potassium (K) relative to calcium (Ca).
- Aluminum treatment resulted in a greater net efflux of calcium from bone compared to controls.
- Changes in Na/Ca and K/Ca ratios indicate aluminum induces greater efflux of Na and K than Ca from the bone surface.
Conclusions:
- Aluminum alters bone surface ion composition, leading to increased calcium efflux.
- The observed ion alterations and calcium release are consistent with aluminum-induced bone removal via combined cell-mediated resorption and physicochemical dissolution.