Increased carbonate associated with phosphate demand in bioapatite crystallites

The mineralogy of bone tissues has important implications
for bone physical and chemical properties. We employed
Raman and FTIR spectroscopy to study bone bioapatite in the
femurs and tibia of healthy mice and those with
hypophosphatemia - a genetic disorder that creates a phosphate
deficiency and results in lower bone mineralization [1].
Specifically we focused on the changes in the carbonate
content of bone from healthy, wild-type mice (WT) and
hypophosphatemic mice (HYP) when increased remodelling
has occurred due to pregnancy and lactation. The contributions
of the carbonate and phosphate symmetrical stretching bands
were used to determined changes in carbonate content. FTIR
spectroscopy indicates an increased carbonate content of the
bone bioapatite in HYP compared to WT mice in response to
increased remodelling during lactation and phosphate demand.
This is particularly evident in the lactating HYP mice where
bone is expected to experience the most intense remodelling.
Raman spectroscopy confirms this trend in lactating, pregnant
and virgin mice. Changes in carbonate content will alter the
crystallinity and thus solubility of the bone crystallites with
concomitant effects on the role of bone crystallites during
homeostasis and remodelling properties of bone. Despite the
impaired mineral metabolism in the HYP mice, these mice
employ similar adaptations to mineral demand as WT mice.