However, given their relative contribution to the total body weight, skeletal muscle content of C far exceeded radiolabel in heart.
Previous work by our group has shown that in the Mg-depleted mouse hypomagnesemia develops and skeletal Mg content falls significantly [ 10].
In the long-term, the actions of the CaSR to regulate PTH and calcitonin will influence the maintenance of skeletal mineral content.
In addition, there may have been effects of the calcium supplement on skeletal mineral content, shape, and architecture that were not addressed in this study.
As previous studies have reported total skeletal calcium content at 1 1.5 kg [ 14] the estimated calcium loss of 571 g reported here seems plausible, albeit with neither spontaneous fractures nor the semiquantative radiological assessment clinically proving this.
In conclusion, the results from this study suggest that rural Gambian women who are accustomed to a low calcium intake have physiologic mechanisms that enable them to replenish the bone mineral that is mobilized during pregnancy and lactation, but that a period of calcium supplementation during pregnancy disrupts this process, which results long term in lower skeletal mineral content.
Preliminary studies have indicated that mice lacking the gene encoding calcitonin and CGRP-α lose more than twice as much skeletal calcium content as their wild-type sisters during three weeks of lactation [ 21], confirming a previously postulated role that calcitonin might protect the maternal skeleton from excessive resorption during lactation.
We have also demonstrated that R225W results in increased skeletal muscle glycogen content (Figure 5) and decreased IMTG content (Figure 6), while there was no change in muscle fiber type composition (Figure 7).
These results are consistent with previous reports showing that PPARα activation decreased skeletal muscle TAG content [ 25] and also heart TAG content of db/db mice [ 26].
