Response of tissue phosphate content to acute dietary phosphate deprivation in the X-linked hypophosphatemic mouse.

In order to evaluate a possible role for tissue phosphate or phosphorylated compounds in mediating the increase in plasma 1,25(OH)2D3 levels during dietary phosphate deprivation, renal cortical phosphate content has been measured in both normal and X-linked hypophosphatemic mice on a normal diet and also after acute dietary phosphate deprivation. We find that the metabolism of inorganic phosphate and phosphorylated organic compounds in the renal cortex of Hyp mice is not altered in response to their very low levels of serum phosphate. Skeletal muscle does not lose inorganic phosphate and/or phosphorylated metabolites to compensate for drastic loses of serum phosphate during acute dietary deprivation in either normal or Hyp mice. Furthermore, the chronic low level of serum phosphate and altered hormonal regulation in Hyp mice do not produce alterations in mineral composition of the bone with the possible exception that the stoichiometry of the apatite might be slightly different.