Effect of experimental chronic renal insufficiency on bone mineral and collagen maturation

The effect of chronic renal disease on bone matrix and mineral maturation was evaluated in rats with experimental renal insufficiency of 2-11 wk duration utilizing bromoform-toluene gradient fractionation of bone powder, pulse labeling experiments with (45)Ca and proline-(3)H differential extraction, and X-ray diffraction techniques.Maturation defects in both collagen and mineral ((45)Ca) metabolism were documented as early as 2 wk after the induction of uremia, when total bone calcium, inorganic phosphate, and hydroxyproline content were unchanged. The maturational defect progressed with advancing uremia despite insignificant changes in plasma pH and calcium, and normal bone carbonate levels. Although circulating levels of 25-hydroxycholecalciferol were significantly lower than normal in the uremic animals, pretreatment with either this vitamin D metabolite or vitamin D(3) itself failed to alter the observed changes in skeletal maturation.