Intestinal calcium and phosphate transport in genetic hypophosphatemic mice

Abstract

Serum phosphate, serum calcium, intestinal phosphate and intestinal calcium transport were measured in normal ( C57BL 6J +/Y) and genetic (X-linked) hypophosphatemic mice ( C57BL 6J Hyp Y ). The hypophosphatemic mice had low serum phosphorus levels and dramatically decreased intestinal phosphate transport compared with normal controls. On the other hand, normal and hypophosphatemic mice had equivalent levels of intestinal calcium transport. The hypophosphatemic mice did illustrate a slightly decreased serum calcium concentration, however. Administration of 1,25-dihydroxy-vitamin D 3, the principal active metabolite of vitamin D, stimulated intestinal calcium transport but not intestinal phosphate transport in the genetic hypophosphatemic mice. The results obtained are consistent with the hypothesis that the primary metabolic disturbance in familial hypophosphatemia involves a defect in phosphate transport mechanisms.