title: Elevated 1,25(OH)2D3, intestinal absorption, and renal mineral conservation in male rats.
abstract: We studied the physiological importance of elevated serum 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] in male rats. Male and female rats of equal weight consumed either a high calcium diet (1.20% calcium; HCD), a low calcium diet (0.02% calcium; LCD), or a normal calcium diet (0.60% calcium; NCD). With all three diets, serum 1,25(OH)2D3 was higher in males than females and rose in both sexes with decreasing diet calcium. There was a direct correlation between serum 1,25(OH)2D3 and proximal duodenal 45Ca uptake (r = 0.667; P less than 0.001). With NCD, we performed a balance study and found a direct correlation between serum 1,25(OH)2D3 and both 5-day fractional calcium absorption (r = 0.703; P less than 0.01) and fractional phosphorus absorption (r = 0.679; P less than 0.01). In addition, serum 1,25(OH)2D3 was directly correlated with 5-day calcium retention (r = 0.772; P less than 0.001) and phosphorus retention (r = 0.830; P less than 0.001). Males grew faster than females (F ratio = 1,194; P less than 0.001). Elevated 1,25(OH)2D3 in males appears to be of biological significance and may help satisfy a greater, growth-related, need for calcium.
mesh_terms: D000042:Absorption; D000818:Animals; D001774:Blood Chemical Analysis; D002117:Calcitriol / Q000097:blood* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008903:Minerals / Q000378:metabolism*; D051381:Rats / Q000254:growth & development / Q000502:physiology*; D011919:Rats, Inbred Strains; D014556:Urine / Q000032:analysis
chemical_list: D008903:Minerals; D002117:Calcitriol; D002118:Calcium