Phosphate intestinal secretion and absorption by isolated ileal loop: effects of cholecalciferol and diet phosphate.
The effect of diet phosphate content and cholecalciferol on intestinal phosphate secretion and absorption was investigated in rachitic chicks. Phosphate absorption was determined by the in situ ligated loop technique. Phosphate secretion was estimated by a method proposed by the authors. Hydroxyapatite, placed in the lumen of a ligated loop, acts as trapping agent of 32P leaving the intestinal tissue. The fraction of rapid exchangeability of tissue phosphate was taken as the precursor pool of secreted phosphate. Control chicks fed diets containing 0.3% P (group 1) or 1.0% (group 2) showed similar Pi absorption; the secretion was larger for group 2. After cholecalciferol treatment for 2 or 4 consecutive days an increment of Pi absorption with simultaneous reduction of Pi secretion was evident for both groups of animals. Chicks treated for 7 days gave values similar to those of controls. It is concluded that the regulation of intestinal phosphate absorption and secretion could be one important mean of homeostatic control. Intestinal phosphate movement is adapted to dietary phosphate and is partially independent of cholecalciferol.
D000818:Animals; D002645:Chickens; D002762:Cholecalciferol / Q000494:pharmacology*; D004032:Diet; D007082:Ileum / Q000378:metabolism; D007408:Intestinal Absorption / Q000187:drug effects*; D007419:Intestinal Secretions / Q000187:drug effects*; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D010758:Phosphorus / Q000378:metabolism; D012279:Rickets / Q000378:metabolism
D010710:Phosphates; D002762:Cholecalciferol; D010758:Phosphorus