Intestinal lead and calcium absorption: effect of 1,25-dihydroxycholecalciferol and lead status.
This study was designed to investigate, in some detail, the relative effects of the hormonal form of vitamin D (1,25-dihydroxycholecalciferol) on duodenal Pb and Ca absorption as a function of dietary Pb level. When cholecalciferol-deficient chicks were chronically repleted with physiologic levels of 1,25-dihydroxycholecalciferol (1,25(OH)2D3), as the sole source of the vitamin, 203Pb and 47Ca absorption were enhanced over 4- and 8-fold, respectively. Ingestion of Pb during the repletion period had no significant effect on the intestinal Ca absorption response to 1,25-(OH)2D3 even at a very high dietary Pb level. The efficiency of intestinal 203Pb absorption was, however, significantly diminished by dietary Pb, in an apparent dose-dependent fashion. The results indicate that the extent to which systemic Ca homeostatic mechanisms influence intestinal Pb absorption is dependent, in large part, on Pb status.
Fullmer
C S
CS
Department of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.
D000469:Alkaline Phosphatase / Q000096:biosynthesis; D000818:Animals; D001835:Body Weight; D064026:Calbindins; D002117:Calcitriol / Q000008:administration & dosage*; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002645:Chickens; D002762:Cholecalciferol / Q000172:deficiency; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000378:metabolism*; D007408:Intestinal Absorption; D007854:Lead / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D010758:Phosphorus / Q000097:blood; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis; D014808:Vitamin D Deficiency / Q000378:metabolism
D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D002762:Cholecalciferol; D010758:Phosphorus; D007854:Lead; D000469:Alkaline Phosphatase; D002117:Calcitriol; D002118:Calcium