1,25 Dihydroxycholecalciferol and the genesis of hypocalcaemia in magnesium-deficient chicks.
The role of 1,25 dihydroxycholecalciferol (1,25 DHCC) in the genesis of hypocalcaemia of magnesium (Mg) deficiency was studied in chicks fed control or Mg-deficient diets with varying calcium (Ca) content. In one study, Ca and Mg deficiencies were induced simultaneously whereas in a second study, exposure to low dietary Ca followed induction of Mg deficiency. In both studies, Mg-deficient chicks fed adequate dietary Ca were hypocalcaemic yet had normal circulating 1,25 DHCC, whereas Mg-deficient chicks fed low dietary Ca maintained normocalcaemia and had increased 1,25 DHCC. Bone Ca content, which was raised in Mg-deficient chicks fed adequate Ca, decreased in association with increased 1,25 DHCC and normalization of plasma Ca during exposure to low dietary Ca. The results suggest that the inappropriately normal 1,25 DHCC observed in conventional Mg deficiency may contribute to the pathological hypocalcaemia. In addition, these studies indicate that hypomagnesaemia per se does not limit 1,25 DHCC production during Mg deficiency.
Weaver
V M
VM
Department of Biochemistry, Faculty of Medicine, University of Ottawa, Ontario, Canada.
Welsh
J
J
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002117:Calcitriol / Q000097:blood*; D002118:Calcium / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage; D002645:Chickens; D006996:Hypocalcemia / Q000209:etiology* / Q000378:metabolism; D008275:Magnesium Deficiency / Q000150:complications* / Q000378:metabolism
D002136:Calcium, Dietary; D002117:Calcitriol; D002118:Calcium