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A comparison of the effects of dietary calcium and phosphorus deficiency on the in vitro and in vivo metabolism of 25-hydroxycholecalciferol in the chick

Published online by Cambridge University Press:  24 July 2007

Barbara A. Sommerville
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
R. Swaminathan
Affiliation:
Department of Chemical Pathology, Leeds General Infirmary, Leeds 1
A. D. Care
Affiliation:
Department of Animal Physiology and Nutrition, University of Leeds, Leeds LS2 9JT
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Abstract

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1. Young chicks fed a diet deficient in calcium showed an eightfold increase in the in vitro renal production of 1,25-dihydroxycholecalciferol (1,25-DHCC) and those fed a diet deficient in phosphorus showed a threefold increase when compared to chicks on a normal diet.

2. The in vivo accumulation of 1,25-DHCC in the gut mucosa was doubled in both low-Ca and low-P groups as was the rate of Ca absorption from the duodenum and the Ca-binding protein activity. The accumulation of 1,25-DHCC in bone increased threefold in the low-Ca group but showed no change in the low-P group.

3. It was concluded that the increased rate of Ca absorption found in dietary P deficiency depends rather upon the capacity of the gut mucosa to accumulate larger amounts of 1,25-DHCC than upon an increased renal production of this metabolite. The mechanism by which this is achieved is unknown, but it unlikely to be a general increase in availability of 1,25-DHCC since no rise occurred in bone 1,25-DHCC levels.

Type
Short Papers
Copyright
Copyright © The Nutrition Society 1978

References

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