QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Siu, G. M. Articles by Draper, H. H. Search for Related Content PubMed PubMed Citation Articles by Siu, G. M. Articles by Draper, H. H.

Self-Regulation of Phosphate Intake in the Rat: The Influence of Age, Vitamin D and Parathyroid Hormone¹

Department of Nutrition, University of Guelph, Guelph, Ontario, Canada, N1G 2W1

Growing rats offered a choice of four pairs of diets, one low in P (0.1%) and the others containing 0.3, 0.6, 1.2 or 1.8% P, selected food mixtures in each case with nearly identical P contents (0.23–0.24%) (Ca:P = 2.2:1). Mature rats offered the same dietary choices exhibited less rigid diet selection but clearly preferred a diet higher in P (0.64–0.69%) (Ca:P = 0.9:1). Vitamin D-deficient animals selected less P than controls and parathyroidectomized rats severely limited their P intake. The increase in self-determined P consumption relative to Ca in mature rats is consonant with the greater decrease in the requirement for Ca associated with maturation and cessation of bone growth. Susceptibility to hypocalcemia in vitamin D deficiency and parathyroidectomy is a probable factor in the increased sensitivity to excess dietary P, which further depresses plasma Ca. These experiments confirm the existence of a feedback mechanism that regulates the voluntary consumption of P in accordance with physiological needs.

KEY WORDS: • phosphorus • calcium • vitamin D • parathyroid hormone

¹ Supported by a grant from the Natural Sciences and Engineering Research Council of Canada.

² To whom reprint requests should be sent.

Manuscript received 23 September 1983.