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. 2011:2011:469783.
doi: 10.1155/2011/469783. Epub 2011 Jun 22.

Influence of Secondary Hyperparathyroidism Induced by Low Dietary Calcium, Vitamin D Deficiency, and Renal Failure on Circulating Rat PTH Molecular Forms

Pierre D'Amour  1 , Louise Rousseau, Stephen Hornyak, Zan Yang, Tom Cantor
Affiliations

Influence of Secondary Hyperparathyroidism Induced by Low Dietary Calcium, Vitamin D Deficiency, and Renal Failure on Circulating Rat PTH Molecular Forms

Pierre D'Amour et al. Int J Endocrinol. 2011.

Abstract

Rats(r) with secondary hyperparathyroidism were studied to define the relationship between vitamin D metabolites and rPTH levels measured by 3 different rat ELISAs. Controls and renal failure (RF) rats were on a normal diet, while 2 groups on a low-calcium (-Ca) or a vitamin D-deficient (-D) diet. RF was induced surgically. Mild RF rats had normal calcium and 25(OH)D but reduced 1,25(OH)(2)D levels (P < .001) with a 2.5-fold increased in rPTH (P < .001). Severe RF rats and those on a -Ca or -D diet had reduced calcium (P < .01) and 25(OH)D levels (P < .05), with rPTH increased by 2 (-Ca diet; P < .05), 4 (-D diet; P < .001), and 20-folds (RF; P < .001) while 1,25(OH)(2)D was high (-Ca diet: P < .001) or low (-D diet, RF: P < .001). 25(OH)D and 1,25(OH)(2)D were positively and negatively related on the -Ca and -D diets, respectively. rPTH molecular forms behaved as expected in RF and on -Ca diet, but not on -D diet with more C-rPTH fragments when less were expected. This may be related to the short-time course of this study compared to prior studies.

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Figures

Figure 1
Figure 1
Relationship between rPTH assays epitopes and circulating rPTH molecular forms detected. N-PTH = amino-terminal rPTH, a posttranslationally modified form of rPTH(1-84) on serine 17. Non(1-84) large C-rPTH fragments have a partially preserved N-structure while smaller C-rPTH fragments miss that structure (18).
Figure 2
Figure 2
Relationship between 25(OH)D and 1,25(OH)2D levels in rats on the calcium-deficient diet (a) and the vitamin D-deficient diet (b).
Figure 3
Figure 3
Relationship between creatinine or 25(OH)D and calcium, phosphate, and rPTH levels in rats with moderate (●) or severe (▲) renal failure.
Figure 4
Figure 4
HPLC profiles of circulating rPTH molecular forms analyzed in Whole (–), Total (- - - -), and Carboxyl-rPTH (-.-.-.-) assays in rats on a normal calcium diet (a), a low-calcium diet (b), a vitamin D-deficient diet (c), or with moderate (d) or severe (e) renal failure. A single HPLC profile obtained with a pool of serum from all rats in a given group is illustrated.
See this image and copyright information in PMC

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