EurekaMag.com logo
+ Site Statistics
References:
53,623,987
Abstracts:
29,492,080
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on LinkedInFollow on LinkedIn

+ Translate

Dietary phosphate deprivation increases renal synthesis and decreases renal catabolism of 1,25-dihydroxycholecalciferol in guinea pigs



Dietary phosphate deprivation increases renal synthesis and decreases renal catabolism of 1,25-dihydroxycholecalciferol in guinea pigs



Journal of Nutrition 121(10): 1635-1642



In guinea pigs, dietary phosphate deprivation decreases plasma phosphate concentration, increases plasma 1.25-dihydroxycholecalciferol [1,25-(OH)2D3] concentration and causes hypercalcemia concurrent with the maximal increase in plasma 1,25-(OH)2D3 levels. Our objective was to determine whether increased synthesis or decreased catabolism contributed to the elevation in plasma 1,25-(OH)2D3. Preliminary experiments using renal mitochondria from guinea pigs fed a control diet revealed that 23,25-dihydroxycholecalciferol [23,25-(OH)2D3], not 24,25-dihydroxycholecalciferol [24,25-(OH)2D3], was the reciprocal side-chain metabolite to 1,25-(OH)2D3 in this species. An assay employing guinea pig renal mitochondria was used to measure the renal synthesis of 1,25-(OH)2D3 and 23,25-(OH)2D3 from [3H]25-OH-D3. These metabolites were unequivocally identified by combinations of HPLC, ultraviolet spectrophotometry and mass spectrometry. This renal mitochondrial assay was subsequently used to investigate the effect of dietary phosphate deprivation on guinea pig vitamin D metabolism. Within 1 wk the rate of synthesis of 1,25-(OH)2D3 was maximal in phosphate-deprived guinea pigs. This rate was significantly (P less than 0.005) higher than that achieved in same-day control guinea pigs. Conversely, within 1 d the synthesis of 23,25-(OH)2D3 was significantly (P less than 0.005) decreased in phosphate-deprived guinea pigs. Similarly, the rate of 1,25-(OH)2D3 metabolism was decreased within 1 d of dietary phosphate deprivation and was at a minimum within 1 wk. This rate was significantly (P less than 0.005) less than that attained in same-day control guinea pigs. These results suggest that both increased synthesis and decreased metabolism of 1,25-(OH)2D3 contribute to the plasma 1,25-(OH)2D3 elevation that occurs in response to dietary phosphate deprivation.

(PDF same-day service: $19.90)

Accession: 002072039

Download citation: RISBibTeXText

PMID: 1765829

DOI: 10.1093/jn/121.10.1635



Related references

Evidence that both acute and chronic gluco corticoid administration increases renal phosphate excretion independent of dietary phosphate restoration of parathyroid hormone sensitivity in phosphate deprivation. Clinical Research 29(2): 464A, 1981

Dietary protein restriction pr decreases renal reabsorption of phosphate during renal failure. Kidney International 33(1): 351, 1988

Dietary calcium and phosphate restriction in guinea-pigs during pregnancy: fetal mineralization induces maternal hypocalcaemia despite increased 1a,25-dihydroxycholecalciferol concentrations. The British Journal of Nutrition 84(4): 5-504, 2000

Dietary calcium and phosphate restriction in guinea-pigs during pregnancy: fetal mineralization induces maternal hypocalcaemia despite increased 1 alpha,25-dihydroxycholecalciferol concentrations. British Journal of Nutrition 84(4): 495-504, 2000

Dietary hydrogenated fat decreases LDL apoB-100 catabolism and increases HDL-apoA-1 catabolism in hypercholesterolemic women. Circulation 108(17 Supplement): IV-784, October 28, 2003

Dietary phosphate deprivation increases 1 25 di hydroxy vitamin d 3 synthesis in rat kidney. Federation Proceedings 40(3 PART 2): 899, 1981

Effect of phosphate restriction on the relationship between intracellular phosphate and renal sodium phosphate cotransport capacity in growing guinea pigs. Kidney International 37(1): 453, 1990

Dietary phosphate deprivation increases 1 25 di hydroxy vitamin d 3 synthesis in rat kidney in vitro. Journal of Biological Chemistry 258(2): 1152-1155, 1983

Studies on the pathogenesis of experimental auto immune renal tubulo interstitial disease in guinea pigs 6. induction of renal lesions by active or passive immunization of strain 2 guinea pigs. International Archives of Allergy and Applied Immunology 60(4): 398-406, 1979

Dietary HCO3 decreases renal endothelin-1 levels and proteinuria in chronic renal failure due to renal mass ablation. Journal of the American Society of Nephrology 9(PROGRAM AND ABSTR ISSUE): 625A, Sept, 1998

Different mechanism of increase of sodium phosphate cotransport in the renal brush border membrane bbm elicited by thyroid hormone t 3 and by dietary phosphate deprivation. Kidney International 33(1): 178, 1988

Effects of changes in phosphate intake on serum phosphate concentration and the transport of phosphate in renal brush border membrane vesicles bbmv of developing guinea pigs. Pediatric Research 25(4 PART 2): 344A, 1989

Modulation of renal protein kinase c by dietary phosphate deprivation. Pediatric Research 21(4 PART 2): 473A, 1987