Open AccessRole of 1,25-Dihydroxyvitamin D 3 in Maintaining Serum Phosphorus and Curing Rickets
Author(s) -
Yoko Tanaka,
Hector F. DeLuca
Publication year - 1974
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.71.4.1040
Subject(s) - endocrinology , phosphorus , medicine , calcification , calcium , vitamin d and neurology , alkaline phosphatase , rickets , chemistry , phosphate , calcitriol , phosphorus deficiency , biology , biochemistry , enzyme , organic chemistry
The intravenous injection of a single dose of 650 pmoles of 1,25-dihydroxyvitamin D3 to rats fed a vitamin D-deficient, low-phosphorus diet caused an elevation of serum phosphorus within 5 hours which reached a maximum in about 10-12 hours. This elevated serum phosphorus returned to deficiency levels 2-3 days later. On the other hand, a single injection of 650 pmoles of 25-hydroxyvitamin D3 produced a significant rise at 12 hours, reached a maximum in 24-36 hours, and was maintained for at least 7 days. The single dose of 1,25-dihydroxyvitamin D3 supported little calcification of bone, whereas the 25-hydroxyvitamin D3 produced marked calcification. Six-hundred and fifty pmoles of 24,25-dihydroxyvitamin D3 increased serum phosphorus only slightly and induced no calcification. When 1,25-dihydroxyvitamin D3 was given each day, a sustained increase in serum phosphorus and marked bone calcification resulted. In contrast to the serum phosphorus responses, intestinal calcium transport remained high 5 days after administration of a single dose of 1,25-dihydroxyvitamin D3 . Serum calcium was not changed appreciably by any of the metabolites.Thyroparathyroidectomized rats or rats fed a diet extremely deficient in phosphate still exhibited a marked elevation of serum phosphorus in response to 1,25-dihydroxyvitamin D3 . The effect of 1,25-dihydroxyvitamin D3 on serum phosphorus was greatly reduced in nephrectomized rats, suggesting that the serum phosphorus response to 1,25-dihydroxyvitamin D3 may arise from an enhancement of phosphate reabsorption in the renal tubules.It is suggested that 1,25-dihydroxyvitamin D3 cures rickets in rats by increasing the concentration of serum phosphorus rather than by increasing serum calcium concentration and calcium absorption.