Document Detail

The influence of 24,25(OH)2D3 on the calcemic effect of 1,25(OH)2D in rats with chronic renal failure is parathyroid hormone dependent.
MedLine Citation:
PMID:  2399255     Owner:  NLM     Status:  MEDLINE    
Previous studies from our laboratory have shown that 24,25(OH)2D3 attenuates the calcemic effect of 1,25(OH)2D3 in rats with reduced renal mass. This study was undertaken to clarify the role of parathyroid hormone in this response. Adult rats (n = 27) with reduced renal mass after parathyroidectomy with an initial plasma calcium of 3.7 +/- 0.1 mEq/liter were divided into four groups: (i) control rats and rats treated with (ii) 24,25(OH)2D3, (iii) 1,25(OH)2D3, and (iv) both 1,25 and 24,25(OH)2D3. After 4 days significant hypercalcemia was seen in PTX animals receiving 1,25(OH)2D3 alone or in combination with 24,25(OH)2D3. Plasma calcium in the combined therapy rats (7.42 +/- 0.22 mEq/liter) was significantly higher than in those treated with 1,25(OH)2D3 alone (6.68 +/- 0.22 mEq/liter, P less than 0.05). After 8 days, plasma calcium was higher in the rats treated with 1,25(OH)2D3 but was of same magnitude in those treated with 1,25(OH)2D3 alone or in combination with 24,25(OH)2D3. In contrast, in a subset of rats (n = 35) with reduced renal mass but intact parathyroid glands similarly treated with the vitamin D metabolites, a blunted calcemic response was seen after the combination of 1,25(OH)2D3 with 25,25(OH)2D3 administration alone. These results show that in rats with reduced renal mass, 24,25(OH)2D3 attenuates the calcemic effect of 1,25(OH)2D3 only in the presence of intact parathyroid glands. The different calcemic responses to 1,25 or combined 1,25 and 24,25(OH)2D3 in intact or parathyroidectomized rats with chronic renal insufficiency may result from different interaction between the vitamin D metabolites and the parathyroid hormone, presumably at the level of bone.
D Rubinger; Y Krause; I Krause; M M Popovtzer
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)     Volume:  195     ISSN:  0037-9727     ISO Abbreviation:  Proc. Soc. Exp. Biol. Med.     Publication Date:  1990 Oct 
Date Detail:
Created Date:  1990-10-18     Completed Date:  1990-10-18     Revised Date:  2007-11-02    
Medline Journal Info:
Nlm Unique ID:  7505892     Medline TA:  Proc Soc Exp Biol Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  13-7     Citation Subset:  IM    
Nephrology and Hypertension Services, Hadassah University Hospital, Jerusalem, Israel.
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MeSH Terms
24,25-Dihydroxyvitamin D 3 / pharmacology*
Calcitriol / pharmacology*
Calcium / blood*,  urine
Kidney / drug effects
Kidney Failure, Chronic / metabolism*
Parathyroid Hormone / physiology*
Reg. No./Substance:
0/Parathyroid Hormone; 32222-06-3/Calcitriol; 40013-87-4/24,25-Dihydroxyvitamin D 3; 7440-70-2/Calcium

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