scholarly journals Role of 1,25-Dihydroxyvitamin D3 on Intestinal Phosphate Absorption in Rats with a Normal Vitamin D Supply

1977 ◽  
Vol 60 (3) ◽  
pp. 639-647 ◽  
Author(s):  
R. Rizzoli ◽  
H. Fleisch ◽  
J-P. Bonjour
Keyword(s):  
Vitamin D ◽  
Dihydroxyvitamin D3 ◽  
Phosphate Absorption ◽  
1,25 Dihydroxyvitamin D3 ◽  
Normal Vitamin ◽  
Intestinal Phosphate Absorption

Intestinal phosphate absorption: influence of vitamin D and non-vitamin D factors

1986 ◽  
Vol 250 (3) ◽  
pp. G369-G373 ◽  
Author(s):  
D. B. Lee ◽  
M. W. Walling ◽  
N. Brautbar
Keyword(s):  
Vitamin D ◽  
Adult Rats ◽  
Dihydroxyvitamin D3 ◽  
Treatment Groups ◽  
Transport Of Inorganic Phosphate ◽  
P Flux ◽  
Intestinal Phosphate Absorption ◽  
P Absorption

The transport of inorganic phosphate (P) was measured in the absence of electrochemical gradients across rat jejunum in vitro. Active P absorption was demonstrated in young, vitamin D-deficient (-D) rats, whereas active P secretion was found in normal, non-vitamin D-deficient adult rats, suggesting regulation of intestinal P transport by age-dependent but vitamin D-independent mechanisms. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] stimulated mucosal-to-serosal P flux (Jm----s) without affecting serosal-to-mucosal P flux (Js----m), causing further increases in net P absorption (Jnet) in -D rats and reduction in net P secretion in normal adult rats, confirming a previously described role of this hormone on P absorption. We then examined the effect of increasing extracellular (buffer) P concentration [P] on this 1,25(OH)2D3-stimulated active P absorption in jejunum from -D rats. At [P] of 0.024, 0.24, and 2.4 mM, 1,25(OH)2D3 consistently stimulated Jm----s without affecting Js----m, causing an increment in Jnet. At 7.5 mM [P], however, this Jm----s stimulatory effect of 1,25(OH)2D3 was no longer observed. Moreover, at this [P] the Js----m exceeded Jm----s in both -D and 1,25(OH)2D3-repleted rats, converting the active P absorption into active P secretion in both treatment groups. These observations suggest the participation of local mechanisms, such as the ambient [P] of the transporting enterocytes, in the regulation of intestinal P absorption. Finally, the influence of dietary P deprivation on P absorption was studied in -D rats, with or without either vitamin D3 or 1,25(OH)2D3 repletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Placental transport of calcium and phosphorus is not regulated by vitamin D

1984 ◽  
Vol 246 (4) ◽  
pp. F526-F529 ◽  
Author(s):  
R. Brommage ◽  
H. F. DeLuca
Keyword(s):  
Vitamin D ◽  
Calcium Content ◽  
Pregnant Rats ◽  
Dihydroxyvitamin D3 ◽  
Fetal Plasma ◽  
Protein Levels ◽  
1,25 Dihydroxyvitamin D3 ◽  
Vitamin D3 Metabolites ◽  
Calcium And Phosphorus

The role of 1,25-dihydroxyvitamin D3 in regulating the maternal-to-fetal transfer of calcium and phosphorus across the placenta was examined by measuring maternal and fetal plasma levels of these elements in vitamin D-replete and -deficient rats. Pregnant rats in their 20th day of gestation and their fetuses were studied. Two diets with different calcium and phosphorus contents were used to produce either hypocalcemia or hypophosphatemia in the vitamin D-deficient rats. Calcium and phosphorus levels in fetal plasma were always higher than maternal values, and in vitamin D deficiency a twofold gradient of calcium and a fivefold gradient of phosphorus concentrations across the placenta were observed. Since protein levels in fetal plasma were approximately fivefold lower than maternal values, protein binding does not account for the higher fetal than maternal concentrations of plasma calcium. These results, together with previous data showing normal calcium content of vitamin D-deficient fetuses, indicate that 1,25-dihydroxyvitamin D3 and other vitamin D3 metabolites are not involved in the active transport of calcium and phosphorus across the placenta in the rat.

Chronic DOCA treatment increases Ca absorption: role of hypercalciuria and vitamin D

1986 ◽  
Vol 251 (3) ◽  
pp. E279-E284 ◽  
Author(s):  
D. Zikos ◽  
C. Langman ◽  
U. Gafter ◽  
B. Delahaye ◽  
K. Lau
Keyword(s):  
Vitamin D ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
High Salt ◽  
High Salt Diet ◽  
Dihydroxyvitamin D3 ◽  
Salt Diet ◽  
1,25 Dihydroxyvitamin D3 ◽  
Best Fit

To examine the effects of mineralocorticoidism on calcium (Ca) absorption and to define the mechanism, rats received a high-salt diet and injections of vehicle or deoxycorticosterone acetate (DOCA). Net (44.2 vs. 31.4 mg/day) and percent Ca absorption (28.1 vs. 20.1%) was increased after 5 days of DOCA. This was associated with increased duodenal 45Ca uptake. Thus despite the hypercalciuria, Ca balance was similar. Although the hypercalciuria persisted chronically, the gut effects were sustained, which maintained normal ionized Ca, bone Ca, and Ca balance. Urinary cyclic adenosine monophosphate was elevated by DOCA. Compared with appropriate controls, neither DOCA alone nor polydipsia (elicited by dextrose) produced similar magnitudes of hypercalciuria as DOCA plus high-salt diet. These maneuvers also failed to increase Ca absorption. Neutralization of the metabolic alkalosis neither attenuated the DOCA-induced hypercalciuria nor abolished the Ca hyperabsorption. In vitamin D-deprived rats, the hypercalciuria but not the intestinal effects of DOCA were reproduced. Serum 1,25-dihydroxyvitamin D3 levels were increased during chronic DOCA treatment (224 vs. 139 pg/ml). These data best fit the hypothesis that increased Ca absorption is secondary to the calciuric effects of DOCA and high-salt diet and is mediated via the increased parathyroid hormone and 1,25-dihydroxyvitamin D3 activities.

The impact of methylmercury on 1,25-dihydroxyvitamin D3-induced transcriptomic responses in dolphin skin cells

2010 ◽  
Vol 391 (2/3) ◽  
Author(s):  
Blake C. Ellis ◽  
Sebastiano Gattoni-Celli ◽  
Mark S. Kindy
Keyword(s):  
Vitamin D ◽  
Target Genes ◽  
Protective Role ◽  
Dihydroxyvitamin D3 ◽  
Skin Cells ◽  
1,25 Dihydroxyvitamin D3 ◽  
Atlantic Bottlenose Dolphin ◽  
Considerable Impact ◽  
The Impact

Abstract The Atlantic bottlenose dolphin has been the focus of much attention owing to the considerable impact of environmental stress on its health and the associated implications for human health. Here, we used skin cells from the dolphin to investigate the protective role of the vitamin D pathway against environmental stressors. We previously reported that dolphin skin cells respond to 1,25-dihydroxyvitamin D3 (1,25D3), the bioactive metabolite of vitamin D3, by upregulation of the vitamin D receptor (VDR) and expression of several genes. Methylmercury is a highly bioaccumulative environmental stressor of relevance to the dolphin. We currently report that in dolphin cells sublethal concentrations of methylmercury compromise the ability of 1,25D3 to upregulate VDR, to transactivate a vitamin D-sensitive promoter, and to express specific target genes. These results help elucidate the effects of vitamin D and methylmercury on innate immunity in dolphin skin and potentially in human skin as well, considering similarities in the vitamin D pathway between the two species.

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