Comparison of the Appearance of Radiolabelled Vitamin D3 and 25-Hydroxy-Vitamin D3 in the Chylomicron Fraction of Plasma after Oral Administration in Man

1981 ◽  
Vol 60 (2) ◽  
pp. 241-243 ◽  
Author(s):  
Juliet E. Compston ◽  
Anne L. Merrett ◽  
F. G. Hammett ◽  
P. Magill

1. The uptake of either orally administered [3H]vitamin D3 or 25-[3H]hydroxy-vitamin D3 into the chylomicron fraction of plasma was studied in 12 healthy male subjects. 2. The amount of [3H]vitamin D3 in the chylomicron fraction expressed as a percentage of the total plasma radioactivity was higher than that of 25-[3H]hydroxy-vitamin D3. 3. It is suggested that the mechanism of intestinal absorption of vitamin D and 25-hydroxy-vitamin D may differ in man, the absorption of 25-hydroxy-vitamin D possibly being less dependent on bile acids.

1981 ◽  
Vol 241 (1) ◽  
pp. G49-G53
Author(s):  
N. Brautbar ◽  
B. S. Levine ◽  
M. W. Walling ◽  
J. W. Coburn

The intestinal absorption of calcium (Ca) has been shown to depend on vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and dietary phosphorus (P) concentration. This study was designed to evaluate the role of dietary P independent of vitamin D3 or 1,25(OH)2D3. Vitamin D-deficient rats were studied during dietary P restriction and were compared with control groups raised on a normal-phosphorus diet (NP). Balance studies were sued. Net intestinal Ca absorption was significantly lower with dietary P restriction compared with the NP group. This malabsorption of Ca was corrected by the administration of either D3 for 1,25(OH)2D3, despite hypophosphatemia. Everted gut sacs showed a marked reduction in the uptake of 45Ca in the duodenum, jejunum, and ileum during dietary P restriction. We concluded that dietary P concentration plays a major role in intestinal Ca absorption in the vitamin D-deficient rats. These findings suggest an effect of the low-phosphate diet on the vitamin D-dependent, Ca-transport mechanism.


1985 ◽  
Vol 40 (1-2) ◽  
pp. 102-108 ◽  
Author(s):  
Ana R. de Boland ◽  
Ricardo Boland

Cultures of vitamin D-deficient chick soleus muscle and 12 day-old chick embryo myoblasts were used to characterize the effects of 1,25-dihydroxy-vitamin D3 and 25-hydroxy-vitamin D3 on muscle cell Ca metabolism. Physiological amounts of both sterols increased the rate and extent of 45Ca uptake by cultures. However. 1.25(OH)2D3 was significantly more effective than 25 OHD3. The greater potency of 1,25(OH)2D3 to increase Ca uptake could be shown after various treatment intervals of cultures and using a wide concentration range of both derivatives. Information about Ca pools affected by vitamin D3 metabolites was obtained through kinetic analysis of Ca efflux in cultured myoblasts. Cytoplasmic and mitochondria Ca pools were identified on the basis of their half-times of desaturation and by selective inhibition of plasma membrane and mitochondrial Ca transport with LaCl3 and Ruthenium Red, respectively. The data suggests that 1,25(OH)2D3 acts on muscle cellular Ca by increasing Ca efflux and influx through mitochondrial and plasma membranes whereas the predominant effect of 25 OHD3 is to increase Ca influx into mitochondria.


Author(s):  
Teodora-Irina Adam-Bonci ◽  
Paraschiva Cherecheș-Panța ◽  
Eduard-Alexandru Bonci ◽  
Sorin Claudiu Man ◽  
Ancuța Cutaș-Benedec ◽  
...  

Even though vitamin D is widely acknowledged as having a potential immunomodulatory role in asthma, its exact beneficial mechanisms are yet to be clarified. An optimal serum 25-hydroxy-vitamin D (25-OH-VitD) level in pediatric asthma patients might not rely solely on the effect of dose-dependent vitamin D3 intake, but might also be influenced by factors related to insufficient asthma control. We aimed to survey the prevalence of serum 25-OH-VitD deficiency and analyze whether suboptimal levels were associated with asthma severity factors. The current cross-sectional study enrolled 131 pediatric asthma or asthma-suggestive recurrent wheezing patients, for whom serum 25-OH-VitD, IgE, and eosinophil count were assessed. The prevalence of suboptimal serum 25-OH-VitD was 58.8%. A suboptimal vitamin D status was associated with asthma exacerbation in the previous month (p = 0.02). Even under seasonal oral vitamin D3 supplementation, patients with a positive history of asthma attack in the previous four weeks presented significantly lower serum 25-OH-VitD concentrations, compared to their peers with no disease exacerbation. In conclusion, sequential measurements of serum 25-OH-VitD might prove useful for future studies evaluating the dynamic changes in vitamin D3 status in regard to asthma, especially in symptomatic patients.


2017 ◽  
Vol 73 (1) ◽  
pp. 183-190 ◽  
Author(s):  
Yewon Choi ◽  
Sang Won Lee ◽  
Anhye Kim ◽  
Kyungho Jang ◽  
Heesook Nam ◽  
...  

2006 ◽  
Vol 62 (5) ◽  
pp. 335-341 ◽  
Author(s):  
Daniel Röshammar ◽  
Trinh Ngoc Hai ◽  
Sofia Friberg Hietala ◽  
Nguyen Van Huong ◽  
Michael Ashton

1981 ◽  
Vol 61 (1) ◽  
pp. 53-59 ◽  
Author(s):  
J. D. Wark ◽  
R. G. Larkins ◽  
J. A. Eisman ◽  
K. R. Wilson

1. Isolated renal tubules were prepared from vitamin D-deficient chicks. The effects of added prostaglandin E2 (PGE2) and agents which modify prostaglandin metabolism on the metabolism of 25-hydroxy-vitamin D3 were studied. 2. Frusemide (0.1 mmol/l) raised the prostaglandin E (PGE) content of the tubule incubation medium; it significantly increased 1,25-dihydroxy-vitamin D3 [1,25-(OH)2D3] production from 25-hydroxy-vitamin D3 [25-(OH)D3] and significantly inhibited the net production of 24,25-dihydroxy-vitamin D3 [24,25-(OH)2D3]. 3. Acetylsalicylic acid (aspirin; 0.1 mmol/l) decreased the PGE content of the tubule incubation medium and significantly inhibited 1,25-(OH)2D3 production. 4. In the presence of 1,25-(OH)2D3, 4 h exposure of tubules from vitamin D-deficient chicks to concentrations of PGE2 between 2.8 × 10−6 and 2.8 × 10−8 mol/l significantly enhanced 1,25-(OH)2D3 production. 5. It is concluded that, in view of the effects of modulation of endogenous prostaglandin levels by frusemide in aspirin, and the stimulatory effect of exogenous PGE2, prostaglandins should be considered potential regulators of the renal 25-hydroxy-vitamin D-1α-hydroxylase [25-(OH)D-1α-hydroxylase] enzyme.


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