Vitamin D-stimulated intestinal calcium absorption may not involve calcium-binding protein directly

Nature ◽  
1976 ◽  
Vol 263 (5573) ◽  
pp. 161-163 ◽  
Author(s):  
R. SPENCER ◽  
M. CHARMAN ◽  
P. WILSON ◽  
E. LAWSON
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Intestinal Calcium Absorption

Calcium absorption and intestinal calcium-binding protein: quantitative relationship.

1979 ◽  
Vol 236 (5) ◽  
pp. E556 ◽  
Author(s):  
J J Feher ◽  
R H Wasserman
Keyword(s):  
Vitamin D ◽  
Vitamin D3 ◽  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Quantitative Relationship ◽  
Calcium Binding Protein ◽  
Vitamin D Status ◽  
Loop Technique

The concentration of the vitamin D-induced calcium-binding protein (CaBP) and calcium absorption from the duodenum were investigated in chicks with an in vivo ligated-loop technique. The relation between CaBP and calcium absorption was dependent on a) source of vitamin D activity (either vitamin D3 or 1,25-dihydroxycholecalciferol); b) dosage of vitamin D3; c) time after administration of vitamin D3 to rachitic animals. To aid in the interpretation of these results, a phenomenological model was developed in which CaBP was viewed as being linearly related to a portion of calcium absorption. The model, when applied to the data, suggests that there is a "nonfunctional" pool of CaBP the size of which is determined by the vitamin D status of the animal. After correction for this nonfunctional pool, the proportionality between CaBP and calcium absorption is independent of the vitamin D status of the animal.

scholarly journals The response of the small intestine to vitamin D. Correlation between calcium-binding-protein production and increased calcium absorption

1974 ◽  
Vol 144 (2) ◽  
pp. 339-346 ◽  
Author(s):  
J S Emtage ◽  
D E M Lawson ◽  
E Kodicek
Keyword(s):  
Vitamin D ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Calcium Binding ◽  
Protein Production ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Intestinal Cell ◽  
Stimulation Of

1. The synthesis of calcium-binding protein, a protein produced in the small intestine in response to vitamin D, was investigated with a view to determining whether calcium-binding-protein production could be correlated with the stimulation of calcium absorption by vitamin D. 2. A radioimmunological assay, which can quantitatively estimate calcium-binding-protein concentrations as low as 1μg/g wet wt., was used to detect the synthesis of soluble calcium-binding protein. 3. When used on intestinal supernatants from chicks dosed with vitamin D, calcium-binding protein was not detectable at 8h but was present after 12h at a concentration of 8.6μg/g wet wt.; in agreement with this an increase in calcium absorption due to vitamin D was detected at 12h but not at 8h. 4. The synthesis of calcium-binding protein was also monitored directly by making use of the ability of the iodinated antiserum to bind specifically to nascent calcium-binding protein chains on intestinal polyribosomes; in this way calcium-binding-protein synthesis could be detected 8h after dosage with vitamin D. Further, the binding reaction indicated a near linear increase in the calcium-binding-protein-synthesizing capacity over a 16h period. 5. From the amount of calcium-binding protein present 12 and 24h after vitamin D administration it is calculated that calcium-binding-protein mRNA is produced at approx. 1mol/min per intestinal cell. 6. It is concluded that the high correlation between the initiation of calcium-binding-protein synthesis and the stimulation of calcium absorption by vitamin D strengthens the proposal that calcium-binding protein plays an important role in calcium transport.

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