EFFECT OF LOW PHOSPHORUS DIETS ON INTESTINAL CALCIUM ABSORPTION AND THE CONCENTRATION OF CALCIUM-BINDING PROTEIN IN INTACT AND PARATHYROIDECTOMIZED PIGS

1978 ◽  
Vol 78 (3) ◽  
pp. 379-387 ◽  
Author(s):  
J. FOX ◽  
D. W. PICKARD ◽  
A. D. CARE ◽  
T. M. MURRAY
Keyword(s):  
Small Intestine ◽  
Intestinal Absorption ◽  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Intestinal Calcium Absorption ◽  
Jejunal Loop ◽  
Dietary Concentration ◽  
Low Phosphorus

The effect of changing the dietary concentration of phosphorus on the intestinal absorption of calcium has been studied in conscious pigs each prepared with a Thiry–Vella loop of jejunum. A reduction in the percentage of phosphorus in the diet from 0·7 to 0·3% caused an increase in the efficiency of absorption of calcium from the fluid used to perfuse the jejunal loop in both intact and parathyroidectomized animals. There was a marked increase in the amount of calcium-binding protein (CaBP) in the small intestine of pigs fed the low phosphorus diet. Parathyroidectomy did not affect the amount of CaBP in the small intestine when either the normal or the low phosphorus diets were fed.

ROLE OF THE PARATHYROID GLANDS IN THE ENHANCEMENT OF INTESTINAL CALCIUM ABSORPTION IN RESPONSE TO A LOW CALCIUM DIET

1977 ◽  
Vol 74 (3) ◽  
pp. 345-354 ◽  
Author(s):  
J. FOX ◽  
R. SWAMINATHAN ◽  
T. M. MURRAY ◽  
A. D. CARE
Keyword(s):  
Small Intestine ◽  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Intestinal Calcium Absorption ◽  
Parathyroid Glands ◽  
Calcium Diet ◽  
Low Calcium Diet ◽  
Low Calcium

SUMMARY The phenomenon of adaptation of intestinal calcium absorption to changes in dietary calcium has been studied in conscious pigs with Thiry–Vella jejunal loops. The result of decreasing the calcium content of the diet from 1·2 to 0·1% was an increase in the efficiency of the net absorption of calcium from the fluid used to perfuse the jejunal loop; this increase took place 4–6 days after the change in diet. A similar effect was noted in four pigs which had previously been parathyroidectomized and in two thyroparathyroidectomized pigs with thyroxine replacement therapy. The effect seen in the parathyroidectomized animals was not attributable to an increase in the concentration gradient of calcium ions between the jejunal lumen and the blood after the change to the low calcium diet. There was a marked increase in the amount of calcium-binding protein in the mucosa taken from the distal three-quarters of the small intestine of intact pigs fed a low calcium diet. However, after parathyroidectomy, the level of calcium in the diet had no significant effect on the amount of calcium-binding protein in the small intestine. It is concluded that, in pigs, neither parathyroid hormone nor calcitonin is necessary for intestinal adaptation to a low calcium diet and that, although this adaptation may be mediated by 1,25-dihydroxycholecalciferol, a significant increase in the level of calcium-binding protein in the intestine is only seen when the parathyroid glands are intact.

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.

Influence of calcium-binding protein in bovine milk on intestinal calcium absorption

1988 ◽  
Vol 6 (3) ◽  
pp. 38-43 ◽  
Author(s):  
Tsuneyuki Oku ◽  
Michiko Tatsuno-Yoshioka ◽  
Norimasa Hosoya
Keyword(s):  
Calcium Binding ◽  
Calcium Absorption ◽  
Binding Protein ◽  
Bovine Milk ◽  
Calcium Binding Protein ◽  
Intestinal Calcium Absorption
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