Radioimmunoassay Studies of Intestinal Calcium-binding Protein in the Pig. I. Identification of Intestinal Calcium-binding Protein in Blood and Response to a Low Calcium Diet

1975 ◽  
Vol 53 (6) ◽  
pp. 1129-1134 ◽  
Author(s):  
B. M. Arnold ◽  
M. Kuttner ◽  
R. Swaminathan ◽  
A. D. Care ◽  
A. J. W. Hitchman ◽  
...  
Keyword(s):  
Small Intestine ◽  
Intestinal Mucosa ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Intestinal Biopsy ◽  
Mixed Venous Blood ◽  
Calcium Diet ◽  
Low Calcium Diet ◽  
Low Calcium

We have developed a radioimmunoassay for porcine intestinal calcium-binding protein (CaBP) and have used it to detect CaBP in pig plasma. Plasma CaBP is identical to intestinal CaBP on the basis of immunological activity, molecular size, and molecular charge properties. The plasma CaBP concentration was greater in the portal blood than in mixed venous blood, suggesting that blood CaBP originates in the gut. Two of four 15-week-old littermate pigs were placed on a low calcium diet (0.15% calcium, 0.65% phosphorus) and two on a control diet (0.65% calcium, 0.65% phosphorus). After 2 weeks, the entire small intestine was removed and divided into nine 1.8-m segments. CaBP was assayed in both plasma and intestinal mucosa. When the two pigs on a low calcium diet were compared with two control pigs, there was a general increase in immunoreactive CaBP in both plasma and intestinal mucosa. However, there was no increment in immunoreactive CaBP in the first 1.8-m segment of small intestine. Seventy-one percent of the increment in CaBP occurred distal to the first two segments. The largest fractional low calcium diet effect occurred in the ileum. The mean CaBP concentration for the total small intestine increased by a factor of 1.9. The plasma CaBP concentration increased by a factor of 2.6. In these pigs, plasma CaBP was a more reliable indicator of change in CaBP status than was the measurement in the proximal gut segment which contained the duodenum. The assay of CaBP in blood is convenient and may obviate the sampling errors inherent in intestinal biopsy.

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.

Regulation of intestinal calcium-binding protein calcium intake in the rat

1975 ◽  
Vol 228 (3) ◽  
pp. 861-869 ◽  
Author(s):  
T Freund ◽  
F Bronner
Keyword(s):  
Calcium Intake ◽  
Calcium Binding ◽  
Calcium Concentration ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Competitive Binding Assay ◽  
Calcium Diet ◽  
Low Calcium Diet ◽  
Low Calcium ◽  
High Calcium

Analytical gel electrophoresis of the vitamin D-dependent intestinal calcium-binding protein (CaBP) has demonstrated two protein bands (1 and 2) of similar molecular weight and similar specific binding activity. The mucosal concentration of CaBP, measured by a quantitative competitive binding assay, has been shown to vary reproducibly and inversely with calcium intake and the mucosal calcium concentration. These same factors also influence the relationship of bands 1 and 2. When animals on a high-calcium diet were placed on a low-calcium diet, their CaBP increased by 35% in 24 h and by 48% in 48 h and reached a level typical of animals on a low-calcium diet. Measurement of the diurnal variation of CaBP and mucosal calcium in animals allowed access to feed only at night revealed significant, but inverse, oscillations. These observations are interpreted as reflecting a regulation of CaBP by the mucosal calcium concentration, which appears to reflect absorbed calcium in transit.

Raised levels of calcium-binding protein in plasma following insulin-induced hypoglycaemia in the pig

1986 ◽  
Vol 109 (1) ◽  
pp. 101-106 ◽  
Author(s):  
E. M. W. Maunder ◽  
A. V. Pillay ◽  
C. Chapman ◽  
A. D. Care
Keyword(s):  
Vitamin D ◽  
Calcium Binding ◽  
Inorganic Phosphate ◽  
Binding Protein ◽  
Plasma Concentrations ◽  
Calcium Binding Protein ◽  
Insulin Administration ◽  
Calcium Diet ◽  
Low Calcium Diet ◽  
Normal Calcium

ABSTRACT Insulin-induced hypoglycaemia in the pig elicited sharp increases in the plasma concentrations of vitamin D-dependent calcium-binding protein (CaBP) and cortisol and a decrease in plasma inorganic phosphate. Glucose infusion following insulin administration abolished the increases in plasma CaBP and cortisol in response to insulin and reduced the hypophosphataemia. The percentage increases in plasma CaBP and cortisol in response to insulin-induced hypoglycaemia were reduced when the pigs were fed a low-calcium diet, but the hypophosphataemic response was similar. We conclude that insulin-induced hypoglycaemia leads to increased plasma CaBP in pigs fed a normal calcium diet, which is associated with the hypoglycaemia rather than being a direct effect of insulin. We therefore suggest that plasma CaBP may represent more than a mere uncontrolled leak from its sites of storage. J. Endocr. (1986) 109, 101–106

The amino acid sequence of porcine intestinal calcium-binding protein

1979 ◽  
Vol 57 (6) ◽  
pp. 737-748 ◽  
Author(s):  
Theo Hofmann ◽  
Michiko Kawakami ◽  
Anthony J. W. Hitchman ◽  
Joan E. Harrison ◽  
Keith J. Dorrington
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Intestinal Mucosa ◽  
Calcium Binding ◽  
Binding Protein ◽  
Troponin C ◽  
Calcium Binding Protein ◽  
Mass Spectrometry Analysis ◽  
Spectrometry Analysis

The complete amino acid sequence of the calcium-binding protein (CaBP) from pig intestinal mucosa has been determined: Ac-Ser-Ala-Gln-Lys-Ser-Pro-Ala-Glu-Leu-Lys-Ser-Ile-Phe-Glu-Lys-Tyr-Ala-Ala-Lys-Glu-Gly-Asp-Pro-Asn-Gln-Leu-Ser-Lys-Glu-Glu-Leu-Lys-Gln-Leu-Ile-Gln-Ala-Glu-Phe-Pro-Ser-Leu-Leu-Lys-Gly-Pro-Arg-Thr-Leu-Asp-Asp-Leu-Phe-Gln-Glu-Leu-Asp-Lys-Asn-Gly-Asn-Gly-Glu-Val-Ser-Phe-Glu-Glu-Phe-Gln-Val-Leu-Val-Lys-Lys-Ile-Ser-Gln-OH. The N-terminal octapeptide sequence was determined by mass spectrometry analysis by Morris and Dell. The first 45 residues of bovine CaBP differ only in six positions from the corresponding sequence of the porcine protein, except that the sequence starts in position two of the porcine sequence. The mammalian intestinal CaBP's belong to the troponin-C superfamily on the basis of an analysis by Barker and Dayhoff.

scholarly journals Vitamin D Dependent Calcium Binding Protein in Rat Intestinal Mucosa

1970 ◽  
Vol 16 (3) ◽  
pp. 228-234 ◽  
Author(s):  
KUMIKO OOIZUMI ◽  
SACHIKO MORIUCHI ◽  
NORIMASA HOSOYA
Keyword(s):  
Vitamin D ◽  
Intestinal Mucosa ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein

Radioimmunoassay Studies of Intestinal Calcium-binding Protein in the Pig. II. The Distribution of Intestinal CaBP in Pig Tissues

1975 ◽  
Vol 53 (6) ◽  
pp. 1135-1140 ◽  
Author(s):  
B. M. Arnold ◽  
M. Kuttner ◽  
D. M. Willis ◽  
A. J. W. Hitchman ◽  
J. E. Harrison ◽  
...  
Keyword(s):  
Small Intestine ◽  
Calcium Binding ◽  
Binding Protein ◽  
Gel Filtration ◽  
Protein S ◽  
Binding Activity ◽  
Calcium Binding Protein ◽  
Distal Small Intestine ◽  
Specific Radioimmunoassay ◽  
Kidney Liver

Using a specific radioimmunoassay for porcine intestinal calcium-binding protein (CaBP), we have measured the concentration of CaBP in the various tissues and organs of normal pigs. Intestinal CaBP was present in highest concentration in the upper small intestine, with lower concentrations in the distal small intestine. Intestinal CaBP was also found, in lower concentrations, in kidney, liver, thyroid, pancreas, and blood. In all other tissues, including parathyroid, bone, skeletal muscle, and brain, CaBP immunoreactivity was undetectable or less than in blood. The elution profile of calcium-binding activity and immunoreactivity from gel filtration analysis of kidney and parathyroid extracts suggest that the calcium-binding protein in the parathyroid gland, and the major calcium-binding protein(s) in the kidney, are chemically and immunochemically different from intestinal CaBP.

Sign in / Sign up

Export Citation Format

Share Document