REVERSAL OF BETAMETHASONE-INDUCED INHIBITION OF INTESTINAL CALCIUM ABSORPTION BY 1α-HYDROXYCHOLECALCIFEROL

1978 ◽  
Vol 78 (2) ◽  
pp. 187-194 ◽  
Author(s):  
J. FOX ◽  
A. D. CARE ◽  
D. H. MARSHALL
Keyword(s):  
Absorption Coefficient ◽  
Oral Administration ◽  
Intestinal Absorption ◽  
Calcium Absorption ◽  
Mean Value ◽  
Intestinal Calcium Absorption ◽  
Control Value ◽  
Isotope Technique ◽  
Intravenous And Oral Administration ◽  
Double Isotope

SUMMARY The intestinal absorption of calcium has been studied in conscious, unstressed pigs, using a modification of the double isotope technique. The oral administration of betamethasone (1 mg/day) to four pigs (25–33 kg) for 4 weeks reduced the calcium absorption coefficient, calculated after the intravenous and oral administration of 47Ca2+, by a mean value of 66%. The oral administration of 1α-hydroxycholecalciferol (2 μg/day) in combination with betamethasone (1 mg/day) for a further 4 weeks returned the absorption coefficient to the control value.

scholarly journals Effects of lα-hydroxylated metabolites of cholecalciferol on intestinal radiocalcium absorption in goats

1984 ◽  
Vol 51 (1) ◽  
pp. 157-164 ◽  
Author(s):  
Knut Hove
Keyword(s):  
Fatty Acid ◽  
Oral Administration ◽  
Intestinal Absorption ◽  
Plasma Concentrations ◽  
Rumen Degradation ◽  
Hydroxylated Metabolites ◽  
Naturally Occurring ◽  
Isotope Technique ◽  
Dose Dependent ◽  
Double Isotope

1. Intestinal absorption of 47Ca was measured by a double-isotope technique in goats treated with 1, 5 or 25 μg of 1,25-dihydroxycholecalciferol (1,25(OH)2D3). The effects of giving 1,25(OH)2D3 by intravenous (iv) infusion for 30–36 h were compared at each dose level with the effects obtained by oral administration of 1,25(OH)2D3 either in ethanol or protected against rumen degradation in fatty acid pellets.2. Dose-dependent increments in absorption followed the treatments, with a doubling of absorption at the 1 μg dose and three- to fivefold increases with the 5 and 25 μg doses. 47Ca absorption was equally stimulated 2 and 6 d after treatment but had returned to pretreatment levels 12–14 d after treatment.3. Intravenous and protected oral administration of 1,25(OH)2D3 stimulated 47Ca absorption to the same extent, in spite of two- to fivefold higher plasma concentrations of 1,25(OH)2D3 after iv treatment. Somewhat lower increments in 47Ca absorption were seen using ethanol as the vehicle for oral administration.4. The naturally occurring metabolites 1,24(R),25-trihydroxycholecalciferol and 1,25(S),26-trihydroxy-cholecalciferol had only one-tenth to one-fifteenth the potency of 1,25(OH)2D3 in stimulating 47Ca absorption, while synthetic lα-hydroxycholecalciferol appeared to be twice as effective as 1,25(OH)2D3 when tested at a high (10μg) dose.

THE ROLE OF THE THYROID IN THE INTESTINAL EFFECT OF VITAMIN D ON RACHITIC RATS

1970 ◽  
Vol 48 (4) ◽  
pp. 541-544 ◽  
Author(s):  
M. WINTER ◽  
E. MORAVA ◽  
G. SIMON
Keyword(s):  
Vitamin D ◽  
Intestinal Absorption ◽  
Calcium Absorption ◽  
Intestinal Calcium Absorption ◽  
Thyroid Glands ◽  
And Control

SUMMARY The effect of 20 i.u. vitamin D3 on the intestinal absorption of calcium was investigated in thyroidectomized and control rachitic rats. Vitamin D3 increased both duodenal and jejunal calcium absorption in the absence of the thyroid glands. These results suggest that neither thyroxine nor calcitonin are necessary for the effect of vitamin D3 on intestinal calcium absorption.

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.

A new technique for measuring intestinal calcium absorption in the rat

1983 ◽  
Vol 245 (3) ◽  
pp. G438-G441
Author(s):  
C. L. Marsh ◽  
A. D. LeBlanc ◽  
P. C. Johnson ◽  
S. L. Pool
Keyword(s):  
Calcium Absorption ◽  
Isotonic Saline ◽  
Isotopic Analysis ◽  
Intestinal Calcium Absorption ◽  
Incisor Tooth ◽  
Isotope Technique ◽  
Multiple Blood ◽  
Old Rats ◽  
A New Technique

A double-isotope technique that does not necessitate urine and fecal collections but requires only the extraction of the incisor teeth for isotopic analysis has been devised. A precalibrated dose of 45Ca in solution with stable carrier calcium is administered to the rat orally. An intraperitoneal injection delivers a precalibrated dose of 47Ca in isotonic saline. The ratio of the percentage uptake of the two radionuclides in the incisor tooth is equal to the fraction of the 45Ca and, therefore, the calcium absorbed by the gut. The fraction of calcium absorbed by 5-mo-old rats, as determined by collection and measurement of excreta, was found to be 39.1%. The ratio of uptake of the two calcium radionuclides in the incisor teeth yields an absorption measurement of 38.8%, nonsignificantly different from the value obtained from the excretion data. The measurement of radiocalcium uptake in the incisor tooth affords one an accurate in vivo determination of intestinal calcium absorption without the collection of excreta or multiple blood sampling.

Calcium Metabolism in Children Suffering from Homozygous ß-Thalassaemia after Oral Administration of 47Ca

1976 ◽  
Vol 15 (02) ◽  
pp. 77-79 ◽  
Author(s):  
D. Liakakos ◽  
P. Ylachos ◽  
Ch. Anoussakis ◽  
C. Constantinides ◽  
I. Tsakalosos
Keyword(s):  
Oral Administration ◽  
Intestinal Absorption ◽  
Calcium Metabolism

SummaryThe study of calcium metabolism in ten thalassaemic children comperatively with controls after oral administration of 47Ca has shown diminished intestinal absorption. It is suggested that this finding is propably related in part with the pathogenesis of the osteoporosis in thalassaemia.

STUDIES ON THYROIDAL COLLOID PINOCYTOSIS USING A DOUBLE ISOTOPE TECHNIQUE

1972 ◽  
Vol 70 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Mario A. Pisarev ◽  
Noe Altschuler ◽  
Leslie J. DeGroot
Keyword(s):  
Acid Phosphatase ◽  
Thyroid Hormone ◽  
Trichloroacetic Acid ◽  
Specific Activity ◽  
Acid Precipitation ◽  
Solvent System ◽  
Blood Stream ◽  
Radioactive Materials ◽  
Isotope Technique ◽  
Double Isotope

ABSTRACT The process of secretion of the thyroid hormone involves several steps: pinocytosis of thyroglobulin, fusion of the colloid droplets with the lysosomes, digestion of thyroglobulin by a cathepsin, dehalogenation of tyrosines and release of thyronines into the blood stream. The present paper describes a double isotope technique for studying the first two steps. Thyrotrophin (TSH) administration to rats increased the radioactivity present in all fractions, specially in the 15 000 × g pellet. When the subcellular distribution of acid phosphatase was determined, the highest specific activity was found in this fraction, thus indicating the presence of lysosomes. The content of radioactive materials in the 15 000 × g pellet was analyzed by trichloroacetic acid precipitation and by ascending paper chromatography using n-butanol:ethanol:ammonium hydroxide (5:1:2;v/v) as solvent system. The results obtained showed that 90% of the radioactivity was protein bound and strongly suggest that this material is thyroglobulin.

Calcium transport in turtle bladder

1987 ◽  
Vol 253 (6) ◽  
pp. R917-R921
Author(s):  
S. Sabatini ◽  
N. A. Kurtzman
Keyword(s):  
Calcium Transport ◽  
Calcium Absorption ◽  
Short Circuit ◽  
Open Circuit ◽  
Calcium Flux ◽  
Bladder Epithelium ◽  
Control Value ◽  
Sodium Calcium ◽  
Turtle Bladder ◽  
Absorptive Flux

Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa) and was 388.3 +/- 84.5 pmol.mg-1.h-1 (n = 20, P less than 0.001). Ouabain (5 X 10(-4) M) reversed JnetCa to an absorptive flux (serosal minus mucosal flux = -195.8 +/- 41.3 pmol.mg-1.h-1; n = 20, P less than 0.001). Amiloride (1 X 10(-5) M) reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory (138.4 +/- 54.3 pmol.mg-1.h-1; n = 9, P less than 0.025). When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was approximately equal to 30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa.

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