Transfer of Ca45 across intestinal wall in vitro in relation to action of vitamin D and cortisol

1960 ◽  
Vol 199 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Harold E. Harrison ◽  
Helen C. Harrison
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Active Transport ◽  
Oxidative Metabolism ◽  
Calcium Transport ◽  
Proximal Part ◽  
Intestinal Wall ◽  
The Other ◽  
Cell Surfaces

The transfer of calcium across the intestinal wall of rats was measured in vitro by the device of everted intestinal loops with Ca45 as an indicator. The conditions were developed so that the rate of diffusion of calcium across the intestinal wall as well as active transport against a concentration gradient could be determined. Vitamin D treatment increases the rate of diffusion of calcium across the intestinal wall. This action of vitamin D is exerted along the entire length of the small intestine and is not affected by inhibition of oxidative metabolism. The active transport of calcium on the other hand is localized to the proximal part of the intestine and is dependent on the energy of oxidative metabolism. Cortisol treatment antagonizes the vitamin D effect on the diffusion of calcium and also reduces the active transport of calcium. It is suggested that vitamin D and cortisol influence calcium transport by action on the permeability of cell surfaces to calcium.

Intestinal calcium transport in the spontaneously hypertensive rat: response to calcium depletion

1986 ◽  
Vol 250 (4) ◽  
pp. G412-G419
Author(s):  
H. P. Schedl ◽  
D. L. Miller ◽  
R. L. Horst ◽  
H. D. Wilson ◽  
K. Natarajan ◽  
...  
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Calcium Transport ◽  
Spontaneously Hypertensive Rat ◽  
Calcium Depletion ◽  
Spontaneously Hypertensive ◽  
Distal Small Intestine ◽  
Wistar Kyoto

We previously found intestinal Ca2+ transport to be lower in the spontaneously hypertensive (SH) as compared with the Wistar-Kyoto control (WKY) rat. These animals were fed a relatively high (1%) Ca2+ diet, and the concentration of 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3] in serum was the same in both groups. In the present experiment we tested the possibility that the lower Ca2+ transport in the SH rat was the result of unresponsiveness to 1 alpha,25(OH)2D3. We fed diets high and low in Ca2+ and measured serum 1 alpha,25(OH)2D3 and Ca2+ transport. Serum 1 alpha,25(OH)2D3 increased in response to Ca2+ depletion at both 5 and 12 wk in both the WKY and SH rat. With high-Ca2+ diet, Ca2+ transport was lower in SH than in WKY when studied 1) in vitro in duodenum at 5 wk of age, and 2) in vivo in proximal and distal small intestine at 12 wk of age. Ca2+ transport increased in SH in response to Ca2+ depletion, but not in WKY, except in distal small intestine in vivo at 12 wk. In summary, although Ca2+ transport is lower in the SH as compared with the WKY rat when vitamin D activity is basal through feeding a high-Ca2+ diet, Ca2+ transport increases in the SH rat in response to the increase in 1 alpha,25(OH)2D3 produced by feeding a low-Ca2+ diet. We conclude that 1) the vitamin D-regulated component of mediated Ca2+ transport is intact in the SH rat and is unrelated to hypertension, and 2) mediated Ca2+ transport under basal conditions, i.e., nonvitamin D-regulated, differs in the SH and WKY rats and may be related to hypertension.

Intestinal transport of phosphate: action of vitamin D, calcium, and potassium

1961 ◽  
Vol 201 (6) ◽  
pp. 1007-1012 ◽  
Author(s):  
Harold E. Harrison ◽  
Helen C. Harrison
Keyword(s):  
Vitamin D ◽  
Inorganic Phosphate ◽  
Potassium Concentration ◽  
Intestinal Transport ◽  
Complete Removal ◽  
Intestinal Wall ◽  
Cell Surfaces ◽  
Concentration Difference ◽  
Mucosal Surfaces

Everted loops of rat small intestine incubated in vitro produce a concentration difference of inorganic phosphate between the solutions bathing the serosal and mucosal surfaces as the result of transport out of the mucosal solution against a concentration difference. Cyanide or anaerobiosis inhibits this process. The concentrative transport of phosphate requires the presence of calcium and is enhanced by increase of potassium concentration in the medium. Loops from vitamin D-treated rats develop higher concentration ratios of phosphate between serosal and mucosal solutions than loops from vitamin D-deficient animals when the concentrations of calcium and potassium in the medium are the same. Complete removal of calcium from the system by EDTA inhibits transfer of phosphate against a concentration difference and eliminates the vitamin D effect. The findings suggest that the concentrative transport of phosphate across the intestinal wall is activated by calcium and potassium and that potassium can not satisfy the requirement for calcium. The effect of vitamin D can be to increase the availability of calcium to the system through an action on the permeability of cell surfaces to calcium.

Active transport of calcium by intestine: effects of dietary calcium

1961 ◽  
Vol 200 (6) ◽  
pp. 1256-1262 ◽  
Author(s):  
Daniel V. Kimberg ◽  
David Schachter ◽  
Harris Schenker
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Active Transport ◽  
Adaptive Response ◽  
Transport Mechanism ◽  
Concentration Gradients ◽  
Active Transport Mechanism ◽  
Entire Small Intestine ◽  
Young Rat

The small intestine of the rat responds facultatively to a diet low in Ca by increasing the active transport of the cation. The effects of calcium deprivation were studied with everted gut sacs and with duodenal slices in vitro, and the experiments demonstrate that following this stimulus almost the entire small intestine of a young rat can transfer calcium from the mucosa to the serosa against concentration gradients. The active transport is maximal in duodenum, less in ileum, and least in the mid small intestine. Following the low-Ca diet, duodenal gut sacs transport Sr89 against concentration gradients, although strontium is transferred much less readily than is calcium. Vitamin D is required for the adaptive response of the active transport in duodenum and ileum. Younger rats respond to Ca deprivation earlier and more markedly than older animals. Neither thyroparathyroidectomy, hypophysectomy, or adrenalectomy prevent response to the low-Ca diet, although these ablations do affect the active transport mechanism in rats on a given diet.

Active transport of calcium by intestine: action and bio-assay of vitamin D

1961 ◽  
Vol 200 (6) ◽  
pp. 1263-1271 ◽  
Author(s):  
David Schachter ◽  
Daniel V. Kimberg ◽  
Harris Schenker
Keyword(s):  
Vitamin D ◽  
Active Transport ◽  
Calcium Transport ◽  
Transport Mechanism ◽  
Simple Diffusion ◽  
Active Mechanism ◽  
Active Transport Mechanism ◽  
Small Doses ◽  
Bio Assay

Vitamin D is required for the active transport of calcium in vitro. Small doses of vitamins D2 and D3 restore the mechanism in depleted rats, and this provides a sensitive bio-assay for the vitamin, independent of an antirachitic effect. Vitamin D influences calcium transfer in all segments of the small intestine, and maximal increments are observed in the duodenum. The effect of vitamin D requires oxidative metabolism in vitro, is maximal where active transport is maximal, and the sterol increases the maximal rates of active transport of calcium. Consequently, vitamin D influences calcium transport by affecting primarily the active mechanism rather than by simple diffusion. Experiments with various monosaccharides demonstrate that two distinct steps are involved in the active transport mechanism in duodenum. Vitamin D is required for both of the steps.

Active transport of Ca45 by the small intestine and its dependence on vitamin D

1959 ◽  
Vol 196 (2) ◽  
pp. 357-362 ◽  
Author(s):  
David Schachter ◽  
Samuel M. Rosen
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Active Transport ◽  
Transport Mechanism ◽  
Calcium Citrate ◽  
Concentration Gradients ◽  
Citrate Complex ◽  
Active Transport Mechanism ◽  
Proximal Small Intestine

Everted gut-sacs prepared from segments of the proximal small intestine of young rabbits, rats and guinea pigs transport Ca45 in vitro from the mucosal to the serosal surfaces against concentration gradients. The active transport mechanism is limited in capacity, is dependent on oxidative phosphorylation, and appears to be relatively specific for Ca++ and Mg++ in contrast to Sr++ and Ba++. Vitamin D deprivation in rabbits and rats markedly impairs the capacity for active Ca45 transport in vitro. The vitamin thus has an effect directly on the upper small intestine. Neither the active Ca45 transport nor the effect of vitamin D on the transport can be explained by an accumulation of citrate and the formation of the calcium-citrate complex.

Active transport of C14-d-glucose by turtle small intestine

1961 ◽  
Vol 201 (2) ◽  
pp. 295-297 ◽  
Author(s):  
Sister Alice Marie Fox
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Intestinal Transport ◽  
Intestinal Wall ◽  
Chrysemys Picta ◽  
Tissue Analysis ◽  
Serosal Side ◽  
Concentration Difference ◽  
Apparent Concentration

An in vitro preparation was used to demonstrate that C14-d-glucose is taken up at the mucosal surface of turtle small intestine at 30 C. Movement of the sugar across the intestinal tissues and its release into the serosal fluid against an apparent concentration difference was shown. The source of the sugar entering the medium on the serosal side appeared to be, in part, the glucose taken up from the mucosal fluid, and, in part, some stored carbohydrate. Tissue analysis indicated the presence of a glycogenlike polysaccharide in the intestinal wall of both active and cold-torpid turtles. It was concluded that, during intestinal transport in Chrysemys picta, some of the glucose absorbed is converted to endogenous carbohydrate, or metabolized, and some is translocated.

Influence of vitamin D on calcium absorption in the chick

1962 ◽  
Vol 203 (3) ◽  
pp. 497-505 ◽  
Author(s):  
J. D. Sallis ◽  
E. S. Holdsworth
Keyword(s):  
Vitamin D ◽  
Small Intestine ◽  
Calcium Transport ◽  
Calcium Absorption ◽  
Metabolic Inhibitors ◽  
Hydroxyl Groups ◽  
Oxidation Reduction ◽  
Active Calcium

The site of absorption of Ca45 was studied in rachitic chicks and rachitic chicks given vitamin D3. Vitamin D3 markedly increases absorption from the small intestine and, in vivo, similar amounts of calcium are absorbed along the entire small intestine. With everted gut sacs, the distal third of the small intestine transported much more calcium than did the duodenal and middle sections. Thus, interpretations of in vitro results may not always depict the natural in vivo process. Vitamin D2 had little activity in the chick, but AT-10 series 2 and AT-10 series 3 were almost as active as vitamin D3 for calcium transport. These results suggest an "active carrier" may be formed by addition of hydrogen or hydroxyl groups to the opened ring B of vitamin D, giving a carrier capable of reversible oxidation-reduction or keto-enol tautomerism. Using metabolic inhibitors, active calcium transport in vitro relied on glycolysis for its energy supply. The transport was independent of the sodium pump.

In vitro absorption of bile salts by small intestine of rats and guinea pigs

1961 ◽  
Vol 200 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Leon Lack ◽  
I. M. Weiner
Keyword(s):  
Small Intestine ◽  
Bile Acid ◽  
Active Transport ◽  
Sodium Azide ◽  
Concentration Gradient ◽  
Guinea Pigs ◽  
Bile Salts ◽  
Ileal Segment

The transport of taurocholic and glycocholic acids by the small intestine of rats and guinea pigs against a concentration gradient was studied by the everted gutsac technique. Transport of these substances is limited to the distal ileal segment. This transport is inhibited by anoxia, dinitrophenol and sodium azide. The system has a transport maximum. On the basis of these criteria bile acid reabsorption is considered to occur by active transport.

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