Phlorizin as a competitive inhibitor of the active transport of sugars by hamster small intestine, in vitro

1962 ◽  
Vol 56 ◽  
pp. 170-172 ◽  
Author(s):  
Francisco Alvarado ◽  
Robert K. Crane
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Competitive Inhibitor

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.

Active transport of calcium by the small intestine of the rat

1960 ◽  
Vol 198 (2) ◽  
pp. 263-268 ◽  
Author(s):  
David Schachter ◽  
Eugene B. Dowdle ◽  
Harris Schenker
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Transport Mechanism ◽  
Cation Transport ◽  
Maximal Rate ◽  
Active Transport Mechanism ◽  
Serosal Surface ◽  
Proximal Small Intestine ◽  
Active Transfer

The rates of active transport of calcium in vitro by everted gut-sacs prepared from the proximal small intestine of the rat have been quantified and expressed in absolute units. A maximal rate of transport has been measured. The bulk of the calcium transferred to the serosal surface of the gut-sac is ionized calcium, suggesting that the process is an active cation transport mechanism. The active transfer is relatively specific for Ca++, and no significant accumulation of Mg++, Sr++, Ba++ or K+ in the fluid bathing the serosal surface could be demonstrated. The active transport of calcium in vitro is greater with gut-sacs from growing than from older rats, and it is greater with gut-sacs from pregnant than from nonpregnant rats. The results suggest that the active transport mechanism can increase the intestinal absorption of calcium facultatively to meet the needs of the organism.

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 Fe59 by everted segments of rat duodenum

1960 ◽  
Vol 198 (3) ◽  
pp. 609-613 ◽  
Author(s):  
Eugene B. Dowdle ◽  
David Schachter ◽  
Harris Schenker
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Transport Process ◽  
Transport Mechanism ◽  
Concentration Gradients ◽  
Active Transport Mechanism ◽  
Proximal Small Intestine ◽  
Rat Duodenum ◽  
Active Transport Process

Everted gut sacs prepared from segments of the proximal small intestine of rats transport Fe59 from the mucosal to the serosal surfaces against concentration gradients in vitro. The active transport mechanism is dependent upon oxidative metabolism and the generation of phosphate-bond energy, and is limited in capacity. The active transport process is maximal in the region of the small intestine immediately distal to the pylorus and diminishes with more distal segments of the gut. Addition of ascorbic acid to the incubation medium markedly increases the active transport of Fe59 in vitro.

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.

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