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Results for “INTESTINAL ABSORPTION”

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PubMed2000

Effects of different medium-chain fatty acids on intestinal absorption of structured triacylglycerols.

To study the effect of the chain length of medium-chain fatty acids on the intestinal absorption of long-chain fatty acids, we examined the lymphatic transport of fat following administration of five purified structured triacylglycerols (STAG) containing different medium-chain fatty acids in the sn-1,3 positions and long-chain fatty acids in the sn-2 position in a rat model. Significant amounts of medium-chain fatty acids were found in lymph samples after intragastric administration of 1,3-dioctanoyl-2-linoleyl-sn-glycerol (8:0/18:2/8:0), 1,3-didecanoyl-2-linoleyl-sn-glycerol, and 1,3-didodecanoyl-2-linoleyl-sn-glycerol. The accumulated lymphatic transport of medium-chain fatty acids increased with increasing carbon chain length. The recoveries of caprylic acid (8:0), capric acid (10:0), and lauric acid (12:0) were 7.3 +/- 0.9, 26.3 +/- 2.4, and 81.7 +/- 6.9%, respectively. No significant differences were observed for the maximal intestinal absorption of linoleic acid (18:2n-6) when the chain length of medium-chain fatty acids at the primary positions was varied, and the absorption of 18:2 and oleic acid (18:1) from 8:0/18:2/8:0 and 1,3-dioctanoyl-2-oleyl-sn-glycerol was similar. We conclude that the chain length of the medium-chain fatty acids in the primary positions of STAG does not affect the maximal intestinal absorption of long-chain fatty acids in the sn-2 position in the applied rat model, whereas the distribution of fatty acids between the lymphatics and the portal vein reflects the chain length of the fatty acids.

Animals↗

PubMed1977

An electron microscope study of the intestinal absorption of medium chain and long chain triglycerides in the rat.

The ultrastructural changes in the intestinal absorptive cells of the rat during the absorption of triglycerides, Particularly medium chain triglyceride (MCT), were studied by electron microscopy. In the absorptive cell of rats fed with MCT, the agranular endoplasmic reticulum in tubular form was remarkably proliferated throughout the cytoplasm as compared with that of fasting rats. The granular endoplasmic reticulum was mostly transformed into the same tubulo-vesicular form as the agranular endoplasmic reticulum. Chylomicra, which were consistently observed in the endoplasmic reticulum of the intestinal absorptive cell of rats fed with long chain triglyceride (LCT), did not appear in that of MCT-fed rats, although small lipid particles were noticed within it. The Golgi lamellae decreased in number and length. During the absorption of MCT, the central lacteal contained some lipid particles which were smaller in size than the chylomicron which appeared in the LCT-fed rats. These evidences might suggest that the majority of MCT administered was transported through the absorptive cell without reesterification in the endoplasmic reticulum into the portal vein system, and only a minor part of the MCT given was transported via the central lacteal after reesterification.

Animals↗

PubMed1986

Apparent small intestinal absorption of nitrogen and minerals from soy and meat-protein-based diets. A study on human ileostomy subjects.

The apparent absorption of nitrogen and minerals was studied in 8 ileostomy subjects. Four different test diets containing 60 g of meat, rice and bread protein, or a 25% replacement of the protein with soy flour, soy concentrate or soy isolate, were randomly assigned to the subjects in 2-d periods. All animal protein was replaced by soy isolate for a fifth 2-d period in two of the subjects. Ileostomy contents were collected in 2-h intervals during the day and in one portion during night and immediately deep-frozen. The fiber components and the phytic acid in the diet were almost completely recovered in the ileostomy contents, whereas unabsorbed starch was less than 2% of the intake. A significantly lower protein digestibility was observed when the diets containing soy protein were fed. No difference in protein digestibility was found between the different soy protein products. A 25% replacement by soy protein had no obvious effect on apparent mineral absorption. A low protein digestibility was also observed when soy was the main source of protein, and a negative apparent absorption of zinc was found in both subjects. Although 25% of soy protein in the diet does not seem to impair mineral absorption significantly, small intestinal net absorption of nitrogen is less from the soy diets than from the meat diet.

Adult↗

PubMed1990

Intestinal absorption of arachidonic acid in experimental azotemia.

The effect of renal failure (RF) on intestinal absorption of dietary fatty acids is not known. We studied the intestinal absorption of arachidonic acid (AA) in rats with experimental short-term (2 weeks post-subtotal nephrectomy) and long-term (5-6 weeks post-subtotal nephrectomy) RF. The results were compared with those obtained in sham-operated animals on liberal food intake (NL) and in those pair-fed (PF) with the respective RF groups. In vivo perfusion and in vitro incubation experiments were performed at a wide range of AA concentrations. The rates of AA transport determined both in vivo and in vitro were significantly lower in the short-term RF group than those found in the NL controls and the PF animals who showed comparable values. In contrast animals with long-term RF exhibited an increased rate of AA transport as compared with the respective controls. The observed changes in the transport rates appeared to parallel directional changes in mucosal mass which was reduced in animals with short-term RF and restored in those with long-term RF.

Animals↗

PubMed1989

[Calcium intestinal absorption in normotensive and essential hypertensive subjects before and after nicardipine].

The part played by calcium in genesis of essential hypertension may be suspected. Yet, the whole of epidemiological research as well in the animal as in man is still not very convincing. The objective of such a research has been to appreciate the calcium intestinal absorption before and after nicardipine treatment in 11 subjects (5 M/6 F) aged between 32 and 82. The group is made up of 7 hypertensive patients (2 M/5 F) and 4 normotensive ones (3 M/1 F). Subjects showing bone disease, kidney insufficiency and stone in kidneys or under such a treatment as to interfere with calcium metabolism had been excluded. Dosage of calcium and phosphate, Na, K, aldosterone, in blood and urine and PTH and PRA in blood had been effectuated. Estimation of true calcium absorption has been made by double isotope deconvolution method. Blood pressure has been measured by semi-ambulatory monitoring method. Similar evaluation has been made after four weeks treatment (60 mg of nicardipine a day). Without any treatment, normotensive subjects have a lower intestinal absorption coefficient than the hypertensive ones, which is normal (non significative statistical results: NS). Under nicardipine, hypertensive patients seem to get lower intestinal absorption (NS); other clinical, biological parameters show no change, except a rise of apoprotein A after nicardipine treatment (P less than or equal to 0.05). So, the intestinal absorption of calcium would become higher in hypertensive subjects and diminished by calcium antagonist treatment.

Aged↗

PubMed2003

Iron and copper homeostasis and intestinal absorption using the Caco2 cell model.

Whole body homeostasis can be viewed as the balance between absorption and excretion, which can be regulated independently. Present evidence suggests that for iron, intestinal absorption is the main site for homeostatic regulation, while for copper it is biliary excretion. There are connections between iron and copper in intestinal absorption and transport. The blue copper plasma protein, ceruloplasmin, and its intracellular homologue, hephaestin, play a role in cellular iron release. The studies reviewed here compare effects of Fe(II) and Cu(II) on their uptake and overall transport by monolayers of polarized Caco2 cells, which model intestinal mucosa. In the physiological range of concentrations, depletion of cellular iron or copper (by half) increased uptake of both metal ions. Depletion of iron or copper also enhanced overall transport of iron from the apical to the basal chamber. Copper depletion enhanced overall copper transport, but iron depletion did not. Pretreatment with excess copper also stimulated copper absorption. Plasma ceruloplasmin (added to the basal chamber) failed to enhance basolateral iron release, and Zn(II) failed to compete with Cu(II) for uptake. Neither copper nor iron deficiency altered expression of IREG1 or DMT1 (-IRE form) at the mRNA level. Thus, in the low-normal range of iron and copper availability, intestinal absorption of both metals appears to be positively related to the need for these elements by the whole organism. The two metal ions also influenced each other's transport; but with copper excess, other mechanisms come into play.

Copper↗

PubMed1987

The influence of aging on intestinal absorption of TCDD in rats.

The effects of age on intestinal absorption of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were studied using adult male Fischer-344 rats of 3 different age groups: 13 weeks old (young), 13 months old (mature), and 26 months old (senescent). Absorption was measured with an in situ intestinal recirculation perfusion procedure. Absorption expressed in terms of ng TCDD absorbed/g intestinal dry weight/h was 166, 149 and 143 ng/g/h in the young, mature and senescent groups, respectively. When absorption was calculated in terms of ng TCDD absorbed/g mucosal dry weight/h, the decrease between the senescent rats and the 2 younger age groups, from 544 ng/g/h (young) to 351 ng/g/h (senescent), was not statistically significant (P less than 0.05). It was demonstrated that absorption of TCDD was unaffected by the presence of 2,4,5,2',4',5'-hexachlorobiphenyl (HCB) in the perfusate, but that HCB absorption was (P less than 0.01) enhanced by the presence of TCDD.

Aging↗

PubMed1984

Flounder intestinal absorptive cells have abundant gap junctions and may be coupled.

We noted that, unlike mammalian intestinal absorptive cells, cells of the winter flounder (Pseudopleuronectes americanus) displayed abundant gap junctions on the lateral plasma membrane. We compared the distribution of gap junctions in winter flounder to that in rabbit intestinal epithelium. We also examined for evidence of gap junction-mediated intercellular coupling by comparing the cell-to-cell variation of electrical potential difference across winter flounder intestinal cell apical membranes with that in rabbit small intestinal epithelium in which gap junctions are rare. Gap junctions were seen in 95% of flounder absorptive cells and were localized largely to the apical third of the lateral membrane. Individual gap junctions often contained several hundred uniform 9-nm intramembrane particles. Gap junction size and structure was independent of the position of individual absorptive cells on mucosal folds. These findings sharply contrasted flounder intestinal absorptive cells with rabbit small intestinal absorptive cells, in which gap junctions were rarely detected and when present consisted of few intramembrane particles. Correlating with this distribution of morphologically detectable gap junctions, rabbit small intestinal epithelial cells demonstrated marked variability in potential difference across their apical membranes, whereas those in flounder small intestine showed little variation in apical membrane potential difference. Thus, in contrast to intestinal epithelium of rabbits, flounder intestinal epithelium demonstrates morphological and functional characteristics, suggesting a substantial degree of electrical coupling.

Animals↗

PubMed1979

Intestinal absorption of cholecalciferol in alcoholic liver disease and primary biliary cirrhosis.

The intestinal absorption of (3H)cholecalciferol was studied in five patients with alcoholic liver disease, six patients with primary biliary cirrhosis, and 15 healthy subjects. The rate of appearance in plasma of (3H)cholecalciferol after oral ingestion and the subsequent appearance of (3H) polar metabolites in the alcoholic subjects were similar to those in the healthy subjects. In subjects with primary biliary cirrhosis the rate of appearance in plasma of (3H)cholecalciferol was significantly reduced. The rate of appearance of labelled polar metabolites of cholecalciferol was also lower in this group, suggesting that increased removal of labelled vitamin by conversion into more polar metabolites could not account for the reduced plasma (3H)cholecalciferol response. It is suggested that intestinal absorption of cholecalciferol is usually normal in alcoholic liver disease but impaired in primary biliary cirrhosis. Hepatic 25-hydroxylation is normal in alcoholic liver disease but may be defective in primary biliary cirrhosis.

Adult↗

PubMed2004

Evaluation of the intestinal absorption of deoxynivalenol and nivalenol by an in vitro gastrointestinal model, and the binding efficacy of activated carbon and other adsorbent materials.

In vitro screening of 14 adsorbent materials, including some commercial products used to detoxify Fusarium-mycotoxins, were tested in the pH range of 3-8 for deoxynivalenol (DON)- and nivalenol (NIV)-binding ability. Only activated carbon showed to be effective with binding capacities of 35.1 micromol and 8.8 micromol DON and NIV/g adsorbent, respectively, calculated from the adsorption isotherms. A dynamic laboratory model simulating the gastrointestinal (GI) tract of healthy pigs (TIM system) was used to evaluate the small-intestinal absorption of DON and NIV and the efficacy of activated carbon in reducing the relevant absorption. The in vitro intestinal absorptions of DON and NIV were 51% and 21%, respectively, as referred to 170 microg DON and 230 microg NIV ingested through contaminated (spiked) wheat. Most absorption occurred in the jejunal compartment for both mycotoxins. The inclusion of activated carbon produced a significant reduction in the intestinal mycotoxin absorption. At 2% inclusion level the absorption with respect to the intake was lowered from 51% to 28% for DON and from 21% to 12% for NIV. The binding activity of activated carbon for these trichothecenes was lower than that observed for zearalenone, a mycotoxin frequently co-occurring with them in naturally contaminated cereals.

Adsorption↗

PubMed1991

The intestinal absorption of 3-O-methyl-D-glucose in methotrexate-treated rats: an in vivo study of small bowel function.

The in vivo absorption of 3-O-methyl-D-glucose (3MG) as a marker of intestinal function has not been studied in an animal model. We evaluated the use of 3MG as a marker of intestinal absorption when given enterally to rats recovering from small bowel mucosal injury induced by methotrexate (MTX). Radiolabeled 3MG was administered into the duodenum of control (CON) and MTX-treated rats and blood samples were obtained at specified intervals. Mucosal permeability was also assessed using radiolabeled mannitol and polyethylene glycol 900 (PEG). Concentration time points were plotted, and area under the curve was calculated as an approximation of absorbed dose. Mucosal weight, maltase activity, and protein content were determined on mucosal scrapings. During the acute phase (day 5), 3MG absorption and maltase-specific activity were significantly decreased in the MTX group when compared to the CON group (p less than 0.001). The MTX group showed a trend toward greater permeability to mannitol when compared to the CON group; however, this was not statistically significant. Mucosal permeability to PEG was similar in both groups. During a later stage in the recovery process (day 12), the area under the curve calculations for 3MG absorption were the same for both CON and MTX animals, with maltase activity in the MTX group recovering to control values. Changes in 3MG absorption paralleled total maltase activities following severe injury. These results suggest that the combined active and passive transport of 3MG in vivo could be of use as a marker of intestinal absorption in states where the small intestine has sustained major damage resulting in compromised absorption as well as brush border digestion.

3-O-Methylglucose↗

PubMed1997

[Molecular characterization of intestinal absorption of drugs by carrier-mediated transport mechanisms].

It has long been thought that intestinal absorption of most of the drugs proceeds by passive diffusion mechanism, in which lipid solubility of the drug molecule is a determinant factor. However, water-soluble natural compounds such as amino acids and sugars can move across cell membranes by the specialized carrier-mediated transport mechanisms. Although some drugs which are structurally analogous to natural compounds have been suggested to be absorbed by such transporters, no clear evidence for the involvement of carrier-mediated transport mechanisms has been obtained. In the present study, through the approach by means of the molecular cloning and functional expression of drug transporters as well as membrane physiological analysis for the drug transport across the intestinal epithelial cell membranes, participation of the carrier-mediated transport mechanisms for the drug absorption was clarified. They include peptide transporter, monocarboxylic acid transporter, anion antiporter, and P-glycoprotein. Most of them have a function for the uptake of drugs into epithelial cells, leading to the increased absorption of drugs, whereas P-glycoprotein excludes drugs into the lumen, thereby decreasing the apparent absorbability of drugs. A rat intestinal monocarboxylic acid-proton cotransporter, MCT1, and an anion antiporter, AE2, were suggested to contribute to the pH-dependent intestinal absorption of monocarboxylic acids such as benzoic acid, lactic acid, nicotinic acid, and valproic acid. An involvement of such pH-dependent transporters in the intestinal absorption of weak organic acids is important, because they may have an alternative mechanism against passive diffusion according to the pH-partition hypothesis. PepT1 cloned from rat intestinal epithelial cells as a peptide transporter was clarified to localize at the intestinal epithelia brush-border membrane and to function for the absorption of beta-lactam antibiotics by the proton-gradient energized mechanism. In contrast, P-glycoprotein functions for the secretion of drugs into the intestinal lumen, thereby decreasing intestinal absorption of an immunosuppressive, cyclosporin A and a 5-HT3 receptor antagonist, azasetron. These lines of studies on the clarification of carrier-mediated drug absorption mechanisms will provide new knowledge for the strategies to the enhancement of intestinal absorption of drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

[Assessment of nutritional status and of intestinal absorption in asymptomatic patients infected with the human immunodeficiency virus (HIV) with and without chronic hepatitis].

OBJECTIVE: To compare nutritional status and intestinal absorption in asymptomatics HIV patients co-infected or not with hepatitis C virus. MATERIAL AND METHODS: 15 patients (9 men and 6 women) HIV seropositive in A1-A2 stage were classified in two groups, A were asymptomatics HIV patients and B were asymptomatic HIV patients with chronic hepatitis C. Nutritional status was determined by weight, height, % ideal weight, body mass index, triceps skinfold, midarm muscle circumference, grip dynamometry and body composition measured by bioelectrical impedance. Intestinal absorption was assesses with D-xilosa test in urine collected over 5 hours after fasting ingestion of 5 grams of D-xylosa. Statistical analysis was made with SPSS (v.11.0). RESULTS: Not statistically significative differences were found in the nutritional status between the two groups of patients. Asymptomatics HIV patients with chronic hepatitis C eliminate less D-xylosa in urine than patients without chronic hepatitis C, being this difference statistically significative. Three out of the eight patients (37.5%) of group B presented malabsorption (< 1.2 grams of D-xylosa in urine). In group A any patient had malabsorption. DISCUSSION: In our study, asymptomatic HIV patients have a good nutritional status, without differences between patients co-infected or not with hepatitis C virus. Intestinal absorption is altered in patients co-infected and this should be considered because of its potential clinical consequences.

Data Interpretation, Statistical↗

PubMed1983

Portal hemodynamics, intestinal absorption, and postshunt encephalopathy.

Although total diversion of portal blood flow has been considered to be the main factor leading to encephalopathy following nonselective shunt (NSS), increased intestinal absorption of cerebral toxins secondary to mesenteric venous decompression could also play a role. Conversely, the low frequency of encephalopathy after the distal splenorenal shunt (DSRS) may be due to preservation of both hepatic portal perfusion and mesenteric venous hypertension. Portal hemodynamics, intestinal absorption of D-xylose, ammonia metabolism, and clinical encephalopathy were assessed preoperatively and in the early and late postoperative periods in cirrhotic patients selected for the DSRS (n = 12) and NSS (n = 10). Preoperatively, NSS patients had significantly less hepatopetal portal blood flow (P = 0.03) and lower D-xylose absorption (P = 0.004) than DSRS patients. DSRS resulted in no significant alterations in hepatic portal perfusion, portal pressure, D-xylose absorption, fasting blood ammonia (NH3), or tolerance to an oral dose of ammonium chloride. In contrast, NSS resulted in complete portal diversion and decompression and significant enhancement of D-xylose absorption on both the early (P = 0.02) and late (P = 0.03) postoperative evaluations. Early and late postoperative levels of MH3 were significantly higher in NSS patients. Encephalopathy was more frequent after NSS (80%) than after DSRS (17%, P = 0.003). When all patients were considered, preoperative to early DSRS (17%, P = 0.003). When all patients were considered, preoperative to early postoperative change in NH3 correlated with change in D-xylose absorption (r = 0.52, p = 0.02), and there were significantly more individuals with a greater than 2 gm increase in D-xylose absorption who developed encephalopathy (83%) than patients with no or minimal increase in D-xylose absorption (33%, P = 0.04). The results of this study suggest that altered intestinal absorption may be one of many factors determining postshunt cerebral function.

Ammonia↗

PubMed2006

A mechanistic study of the intestinal absorption of cryptotanshinone, the major active constituent of Salvia miltiorrhiza.

The nature of intestinal absorption of most herbal medicine is unknown. Cryptotanshinone (CTS) is the principal active constituent of the widely used cardiovascular herb Salvia miltiorrhiza (Danshen). We investigated the oral bioavailability of CTS in rats and the mechanism for its intestinal absorption using several in vitro and in vivo models: 1) Caco-2 cell monolayers; 2) monolayers of MDCKII cells overexpressing P-glycoprotein (PgP); and 3) single-pass rat intestinal perfusion with mesenteric vein cannulation. The systemic bioavailabilities of CTS after oral and intraperitoneal administration at 100 mg/kg were 2.05 and 10.60%, respectively. In the perfused rat intestinal model, permeability coefficients based on CTS disappearance from the luminal perfusate (Plumen) were 6.7- to 10.3-fold higher than permeability coefficients based on drug appearance in venous blood (Pblood). Pblood significantly increased in the presence of the P-gP inhibitor, verapamil. CTS transport across Caco-2 monolayers was pH-, temperature- and ATP-dependent. The transport from the apical (AP) to the basolateral (BL) side was 3- to 9-fold lower than that from the BL to the AP side. Inclusion of verapamil (50 microM) in both AP and BL sides abolished the polarized CTS transport across Caco-2 cells. Moreover, CTS was significantly more permeable in the BL to AP than in the AP to BL direction in MDCKII and MDR1-MDCKII cells. The permeability coefficients in the BL to AP direction were significantly higher in MDCKII cells overexpressing PgP. These findings indicate that CTS is a substrate for PgP that can pump CTS into the luminal side.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1981

Intestinal absorption of calcium: role of dietary phosphate and vitamin D.

The intestinal absorption of calcium (Ca) has been shown to depend on vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], and dietary phosphorus (P) concentration. This study was designed to evaluate the role of dietary P independent of vitamin D3 or 1,25(OH)2D3. Vitamin D-deficient rats were studied during dietary P restriction and were compared with control groups raised on a normal-phosphorus diet (NP). Balance studies were sued. Net intestinal Ca absorption was significantly lower with dietary P restriction compared with the NP group. This malabsorption of Ca was corrected by the administration of either D3 for 1,25(OH)2D3, despite hypophosphatemia. Everted gut sacs showed a marked reduction in the uptake of 45Ca in the duodenum, jejunum, and ileum during dietary P restriction. We concluded that dietary P concentration plays a major role in intestinal Ca absorption in the vitamin D-deficient rats. These findings suggest an effect of the low-phosphate diet on the vitamin D-dependent, Ca-transport mechanism.

Animals↗

PubMed1984

Intestinal absorption of ST-1435 in rats.

The intestinal absorption of a 19-norprogesterone (ST-1435) was studied in rats after an oral dose of 5 mg ST-1435/kg body weight. Blood samples were collected simultaneously from the portal vein and by cardiac puncture. Plasma ST-1435 concentrations were measured from the samples by radioimmunoassay (RIA). Chromatographic purification of ST-1435 in rat plasma revealed a metabolite cross-reacting in the RIA. A peak concentration of 240 ng ST-1435/ml was found in portal plasma 75 minutes after administration, indicating that the steroid is well absorbed from the small intestine. However, in spite of the relatively high dose used, the plasma concentrations of ST-1435 in the systemic circulation remained low and of short duration. Thus, it seems that ST-1435 in hepatic portal blood is extensively taken-up and metabolized by the liver, resulting in low plasma concentrations of ST-1435 in the systemic circulation when the steroid is administered orally. This is also supported by the observation that higher metabolite levels were found in systemic plasma than in portal plasma during the first 90 minutes after administration. This pronounced first-pass effect may also explain why in women oral administration of ST-1435 has failed to result in any biological effect.

Administration, Oral↗

PubMed1993

Development of new lipophilic derivatives of tetragastrin: physicochemical characteristics and intestinal absorption of acyl-tetragastrin derivatives in rats.

In order to improve the intestinal absorption of tetragastrin (TG), we synthesized lipophilic derivatives of TG by acylation of its N-terminal amino group with acetic acid, caproic acid, and lauric acid. The purified TG derivatives, acetyl-tetragastrin (Ac-TG), caproyl-tetragastrin (Cap-TG), and lauroyl-tetragastrin (Lau-TG), were confirmed to be more lipophilic than the parent TG by high-performance liquid chromatography (HPLC). The pharmacological activities and the intestinal absorption of TG and its derivatives were examined by measuring gastric acid secretion. Stimulation of gastric acid secretion by these derivatives after intravenous administration was stronger than with native TG. When the acetyl- and caproyl-derivatives were administered into the large intestinal loops, a marked increase in gastric acid secretion was observed in comparison with TG, while no significant effect occurred following administration of the TG derivatives into the small intestines. These results indicated that chemical modification of TG with fatty acids improves the absorption of TG from the large intestines.

Acetates↗