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PubMed2001

Intestinal absorption of specific structured triacylglycerols.

To clarify the intestinal absorption pathway of medium-chain fatty acids from MLM-type structured triacylglycerols containing both medium- and long-chain fatty acids, we studied the lymphatic transport of 1,3-dioctanoyl-2-linoleoyl-sn-glycerol (8:0/18:2/8:0), 1,3-didecanoyl-2-linoleoyl-sn-glycerol (10:0/18:2/10:0), and 1,3-didodecanoyl-2-linoleoyl-sn-glycerol (12:0/18:2/12:0) in a rat model. Safflower oil was used in the absorption study in order to compare the absorption of medium-chain fatty acids and long-chain fatty acids. The triacylglycerol species of lymph lipids were separated on a reversed-phase high performance liquid chromatograph (RP-HPLC) and identified by atmospheric pressure chemical ionization mass spectrometry. The composition of triacylglycerols was quantified by RP-HPLC with evaporative light scattering detection. The intact MLM-type triacylglycerols were detected in the lymph lipids after administration of the specific structured triacylglycerols (STAG). The recoveries of 8:0/18:2/8:0, 10:0/18:2/10:0, and 12:0/18:2/12:0 were 0.6%, 12%, and 5%, respectively. Several new triacylglycerol species were detected in the lymph lipids, including MLL-, LLL-, and MMM-type triacylglycerols. From the present study we conclude that the medium-chain fatty acids from STAG, in addition to absorption into the portal blood as free fatty acids, are absorbed by the same pathway as the conventional long-chain triacylglycerols, that is, they are hydrolyzed into free fatty acids, absorbed and activated into CoA, and reacylated into triacylglycerols in the enterocyte. The hydrolysis of MLM-type STAG is predominantly partial hydrolysis, whereas part of the STAG can also be hydrolyzed to free glycerol and free fatty acids.

Animals↗
PubMed1964

ON THE USE OF TRITIUM-LABELLED ALBUMIN FOR STUDIES OF INTESTINAL ABSORPTION.

Human serum albumin has been successfully labelled with tritium. It is considerably denatured in the process and has a shorter half life when given intravenously than (131)I-labelled albumin. Nevertheless it is satisfactory for absorption studies, although not for turnover observations. These studies on absorption in control subjects and in patients with intestinal malabsorption indicate that the excreted radioactivity may have been derived from endogenous sources rather than from the results of malabsorption alone.

Biomedical Research↗
PubMed1975

Interaction between sugars and amino acids in intestinal absorption by rat, in vivo.

The inhibitory action of L-leucine on the intestinal absorption of D-glucose and D-galactose, as well as the inhibitory action of D-galactose on the absorption of L-leucine at various concentrations by rat small intestine has been studied. The further effect was more clearly evidenced when the medium was perfunded through the intestine in a closed circuit system using a peristaltic pump.

Animals↗
PubMed1988

Intestinal absorption of colostral lymphoid cells in newborn piglets.

Intestinal absorption of colostral lymphoid cells was studied in 23 piglets of four sows (sows A, B, C and D). From the colostrum and blood of the sows the lymphoid cells were isolated with Ficoll-Paque and labelled with technetium (Na99mTcO4). In the 7th hour after birth, 5-ml volumes of the cell suspensions were injected, following laparotomy, directly into the stomach (piglets of sow A) or into the jejunum (piglets of sow B), whereas piglets of sows C and D received the suspensions through a naso-oesophageal tube. Cryostat sections of duodenum, jejunum and lymph node samples of piglets killed by bleeding 8 h after the treatment were examined by autoradiography. It was found that lymphoid cells present in the colostrum of a piglet's own mother were absorbed from the digestive tract and, via the lymphatic vessels, were transported to the mesenteric lymph nodes. Electron microscopy revealed that absorption took place intercellularly. Colostral cells of sows other than a piglet's own mother were observed only in the epithelial layer of the mucous membrane. The lymphoid cells isolated from the sows' blood and heat-treated colostral lymphoid cells were not absorbed. The results indicate that in the pig, an animal having an epitheliochorial placenta, the colostral lymphoid cells are absorbed from the digestive tract and, hence, they can confer an active cellular immunity on the newborn piglets.

Animals↗
PubMed2005

Class B scavenger receptor-mediated intestinal absorption of dietary beta-carotene and cholesterol.

There is now a general consensus that the intestinal absorption of water-insoluble, dietary lipids is protein-mediated, but the assignment of protein(s) to this function is still a matter of debate. To address this issue, we measured beta-carotene and cholesterol absorption in wild-type and SR-BI knockout mice and the uptake of these lipids in vitro using brush border membrane (BBM) vesicles. From the comparison of the in vivo and in vitro results we conclude that both BBM-resident class B scavenger receptors, SR-BI and CD36, can facilitate the absorption of beta-carotene and cholesterol. SR-BI is essential for beta-carotene absorption, at least in mice on a high fat diet. This is due to the fact that the absorption of beta-carotene is restricted to the duodenum and SR-BI is the predominant receptor in the mouse duodenum. In contrast, SR-BI may be involved but is not essential for cholesterol absorption in the small intestine. The question of whether SR-BI contributes to cholesterol absorption in vivo is still unresolved. Transfection of COS-7 cells with SR-BI or CD36 confers on these cells lipid uptake properties closely resembling those of enterocytes and BBM vesicles. Both scavenger receptors facilitate the uptake of dietary lipids such as beta-carotene, free and esterified cholesterol, phospholipids, and fatty acids into COS-7 cells. This lipid uptake is effected from three different lipid donor particles: mixed bile salt micelles, phospholipid small unilamellar vesicles, and trioleoylglycerol emulsions which are all likely to be present in the small intestine. Ezetimibe, a representative of a new class of drugs that inhibit intestinal cholesterol absorption, blocks SR-BI- and CD36-facilitated uptake of cholesterol into COS-7 cells.

Animal Feed↗
PubMed1983

Intestinal absorption of glandular kallikrein in the rat.

We studied the possibility of intestinal absorption of glandular kallikrein in unanesthetized rats after administration of 5 mg of active or phenylmethylsulfonyl fluoride-inactivated pig pancreatic kallikrein (PPK). Immunoreactive PPK was measured in plasma and urine by radioimmunoassay using an antiserum to PPK that does not cross-react with rat glandular kallikrein. In addition, we studied the effect of intestinally administered active PPK on the intestinal blood flow distribution. Although immunoreactive PPK could not be detected (less than 10 ng/ml) in plasma after active PPK was administered, very small amounts were found in urine (20-40 ng/3 h). In the urine most of the PPK was in active form because over 75% could be bound to aprotinin-Sepharose. After inactive PPK was administered, immunoreactive PPK was detectable in the plasma of all rats, and urinary excretion was higher than after administration of active PPK. Blood flow distribution to the small intestine as a percentage of cardiac output was significantly greater 30 min after intestinal application of active PPK (5 mg) than after administration of the vehicle alone (1 ml of 0.9% saline). These results suggest that active and inactive PPK is absorbed from the gut in very small amounts. The finding of higher amounts of immunoreactive PPK in plasma and urine after inactive PPK was administered is probably due to the fact that the inactive form of the enzyme is not bound by the plasma inhibitors. These small amounts of kallikrein absorbed appear to have some effect on intestinal blood flow distribution.

Animals↗
PubMed2004

Stimulatory effect of inulin on intestinal absorption of calcium and magnesium in rats is modulated by dietary calcium intakes short- and long-term balance studies.

Previous studies have shown that short-term intake of fermentable oligosaccharides (OS), including inulin, can increase mineral intestinal absorption in humans and animals. While the stimulatory effect of these substances on intestinal magnesium (Mg) absorption is generally high and consistent, their effect on calcium (Ca) seems to depend on experimental conditions, particularly the duration of fermentable OS intake. The aim of this study was to determine how the short- and long-term dietary Ca intake may modulate the effect of inulin on Ca absorption. Sixty male Wistar rats, weighing 275 g, were randomized into two groups to receive or not 10% of inulin in their diet. Each group was divided into three sub-groups to receive one of the following dietary Ca levels 0.25%, 0.50% and 0.75% in their food. The animals were fed fresh food and water ad libitum for 40 days. Apparent intestinal absorptions of Ca and Mg were determined at D13 and D36 of the experiment. As expected, inulin feeding increased Ca and Mg absorption in both periods at all dietary Ca levels. However, the effect of inulin on intestinal Ca absorption was dependent on dietary Ca levels and on experiment duration. In the short-term period, the inulin effect was prominent in the groups receiving high or low Ca levels, but in long-term period inulin improved intestinal Ca absorption much more in the group receiving the low Ca level. In addition, efficiency of intestinal absorption of Ca and Mg (%) was negatively affected by Ca intake levels. These results show that the beneficial effect of inulin on intestinal Ca absorption may be more marked in cases where the Ca intake is low or where the organism's Ca requirement is high. Further studies are required to confirm these results in humans.

Animals↗
PubMed1994

Intestinal absorption of octanoic, decanoic, and linoleic acids: effect of triglyceride structure.

The influence of triglyceride structure on the intestinal absorption of specific triglycerides was investigated. A bolus of either a structured or a randomized oil was given to lymph-cannulated rats. The structured oil contained medium-chain fatty acids (MCFA) in the sn-1 and sn-3 position of the triglyceride, and linoleic acid (C18:2 n-6) in the sn-2 position, whereas in the randomized oil the same fatty acids were distributed randomly between the three positions. The absorption of MCFA was highest from the randomized oil, where approximately 33% of the MCFA were located in the sn-2 position. The absorption of C18:2 n-6 was highest from the structured oil, where C18:2 n-6 is located in the sn-2 position, indicating that the intestinal absorption is influenced by triglyceride structure, and that the absorption is enhanced for fatty acids located in the sn-2 position. Prior to lymph collection, the rats were fed either a fish oil or a vegetable oil diet. The absorption of C18:2 n-6 was highest in the rats previously fed the fish oil diet. The incorporation of the highly unsaturated fatty acids from the fish oil into the membrane phospholipids may thus influence the absorption of fat.

Animals↗
PubMed1984

[Function diagnosis of small intestine absorption using the modified D-xylose absorption test].

Based on a biophysical model of the absorptive system a modified D-xylose test has been inaugurated, which is well suited to comprehensively assess the process of intestinal absorption. According to the author's experience of many years the test is a well-suited method for detecting changes in intestinal absorption. It excels by its high validity and reliability. Its practical accomplishment is easy and needs no expensive equipment. The method and the processing and evaluation of the measured values are described in detail.

Adolescent↗
PubMed1975

Intestinal absorption of cytidine diphosphate choline and its changes in the digestive tract.

Intestinal absorption of cytidine diphosphate choline (CDP-choline), its structural changes in the digestive tract, and hepatic uptake have been investigated in rats using 14C-labeled (14CH3 attached to N of choline) and 3H-labeled (at C5 of pyrimidine) compounds. The results indicate that: 1)CDP-choline is relatively stable in the stomach, but is quickly degraded into cytidine and choline in the intestine; 2) The hepatic uptakes of 14C and 3H reach the maximum in two to three hours after oral administration; 3) Whereas the amount of 14C remaining in the gut is inversely related to the hepatic uptake, no similar correlation is seen with 3H-labeled CDP-choline, and 4) Extrahepatic uptake of 14C and 3H is very small. The possibility of phosphorylation in the mucosa of choline and cytidine has been discussed, based on the differences in individual broken-down products in the intestinal lumen and mucosa.

Animals↗
PubMed1984

Physical model approach to gastrointestinal absorption of prostaglandins II: In situ rat intestinal absorption of dinoprost.

In situ absorption studies with dinoprost in the rat jejunum were carried out using a modified Doluisio technique. The absorption rate was first order. There was a sigmoidal decrease in the rate with increasing buffer pH (from 3.5 to 9.5), which strongly indicated the partitioning of weak acid species into the lipoidal membrane. An asymptotic minimum rate was attained from buffer pH 7.5 to 9.5, operationally indicative of transport of anions across aqueous pores. The importance of the aqueous diffusion layer on the mucosal side of the membrane was evident; rates at pH 3.5 and 4.5 were faster at high agitation hydrodynamics in the lumen solution. Preliminary studies showed that there was no metabolism in the lumenal solution and that metabolism occurred within the membrane. The transport mechanism involved simultaneous passive diffusion and bioconversion in the membrane because (a) a 1.5 X 10(4)-fold range in dinoprost concentration (0.014-210 microM) showed no saturable carrier-mediated tendency on the rate, (b) iodoacetic acid and indomethacin did not inhibit the absorption rate, and (c) the shape of the absorption-pH profiles was suggestive of passive diffusion. The prostaglandin did not have apparent adverse membrane and vascular effects under the conditions employed. The quantification and factorization of the physically meaningful transport parameters were accomplished using the physical model previously described. The permeability coefficients of the aqueous diffusion layer for the oscillation and static hydrodynamic situations were 0.8 X 10(-4) and 1.7 X 10(-4) cm/s, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

[Effects of perfusion flow rates on the intestinal absorption of carbohydrates].

The effects of five perfusion flow rates (4,5, 9, 12, 30 and 60 ml/h) on the intestinal absorption of glucose, fructose and sucrose were studied in the rat with a "temporary" Thiry-Vella loop (jejunum = 20 cm). Sucrose hydrolysis and intestinal transport of actively and passively absorbed solutes were markedly affected when the flow rates rose to a value higher than the limiting rate of 12 ml/h. With a flow rate up to 60 ml/h, glucose and fructose were absorbed at the same rate, but this was not due to thinning of the unstirred water layer. Sucrose hydrolysis was likewise completely inhibited. This result cannot be attributed to a product inhibition because of the absence of hexoses in the exit perfusate. These observations had important implications in the comparison of the intestinal absorption of many nutrients to evaluate the optimal perfusion rate corresponding to intestinal function integrity.

Animals↗
PubMed2000

Intestinal transport and metabolism of glucose-conjugated kyotorphin and cyclic kyotorphin: metabolic degradation is crucial to intestinal absorption of peptide drugs.

Intestinal transport and metabolism of modified kyotorphin (KTP) were studied in rats. Modified KTPs studied were C-terminally modified KTP with p-aminophenyl-beta-D-glucoside (KTP-pAPbeta glc), N-terminally modified KTP-pAPbeta glc with t-butyloxycarbonyl group (Boc-KTP-pAPbeta glc) and the N- and C-terminally modified KTP by cyclization (cyclic KTP). KTP-pAPbeta glc was metabolized at a similar rate to that of KTP, and did not appear on the serosal side. Although Boc-KTP-pAPbeta glc was also metabolized, it was more stable than KTP and appeared on the serosal side. Cyclic KTP was also quite stable and appeared on the serosal side. The modified KTPs were evaluated kinetically for absorption consisting of membrane transport and metabolism. Absorption clearance (CL(abs)) of cyclic KTP, Boc-KTP-pAPbeta glc and Boc-KTP was higher than that of KTP (0.247 microl/min/cm) (Mizuma et al., Biochim. Biophys. Acta 1335 (1997) 111-119), which is the theoretical maximum by complete inhibition of peptidase activity, indicating that derivatization of KTP increases the membrane permeability. Furthermore, the data clearly showed that the greater the metabolic clearance (CL(met)) of KTP and the KTP derivatives, the lower the absorption clearance (CL(abs)). These results and further simulation study led to the conclusion that metabolic degradation in the intestinal tissues is more critical than membrane permeability (transport) for oral delivery of peptide drugs. Based on the stability of cyclic KTP in serum, this appears to be a good candidate analgesic peptide drug.

Acetaminophen↗
PubMed1984

Morphine-neural interactions on canine intestinal absorption and blood flow.

Intestinal Na and H2O fluxes and blood flow were determined in extrinsically denervated or innervated ileum of fed dogs during intra-arterial (0.2, 2, 20 micrograms min-1) or intraluminal (4, 40, 400 micrograms ml-1) morphine sulphate infusion. 3H2O and 22Na were used to determine unidirectional fluxes and 3H2O clearances were used to determine total segmental and absorptive site blood flow. Net Na and H2O absorption decreased with time in innervated gut segments but were unchanged in denervated segments. Intra-arterial morphine prevented the decrease in net Na and H2O absorption in innervated segments due to increases in unidirectional absorptive fluxes. Intra-arterial morphine did not affect absorption in denervated segments. Intraluminal morphine increased net Na and H2O absorption from both innervated and denervated ileal segments due to increases in the unidirectional absorptive fluxes. Absorptive site blood flow was linearly related to unidirectional absorptive Na fluxes in each group although not with the same slopes. The increment in absorptive site blood flow vs. absorptive Na flux was greatest with luminal morphine, intermediate with intra-arterial morphine and in denervated segments without morphine and least in innervated segments. It was concluded that intra-arterial morphine inhibits an antiabsorptive effect of extrinsic nerves and that intraluminal morphine promotes an absorptive effect which could be direct or mediated through intrinsic nerves.

Animals↗
PubMed1975

Intestinal absorption of free and protein-bound dietary methionine in the rat.

Intestinal absorption of radioactive free and protein-bound dietary methionine (Met) and changes in plasma amino acids were observed after feeding Met-supplemented test meals. Plasma and gastrointestinal contents were collected from 15 minutes to 16 hours after feeding. Plasma amino acids were determined after ad libitum ingestion of diets containing free Met. Protein-bound Met in fresh egg white and free Met left the stomach at the same rate, but protein-bound Met in dried egg white and free Met were emptied from the stomach at different rates. Free Met was absorbed from the intestine more rapidly than protein-bound Met. Concentrations and molar ratios of various free amino acids in plasma changed briefly in response to Met-supplemented single test meals. Long-term changes were observed when Met-supplemented diets were fed ad libitum. Prolonged ingestion of supplemented diets may cause sustained alterations in the plasma amino acid pattern.

Amino Acids↗
PubMed2005

Insulin-cell penetrating peptide hybrids with improved intestinal absorption efficiency.

Cell-penetrating peptide (CPP) was linked to insulin to form insulin-CPP hybrids. The intestinal absorption efficiency of CPP hybridized insulin was 6-8 times increased compared to normal insulin as tested on Caco-2 cell monolayer, a widely used in vitro model for intestinal absorption. Insulin-CPP hybrid transportation seemed to be through an active and transcytosis-like mechanism. Importantly, insulin in hybrids kept intact after they passed through the Caco-2 cell monolayer. This study provides a new clue for oral insulin development.

Administration, Oral↗