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Results for “INTESTINAL ABSORPTION”

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At least 19 recordsLinked to original sources
PubMed1982

Blood flow an intestinal absorption.

Intestinal blood flow interacts with intestinal absorption at several levels and affects absorption through several mechanisms. The precise relationships are difficult to define because, at present, there is not an adequate technique available for measuring blood flow to the absorptive site. The absorption of certain nutrients requires O2 delivered through the blood for maintenance of carrier-mediated transcellular transport. Both altered capillary pressure, which may or may not accompany altered blood flow because of myogenic autoregulation, and changes in absorption can influence tissue hydrostatic and colloid osmotic pressure and also epithelial and interstitial space conductance. These latter, in turn, can change the rate of passive ultrafiltration for a constant driving force. Changes in blood flow can also influence the rate of washout of absorbed substances. Countercurrent exchange in the villous vasculature can buffer the rate of absorption of some substances and may also facilitate the absorption of water. Regulatory agents such as hormones or neurotransmitters can affect blood flow and absorption both independently and interactively. Agents that cause active intestinal secretion may have their effects modified by consequent changes in blood flow.

Animals↗
PubMed1995

Effect of sodium concentration in a carbohydrate-electrolyte solution on intestinal absorption.

Intestinal absorption during infusion (15 ml.min-1) of a 6% carbohydrate (2% glucose and 4% sucrose) solution containing either 0, 25 or 50 mEq.l-1 Na+ was measured by segmental perfusion with a triple lumen tube in males (age 24.3 +/- 1.6) at rest in a neutral environment (22 degrees C). Infusion of the 25 and 50 mEq.l-1 Na+ solutions was performed using a balanced design on the same day, separated by a 1-hr period of no infusion. Infusion of 0 mEq.l-1 Na+ solution was performed on a separate day. A 45-min equilibration period preceded a 90-min test session. Water and solute fluxes were determined from differences in concentration of polyethylene glycol and solute across a 40-cm intestinal segment of the duodenojejunum. A two-factor repeated measures ANOVA indicated no differences (P > 0.1) over time for water, Na+, or glucose flux for all solutions. Plasma volume increased (P < 0.01) approximately 5% over time for all solutions. We conclude that Na+ concentrations of 0, 25, or 50 mEq.l-1 in a 6% carbohydrate solution have similar effects on the absorption of water, Na+, and glucose from the duodenojejunum. Glucose in the infusion solution is the more important factor determining intestinal water absorption than Na+. This study suggests that adding Na+ to fluid replacement beverages may not be a factor in fluid absorption.

Adult↗
PubMed1978

Vitamin D-3 intestinal absorption in vivo: influence of fatty acids, bile salts, and perfusate pH on absorption.

Intestinal absorption of vitamin D-3 in physiological concentrations was studied in the live unanesthetised rat. In both the jejunum and the ileum a linear relationship was found between the absorption rate of the vitamin and its intraluminal concentration. Increasing the sodium taurocholate concentation in the perfusate above 5mM did not change ileal absorption rate but did decrease jejunal absorption rate. The vitamin's rate of absorption was raised by increases in either the hydrogen ion concentration in vivo is mediated by passive diffusion. The rate of absorption of ttion or the perfusate's flow rate. Addition of 2.5 mM fatty acids of varying chain length and degrees of saturation resulted in a decrease in the rate of vitamin D-3 absorption. These experiments indicate that vitamin D-3 absorption in vivo is mediated by passive diffusion. The rate of absorption of the vitamin is influenced by the composition of the perfusate and the thickness of the unstirred layer.

Animals↗
PubMed1996

A surgical model to increase the intestinal absorptive surface: intestinal lengthening and growing neomucosa in the same approach.

Despite numerous investigations short bowel syndrome (SBS) is still an unsolved clinical problem. The purpose of this study was to develop a new surgical approach that combines both intestinal lengthening and growing neomucosa. The operative principle is based on a longitudinal division of an intestinal segment antimesenterically and a formation of two intestinal tubes out of bowel halves anastomosing one cutting edge to the incised mucosal midline and the other to the antimesenteric side of the constructed first intestinal tube, so that a common wall between the two hemiloops was created which leads to grow neomucosa. This procedure was applied to 11 rabbits. The hemiloops and neomucosa were investigated for its feasibility and morphologic characteristics. Gross and microscopic examinations at 8 weeks revealed that all the intestinal tubes were viable and patent. No anastomotic leakage was present. In all animals, the serosal surfaces of the common walls were covered with neomucosa that resembles the mucosa of the existing intestine morphologically; there was no significant difference in villus height, villus width at base, crypt depth, number of villi per unit serosal length, villus surface, and villus surface per unit serosa. The growth of neomucosa was completely a result of epithelialization without any evidence of contraction. The quantity and rate of neomucosal growth seems unaffected by intestinal segment length. Finally a two times increase in intestinal length, whereas the diameter halved and a statistically significant increase (P < 0.001) in total villus surface via growing neomucosa was obtained. This model might be useful in the management of SBS when supported by clinical and functional investigations.

Animals↗
PubMed1995

Intestinal absorptive capacity, intestinal permeability and jejunal histology in HIV and their relation to diarrhoea.

Intestinal function is poorly defined in patients with HIV infection. Absorptive capacity and intestinal permeability were assessed using 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and lactulose in 88 HIV infected patients and the findings were correlated with the degree of immunosuppression (CD4 counts), diarrhoea, wasting, intestinal pathogen status, and histomorphometric analysis of jejunal biopsy samples. Malabsorption of 3-O-methyl-D-glucose and D-xylose was prevalent in all groups of patients with AIDS but not in asymptomatic, well patients with HIV. Malabsorption correlated significantly (r = 0.34-0.56, p < 0.005) with the degree of immune suppression and with body mass index. Increased intestinal permeability was found in all subgroups of patients. The changes in absorption-permeability were of comparable severity to those found in patients with untreated coeliac disease. Jejunal histology, however, showed only mild changes in the villus height/crypt depth ratio as compared with subtotal villus atrophy in coeliac disease. Malabsorption and increased intestinal permeability are common in AIDS patients. Malabsorption, which has nutritional implications, relates more to immune suppression than jejunal morphological changes.

Adult↗
PubMed1990

Influence of antimicrotubular drugs on the Golgi apparatus of stomach secretory mucoid cells and small intestine absorptive cells.

The effects of vinblastine and colchicine on the Golgi apparatus of stomach surface mucoid and absorptive intestinal cells were compared by cytochemical analysis. The two epithelial cells were chosen because of their different specific functions in the formation of secretory granules, the production of lysosomes and the intensity of membrane traffic in the cytoplasm. For the analysis, adult mice were injected with 1 mg/100 g b.w. of vinblastine and 1 mg/100 g b.w. of colchicine. For the demonstration of cis and trans cisternae of the Golgi apparatus, prolonged osmification, thiamine pyrophosphatase and acid phosphatase activity identification were applied. After treatment with vinblastine or colchicine, polarity of stacks in the Golgi apparatus of surface mucoid cells is preserved although the number of cisternae with thiamine pyrophosphatase or acid phosphatase activity decreases. However, the Golgi apparatus of intestinal absorptive cells completely disintegrates and only a few separated cis or trans cisternae can be identified. The main effect seems to be a reduction of vesicles which can be cytochemically identified as parts of the Golgi apparatus and an accumulation of vesicles which probably originate from budding ER. Communication between the ER and the Golgi apparatus seems to be interrupted.

Animals↗
PubMed2003

The use of protein hydrolysate improves the protein intestinal absorption in undernourished mice infected with Schistosoma mansoni.

Patients residing in endemic areas for schistosomiasis in Brazil are usually undernourished and when they develop the hepatosplenic clinical form of the disease should usually receive hospital care, many of them being in need of nutritional rehabilitation before specific treatment can be undertaken. In the mouse model, investigations carried out in our laboratory detected a reduced aminoacid uptake in undernourished animals which is aggravated by a superimposed infection with Schistosoma mansoni. However, in well-nourished infected mice no dysfunction occurs. In this study, we tried to improve the absorptive intestinal performance of undernourished mice infected with S. mansoni by feeding them with hydrolysed casein instead of whole casein. The values obtained for the coefficient of protein intestinal absorption (cpia) among well-nourished mice were above 90% (either hydrolysed or whole protein). In undernourished infected mice, however, the cpia improved significantly after feeding them with hydrolysed casein, animals reaching values close to those obtained in well-nourished infected mice.

Animals↗
PubMed1988

Intestinal absorption of cephalosporin antibiotics: correlation between intestinal absorption and brush-border membrane transport.

The absorption of seven cephalosporin antibiotics from the in-situ intestinal loop at pH 7.4 and their transport by brush-border membrane vesicles in the presence of an inward H+ gradient ([pH]i = 7.5, [pH]o = 6.0) were examined. A good correlation was found between the intestinal absorption rate and the initial uptake rate by brush-border membrane vesicles. The data suggest that the transport study using intestinal brush-border membrane vesicles is useful as a model system for the intestinal absorption of beta-lactam antibiotics.

Animals↗
PubMed1992

[Mucus models for investigation of intestinal absorption mechanisms. 4. Comparison of mucus models with absorption models in vivo and in situ for prediction of intestinal drug absorption].

Intestinal absorption with an in vitro model using pig intestinal mucus was examined by means of in vivo and in situ experiments in the rat. With 10 compounds of different structure, in vitro, in situ, and in vivo models were tested. The in vitro model in the present form can only simulate the first step of intestinal absorption, namely diffusion through the mucus layer. Indeed, we found that one function of the intestinal mucus can be described being a molecular sieve with a molecular mass (MM) cut off within the range of about 600 to 700 [g/mol]. Absorption of substances with higher molecular mass remains at a low level. With the mucus model prediction of intestinal absorption of hydrophilic substances with MM < 600 to 700 [g/mol] will be possible, if the mass transport in the mucus layer is rate limiting. Independent of polarity, it is also valid for substances of MM > 600 to 700 [g/mol]. Estimation however, is not valid for lipophilic substances and MM < 600 to 700 [g/mol], when mass transport from the mucus to the adjacent compartments is rate limiting. Further optimization of the mucus model for a more extensive application seems possible and reasonable with respect to saving in vivo experiments with animals.

Animals↗
PubMed2003

Evaluation of rat intestinal absorption data and correlation with human intestinal absorption.

The absorption of 111 drug and drug-like compounds was evaluated from 111 references based on the ratio of urinary excretion of drugs following oral and intravenous administration to intact rats and biliary excretion of bile duct-cannulated rats. Ninety-eight drug compounds for which both human and rat absorption data were available were selected for correlation analysis between the human and rat absorption. The result shows that the extent of absorption in these two species is similar. For 94% of the drugs the absorption difference between humans and rats is less than 20% and for 98% of drugs the difference is less than 30%. There is only one drug for which human absorption is significantly different from rat absorption. The standard deviation is 11% between human and rat absorption. The linear relationship between human and rat absorption forced through the origin, as determined by least squares regression, is %Absorption (human)=0.997%Absorption (rat) (n=98, SD=11). It is suggested that the absorption in rats could be used as an alternative method to human absorption in pre-clinical oral absorption studies.

Algorithms↗
PubMed1995

Small intestinal absorption of bropirimine in rats and effect of bile salt on the absorption.

The intestinal absorption characteristics of a poorly water-soluble drug, bropirimine, were investigated by the in-situ small intestinal loop method using male Sprague-Dawley rats. Bropirimine in solution was well absorbed in the overall small intestine, following first-order kinetics. The rate determining step for the disappearance of bropirimine from the small intestinal loop after dosing in the suspension was the dissolution process from suspension. Bropirimine was solubilized by sodium glycocholate. The disappearance of bropirimine from the small intestinal loop was suppressed by sodium glycocholate contained in the solution, because of the loss of thermodynamic activity of bropirimine after its involvement in the micellar complex, not by the direct effect of bile salt on the permeability of intestinal mucosa. The disappearance of bropirimine was also suppressed by sodium glycocholate contained in the suspension. The suppression by sodium glycocholate seemed to be caused by the greater influence of sodium glycocholate on the thermodynamic activity of bropirimine than on the dissolution from suspension.

Adjuvants, Immunologic↗
PubMed1982

Synthetic human gastrin I and gastrin-like pentapeptide in studies of intestinal absorption in man. Role of gastrin in human intestinal absorption.

The effects of synthetic human gastric I (SHG I) and gastrin-like pentapeptide (PG) on jejunal water, electrolyte, and glucose absorption were studied in 11 normal subjects. The i.v. administration of graded doses of SHG I increased plasma gastrin levels similar to those after food intake and in the Zollinger-Ellison syndrome. SHG I and PG caused no significant changes in the net movement of water and solute. The findings indicate that gastrin has no direct effect on intestinal absorption in normal man, and does not account for the mechanism of diarrhea in the Zollinger-Ellison syndrome.

Adult↗