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At least 37 records · Page 2Linked to original sources
PubMed1990

Mutual inhibition of sugars and amino acid intestinal absorption.

1. Intestinal absorption of sugars shows interaction with amino acids and vice versa. 2. The percentage of inhibition induced by a substrate depends on the type of substrate and the substance affected. 3. The mutual inhibition of monosaccharides and amino acids can be explained by five different hypotheses. 4. The most accepted hypotheses are the "allosteric interaction" and the "accelerated efflux". 5. From the results in the literature it is difficult to decide which of the two hypotheses is the more accurate.

Amino Acids↗
PubMed1982

Intestinal absorption of several beta-lactam antibiotics. III. Competitive inhibition behavior among zwitterionic beta-lactam antibiotics in the rat intestinal absorption.

Competitive inhibitory behavior among zwitterionic beta-lactam antibiotics in the rat intestinal absorption process was examined. Intestinal absorption of cephradine and cephalexin was significantly inhibited by cyclacillin. The mutual inhibition between these amino-cephalosporins was also observed. On the other hand, in the pretreatment experiments with cyclacillin, it was found that absorption of cephradine was significantly inhibited, but the inhibitory effect of cyclacillin was not observed for cephalexin. These results showed that cephradine had a common carrier-mediated transport mechanism with cyclacillin which is not present in the absorption process of cephalexin. It was postulated that the mutual inhibition between cephradine and cephalexin is based on the competitive inhibition in the accumulation or uptake by the intestinal mucosa.

Animals↗
PubMed1997

Effects of various absorption enhancers on the intestinal absorption of water soluble drugs by in vitro Ussing chamber method: correlation with an in situ absorption experiment.

The effect of absorption enhancers on the small and large intestinal absorption of drug in rats was examined using an in vitro modified Ussing chamber method, and the results were compared with those from an in situ absorption experiment. Phenol red was chosen as a model drug, while the absorption enhancers used were sodium glycocholate (Na-GC), sodium taurocholate (Na-TC), sodium deoxycholate (Na-DC), EDTA, sodium salicylate (Na-Sal), sodium caprate (Na-Cap), diethyl maleate (DEM) and N-lauryl-beta-D-maltopyranoside (LM), all used at a concentration of 20 mM. This modified Ussing chamber method showed that Na-DC, EDTA and LM were the most effective absorption enhancers in the large intestine. A good correlation exists between the area under the curve (AUC) (in situ loop model) and the cumulative amount of phenol red absorbed (in vitro modified Ussing chamber method). These results indicated that the in vitro modified Ussing chamber method can be used to evaluate the effects of various absorption enhancers in the intestine.

Animals↗
PubMed2003

Concentration-dependent atypical intestinal absorption of cyclic phenylalanylserine: small intestine acts as an interface between the body and ingested compounds.

Intestinal absorption of peptides in linear form has been studied extensively, but there is little knowledge of peptides in a cyclic form. In this report, intestinal absorption of cyclic phenylalanylserine (cyclo(Phe-Ser)), a precursor of gliotoxin, was studied in isolated rat small intestine as a model cyclic dipeptide. Absorption clearance (CLabs) decreased in the presence of glycylsarcosine, cephalexin or cephradine, substrates for H+/oligopeptide cotransporter (PEPT1). CLabs of cyclo(Phe-Ser) also decreased at 4 degrees C, thus indicating that cyclo(Phe-Ser) is in part transported by PEPT1. However, the Eadie-Hofstee plot of absorption revealed an atypical profile at lower concentrations of cyclo(Phe-Ser) (around 0.1 mM). Moreover, comparative experiments of absorptive and excretive transport showed that excretive transport from the serosal to mucosal side of isolated intestinal tissue at a 0.1 mM cyclo(Phe-Ser) was superior to absorptive transport from the mucosal side to the serosal side, and vice versa at a 1 mM cyclo(Phe-Ser). A kinetic model was constructed, in which cyclo(Phe-Ser) concentration for excretive transport was assumed to be at the binding site of excretive transporter, but not the unbound cytoplasmic concentration. These results as well as the results of kinetic analysis indicate that intestinal absorption consists of passive transport, carrier-mediated absorptive transport by PEPT1 and carrier-mediated excretive transport, resulting in atypical absorption. Although cyclic dipeptides have potentials as drugs, their intestinal absorption may be complex. The results of this study lead us to conclude that absorptive and excretive transport by the small intestine acts as an interface between the body and ingested compounds.

Animals↗
PubMed1993

Dose-dependent intestinal absorption and significant intestinal excretion (exsorption) of the beta-blocker pafenolol in the rat.

The elimination of [3H]pafenolol and metabolites was investigated in fasted and fed rats. Separate groups received intravenous doses (0.3 and 3.0 mumol/kg) and oral doses (1 and 25 mumol/kg). After iv administration of pafenolol, the excretion of unchanged drug into urine and feces was about 50 and 25-30% of the given dose, respectively. The predominating mechanism for the excretion of pafenolol into feces was intestinal excretion (exsorption) directly from blood into gut lumen, since only about 3% of a given iv dose was recovered as pafenolol in the bile. When the oral dose was raised from 1 to 25 mumol/kg, the mean (+/- SD) bioavailability, calculated from urine data, increased from 14 +/- 9 to 30 +/- 11% (P < 0.05) in the starved rats and from 14 +/- 3 to 16 +/- 3% in the fed animals. In parallel, the fraction absorbed from the gut (fa) increased from 19 +/- 9 to 31 +/- 10% in the starved rats and from 16 +/- 4 to 19 +/- 5% in the fed animals, respectively. This indicates that the low bioavailability is due primarily to poor intestinal uptake.

Administration, Oral↗
PubMed1992

Research note: age-dependent changes in 3-oxy-methyl-D-glucose and leucine intestinal absorption in chickens.

Intestinal absorption of 3-oxy-methyl-D-glucose (3-OMG) and leucine were studied in intestinal slices from fasted 1-, 2-, and 3-wk-old chickens. The intestinal segments studied were the duodenum, jejunum, ileum, and cecum, with the latter divided into proximal and medial regions. There was a decrease in the intestinal absorption of 3-OMG and leucine in the duodenal, jejunal, and proximal cecal segments with increasing age of the chicken. The medial cecum did not show age-dependent differences in the uptake of substrates. In the ileum, there was a decrease in intestinal absorption of 3-OMG and leucine between Weeks 1 and 2, but thereafter the uptake was similar to that of the 2nd wk.

3-O-Methylglucose↗
PubMed1964

STUDIES ON INHIBITION OF INTESTINAL ABSORPTION OF RADIOACTIVE STRONTIUM. I. PREVENTION OF ABSORPTION FROM LIGATED INTESTINAL SEGMENTS.

A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, permitting the calcium to be available to the body. Studies were carried out in vivo by injection of Sr(89) and Ca(45) in the presence of inert carrier into ligated intestinal segments in rats, and the amount of absorption was measured by standard monitoring techniques. The pattern of absorption of both ions is very similar but the rate of absorption is different. It was found that the polyelectrolyte, sodium alginate, obtained from brown algae (Phaeophyceae), injected simultaneously with radiostrontium effectively reduces the absortion of Sr(89) from all segments of the intestine by as much as 50-80% of the control values. No significant reduction in absorption of Ca(45) was observed in equivalent concentrations. The reduction in blood levels of Sr(89) and in bone uptake corresponded to the absorption pattern. The difference in the effect on strontium and calcium absorption may be due to differences in the binding capacity of sodium alginate from the two metal ions under the conditions present in vivo.

Absorption↗
PubMedDate not supplied

Disaccharidase activities and intestinal absorption in infants with congenital intestinal obstruction.

The results of studies on disaccharidase activities and on intestinal absorption in cases of complete and incomplete congenital small bowel obstruction are presented. Assays of the activities of maltase, isomaltase, sucrase, trehalase, and lactase have been performed on biopsy specimens taken at the time of surgery. In specimens taken from above the site of obstruction, the activities are reduced for all disaccharidases, and are particularly low for trehalase and lactase. There was no difference between the cases with complete and incomplete obstruction. Distal to a complete obstruction, trehalase and lactase were reduced, whereas in cases of incomplete obstruction, the activities of all disaccharidases were within what is considered normal in the reference material. Two months after surgery, the disaccharidase activities were found to be normal. One month after surgery, the absorption of glucose and vitamin A was markedly impaired in cases with complete obstruction, whereas that of D-xylose was not significantly reduced from normal. In cases with incomplete obstruction, the results did not differ from those found in normal infants. The fact that failure to thrive is common during the first months after birth in patients with congenital intestinal atresia, even when surgery is successful, may be explained by deficient intestinal absorption, particularly in patients with complete obstruction.

Body Weight↗
PubMed2002

Concentration-dependent preferences of absorptive and excretive transport cause atypical intestinal absorption of cyclic phenylalanylserine: small intestine acts as an interface between the body and ingested compounds.

Intestinal absorption of cyclic phenylalanylserine (cyclo(Phe-Ser)), a precursor of gliotoxin, was studied in isolated rat small intestine as a model cyclic dipeptide. Absorption clearance (CLabs) decreased in the presence of glycylsarcosine, cephalexin or cephradine, substrates for H+/oligopeptide cotransporter (PEPT1). CLabs of cyclo(Phe-Ser) also decreased at 4 degrees C. These indicate that cyclo(Phe-Ser) is in part transported by PEPT1. However, Eadie-Hofstee plot of absorption revealed an atypical profile at lower concentrations of cyclo(Phe-Ser) (around 0.1 mM). Moreover, comparative experiments of absorptive and excretive transport showed that excretive transport from the serosal to mucosal side of isolated intestinal tissue at a 0.1 mM cyclo(Phe-Ser) was superior to absorptive transport from the mucosal side to the serosal side, and vise versa at a 1 mM cyclo(Phe-Ser). These results as well as the results of kinetic analysis indicate that intestinal absorption consists of passive transport, carrier-mediated absorptive transport by PEPT1 and carrier-mediated excretive transport, resulting in atypical absorption. Although cyclic dipeptides have potentials for drug, their intestinal absorption may be complex. The results of this study lead us conclude that absorptive and excretive transport by the small intestine acts as an interface between the body and ingested compounds.

Algorithms↗