Sites of Maximal Absorption and Hydrolysis of Two Dipeptides by Rat Small Intestine in Vivo

1973 ◽  
Vol 44 (6) ◽  
pp. 583-594 ◽  
Author(s):  
R. F. Crampton ◽  
Maria T. Lis ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Intestinal Lumen ◽  
Proximal Half ◽  
Proximal Small Intestine ◽  
Significant Difference ◽  
Maximal Absorption ◽  
Hydrolysis Of ◽  
Mucosal Uptake

1. Though mucosal uptake of peptides plays an important part in protein absorption, little is known about the site of maximal absorption of peptides in the small intestine. This paper reports an investigation of the characteristics of absorption and hydrolysis of l-methionyl-l-methionine (Met-Met) and glycylglycine (Gly-Gly) by tied loops along the length of the small intestine of the rat, and those of absorption of the equivalent l-methionine (Met) and glycine (Gly). 2. Absorption of Met-Met, or a mixture of Met-Met and Met, was maximal in the proximal half of the small intestine, whereas absorption of Met was maximal in the distal half. Absorption of Met-Met was greater than that of the equivalent Met, especially in the proximal small intestine. In most sites, absorption of a mixture of Met-Met and Met was not significantly different from that of the equivalent Met-Met. Absorption of Met was not increased by raising its concentration from 100 to 200 μmol/ml, but addition of Met-Met (50 μmol/ml) produced a large increase in absorption, indicating that absorption of Met from Met-Met is independent of that from free Met. During absorption of Met-Met, large amounts of free Met appeared in the intestinal lumen. Most of this resulted from intralumen hydrolysis. The hydrolytic ability of mucosal homogenates was several times greater than that required to hydrolyse the Met-Met disappearing from the lumen during absorption. 3. The sites of maximal absorption of Gly-Gly, Gly and a mixture of Gly-Gly and Gly, were all in the proximal half of the intestine near the mid-point. Absorption of Gly-Gly was greater than that of the equivalent Gly, especially in the proximal sites. In several sites, there was no significant difference between absorption of a mixture of Gly-Gly and Gly and that of the equivalent Gly-Gly. During absorption of Gly-Gly, the amounts of free Gly appearing in the lumen were small except in the two most distal sites. Most of the free Gly resulted from back-diffusion from the mucosa. The hydrolytic ability of mucosal homogenates was barely adequate to hydrolyse the Gly-Gly disappearing from the lumen during absorption. 4. The results suggest that there is no real discrepancy between the site of maximal absorption of protein digestion products from tied loops of small intestine and that of their absorption in the intact animal. They indicate that absorption of Met and Met-Met involves independent mechanisms, and confirm previous evidence that the capacity of the intestine to absorb mixtures of peptides and amino acids is greater than its capacity to absorb amino acids alone.

scholarly journals Starch digestion kinetics and mechanisms of hydrolysing enzymes in growing pigs fed processed and native cereal-based diets

2019 ◽  
Vol 121 (10) ◽  
pp. 1124-1136 ◽  
Author(s):  
Bianca M. J. Martens ◽  
Thomas Flécher ◽  
Sonja de Vries ◽  
Henk A. Schols ◽  
Erik M. A. M. Bruininx ◽  
...  
Keyword(s):  
Small Intestine ◽  
Growing Pigs ◽  
Intestinal Lumen ◽  
Starch Digestion ◽  
Proximal Small Intestine ◽  
Digestion Kinetics ◽  
High Amylose

AbstractThis study aimed to examine in vivo starch digestion kinetics and to unravel the mechanisms of starch hydrolysing enzymes. Ninety pigs (23 (sd 2·1) kg body weight) were assigned to one of nine treatments in a 3×3 factorial arrangement, with starch source (barley, maize, high-amylose (HA) maize) and form (isolated, within cereal matrix, extruded) as factors. We determined starch digestion coefficients (DC), starch breakdown products and digesta retention times in four small-intestinal segments (SI1–4). Starch digestion in SI2 of pigs fed barley and maize, exceeded starch digestion of pigs fed HA maize by 0·20–0·33 DC units (P<0·01). In SI3–4, barley starch were completely digested, whereas the cereal matrix of maize hampered digestion and generated 16 % resistant starch in the small intestine (P<0·001). Extrusion increased the DC of maize and HA maize starch throughout the small intestine but not that of barley (P<0·05). Up to 25 % of starch residuals in the proximal small intestine of pigs was present as glucose and soluble α(1–4) maltodextrins. The high abundance of glucose, maltose and maltotriose in the proximal small intestine indicates activity of brush-border enzymes in the intestinal lumen, which is exceeded by α-amylase activity. Furthermore, we found that in vivo starch digestion exceeded our in vitro predictions for rapidly digested starch, which indicates that the role of the stomach on starch digestion is currently underestimated. Consequently, in vivo glucose release of slowly digestible starch is less gradual than expected, which challenges the prediction quality of the in vitro assay.

Interaction of amino acids, peptides and peptidases in the small intestine

1975 ◽  
Vol 190 (1099) ◽  
pp. 149-163 ◽  
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Intestinal Absorption ◽  
Intestinal Lumen ◽  
Effective Inhibitor ◽  
Rat Intestine ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Entry Mechanism ◽  
Stimulation Of

Experiments were carried out with rat intestine to investigate the interaction of various amino acids, peptides and peptidases in intestinal absorption. A number of amino acids reduced the rate of hydrolysis of glycylglycine and glycyl-L-leucine and in both cases L-histidine was the most effective inhibitor. With L-leucyl-glycine the effects were quite different, and most amino acids tested caused some stimulation of hydrolysis, except L-histidine which caused inhibition. There was no evidence of competition between amino acids and dipeptides for an entry mechanism, but there was evidence for competition between different dipeptides. Cobalt caused stimulation of dipeptidases in homogenates but not in intact intestine, and this suggested that the dipeptidase is not accessible to cobalt in the intestinal lumen. The results are discussed in relation to the terminal stages of absorption and digestion of protein.

Renal interstitial Ca2+

2000 ◽  
Vol 278 (4) ◽  
pp. F644-F649 ◽  
Author(s):  
Maria M. Mupanomunda ◽  
Bing Tian ◽  
Norio Ishioka ◽  
Richard D. Bukoski
Keyword(s):  
Small Intestine ◽  
Wistar Rats ◽  
Interstitial Fluid ◽  
Muscle Tone ◽  
Intestinal Lumen ◽  
Kidney Cortex ◽  
Proximal Small Intestine ◽  
Mean Diameter

Renal interstitial fluid Ca2+concentration ([Ca2+]isf) was measured in anesthetized Wistar rats by using in situ microdialysis. During perfusion of 20 cm of the proximal small intestine with Ca2+-free buffer, renal [Ca2+]isf was 1.63 ± 0.19 mmol/l in the cortex ( n = 6) and 1.93 ± 0.12 mmol/l in the medulla ( n = 5, P = 0.223). When Ca2+ in the intestinal lumen was increased to 3 mmol/l, no change was seen in total or ionized serum Ca2+(SCa), urinary Ca2+ excretion (UCa), or Ca2+ in a microdialysate of the kidney cortex. Increasing intestinal Ca2+ further, to 6 mmol/l, was without effect on SCa but significantly increased UCa by 38% and microdialysate Ca2+by 36% (1.25 ± 0.0.09 vs. 1.70 ± 0.14 mmol/l, n = 4, P < 0.05). Intravenous infusion of 28 ng ⋅ kg− 1 ⋅ min− 1of parathyroid hormone for 1 h during perfusion of the intestinal lumen with 1 mmol/ Ca2+caused a 7–10% rise in SCa, a 40% fall in UCa, and a 32% increase in microdialysate Ca2+ (1.32 ± 0.13 vs. 1.74 ± 0.13 mmol/l, n = 6, P < 0.05). Interlobar arteries with a mean diameter of 120 μm were studied by using a wire myograph to determine whether changes in extracellular Ca2+ affect muscle tone. When precontracted with 5 μmol/l serotonin, the arteries relaxed in response to cumulative addition of Ca2+(1–5 mmol/l) with an ED50 value for Ca2+of 3.30 ± 0.08 mmol/l, n = 3. These data demonstrate that [Ca2+]isf changes dynamically during manipulation of whole-animal Ca2+ homeostasis and that intrarenal arteries relax in response to extracellular Ca2+ varied over the range measured in vivo.

scholarly journals SUPPRESSION EFFECT OF MAHKOTA DEWA (PHALERIA MACROCARPA) LEAF EXTRACT IN CHITOSAN NANOPARTICLES ON THE SMALL INTESTINE OF DEXTRAN SULFATE SODIUM-INDUCED MICE: FOCUS ON MITOSIS AND HYPERPLASIA

2018 ◽  
Vol 11 (6) ◽  
pp. 118
Author(s):  
Kusmardi Kusmardi ◽  
Arif Ramadhan Tamzir ◽  
Santi Widiasari ◽  
Ari Estuningtyas
Keyword(s):  
Small Intestine ◽  
Leaf Extract ◽  
Dextran Sulfate ◽  
Dextran Sulfate Sodium ◽  
Chitosan Nanoparticles ◽  
Negative Control ◽  
Suppression Effect ◽  
Significant Difference ◽  
Phaleria Macrocarpa

Objective: The incidence of small intestine cancer (SIC) is rising despite available preventive measures. Kaempferol and quercetin are a potential chemopreventive agent for SIC, but in vivo findings are inconclusive. We aim to study the effects of kaempferol and quercetin on colitis-associated small intestine carcinogenesis in mice.Methods: Suppression effect was tested using mice divided into 6 groups of treatment, i.e.; normal (N) group, negative control (NC), leaf extract (medium dose [MD]) dose 12.5 and 25 mg/kg body weight (BW), leaf extract chitosan and nanoparticle of mahkota dewa (NPMD) dose 6.25 and 12.5 mg/kg BW. Dextran sulfate sodium induction of 1% w/v was administered through drinking water for 6 weeks of treatment. The suppression effect was observed histopathologically by counting the mitotic cells and hyperplasia cells of the crypt of small intestine with hematoxylin-eosin staining.Results: Mitosis cells mean of NC group was not significant difference either with MD 12.5 (p=0.394) or MD 6.5 (p=0.310). However, mitosis cell mean appears to be lower in the NPMD 12.5 (p=0.09) and NPMD 6.25 (p=0.05) groups than the NC group. There was a significant difference among the mean of hyperplasia NC group and MD and also NPMD group. Significant difference also can be showed between MD 12.5 and MD 25 (p=0.026), and between NPMD 6.25 and NPMD 12.5 (p=0.002), and between MD 12.5 and NPMD 12.5 (p=0.002).Conclusion: Our results demonstrate suppression of hyperplasia small intestine by either nanoparticle or extract of Phaleria macrocarpa extracts. The suppression of mitosis was showed by administration of nanoparticle.

In vivo and in vitro Absorption of Amino Acids and Dipeptides in the Small Intestine of Uremic Rats

Nephron ◽  
1982 ◽  
Vol 31 (3) ◽  
pp. 273-276 ◽  
Author(s):  
G. Sterner ◽  
T. Lindberg ◽  
T. Denneberg
Keyword(s):  
Amino Acids ◽  
Small Intestine

Amino acid modulation of in vivo intestinal zinc absorption in freshwater rainbow trout

2002 ◽  
Vol 205 (1) ◽  
pp. 151-158 ◽  
Author(s):  
Chris N. Glover ◽  
Christer Hogstrand
Keyword(s):  
Amino Acids ◽  
Rainbow Trout ◽  
Amino Acid ◽  
Zinc Ion ◽  
Zinc Uptake ◽  
Intestinal Lumen ◽  
Zinc Absorption ◽  
Zinc Accumulation ◽  
Rainbow Trout Oncorhynchus Mykiss

SUMMARY The composition of the intestinal lumen is likely to have considerable influence upon the absorption, and consequently the nutrition and/or toxicity, of ingested zinc in aquatic environments, where zinc is both a nutrient and a toxicant of importance. The effects of amino acids upon intestinal zinc uptake in freshwater rainbow trout (Oncorhynchus mykiss) were studied using an in vivo perfusion technique. The presence of histidine, cysteine and taurine had distinct modifying actions upon quantitative and qualitative zinc absorption, compared to perfusion of zinc alone. Alterations in zinc transport were not correlated with changes in levels of free zinc ion. The chemical nature of the zinc–amino acid chelate, rather than the chelation itself, appeared to have the most important influence upon zinc absorption. l-histidine, despite a strong zinc-chelating effect, maintained quantitative zinc uptake at control (zinc alone) levels. This effect correlated with the formation of Zn(His)2 species. d-histidine at a luminal concentration of 100 mmol l–1 significantly enhanced subepithelial zinc accumulation, but reduced the fraction of zinc that was retained and absorbed by the fish. The possibility of a Zn(His)2-mediated pathway for intestinal uptake is discussed. l-cysteine specifically stimulated the accumulation of zinc post-intestinally, an effect attributed to enhanced zinc accumulation in the blood. Taurine increased subepithelial zinc accumulation, but decreased the passage of zinc to post-intestinal compartments. Amino acids are proposed to have important roles in modifying intestinal zinc uptake with potential implications for environmental toxicity as well as aquaculture.

Effects of ileal infusions of nutrients on motor patterns of canine small intestine

1990 ◽  
Vol 259 (1) ◽  
pp. G78-G85 ◽  
Author(s):  
M. L. Siegle ◽  
H. R. Schmid ◽  
H. J. Ehrlein
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Gastric Emptying ◽  
Motor Pattern ◽  
Inhibitory Effects ◽  
Contraction Force ◽  
Motor Patterns ◽  
Proximal Small Intestine ◽  
Dose Dependent ◽  
Different Doses

In the present study, effects of ileal infusions of nutrients on motor patterns of the proximal small intestine and on gastric emptying were investigated in dogs. An acaloric meal was administered orally, and equicaloric loads of amino acids, oleate, and glucose were infused into the ileum at different doses (0.3, 0.6, and 0.9 kJ/min). The computerized analysis of motor patterns was focused on the differentiation between stationary and propagated contractions recorded by closely spaced extraluminal strain gauges. All three nutrients exerted inhibitory effects on gastric emptying and on contraction force and frequency of the proximal small intestine. Additionally, the propulsive motor pattern induced by the acaloric meal was modulated by reducing the number of contraction waves and their length of spread. All the effects were dose dependent. Among the three nutrients, glucose significantly changed motility at lower doses compared with amino acids and oleate. We conclude that in dogs the ileal brake mechanism is induced by all three nutrients and that it influences not only contraction force and frequency but also the motor patterns of the proximal small intestine.

scholarly journals In vivo Determination of Amino Acid Bioavailability in Humans and Model Animals

2005 ◽  
Vol 88 (3) ◽  
pp. 923-934 ◽  
Author(s):  
Malcolm F Fuller ◽  
Daniel Tomé
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
The Body ◽  
Whole Body ◽  
Intestinal Lumen ◽  
Stable Isotope Labelling ◽  
Ileal Digestibility ◽  
Hydrolyzed Protein ◽  
Protein Free Diet

Abstract Because the digestion of many dietary proteins is incomplete, and because there is a continuous (but variable) entry into the intestinal lumen of endogenous protein and amino acid nitrogen that is also subject to digestion, the fluxes of nitrogen, amino acids, and protein in the gut exhibit a rather complicated pattern. Methods to distinguish and quantitate the endogenous and dietary components of nitrogen and amino acids in ileal chyme or feces include the use of a protein-free diet, the enzyme-hydrolyzed protein method, different levels of protein intake, multiple regression methods, and stable-isotope labelling of endogenous or exogenous amino acids. Assessment of bioavailability can be made, with varying degrees of difficulty, in man directly but, for routine evaluation of foods, the use of model animals is attractive for several reasons, the main ones being cost and time. Various animals and birds have been proposed as models for man but, in determining their suitability as a model, their physiological, enzymological, and microbiological differences must be considered. Fecal or ileal digestibility measurements, as well as apparent and true nitrogen and amino acid digestibility measurements, have very different nutritional significance and can, thus, be used for different objectives. Measurements at the ileal level are critical for determining amino acid losses of both dietary and endogenous origin, whereas measurements at the fecal level are critical in assessing whole-body nitrogen losses. A complementary and still unresolved aspect is to take into account the recycling of intestinal nitrogen and bacterial amino acids to the body.

scholarly journals The Relative Importance of the Small Intestine and the Liver in Phase II Metabolic Transformations and Elimination of p-Nitrophenol Administered in Different Doses in the Rat

2020 ◽  
Vol 88 (4) ◽  
pp. 51
Author(s):  
Attila Almási ◽  
Pál Perjési ◽  
Emil Fischer
Keyword(s):  
High Pressure ◽  
Small Intestine ◽  
Phase Ii ◽  
Hepatic Function ◽  
Intestinal Lumen ◽  
Jejunal Loop ◽  
Relative Importance ◽  
Significant Difference ◽  
Metabolic Reactions ◽  
Different Doses

Intestinal and hepatic function have been investigated in phase II metabolic reactions and elimination of p-nitrophenol (PNP) in the rat. A jejunal loop was cannulated and recirculated with isotonic solutions containing PNP in different concentrations (0, 20, 100, 500, 1000 µM). Samples were obtained from the perfusate at given intervals. To investigate the metabolic and excretory functions of the liver, the bile duct was cannulated, and the bile was collected. Metabolites of PNP were determined by validated HPLC (high pressure liquid chromatography) methods. The results demonstrated the relative importance of the small intestine and the liver in phase II metabolic transformations and elimination of PNP. There were significant differences between the luminal and biliary appearances of p-nitrophenol-glucuronide (PNP-G) and p-nitrophenol–sulfate (PNP-S). The PNP-G appeared in the intestinal lumen at the lower PNP concentrations (20 µM and 100 µM) at higher rate than in the bile. No significant difference was found between the intestinal and the biliary excretion of PNP-G when PNP was administered at a concentration of 500 µM. However, a reverse ratio of these parameters was observed at the administration of 1000 µM PNP. The results indicated that both the small intestine and the liver might play an important role in phase II metabolic reactions and elimination of PNP. However, the relative importance of the small intestine and the liver can be dependent on the dose of drugs.

Serum interspecies differences in metabolic pathways of bradykinin and [des-Arg9]BK: influence of enalaprilat

1996 ◽  
Vol 271 (4) ◽  
pp. H1340-H1347 ◽  
Author(s):  
A. Decarie ◽  
P. Raymond ◽  
N. Gervais ◽  
R. Couture ◽  
A. Adam
Keyword(s):  
Metabolic Pathways ◽  
Neutral Endopeptidase ◽  
Thrombin Inhibitor ◽  
Rat Serum ◽  
Highly Sensitive ◽  
Significant Difference ◽  
Hydrolysis Of

Among the different enzymes responsible for the metabolism of bradykinin (BK), three peptidases look relevant in vivo: kininase I (KI), which transforms BK into its active metabolite, [des-Arg9]BK; kininase II (KII); and neutral endopeptidase, which inactivate BK and [des-Arg9]BK. The in vitro incubation of BK and [des-Arg9]BK in the serum of four species with or without enalaprilat and the quantification of the immunoreactivity of both peptides at different time intervals allowed the measurement of the kinetic parameters characterizing their metabolic pathways. Highly sensitive chemiluminescent enzyme immunoassays were used to measure the residual concentrations of BK and [des-Arg9]BK. Half-life (t1/2) of BK showed significant difference among species: rats (10 +/- 1 s) = dogs (13 +/- 1 s) < rabbits (31 +/- 1 s) < humans (49 +/- 2 s). t1/2 values of [des-Arg9]BK were also species dependent: rats (96 +/- 6 s) < < rabbits (314 +/- 6 s) = dogs (323 +/- 11 s) = humans (325 +/- 12 s). Enalaprilat significantly prevented the rapid BK and [des-Arg9]BK degradation in all species except that of [des-Arg9]BK in rat serum. Relative amount of BK hydrolyzed by serum KII was given as follows: rabbits (93.7 +/- 14.8%) = rats (83.6 +/- 6.7%) = humans (76.0 +/- 7.5%) > dogs (50.0 +/- 3.9%). Its importance in the hydrolysis of [des-Arg9]BK was 5.2 +/- 0.5% in rats < < 33.9 +/- 1.5% in humans < 52.0 +/- 1.1% in rabbits < 65.1 +/- 3.4% in dogs. The participation of serum KI in the transformation of BK into [des-Arg9]BK was dogs (67.2 +/- 5.3%) > > humans (3.4 +/- 1.2%) = rabbits (1.8 +/- 0.2%) = rats (1.4 +/- 0.3%). Finally, no significant difference on t1/2 values for BK and [des-Arg9]BK could be demonstrated between serum and plasma treated with either sodium citrate or a thrombin inhibitor. These results revealed striking species differences in the serum metabolism of kinins that could address at least partially some of the controversial data related to the cardioprotective role of kinins.

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