Amino acids in the rat intestinal lumen regulate their own absorption from a distant intestinal site

2009 ◽  
Vol 297 (2) ◽  
pp. G292-G298 ◽  
Author(s):  
Fadi H. Mourad ◽  
Kassem A. Barada ◽  
Carmen Khoury ◽  
Tamim Hamdi ◽  
Nayef E. Saadé ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Inhibitory Effect ◽  
Intestinal Lumen ◽  
Jejunal Segment ◽  
Subdiaphragmatic Vagotomy ◽  
Regulatory Loop ◽  
Dependent Transport

Intestinal nutrient transport is altered in response to changes in dietary conditions and luminal substrate level. It is not clear, however, whether an amino acid in the intestinal lumen can acutely affect its own absorption from a distant site. Our aim is to study the effect of an amino acid present in rat small intestinal segment on its own absorption from a proximal or distal site and elucidate the underlying mechanisms. The effect of instillation of alanine (Ala) in either jejunum or ileum on its own absorption at ileal or jejunal level was examined in vivo. The modulation of this intestinal regulatory loop by the following interventions was studied: tetrodotoxin (TTX) added to Ala, subdiaphragmatic vagotomy, chemical ablation of capsaicin-sensitive primary afferent (CSPA) fibers, and IV administration of calcitonin gene-related peptide (CGRP) antagonist. In addition, the kinetics of jejunal Ala absorption and the importance of Na+-dependent transport were studied in vitro after instilling Ala in the ileum. Basal jejunal Ala absorption [0.198 ± 0.018 μmol·cm−1·20 min−1 (means ± SD)] was significantly decreased with the instillation of 20 mM Ala in the ileum or in an adjacent distal jejunal segment (0.12 ± 0.015; P < 0.0001 and 0.138 ± 0.014; P < 0.002, respectively). Comparable inhibition was observed in the presence of proline in the ileum. Moreover, basal Ala absorption from the ileum (0.169 ± 0.025) was significantly decreased by the presence of 20 mM Ala in the jejunum (0.103 ± 0.027; P < 0.01). The inhibitory effect on jejunal Ala absorption was abolished by TTX, subdiaphragmatic vagotomy, neonatal capsaicin treatment, and CGRP antagonism. In vitro studies showed that Ala in the ileum affects Na+-mediated transport and increases Km without affecting Vmax. Intraluminal amino acids control their own absorption from a distant part of the intestine, by affecting the affinity of the Na+-mediated Ala transporter, through a neuronal mechanism that involves CSPA and CGRP.

Effect of Cycloheximide on In Vitro and In Vivo Protein Synthesis by Certain Tissues of Rats and Pigeons with Special Reference to Muscle

1973 ◽  
Vol 51 (12) ◽  
pp. 933-941 ◽  
Author(s):  
Njanoor Narayanan ◽  
Jacob Eapen
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Incorporation ◽  
Contrast Administration ◽  
Acid Incorporation ◽  
Tissue Homogenates

The effect of cycloheximide in vitro and in vivo on the incorporation of labelled amino acids into protein by muscles, liver, kidneys, and brain of rats and pigeons was studied. In vitro incorporation of amino acids into protein by muscle microsomes, myofibrils, and myofibrillar ribosomes was not affected by cycloheximide. In contrast, administration of the antibiotic into intact animals at a concentration of 1 mg/kg body weight resulted in considerable inhibition of amino acid incorporation into protein by muscles, liver, kidneys, and brain. This inhibition was observed in all the subcellular fractions of these tissues during a period of 10–40 min after the administration of the precursor. Tissue homogenates derived from in vivo cycloheximide-treated animals did not show significant alteration in in vitro amino acid incorporation with the exception of brain, which showed a small but significant enhancement.

Engineering an acetyllysine reader with photocrosslinking amino acid for interactome profiling

2021 ◽  
Author(s):  
Babu Sudhamalla ◽  
Anirban Roy ◽  
Soumen Barman ◽  
Jyotirmayee Padhan
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Interactions ◽  
Unnatural Amino Acids ◽  
Protein Protein Interactions ◽  
Site Specific ◽  
Powerful Approach

The site-specific installation of light-activable crosslinker unnatural amino acids offers a powerful approach to trap transient protein-protein interactions both in vitro and in vivo. Herein, we engineer a bromodomain to...

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.

Comparison of rat liver response to coumarin administered in vivo versus in vitro

1964 ◽  
Vol 206 (1) ◽  
pp. 229-238 ◽  
Author(s):  
Judith G. Pool ◽  
C. F. Borchgrevink
Keyword(s):  
Amino Acid ◽  
Oxidative Phosphorylation ◽  
Vitamin K ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
General Effect ◽  
Liver Slices ◽  
Cell Energy

Warfarin added to incubated liver slices inhibits the synthesis of factor VII (proconvertin) in proportion to the log of its concentration; surprisingly, it has the same inhibitory effect on the transport and incorporation of amino acid into protein of the liver slices. This latter finding seems to support the frequently proposed concept that vitamin K has a role in oxidative phosphorylation and that coumarin compounds, by antagonizing vitamin K, uncouple oxidative phosphorylation and thus have a general effect on cell energy supply. However, when we studied the liver of rats depleted of vitamin K the same effect was not seen. Liver slices from such animals produced little factor VII but they incorporated amino acid at the normal rate. Furthermore, administration of warfarin in vivo had the same result as vitamin K depletion: a fall in circulating prothrombin complex but no decrease in either labeling of plasma proteins by intravenous C14-amino acid or incorporation of amino acid into subsequently excised liver slices. There is thus a striking discrepancy between the action of warfarin administered in vitro and that administered in vivo.

Amino acid fluxes in rat thin limb segments of Henle’s loop during in vitro microperfusion

1999 ◽  
Vol 277 (2) ◽  
pp. F204-F210 ◽  
Author(s):  
Olga H. Brokl ◽  
William H. Dantzler
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Apparent Movement ◽  
Transepithelial Transport ◽  
Acid Transport ◽  
Henle's Loop ◽  
Vasa Recta ◽  
The Difference

Amino acids are apparently recycled between loops of Henle and vasa recta in the rat papilla in vivo. To examine more closely papillary amino acid transport, we measured transepithelial fluxes ofl-[14C]alanine and [14C]taurine in thin limbs of Henle’s loops isolated from rat papilla and perfused in vitro. In descending thin limbs (DTL) in vitro, unidirectional bath-to-lumen fluxes tended to exceed unidirectional lumen-to-bath fluxes for both radiolabeled amino acids, although the difference was statistically significant only for taurine. In ascending thin limbs (ATL) in vitro, unidirectional lumen-to-bath fluxes tended to exceed unidirectional bath-to-lumen fluxes, although the difference was again statistically significant only for taurine. These results are compatible with apparent directional movements of amino acids in vivo. However, none of the unidirectional fluxes was saturable or inhibitable, an observation compatible with apparent reabsorption from the ATL in vivo but not compatible with apparent movement from vasa recta to DTL in vivo. There was no evidence of net active transepithelial transport when concentrations of radiolabeled amino acids were matched on both sides of perfused tubule segments. These data suggest that regulation of amino acid movement in vivo may involve the vasa recta, not the DTL of Henle’s loops. The data also suggest that transepithelial movement of amino acids in thin limbs of Henle’s loop may occur via a paracellular route.

scholarly journals Studies on Analogues of L-Cysteine and L-Cystine

Blood ◽  
1956 ◽  
Vol 11 (1) ◽  
pp. 1-10 ◽  
Author(s):  
AUSTIN S. WEISBERGER ◽  
LEIF G. SUHRLAND ◽  
JOSEPH SEIFTER
Keyword(s):  
Amino Acids ◽  
Spatial Configuration ◽  
Spatial Relationship ◽  
Inhibitory Effect ◽  
Selenium Compounds ◽  
Low Concentrations ◽  
Relationship Of ◽  
Normal Cellular Function

Abstract The amino acids L-cysteine and L-cystine appear to have an important role in the metabolism of leukocytes. Decreased availability of these amino acids may therefore have important effects on leukocytes. The possibility of decreasing the influx of radioactive L-cystine into leukemic leukocytes was investigated by exposing the leukocytes to various analogues of cysteine (cystine) prior to incubation with S35 L-cystine. It was found that a highly specific structural and spatial configuration is required to decrease the influx of S35 L-cystine. Thus unlabeled L-cysteine is effective in decreasing the incorporation of radioactive L-cystine. However, analogues of cystine in which there is modification or substitution of the sulfhydryl, amino or carboxyl group do not decrease the influx of S35 L-cystine. Furthermore, any alteration in the spatial relationship of the sulfhydryl and amino groups of L-cysteine also results in a loss of the ability of an analogue to decrease the incorporation of S35 L-cystine. Of the compounds studied and in the concentrations employed, only unlabeled L-cysteine, selenium cystine and phenyl selenium cysteine were effective. Selenium cystine is identical with cystine except that selenium replaces the sulfur in the molecule. Phenyl selenium cysteine is also closely related structurally to cysteine. The mechanism of action of selenium cystine and phenyl selenium cysteine in decreasing the influx of S35 L-cystine is not known. Other selenium compounds tested were ineffective. These compounds may exert their inhibitory effect by (a) competitive combination with specific intracellular receptors for L-cysteine (L-cystine), (b) inactivation of enzymes or compounds essential for normal cellular function, (c) alteration in membrane permeability or (d) a toxic effect of selenium. Since selenium cystine and phenyl selenium cystine are inhibitory in low concentrations in vitro, these compounds may have important effects on leukemic leukocytes in vivo.

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.

Correlation between osmoregulation and cell volume regulation

1987 ◽  
Vol 252 (4) ◽  
pp. R768-R773
Author(s):  
M. A. Lang
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Osmotic Pressure ◽  
Cell Volume ◽  
Free Amino Acids ◽  
Volume Regulation ◽  
Free Amino ◽  
Cell Volume Regulation

The euryhaline crab, Callinectes sapidus, behaves both as an osmoregulator when equilibrated in salines in the range of 800 mosM and below and an osmoconformer when equilibrated in salines above 800 mosM. There exists a close correlation between osmoregulation seen in the whole animal in vivo and cell volume regulation studied in vitro. Hyperregulation of the hemolymph osmotic pressure and cell volume regulation both occurred in salines at approximately 800 mosM and below. During long-term equilibration of the crabs to a wide range of saline environments, the total concentration of hemolymph amino acids plus taurine remained below 3 mM. During the first 6 h after an acute osmotic stress to the whole animal, the hemolymph osmotic pressure and Na activity gradually decreased, whereas the free amino acids remained below 3 mM. As the hemolymph osmotic pressure decreased below approximately 850 mosM, the amino acid level began to increase to 17-25 mM. This change was primarily due to increases in glycine, proline, taurine, and alanine. The likely source of the increase in hemolymph free amino acids in vivo is the free amino acid loss from muscle cells observed during cell volume regulation in vitro.

Incorporation of C14-amino acids into protein of isolated diaphragms: effect of epinephrine and norepinephrine

1960 ◽  
Vol 198 (1) ◽  
pp. 54-56 ◽  
Author(s):  
Ira G. Wool
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glucose Concentration ◽  
Muscle Protein ◽  
Effective Concentration ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Minimal Effective Concentration

When diaphragms isolated from normal rats were incubated with a C14-amino acid the addition of epinephrine or norepinephrine decreased incorporation of C14 into muscle protein. The inhibition occurred whether epinephrine was added in vitro or administered in vivo. The minimal effective concentration of epinephrine in vitro was 0.1 µg/ml. When the glucose concentration in the medium was raised to 300 mg % or more the epinephrine induced inhibition of amino acid incorporation into muscle protein was no longer observed.

Early Hematopoietic Progenitors of Dkc1 Hypomorphic Mutant Mice Display Decreased Proliferation Rate and an Impaired Control of Serine/Arginine-Rich Splicing Factor 4 (Srsf4) Translation

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2937-2937
Author(s):  
Antonio R Lucena-Araujo ◽  
Bárbara A Santana-Lemos ◽  
Carol H Thome ◽  
Germano A Ferreira ◽  
Davide Ruggero ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Ribosomal Rna ◽  
Proliferation Rate ◽  
Splicing Factor ◽  
Differentially Expressed Proteins ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Progenitor

Abstract The X-linked form of dyskeratosis congenita (X-DC) is caused by mutations in DKC1, which encodes for dyskerin: a putative pseudouridine synthase that mediate the posttranscriptional modification of ribosomal RNA (rRNA) through the conversion of uridine (U) to pseudouridine (Ψ). Patients with X-DC display defects in the pseudouridylation of ribosomal RNA that leads to translational upregulation of IRES-containing mRNAs and affects the affinity of the ribosome for these mRNAs. Studies in vivo and in vitro suggest that the pseudouridylation of ribosomal RNA is the underlying mechanism responsible for the enhanced susceptibility to cancer in these patients. Ruggero et al. have previously reported (Ruggero et al. Science. 2003 Jan 10;299(5604):259-62) that hypomorphic Dkc1m (Dkc1m) mice present pancytopenia associated with hypocellularity of the bone marrow (BM) and increased susceptibility to cancer, therefore constituting a reliable model to study the effect of impaired ribogenesis on hematopoiesis and oncogenesis. However, the cellular and molecular mechanisms leading to BM failure in X-DC remain unknown. Here, we describe the in vivo analysis of the proliferation rate of hematopoietic progenitors in Dkc1m mice and compare the proteomic profile of hematopoietic progenitors between Dkc1m mice and wild-type (WT) controls. For in vivo proliferation assays, 1mg of bromodeoxyuridine (BrdU) was injected intraperitoneally, every 6 hours during 24 hours, in 16 mice (eight WT and eight Dkc1m), and BM cells were harvested by flushing bone cavity, followed by immunofluorescence staining of incorporated BrdU and flow cytometric analysis. No differences were detected in the number of lineage-negative (Lin−), Sca1-positive, c-kit-negative (LSK−) cells, multipotent precursors (MPP), common myeloid progenitors (CMP), common lymphoid progenitors (CLP) and immature B (B lin) and erythroid (Eryt) cells between Dkc1m and WT mice. Nevertheless, the BrdU incorporation was lower in LSK cells and CMPs from Dkc1m mice (P<0.05), indicating a lower proliferation rate. Using in vitro stable isotope labelling of amino acids (SILAC) hematopoietic progenitor cells were cultured in complete medium containing 10% fetal bovine serum and cytokines (6 ng/ml mIL-3, 10 ng/ml mIL-6 and 100 ng/ml mSCF). Of note, SILAC is one of the most applied approaches for quantitative proteomics, which uses labeled amino acids contain atoms of different isotopes in cell culture. Briefly, one cell population is cultured in unlabeled medium (control), while a second population is grown in medium substituted with a heavy amino acid (usually arginine 13C and/or lysine 15N). After 2-3 weeks culture, murine hematopoietic progenitors were collected and equal amounts of cells from Dkc1m and WT mice (labeled or not with heavy amino acid) were mixed for protein extraction and analyses. Using this approach, we identified about 3,500 differentially expressed proteins; including proteins related to mRNA assembling and splicing, chromatin remodeling, apoptosis and cell cycle arrest. Interestingly, one of the most differentially expressed proteins between WT and Dkc1m mice (WT light /Dkc1m heavy ratio: 18-fold) was the Serine/arginine-rich splicing factor 4(Srsf4); a member of the splicing factor family (SRSF1, SRSF3 and SRSF4) frequently associated with alternative splicing of genes related to hematopoietic progenitor cell differentiation. Altogether, our preliminary results reveal defects in the transcription/translation of specific mRNAs in Dkc1m cells. Additionally, it is conceivable that the down-regulation of Srsf4 protein could be associated with the low proliferative rate in DKC1m mice and explain the impairment of hematopoiesis in X-DC patients. Disclosures No relevant conflicts of interest to declare.

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