scholarly journals Characterization of urea transport mechanisms in the intestinal tract of growing pigs

2019 ◽  
Vol 317 (6) ◽  
pp. G839-G844 ◽  
Author(s):  
Jack E. C. Krone ◽  
Atta K. Agyekum ◽  
Miriam ter Borgh ◽  
Kimberley Hamonic ◽  
Gregory B. Penner ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Intestinal Tract ◽  
Growing Pigs ◽  
Urea Transport ◽  
Urea Transporter ◽  
Tissue Samples ◽  
Ussing Chambers ◽  
Relative Contribution ◽  
Growing Pig ◽  
Urea Recycling

Pigs are capable of nitrogen salvage via urea recycling, which involves the movement of urea in the gastrointestinal tract. Aquaporins (AQP) and urea transporter B (UT-B) are involved in urea recycling in ruminants; however, their contribution to urea flux in the intestinal tract of the pig is not known. The objective of this study was to characterize the presence and relative contribution of known urea transporters to urea flux in the growing pig. Intestinal tissue samples (duodenum, jejunum, ileum, cecum, and colon) were obtained from nine barrows (50.8 ± 0.9 kg) and analyzed for mRNA abundance of UT-B and AQP-3, -7, and -10. Immediately after tissue collection, samples from the jejunum and cecum were placed in Ussing chambers for analysis of the serosal-to-mucosal urea flux ( Jsm-urea) with no inhibition or when incubated in the presence of phloretin to inhibit UT-B-mediated transport, NiCl2 to inhibit AQP-mediated transport, or both inhibitors. UT-B expression was greatest ( P < 0.05) in the cecum, whereas AQP-3, -7, and -10 expression was greatest ( P < 0.05) in the jejunum. The Jsm-urea was greater in the cecum than the jejunum (67.8 . 42.7 ± 5.01 µmol·cm−2·h−1; P < 0.05), confirming the capacity for urea recycling in the gut in pigs; however, flux rate was not influenced ( P > 0.05) by urea transporter inhibitors. The results of this study suggest that, although known urea transporters are expressed in the gastrointestinal tract of pigs, they may not play a significant functional role in transepithelial urea transport. NEW & NOTEWORTHY We characterized the location and contribution of known urea transporters to urea flux in the pig. Aquaporins are located throughout the intestinal tract, and urea transporter B is expressed only in the cecum. Urea flux occurred in both the jejunum and cecum. Transporter inhibitors had no affect on urea flux, suggesting that their contribution to urea transport in the intestinal tract is limited. Further work is required to determine which factors contribute to urea flux in swine.

scholarly journals 173 Characterization of urea transport mechanisms in the intestinal tract of growing pigs

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 176-176
Author(s):  
Daniel Columbus ◽  
Jack Krone ◽  
Miriam ter borgh ◽  
Kasia Burakowska ◽  
Gillian Gratton ◽  
...  
Keyword(s):  
Gastrointestinal Tract ◽  
Intestinal Tract ◽  
Growing Pigs ◽  
Urea Transport ◽  
Urea Transporter ◽  
Intestinal Tissue ◽  
Tissue Samples ◽  
Ussing Chambers ◽  
Relative Contribution ◽  
Urea Recycling

Abstract Previous studies have indicated that pigs are capable of nitrogen salvage via urea recycling, which involves the movement of urea into the gastrointestinal tract and incorporation of nitrogen into endogenous or microbially produced amino acids. Aquaporins (AQP) and urea transporter B (UT-B) have been shown to contribute to urea transport in ruminants; however, it is unclear whether the same processes contribute to urea movement in the intestinal tract of the pig. The objective of this study was to characterize the presence and relative contribution of known urea transporters to urea flux in the growing pig. A total of 9 barrows of 50.8±0.9 kg BW were euthanized and samples of intestinal tissue were obtained from the duodenum, jejunum, ileum, cecum, and colon. All tissue samples were analyzed for mRNA abundance of UT-B and AQP-3, 7, and 10 via qPCR. Immediately after tissue collection, samples from jejunum and cecum were placed in Ussing chambers for analysis of serosal-to-mucosal urea flux using 14C-urea (49.95 kBq). Serosal-to-mucosal urea flux was measured across intestinal tissue samples with no inhibition or with addition of phloretin (1 mM) to inhibit UT-B-mediated transport, NiCl2 (1 mM) to inhibit AQP-mediated transport, or both inhibitors. UT-B was most highly expressed in the cecum (P &lt; 0.05), while AQP-3, 7, and 10 were most highly expressed in the jejunum (P &lt; 0.05). Serosal-to-mucosal urea flux occurred in both the jejunum and the cecum and was higher in the cecum (42.7 vs. 67.8±5.01 µmol/cm2/h; P &lt; 0.05), confirming the capacity for urea recycling into the gut in pigs; however, neither flux rate was influenced by urea transporter inhibitors (P &gt; 0.05). The results of this study indicate that while known urea transporters are present in the gastrointestinal tract of pigs, they do not play a significant role in urea transport.

The effect of diet on skatole concentrations in the intestine and adipose tissue of growing pigs

1990 ◽  
Vol 1990 ◽  
pp. 22-22
Author(s):  
S.H. Hawe ◽  
N. Walker
Keyword(s):  
Adipose Tissue ◽  
Gastrointestinal Tract ◽  
Intestinal Tract ◽  
Microbial Metabolism ◽  
Growing Pigs ◽  
Gastro Intestinal Tract ◽  
Entire Male

Microbial metabolism of dietary tryptophan in the gastro-intestinal tract results in the production of skatole and indole. These compounds, collectively classed as indoles, may be absorbed and deposited in carcass tissue and have been associated with taints especially in entire male pigs (Hansson et al., 1980). As indoles are readily absorbed over the entire tract in humans (Fordtran et al., 1964), it was suggested by Lundstrom et al. (1988) that diet may influence skatole production and hence levels in the carcass. The objectives of this study were to determine the sites of skatole production in the gastrointestinal tract and the effect of diet on production and carcass levels.

scholarly journals Effects of guar gum on plasma urea, insulin and glucose in the growing pig

1989 ◽  
Vol 61 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Kjell MalmlÖf ◽  
Carlos Simoes Nunes ◽  
Stefan Askbrant
Keyword(s):  
Gastrointestinal Tract ◽  
Test Meal ◽  
Guar Gum ◽  
Basal Diet ◽  
Growing Pigs ◽  
Plasma Urea ◽  
Blood Samples ◽  
Arterial Blood ◽  
Time Period ◽  
Growing Pig

1. Six growing pigs fitted with portal and arterial blood cannulas were given a barley-fishmeal diet, either alone or supplemented with guar gum at 60 g/kg basal diet. Blood samples were taken during 8 h following test meals given at 08.00 hours.2. Ingestion of the guar-gum-supplemented diet appeared to increase systematically portal and arterial levels of plasma urea. At peak values, 4 and 5 h after the test meal, this effect was statistically significant (P <0.05).3. Irrespective of which diet was given, portal and arterial blood samples, withdrawn at the same time, were found to have about the same concentration of urea. This was found throughout the 8 h studied and implies that no net exchange of urea between the circulation and the gastrointestinal tract, as a whole, took place.4. In the time-period 30–60 min following the test meal, guar gum significantly reduced the postprandial hyperglycaemia and hyperinsulinaemia in portal blood.

Urinary concentrating ability in patients with Jk(a-b-) blood type who lack carrier-mediated urea transport.

1992 ◽  
Vol 2 (12) ◽  
pp. 1689-1696
Author(s):  
J M Sands ◽  
J J Gargus ◽  
O Fröhlich ◽  
R B Gunn ◽  
J P Kokko
Keyword(s):  
Animal Studies ◽  
Collecting Duct ◽  
Single Gene ◽  
Blood Type ◽  
Blood Group Antigens ◽  
Urea Transport ◽  
Urea Transporter ◽  
Concentrate Urine ◽  
Urinary Concentrating Ability ◽  
Urea Recycling

Water homeostasis is regulated in large part by the proper operation of the urinary concentrating mechanism. In the renal inner medulla, urea recycling from the inner medullary collecting duct to the inner medullary interstitium is thought to be essential for the production of a concentrated urine; however, it has not been possible to test this hypothesis in humans. Recently, a unique combination of genetic abnormalities has been described: absence of Kidd blood group antigens and absence of carrier-mediated urea transport in erythrocytes. Because animal studies indicate a similarity between urea transport in red blood cells and the nephron, it was postulated that patients without the Kidd antigen might lack facilitated urea transport in their kidneys. Hence, their ability to concentrate urine maximally was measured. Current models of nephron function would predict that in the complete absence of urea transport, the maximal concentrating ability would be around 800 to 900 mosM/kg H2O. Two homozygous patients had a moderate decrease in maximal concentrating ability (UosM,max = 819 mosM/kg H2O); a heterozygote also had some limitation. These studies raise the possibility that the erythrocyte urea transporter and the kidney urea transporter are encoded by a single gene (detected by the mutational loss of the Kidd antigen) and that a lack of facilitated urea transport impairs urea recycling in the kidney and, hence, maximal urinary concentrating ability.

Novel bUT-B2 urea transporter isoform is constitutively activated

2009 ◽  
Vol 297 (2) ◽  
pp. R323-R329 ◽  
Author(s):  
P. Tickle ◽  
A. Thistlethwaite ◽  
C. P. Smith ◽  
G. S. Stewart
Keyword(s):  
Protein Kinase ◽  
Transient Response ◽  
Mdck Cell ◽  
Kinase Activity ◽  
Intracellular Camp ◽  
Protein Kinase Activity ◽  
Urea Transport ◽  
Urea Transporter ◽  
Cell Monolayers ◽  
Human Orthologs

Our previous studies have detailed a novel facilitative UT-B urea transporter isoform, bUT-B2. Despite the existence of mouse and human orthologs, the functional characteristics of UT-B2 remain undefined. In this report, we produced a stable MDCK cell line that expressed bUT-B2 protein and investigated the transepithelial urea flux across cultured cell monolayers. We observed a large basal urea flux that was significantly reduced by known inhibitors of facilitative urea transporters; 1,3 dimethylurea ( P < 0.001, n = 17), thionicotinamide ( P < 0.05, n = 11), and phloretin ( P < 0.05, n = 9). Pre-exposure for 1 h to the antidiuretic hormone vasopressin had no effect on bUT-B2-mediated urea transport (NS, n = 3). Acute vasopressin exposure for up to 30 min also failed to elicit any transient response (NS, n = 9). Further investigation confirmed that bUT-B2 function was not affected by alteration of intracellular cAMP (NS, n = 4), intracellular calcium (NS, n = 3), or protein kinase activity (NS, n = 4). Finally, immunoblot data suggested a possible role for glycosylation in regulating bUT-B2 function. In conclusion, this study showed that bUT-B2-mediated transepithelial urea transport was constitutively activated and unaffected by known regulators of renal UT-A urea transporters.

PSIV-B-25 Digestible energy and metabolizable energy of high-fiber ingredients in growing pig diets

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 394-395
Author(s):  
Jongkeon Kim ◽  
Yun Yeong Jo ◽  
Beob Gyun G Kim
Keyword(s):  
Latin Square ◽  
Basal Diet ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Adaptation Period ◽  
Digestible Energy ◽  
High Fiber ◽  
Cashew Nut ◽  
Growing Pig ◽  
Gluten Feed

Abstract The objective of this study was to determine the digestible energy (DE) and metabolizable energy (ME) concentrations in high-fiber ingredients fed to growing pigs. Twelve barrows with an initial body weight of 57.5 kg (SD = 5.7) were individually housed in metabolism crates. A replicated 6 × 3 incomplete Latin square design with 12 animals, 6 experimental diets and 3 periods was employed. A basal diet was composed of 75.0% corn and 22.7% soybean meal (SBM) as the sole energy sources. Four experimental diets were prepared by replacing 40% of corn and SBM with soybean hulls (SH), corn gluten feed (CGF), wheat bran (WB), or rice bran (RB). An additional diet was prepared by replacing 10% of corn and SBM with cashew nut hulls (CNH). Each period consisted of a 4-d adaptation period and a 4-d collection period, and the marker-to-marker procedure was used for total collection of feces and urine. The DE and ME values in RB (3,969 and 3,936 kcal/kg DM) were greater (P &lt; 0.05) than those in CGF (2,654 and 2,520 kcal/kg DM) and SH (2,492 and 2,541 kcal/kg DM) and the energy values in WB (3,162 and 3,118 kcal/kg DM) were not different from those in RB, CGF, or SH. The DE and ME values in CNH (350 and 572 kcal/kg DM) were less (P &lt; 0.05) than those in all other test ingredients. In conclusion, energy concentrations in RB were greatest among the high-fiber test ingredients, whereas CNH had the lowest values.

The mechanisms of urea transport by early life stages of rainbow trout (Oncorhynchus mykiss)

2000 ◽  
Vol 203 (20) ◽  
pp. 3199-3207 ◽  
Author(s):  
C.M. Pilley ◽  
P.A. Wright
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Urea Transport ◽  
Early Life Stages ◽  
Urea Transporter ◽  
Urea Excretion ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Collecting Ducts ◽  
External Water ◽  
Very High

We tested the hypothesis that urea transport in rainbow trout (Oncorhynchus mykiss) embryos is dependent, in part, on a bidirectional urea-transport protein. Acute exposure to phloretin and urea analogs [acetamide, thiourea, 1,(4-nitrophenyl)-2-thiourea] reversibly inhibited urea excretion from the embryos to the external water. Unidirectional urea influx was inhibited by acetamide and thiourea, with IC(50) values of 0.04 and 0.05 mmol l(−1), respectively. Influx of urea from the external water to the embryo tended to saturate at elevated external urea concentrations (V(max)=10.50 nmol g(−1) h(−1); K(m)=2 mmol l(−1)). At very high urea concentrations (20 mmol l(−1)), however, a second, non-saturable component was apparent. These results indicate that urea excretion in trout embryos is dependent, in part, on a phloretin-sensitive facilitated urea transporter similar to that reported in mammalian inner medullary collecting ducts and elasmobranch kidney.

scholarly journals Histopathological Evaluation of the Exposure by Cyanobacteria Cultive Containing [d-Leu1]Microcystin-LR on Lithobates catesbeianus Tadpoles

Toxins ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 318 ◽  
Author(s):  
Osmindo Rodrigues Pires Júnior ◽  
Natiela de Oliveira ◽  
Renan Bosque ◽  
Maria Nice Ferreira ◽  
Veronica Morais Aurélio da Silva ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Microcystis Aeruginosa ◽  
Intestinal Tract ◽  
Mass Spectrometry Analysis ◽  
Clean Water ◽  
Tissue Samples ◽  
Spectrometry Analysis ◽  
Lithobates Catesbeianus ◽  
Histopathological Evaluation ◽  
Unialgal Culture

This study evaluated the effects of [d-Leu1]Microcystin-LR variant by the exposure of Lithobates catesbeianus tadpole to unialgal culture Microcystis aeruginosa NPLJ-4 strain. The Tadpole was placed in aquariums and exposed to Microcystis aeruginosa culture or disrupted cells. For 16 days, 5 individuals were removed every 2 days, and tissue samples of liver, skeletal muscle, and intestinal tract were collected for histopathology and bioaccumulation analyses. After exposure, those surviving tadpoles were placed in clean water for 15 days to evaluate their recovery. A control without algae and toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed tadpoles, samples were characterized by serious damages that similarly affected the different organs, such as loss of adhesion between cells, nucleus fragmentation, necrosis, and hemorrhage. Samples showed signs of recovery but severe damages were still observed. Neither HPLC-PDA nor mass spectrometry analysis showed any evidence of free Microcystins bioaccumulation.

Ultramicrodetermination of vasopressin-regulated urea transporter protein in microdissected renal tubules

1997 ◽  
Vol 272 (4) ◽  
pp. F531-F537 ◽  
Author(s):  
B. K. Kishore ◽  
J. Terris ◽  
P. Fernandez-Llama ◽  
M. A. Knepper
Keyword(s):  
Collecting Duct ◽  
Enzyme Linked Immunosorbent Assay ◽  
Apical Plasma Membrane ◽  
Renal Tubules ◽  
Urea Transport ◽  
Urea Transporter ◽  
Transporter Protein ◽  
Low Protein ◽  
Collecting Duct Cells ◽  
Medullary Collecting Duct

The vasopressin-regulated urea transporter (VRUT) is a 97-kDa protein (also called “UT-1”) responsible for facilitated urea transport across the apical plasma membrane of inner medullary collecting duct (IMCD) cells. To determine the abundance of VRUT protein in collecting duct cells of the rat, we designed a sensitive fluorescence-based enzyme-linked immunosorbent assay capable of detecting <5 fmol of VRUT protein. In collecting duct segments, measurable VRUT was found in microdissected IMCD segments but not in other portions of the collecting duct. In the mid-IMCD, the measured level averaged 5.3 fmol/mm tubule length, corresponding to approximately 5 million copies of VRUT per cell. Thus VRUT is extremely abundant in the IMCD, accounting, in part, for the extremely high urea permeability of this segment. Feeding a low-protein diet (8% protein) markedly decreased urea clearance but did not alter the quantity of VRUT protein in the IMCD. Thus increased urea transport across the collecting duct with dietary protein restriction is not a consequence of increased expression of VRUT. Based on urea fluxes measured in the IMCD and our measurements of the number of copies of VRUT, we estimate a turnover number of > or = 0.3-1 x 10(5) s. In view of the large magnitude of this value and previously reported biophysical properties of urea transport in collecting ducts, we hypothesize that the VRUT may function as a channel rather than a carrier.

Sign in / Sign up

Export Citation Format

Share Document