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Nichols K, Rauch R, Lippens L, Seymour DJ, Martín-Tereso J. Dose response to postruminal urea in lactating dairy cattle. J Dairy Sci 2023; 106:8694-8709. [PMID: 37641248 DOI: 10.3168/jds.2023-23402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 06/16/2023] [Indexed: 08/31/2023]
Abstract
Inclusion of urea in dairy cattle diets is often limited by negative effects of high levels of feed urea on dry matter intake (DMI) and efficiency of rumen N utilization. We hypothesized that supplying urea postruminally would mitigate these limitations and allow greater inclusion of urea in dairy cattle diets. Four rumen-fistulated Holstein-Friesian dairy cows (7 ± 2.1 lactations, 110 ± 30.8 d in milk; mean ± standard deviation) were randomly assigned to a 4 × 4 Latin square design to examine DMI, milk production and composition, digestibility, rumen fermentation, N balance, and plasma constituents in response to 4 levels of urea continuously infused into the abomasum (0, 163, 325, and 488 g/d). Urea doses were targeted to linearly increase the crude protein (CP) content of total DMI (diet plus infusion) by 0%, 2%, 4%, and 6% and equated to 0%, 0.7%, 1.4%, and 2.1% of expected DMI, respectively. Each 28-d infusion period consisted of a 7-d dose step-up period, 14 d of adaptation, and a 7-d measurement period. The diet was fed ad libitum as a total mixed ration [10.9% CP, 42.5% corn silage, 3.5% grass hay, 3.5% wheat straw, and 50.5% concentrate (dry matter basis)] and was formulated to meet 100%, 82%, and 53% of net energy, metabolizable protein, and rumen-degradable protein requirements, respectively. Linear, quadratic, and cubic effects of urea dose were assessed using polynomial regression assuming the fixed effect of treatment and random effects of period and cow. Dry matter intake and energy-corrected milk yield responded quadratically to urea dose, and milk urea content increased linearly with increasing urea dose. Apparent total-tract digestibility of CP increased linearly with increasing urea dose and ruminal NH3-N concentration responded quadratically to urea dose. Mean total VFA concentration was not affected by urea dose. The proportion of N intake excreted in feces decreased linearly and that excreted in urine increased linearly in response to increasing urea dose. The proportion of N intake excreted in milk increased linearly with increasing urea dose. Urinary urea excretion increased linearly with increasing urea dose. Microbial N flow responded cubically to urea dose, but the efficiency of microbial protein synthesis was not affected. Plasma urea concentration increased linearly with increasing urea dose. Regression analysis estimated that when supplemented on top of a low-CP diet, 179 g/d of postruminal urea would maximize DMI at 23.4 kg/d, corresponding to a dietary urea inclusion level of 0.8% of DMI, which is in line with the current recommendations for urea inclusion in dairy cattle diets. Overall, these results indicate that postruminal delivery of urea does not mitigate DMI depression as urea dose increases.
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Affiliation(s)
- K Nichols
- Trouw Nutrition R&D, 3800 AG Amersfoort, the Netherlands.
| | - R Rauch
- Trouw Nutrition R&D, 3800 AG Amersfoort, the Netherlands
| | - L Lippens
- Trouw Nutrition R&D, Puslinch, Ontario, N0B 2J0 Canada
| | - D J Seymour
- Trouw Nutrition R&D, 3800 AG Amersfoort, the Netherlands
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Prahl MC, Müller CBM, Wimmers K, Kuhla B. Mammary gland, kidney and rumen urea and uric acid transporters of dairy cows differing in milk urea concentration. Sci Rep 2023; 13:17231. [PMID: 37821556 PMCID: PMC10567808 DOI: 10.1038/s41598-023-44416-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 10/08/2023] [Indexed: 10/13/2023] Open
Abstract
The milk urea concentration (MUC) serves as indicator of urinary nitrogen emissions, but at comparable crude protein (CP) intake, cows with high (HMU) and low (LMU) MUC excrete equal urea amounts. We hypothesized that urea and uric acid transporters and sizes of the kidney, mammary gland, and rumen account for these phenotypes. Eighteen HMU and 18 LMU Holstein dairy cows fed a low (LP) and normal (NP) CP diet were studied. Milk, plasma and urinary urea concentrations were greater with NP feeding, while plasma and urinary urea concentrations were comparable between phenotypes. Milk and plasma uric acid concentrations were higher with LP feeding but not affected by phenotype. The milk-urine uric acid ratio was greater in HMU cows. The mRNA expressions of the ruminal urea transporter SLC14A1 and AQP10, the mammary gland and rumen AQP3, and the mammary gland uric acid transporter ABCG2 were not affected by group or diet. Renal AQP10, but not AQP3, AQP7, and SLC14A2 expressions, and the kidney weights were lower in HMU cows. These data indicate that renal size and AQP10 limit the urea transfer from blood to urine, and that MUC determines if uric acid is more released with milk or urine.
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Affiliation(s)
- Marie C Prahl
- Research Institute for Farm Animal Biology (FBN), Institute of Nutritional Physiology 'Oskar Kellner', Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Carolin B M Müller
- Research Institute for Farm Animal Biology (FBN), Institute of Nutritional Physiology 'Oskar Kellner', Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Klaus Wimmers
- Research Institute for Farm Animal Biology (FBN), Institute of Genome Biology, Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany
| | - Björn Kuhla
- Research Institute for Farm Animal Biology (FBN), Institute of Nutritional Physiology 'Oskar Kellner', Wilhelm-Stahl-Allee 2, 18196, Dummerstorf, Germany.
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Localization of urea transporter B in the developing bovine rumen. ANIMAL NUTRITION 2022; 10:216-222. [PMID: 35785258 PMCID: PMC9207548 DOI: 10.1016/j.aninu.2022.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 03/02/2022] [Accepted: 03/29/2022] [Indexed: 11/20/2022]
Abstract
Urea nitrogen secreted from blood to rumen is a crucial factor shaping the symbiotic relationship between host ruminants and their microbial populations. Passage of urea across rumen epithelia is facilitated by urea transporter B (UT-B), but the long-term regulation of these proteins remains unclear. As ruminal function develops over a period of months, the developing rumen is an excellent model with which to investigate this regulation. Using rumen epithelium samples of calves from birth to 96 d of age, this study performed immunolocalization studies to localize and semi-quantify UT-B protein development. As expected, preliminary experiments confirmed that ruminal monocarboxylate transporter 1 (MCT1) short chain fatty acid transporter protein abundance increased with age (P < 0.01, n = 4). Further investigation revealed that ruminal UT-B was present in the first few weeks of life and initially detected in the basolateral membrane of stratum basale cells. Over the next 2 months, UT-B staining spread to other epithelial layers and semi-quantification indicated that UT-B abundance significantly increased with age (P < 0.01, n = 4 or 6). These changes were in line with the development of rumen function after the advent of solid feed intake and weaning, exhibiting a similar pattern to both MCT1 transporters and papillae growth. This study therefore confirmed age-dependent changes of in situ ruminal UT-B protein, adding to our understanding of the long-term regulation of ruminal urea transporters.
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Zhong C, Long R, Stewart GS. The role of rumen epithelial urea transport proteins in urea nitrogen salvage: A review. ANIMAL NUTRITION 2022; 9:304-313. [PMID: 35600543 PMCID: PMC9097623 DOI: 10.1016/j.aninu.2022.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/26/2021] [Accepted: 01/24/2022] [Indexed: 11/27/2022]
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Zhong C, Griffin LL, Heussaff O, O’Dea R, Whelan C, Stewart G. Sex-Related Differences in UT-B Urea Transporter Abundance in Fallow Deer Rumen. Vet Sci 2022; 9:vetsci9020073. [PMID: 35202326 PMCID: PMC8878845 DOI: 10.3390/vetsci9020073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/31/2022] [Accepted: 02/04/2022] [Indexed: 12/10/2022] Open
Abstract
Rumen studies have focused almost exclusively on livestock species under strictly regimented diets. This means that the ruminal condition of free-living and free-feeding wildlife remains practically unstudied. Urea nitrogen salvaging, a process by which urea is passed into the rumen, to both provide a valuable source of nitrogen for bacterial growth and to buffer the potentially harmful acidic effects of bacterial short chain fatty acids, has remained unexplored in wild ruminants, such as deer. UT-B2 transporters are the key proteins reported to facilitate the transepithelial ruminal urea transport. In this study, we investigate the expression, abundance and localisation of urea transporters in the rumen of a semi-wild fallow deer (Dama dama) population. Physical measurements confirmed that males had larger rumen than females, while adults had longer papillae than juveniles. Initial RT-PCR experiments confirmed the expression of UT-B2, while immunolocalisation studies revealed that strong UT-B staining was present in the stratum basale of deer rumen. Western blotting analysis demonstrated that a 50 kDa UT-B2 protein was significantly more abundant in adult females compared to adult males. This study confirms the presence of UT-B2 urea transporters in deer rumen and suggests that sex-related differences occur, bringing new insight into our understanding of rumen physiology.
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Affiliation(s)
- Chongliang Zhong
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
- School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Laura L. Griffin
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
| | - Orla Heussaff
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
| | - Ruairi O’Dea
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
| | - Conor Whelan
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
| | - Gavin Stewart
- School of Biology & Environmental Science, University College Dublin, D04 V1W8 Dublin, Ireland; (C.Z.); (L.L.G.); (O.H.); (R.O.); (C.W.)
- Correspondence:
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Zhong C, Farrell A, Stewart GS. Localization of aquaporin-3 proteins in the bovine rumen. J Dairy Sci 2020; 103:2814-2820. [PMID: 31980228 DOI: 10.3168/jds.2019-17735] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 11/29/2019] [Indexed: 11/19/2022]
Abstract
Urea nitrogen salvaging is a crucial mechanism that ruminants have evolved to conserve nitrogen. Facilitative urea transporter-B proteins are known to be involved in urea transport across the rumen epithelium and thus efficiently facilitate the urea nitrogen salvaging process. Recently, functional studies have suggested that aquaglyceroporin transporters might also play a significant role in ruminal urea transport and aquaporin-3 (AQP3) protein has previously been detected in rumen tissue. In this current study, we investigated the specific localization of AQP3 transporters in the bovine rumen. First, end-point reverse-transcription PCR experiments confirmed strong AQP3 expression in both bovine rumen and kidney. Immunoblotting analysis using 2 separate anti-AQP3 antibodies detected AQP3 protein signals at 25, 32, and 42-45 kDa. Further immunolocalization studies showed AQP3 protein located in all the layers of rumen epithelium, especially in the stratum basale, and in the basolateral membranes of kidney collecting duct cells. These data confirm that AQP3 transporters are highly abundant within the bovine rumen and appear to be located throughout the ruminal epithelial layers. The physiological significance of the multiple AQP3 proteins detected and their location is not yet clear, hence further investigation is required to determine their exact contribution to ruminal urea transport.
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Affiliation(s)
- Chongliang Zhong
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Alan Farrell
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland
| | - Gavin S Stewart
- School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland.
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Yu L, Liu T, Fu S, Li L, Meng X, Su X, Xie Z, Ren J, Meng Y, Lv X, Du Y. Physiological functions of urea transporter B. Pflugers Arch 2019; 471:1359-1368. [PMID: 31734718 PMCID: PMC6882768 DOI: 10.1007/s00424-019-02323-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 11/04/2022]
Abstract
Urea transporters (UTs) are membrane proteins in the urea transporter protein A (UT-A) and urea transporter protein B (UT-B) families. UT-B is mainly expressed in endothelial cell membrane of the renal medulla and in other tissues, including the brain, heart, pancreas, colon, bladder, bone marrow, and cochlea. UT-B is responsible for the maintenance of urea concentration, male reproductive function, blood pressure, bone metabolism, and brain astrocyte and cardiac functions. Its deficiency and dysfunction contribute to the pathogenesis of many diseases. Actually, UT-B deficiency increases the sensitivity of bladder epithelial cells to apoptosis triggers in mice and UT-B-null mice develop II-III atrioventricular block and depression. The expression of UT-B in the rumen of cow and sheep may participate in digestive function. However, there is no systemic review to discuss the UT-B functions. Here, we update research approaches to understanding the functions of UT-B.
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Affiliation(s)
- Lanying Yu
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Tiantian Liu
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Shuang Fu
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Li Li
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Xiaoping Meng
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Xin Su
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Zhanfeng Xie
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Jiayan Ren
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China
| | - Yan Meng
- Department of Pathophysiology, College of Basic Medicine, Jilin University, Changchun, 130021, Jilin, People's Republic of China.
| | - Xuejiao Lv
- Department of Respiratory Medicine, the Second Affiliated Hospital of Jilin University, Changchun, 130041, Jilin, People's Republic of China.
| | - Yanwei Du
- Changchun University of Chinese Medicine, Changchun, 130117, People's Republic of China.
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Chaves LD, McSkimming DI, Bryniarski MA, Honan AM, Abyad S, Thomas SA, Wells S, Buck M, Sun Y, Genco RJ, Quigg RJ, Yacoub R. Chronic kidney disease, uremic milieu, and its effects on gut bacterial microbiota dysbiosis. Am J Physiol Renal Physiol 2018; 315:F487-F502. [PMID: 29693447 PMCID: PMC6172581 DOI: 10.1152/ajprenal.00092.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Revised: 04/19/2018] [Accepted: 04/19/2018] [Indexed: 12/12/2022] Open
Abstract
Several lines of evidence suggest that gut bacterial microbiota is altered in patients with chronic kidney disease (CKD), though the mechanism of which this dysbiosis takes place is not well understood. Recent studies delineated changes in gut microbiota in both CKD patients and experimental animal models using microarray chips. We present 16S ribosomal RNA gene sequencing of both stool pellets and small bowel contents of C57BL/6J mice that underwent a remnant kidney model and establish that changes in microbiota take place in the early gastrointestinal tract. Increased intestinal urea concentration has been hypothesized as a leading contributor to dysbiotic changes in CKD. We show that urea transporters (UT)-A and UT-B mRNA are both expressed throughout the whole gastrointestinal tract. The noted increase in intestinal urea concentration appears to be independent of UTs' expression. Urea supplementation in drinking water resulted in alteration in bacterial gut microbiota that is quite different than that seen in CKD. This indicates that increased intestinal urea concentration might not fully explain the CKD- associated dysbiosis.
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Affiliation(s)
- Lee D Chaves
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Daniel I McSkimming
- Genome, Environment, and Microbiome Community of Excellence, University at Buffalo , Buffalo, New York
| | - Mark A Bryniarski
- Department of Pharmaceutical Sciences, University at Buffalo School of Pharmacy and Pharmaceutical Sciences , Buffalo, New York
| | - Amanda M Honan
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Sham Abyad
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Shruthi A Thomas
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Steven Wells
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Michael Buck
- Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Yijun Sun
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Robert J Genco
- Department of Oral Biology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Richard J Quigg
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
| | - Rabi Yacoub
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo , Buffalo, New York
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Walpole C, McGrane A, Al‐mousawi H, Winter D, Baird A, Stewart G. Investigation of facilitative urea transporters in the human gastrointestinal tract. Physiol Rep 2018; 6:e13826. [PMID: 30101448 PMCID: PMC6087735 DOI: 10.14814/phy2.13826] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 07/12/2018] [Accepted: 07/16/2018] [Indexed: 01/10/2023] Open
Abstract
The symbiotic relationship between humans and their intestinal microbiome is supported by urea nitrogen salvaging. Previous studies have shown that colonic UT-B urea transporters play a significant role in this important physiological process. This current study investigated UT-A and UT-B urea transporter expression along the human gastrointestinal tract. Initial end-point PCR experiments determined that UT-A RNA was predominantly expressed in the small intestine, while UT-B RNA was expressed in stomach, small intestine, and colon. Using western blotting experiments, a strong 40-60 kDa UT-B signal was found to be abundant in both ileum and colon. Importantly, this signal was deglycosylated by PNGaseF enzyme treatment to a core protein of 30 kDa in both tissues. Further immunolocalization studies revealed UT-B transporter proteins were present at the apical membrane of the villi in the ileum, but predominantly at the basolateral membrane of the colonic surface epithelial cells. Finally, a blind scoring immunolocalization study suggested that there was no significant difference in UT-B abundance throughout the colon (NS, ANOVA, N = 5-21). In conclusion, this current study suggested UT-B to be the main human intestinal urea transporter. Intriguingly, these data suggested that the same UT-B isoform was present in all intestinal epithelial cells, but that the precise cellular location varied.
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Affiliation(s)
- Caragh Walpole
- School of Biology & Environmental ScienceUniversity College DublinDublinIreland
| | - Alison McGrane
- School of Biology & Environmental ScienceUniversity College DublinDublinIreland
| | | | - Desmond Winter
- Institute for Clinical Outcomes Research and EducationSt. Vincent's University HospitalDublinIreland
| | - Alan Baird
- College of Life SciencesConway Institute of Biomedical and Biomolecular ScienceDublinIreland
| | - Gavin Stewart
- School of Biology & Environmental ScienceUniversity College DublinDublinIreland
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Abstract
PURPOSE OF REVIEW Urea is transported by urea transporter proteins in kidney, erythrocytes, and other tissues. Mice in which different urea transporters have been knocked out have urine-concentrating defects, which has led to the development and testing of urea transporters Slc14A2 (UT-A) and Slc14A1 (UT-B) inhibitors as urearetics. This review summarizes the knowledge gained during the past year on urea transporter regulation and investigations into the clinical potential of urearetics. RECENT FINDINGS UT-A1 undergoes several posttranslational modifications that increase its function by increasing UT-A1 accumulation in the apical plasma membrane. UT-A1 is phosphorylated by protein kinase A, exchange protein activated by cyclic AMP, protein kinase Cα, and AMP-activated protein kinase, all at different serine residues. UT-A1 is also regulated by 14-3-3, which contributes to UT-A1 removal from the membrane. UT-A1 is glycosylated with various glycan moieties in animal models of diabetes mellitus. Transgenic expression of UT-A1 into UT-A1/UT-A3 knockout mice restores urine-concentrating ability. UT-B is present in descending vasa recta and urinary bladder, and is linked to bladder cancer. Inhibitors of UT-A and UT-B have been developed that result in diuresis with fewer abnormalities in serum electrolytes than conventional diuretics. SUMMARY Urea transporters play critical roles in the urine-concentrating mechanism. Urea transport inhibitors are a promising new class of diuretic agent.
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Affiliation(s)
- Janet D Klein
- Renal Division, Department of Medicine, and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
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