Effects of dietary fibre and protein on urea transport across the cecal mucosa of piglets

Stumpff, Friederike; Lodemann, Ulrike; Kessel, Andrew G. Van; Pieper, Robert; Klingspor, S.; Wolf, Katarina; Martens, H.; Zentek, Jürgen; Aschenbach, Jörg R.

doi:10.1007/s00360-013-0771-2

Cited by 17 publications

(13 citation statements)

References 49 publications

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“…In a first step, we demonstrate that, as previously shown for the ovine rumen [1,10] and the porcine cecum [54], application of NH 4 + increased both the transepithelial potential and the short-circuit current across the bovine ruminal epithelium (Figs. 2 and 3, Tables 3 and 4).…”

Section: Discussionmentioning

confidence: 73%

Evidence for the functional involvement of members of the TRP channel family in the uptake of Na+ and NH4 + by the ruminal epithelium

Rosendahl

Braun

Schrapers

et al. 2016

Pflugers Arch - Eur J Physiol

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Large quantities of protein are degraded in the fermentative parts of the gut to ammonia, which is absorbed, detoxified to urea, and excreted, leading to formation of nitrogenous compounds such as N2O that are associated with global warming. In ruminants, channel-mediated uptake of NH4 (+) from the rumen predominates. The molecular identity of these channels remains to be clarified. Ruminal cells and epithelia from cows and sheep were investigated using patch clamp, Ussing chamber, microelectrode techniques, and qPCR. In patch clamp experiments, bovine ruminal epithelial cells expressed a conductance for NH4 (+) that could be blocked in a voltage-dependent manner by divalent cations. In the native epithelium, NH4 (+) depolarized the apical potential, acidified the cytosol and induced a rise in short-circuit current (I sc) that persisted after the removal of Na(+), was blocked by verapamil, enhanced by the removal of divalent cations, and was sensitive to certain transient receptor potential (TRP) channel modulators. Menthol or thymol stimulated the I sc in Na(+) or NH4 (+) containing solutions in a dose-dependent manner and modulated transepithelial Ca(2+) fluxes. On the level of messenger RNA (mRNA), ovine and bovine ruminal epithelium expressed TRPA1, TRPV3, TRPV4, TRPM6, and TRPM7, with any expression of TRPV6 marginal. No bands were detected for TRPV1, TRPV5, or TRPM8. Functional and molecular biological data suggest that the transport of NH4 (+), Na(+), and Ca(2+) across the rumen involves TRP channels, with TRPV3 and TRPA1 emerging as prime candidate genes. TRP channels may also contribute to the transport of NH4 (+) across other epithelia.

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Section: Discussionmentioning

confidence: 73%

Evidence for the functional involvement of members of the TRP channel family in the uptake of Na+ and NH4 + by the ruminal epithelium

Rosendahl

Braun

Schrapers

et al. 2016

Pflugers Arch - Eur J Physiol

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“…The short-chain fatty acids (SCFA) produced in the large intestine by microbial fermentation of dietary fibre are rapidly absorbed from the large intestinal mucosa to provide the host with energy for basal metabolism 22 . Additionally, the caecal mucosa plays an important role in urea recycling in the gut of monogastric animals 23 .…”

Section: Discussionmentioning

confidence: 99%

Differentially expressed genes in the caecal and colonic mucosa of Landrace finishing pigs with high and low food conversion ratios

Tan

Wang

Yang

et al. 2017

Sci Rep

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The feed conversion ratio (FCR) is an essential economic trait for pig production, and is directly related to feed efficiency. Studies identifying the differential expression of functional genes involved in biological and molecular mechanisms in the intestine in relation to growth performance are rare. In this study, RNA-Seq was used to identify transcriptomes in caecal and colonic mucosal tissues in order to determine the differential expression of genes from two full-sibling pairs and two half-sibling pairs of Landrace finishing pigs with opposing FCR phenotypes. In total, 138 (comparison of high and low FCR in caecal mucosa), 64 (comparison of high and low FCR in colonic mucosa), and 165 (contrast between the caecal and colonic mucosa) differentially expressed genes were identified. Some of these genes were functionally related to energy and lipid metabolism, particularly short chain fatty acids metabolism, as well as gastrointestinal peristalsis and ion transport. Functional annotation were performed to identify differentially expressed genes, such as GUCA2A, GUCA2B, HSP70.2, NOS2, PCK1, SLCs, and CYPs, which may positively influence feed efficiency in Landrace pigs. These differentially expressed genes need to be further tested for candidate genes that are related to feed efficiency.

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“…Possibly, both UT-B and AQP3 are involved in ruminal transport of urea. In this context, it should be mentioned that results of a parallel study of pig cecum suggest that in this organ urea transport is not regulated in the manner found in the rumen (58). A differential pattern of expression and/or regulation of urea-transporing proteins thus appears likely.…”

Section: Effects Of Protons and Ammonia On Urea Transport: Acid Sensimentioning

confidence: 95%

Modulation of sheep ruminal urea transport by ammonia and pH

Stumpff

Deiner

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

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Ruminal fermentation products such as short-chain fatty acids (SCFA) and CO2 acutely stimulate urea transport across the ruminal epithelium in vivo, whereas ammonia has inhibitory effects. Uptake and signaling pathways remain obscure. The ruminal expression of SLC14a1 (UT-B) was studied using polymerase chain reaction (PCR). The functional short-term effects of ammonia on cytosolic pH (pHi) and ruminal urea transport across native epithelia were investigated using pH-sensitive microelectrodes and via flux measurements in Ussing chambers. Two variants (UT-B1 and UT-B2) could be fully sequenced from ovine ruminal cDNA. Functionally, transport was passive and modulated by luminal pH in the presence of SCFA and CO2, rising in response to luminal acidification to a peak value at pH 5.8 and dropping with further acidification, resulting in a bell-shaped curve. Presence of ammonia reduced the amplitude, but not the shape of the relationship between urea flux and pH, so that urea flux remained maximal at pH 5.8. Effects of ammonia were concentration dependent, with saturation at 5 mmol/l. Clamping the transepithelial potential altered the inhibitory potential of ammonia on urea flux. Ammonia depolarized the apical membrane and acidified pHi, suggesting that, at physiological pH (< 7), uptake of NH4 (+) into the cytosol may be a key signaling event regulating ruminal urea transport. We conclude that transport of urea across the ruminal epithelium involves proteins subject to rapid modulation by manipulations that alter pHi and the cytosolic concentration of NH4 (+). Implications for epithelial and ruminal homeostasis are discussed.

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Effects of dietary fibre and protein on urea transport across the cecal mucosa of piglets

Cited by 17 publications

References 49 publications

Evidence for the functional involvement of members of the TRP channel family in the uptake of Na+ and NH4 + by the ruminal epithelium

Evidence for the functional involvement of members of the TRP channel family in the uptake of Na+ and NH4 + by the ruminal epithelium

Differentially expressed genes in the caecal and colonic mucosa of Landrace finishing pigs with high and low food conversion ratios

Modulation of sheep ruminal urea transport by ammonia and pH

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