A vH<sup>+</sup>-ATPase is present in cultured sheep ruminal epithelial cells

Etschmann, Benjamin; Heipertz, Katrin Sophie; Schulenburg, Annabelle von der; Schweigel, Monika

doi:10.1152/ajpgi.00099.2006

Cited by 19 publications

(30 citation statements)

References 46 publications

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“…Then, NHE2 and other NHE maintain intracellular pH through H 1 export as the cytosol becomes acidified by SCFA uptake. In support of this hypothesis, Etschmann et al (2006) demonstrated that NHE1 and NHE3 are the predominant isoforms expressed in cultured primary rumen epithelial cells, with expression of NHE2 being considerably lower, as determined by realtime qRT-PCR. The authors demonstrated through the use of specific inhibitors that NHE1 and NHE3 are responsible for 50% and 20% of the export of H 1 from epithelial cells, respectively, in the absence of HCO 3 2 and work in concert with other transporters described below in the maintenance of intracellular pH.…”

Section: Maintenance Of Rumen Phmentioning

confidence: 58%

“…Recent in vitro studies of primary ovine rumen epithelial cells showed that the vH 1 -ATPase contributes to approximately 30% of H 1 extrusion (Etschmann et al, 2006) for maintenance of intracellular pH in the absence of HCO 3 2 . Expression of vH 1 -ATPase mRNA was detected by RT-PCR in both isolated ovine and bovine rumen epithelial cells, as well as whole rumen epithelium collected at slaughter (Etschmann et al, 2006;Albrecht et al, 2008).…”

Section: Maintenance Of Rumen Phmentioning

confidence: 99%

“…Expression of vH 1 -ATPase mRNA was detected by RT-PCR in both isolated ovine and bovine rumen epithelial cells, as well as whole rumen epithelium collected at slaughter (Etschmann et al, 2006;Albrecht et al, 2008). Studies of vH 1 -ATPase protein distribution in bovine rumen epithelium indicated expression in small groups primarily within the cell membranes, but also within the cytosol in the epithelial layers of the stratum spinosum and granulosum, and in a few epithelia of the stratum basale (Albrecht et al, 2008).…”

Section: Maintenance Of Rumen Phmentioning

confidence: 99%

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Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Connor

Baldwin

et al. 2010

Animal

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The gastrointestinal tract (GIT) has multiple functions including digestion, nutrient absorption, secretion of hormones and excretion of wastes. In the ruminant animal, development of this organ system is more complex than that of the monogastric animal due to the necessity to establish a fully functional and differentiated rumen, in which a diverse microbial population of bacteria, fungi and protozoa support fermentation and digestion of dietary fiber. Central to the goal of animal scientists to enhance nutrient uptake and production efficiency of ruminants is the need for a comprehensive understanding of GIT development, as well as conditions that alter the digestion process. The relatively recent availability of genome sequence information has permitted physiological investigations related to the process of digestion for many agriculturally important species at the gene transcript level. For instance, numerous studies have evaluated the expression of ruminant GIT genes to gain insight into mechanisms involved in normal function, physiology and development, such as nutrient uptake and transport across the epithelial cell barrier throughout the alimentary canal, maintenance of rumen pH, and regulation of GIT motility and cell proliferation. Further, multiple studies have examined the effects of dietary modification, including feeding of supplemental fat, starch and protein, or a forage-v. concentrate-based diet on expression of critical gene pathways in the gut. In addition, the expression of genes in the GIT in response to disease, such as infection with gastrointestinal parasites, has been investigated. This review will summarize some of the recent scientific literature related to the gene expression in the GIT of ruminants, primarily cattle, sheep and goats, as it pertains to normal physiology, and dietary, developmental, and disease effects to provide an overview of critical proteins participating in the overall digestive processes, and their physiological functions. Recent findings from our laboratory will be highlighted also related to expression of the glucagon-like peptide two-hormone pathway in the GIT of dairy cattle during in various stages of the development and lactation, alterations in gene pathways associated with the rumen development and differentiation in the weaning calf, and genes of the GIT responding to Ostertagia, a common nematode infection of the cattle. Finally, prospective areas of investigation will be highlighted.

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Section: Maintenance Of Rumen Phmentioning

confidence: 58%

Section: Maintenance Of Rumen Phmentioning

confidence: 99%

Section: Maintenance Of Rumen Phmentioning

confidence: 99%

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Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Connor

Baldwin

et al. 2010

Animal

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“…The presence of the protein involved in sodium-proton exchange (NHE) in ruminal epithelium is well documented (2,22,27,31,74), and SCFA are known to stimulate this pH-regulating transport protein in the rumen (25,76). If urea transport is mediated by changes in cytosolic pH, inhibition of NHE should lead to measurable effects.…”

Section: Effect Of Amiloride On Urea Flux At Ph 74mentioning

confidence: 99%

Modulation of urea transport across sheep rumen epithelium in vitro by SCFA and CO₂

Abdoun

Stumpff

Rabbani

et al. 2010

American Journal of Physiology-Gastrointestinal and Liver Physi

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Urea transport across the gastrointestinal tract involves transporters of the urea transporter-B group, the regulation of which is poorly understood. The classical stimulatory effect of CO2 and the effect of short-chain fatty acids (SCFA) on the ruminal recycling of urea were investigated by using Ussing chamber and microelectrode techniques with isolated ruminal epithelium of sheep. The flux of urea was found to be phloretin sensitive and passive. At a luminal pH of 6.4, but not at 7.4, the addition of SCFA (40 mmol/l) or CO2/HCO 3 Ϫ (10% and 25 mmol/l) led to a fourfold increase in urea flux. The stepwise reduction of luminal pH in the presence of SCFA from 7.4 to 5.4 led to a bell-shaped modification of urea transport, with a maximum at pH 6.2. Lowering the pH in the absence of SCFA or CO2 had no effect. Inhibition of Na ϩ /H ϩ exchange increased urea flux at pH 7.4, with a decrease being seen at pH 6.4. In experiments with double-barreled, pH-sensitive microelectrodes, we confirmed the presence of an apical pH microclimate and demonstrated the acidifying effects of SCFA on the underlying epithelium. We confirm that the permeability of the ruminal epithelium to urea involves a phloretin-sensitive pathway. We present clear evidence for the regulation of urea transport by strategies that alter intracellular pH, with permeability being highest after a moderate decrease. The well-known postprandial stimulation of urea transport to the rumen in vivo may involve acute pH-dependent effects of intraruminal SCFA and CO2 on the function of existing urea transporters. pH i; urea transporter-B; short-chain fatty acids; microclimate; volatile fatty acid UREA, POSSIBLY BECAUSE OF its small size, was long thought to move passively across epithelia, depending only on the rate of delivery via blood. The urea permeability of cellular membranes has now been established to be several orders of magnitude above that of lipid membranes (11,92) and is coupled to the expression of specific urea-transporting proteins with channel-like kinetics (7,46,71,81,82,95). Whereas the role that these proteins play in the elegant renal concentrating mechanism has received much attention, their function and regulation in other parts of the body, such as the gut (39), continues to be poorly understood.In contrast to the paucity of our knowledge concerning extrarenal urea transport in humans, we have long known of the ability of camels, cows, or sheep to shift the excretion of urea from the kidney (62, 72) to the gastrointestinal tract (79). The transport of urea through the rumen epithelium was first demonstrated many years ago in vivo and in vitro (16,29,79,89) and the physiological significance is clear: in the rumen, dietary cellulose is broken down by bacteria that utilize ureanitrogen for the synthesis of microbial proteins. After passage into the duodenum, the amino acids of these proteins are absorbed and reach the liver, where new urea for secretion into the rumen can be formed. Recycling of nitrogen via urea secretion into the rumen thus ...

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“…In addition to the Na ϩ /K ϩ -ATPase, the existence of functional vacuolar-type H ϩ -ATPases (vH ϩ -ATPase) in REC has been shown by our group (1,9). The vH ϩ -ATPase is a multisubunit enzyme complex composed of the V 1 sector (subunits A to H) responsible for the ATPase activity, and the membrane inserted V o sector (with at least subunits a to e), which functions in H ϩ translocation across limiting membranes (51).…”

mentioning

confidence: 91%

Modulation of vH⁺-ATPase is part of the functional adaptation of sheep rumen epithelium to high-energy diet

Kuzinski

Žitňan

Albrecht

et al. 2012

American Journal of Physiology-Regulatory, Integrative and Comp

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Ruminal vacuolar H(+)-ATPase (vH(+)-ATPase) activity is regulated by metabolic signals. Thus, we tested whether its localization, expression, and activity were changed by different feeding. Young male sheep (n = 12) were either fed hay ad libitum (h) or hay ad libitum plus additional concentrate (h/c) for 2 wk. The vH(+)-ATPase B subunit signal was predominantly found in the cell membrane and cytosol of rumen epithelial cells (REC) with basal/parabasal phenotype. The elevated number (threefold) of these cells in rumen mucosa of h/c-fed sheep reflects a high proliferative capacity and, explains the 2.3-fold increase of the total number of vH(+)-ATPase-expressing REC. However, in accordance with a 58% reduction of the vH(+)-ATPase B subunit mRNA expression in h/c-fed sheep, its protein amount per single REC was decreased. Using the fluorescent probe BCECF and selective inhibitors (foliomycin, amiloride), the contribution of vH(+)-ATPase and Na(+)/H(+) exchanger to intracellular pH (pH(i)) regulation was investigated. REC isolated from h/c-fed sheep keep their pH(i) at a significantly higher level (6.91 ± 0.03 vs. 6.74 ± 0.05 in h-fed sheep). Foliomycin or amiloride decreased pH(i) by 0.16 ± 0.02 and 0.57 ± 0.04 pH units when applied to REC from h-fed sheep, but the effects were markedly reduced (-88 and -33%) after concentrate feeding. Nevertheless, we found that REC proliferation rate and [cAMP](i) were reduced after foliomycin-induced vH(+)-ATPase inhibition. Our results provide the first evidence for a role of vH(+)-ATPase in regulation of REC proliferation, most probably by linking metabolically induced pH(i) changes to signaling pathways regulating this process.

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A vH⁺-ATPase is present in cultured sheep ruminal epithelial cells

Abstract: Etschmann, Benjamin, Katrin Sophie Heipertz, Annabelle von der Schulenburg, and Monika Schweigel. A vH ϩ -ATPase is present in cultured sheep ruminal epithelial cells.

Cited by 19 publications

References 46 publications

Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Modulation of urea transport across sheep rumen epithelium in vitro by SCFA and CO₂

Modulation of vH⁺-ATPase is part of the functional adaptation of sheep rumen epithelium to high-energy diet

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A vH+-ATPase is present in cultured sheep ruminal epithelial cells

Abstract: Etschmann, Benjamin, Katrin Sophie Heipertz, Annabelle von der Schulenburg, and Monika Schweigel. A vH ϩ -ATPase is present in cultured sheep ruminal epithelial cells.

Cited by 19 publications

References 46 publications

Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Gene expression in the digestive tissues of ruminants and their relationships with feeding and digestive processes

Modulation of urea transport across sheep rumen epithelium in vitro by SCFA and CO2

Modulation of vH+-ATPase is part of the functional adaptation of sheep rumen epithelium to high-energy diet

Contact Info

Product

Resources

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A vH⁺-ATPase is present in cultured sheep ruminal epithelial cells

Modulation of urea transport across sheep rumen epithelium in vitro by SCFA and CO₂

Modulation of vH⁺-ATPase is part of the functional adaptation of sheep rumen epithelium to high-energy diet