Inhibition of Chloride Absorption from the Sheep Rumen by Nitrate

Würmli, Regula; Wolffram, Siegfried; Scharrer, E.

doi:10.1111/j.1439-0442.1987.tb00306.x

Cited by 20 publications

(12 citation statements)

References 9 publications

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“…Aronson & Seiffer (1984) have shown that Cl-HCO3 exchange is inhibited by nitrate. Recently Wuirmli, Wolffram & Scharrer (1987) demonstrated that nitrate significantly reduced the mucosal-to-serosal Cl flux in sheep rumen without altering the Na transport. (Knickelbein et al 1985 a, b;Hoffmann, 1986).…”

Section: The Role Of CL and Hco3mentioning

confidence: 99%

Mechanism of electrically silent Na and Cl transport across the rumen epithelium of sheep

Martens

Gäbel²,

Strozyk³

1991

Experimental Physiology

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SUMMARYThis study was designed to study the mechanism of electroneutral Na and Cl transport across the isolated rumen epithelium of sheep. Net sodium transport (5 75 + 0-35 ,uequiv cm-2 h-1) was significantly higher than the short-circuit current (0 95 + 0-08 ,uequiv cm-2 h-'). Both, net sodium and net chloride transport were markedly reduced by replacement of chloride, bicarbonate and sodium, respectively, but were not changed by the absence of mucosal potassium. Net sodium and net chloride absorption was significantly decreased by 10 mmamiloride. Mucosal addition of bumetanide, furosemide, hydrochlorothiazide or low concentrations of amiloride (< 0 1 mM) did not change sodium fluxes. These results provide compelling evidence consistent with the presence of Na-H exchange as the predominant electroneutral mechanism for transepithelial sodium movement. The ion replacement studies and data from literature suggest that the Na-H exchange is working in parallel with a Cl-HCO3 exchange although luminal addition of DIDS (4,4'diisothiocyanatostilbene-2,2'-disulphonate, 1 mM) did not significantly influence Cl transport.

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Section: The Role Of CL and Hco3mentioning

confidence: 99%

Mechanism of electrically silent Na and Cl transport across the rumen epithelium of sheep

Martens

Gäbel²,

Strozyk³

1991

Experimental Physiology

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“…In vivo studies showed negative impacts of acetate or chloride on the disappearance of the respective other anion. Nitrate that had been shown to block ruminal Cl 2 and propionate absorption in the presence of bicarbonate (Wü rmli et al, 1987;Kramer et al, 1996) blocked ruminal acetate absorption in the presence and in the absence of bicarbonate to almost the same final level (Aschenbach et al, 2009). From these observations the investigators conclude the presence of bicarbonate dependent and independent anion exchangers in addition to lipophilic uptake as mechanisms of acetate absorption.…”

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confidence: 99%

Transport of cations and anions across forestomach epithelia: conclusions from in vitro studies

Leonhard-Marek

Stumpff

Martens

2010

Animal

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Secretion of saliva as well as absorptive and secretory processes across forestomach epithelia ensures an optimal environment for microbial digestion in the forestomachs. Daily salivary secretion of sodium (Na 1 ) exceeds the amount found in plasma by a factor of 2 to 3, while the secretion of bicarbonate (HCO 3 2 ) is 6 to 8 times higher than the amount of HCO 3 2 in the total extracellular space. This implies a need for efficient absorptive mechanisms across forestomach epithelia to allow for an early recycling. While Na 1 is absorbed from all forestomachs via Na 1 /H 1 exchange and a non-selective cation channel that shows increased conductance at low concentrations of Mg 21 , Ca 21 or H 1 in the luminal microclima and at low intracellular Mg 21 , HCO 3 2 is secreted by the rumen for the buffering of ingesta but absorbed by the omasum to prevent liberation of CO 2 in the abomasum. Fermentation provides short chain fatty acids and ammonia (NH 3 ) that have to be absorbed both to meet nutrient requirements and maintain ruminal homeostasis of pH and osmolarity. The rumen is an important location for the absorption of essential minerals such as Mg 21 from the diet. Other ions can be absorbed, if delivered in sufficient amounts (Ca 21 , P i , K 1 , Cl 2 and NH 4 1 ). Although the presence of transport mechanisms for these electrolytes has been described earlier, our knowledge about their nature, regulation and crosstalk has increased greatly in the last years. New transport pathways have recently been added to our picture of epithelial transport across rumen and omasum, including an apical non-selective cation conductance, a basolateral anion conductance, an apical H 1 -ATPase, differently expressed anion exchangers and monocarboxylate transporters.Keywords: ruminants, sodium potassium magnesium and calcium, short chain fatty acids, chloride and bicarbonate, channels transporters and exchangers ImplicationsThe improved knowledge of ruminal ion transport clearly underlines its physiological meaning for the whole animal. For example, magnesium absorption is markedly reduced at low Mg and high K intake and the effect of potassium is diminished at high Mg intake. This variable interaction has been quantified recently permitting the prediction of Mg absorption. Great progress has also been made in understanding the interactions between the absorptive pathways for Na, short chain fatty acids and ammonium. The new findings on structure and regulation of various ion transporters will allow a better understanding of the challenges that different diets pose to the maintenance of homeostatic conditions within the rumen and within the cells of the surrounding epithelium, with the implications for the investigation of ruminal adaptation to different diets. Future studies on transport pathways should include the barrier function of rumen epithelium and its possible impairment under harsh feeding conditions.

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“…

{NO}_{3}^{-}

acts in a competitive way, that is, it competes with the original substrate for the transporters' binding site (Seifter & Aronson , Würmli et al . ). Thus, the addition of

{NO}_{3}^{-}

to the serosal side would enhance the flux of SCFA from the mucosal to the serosal side if it were mediated by an anion exchange mechanism.…”

Section: Resultsmentioning

confidence: 97%

“…

{NO}_{3}^{-}

is known to interact with anion exchange mechanisms in several tissues (Seifter & Aronson , Würmli et al . ), including the transport of SCFA across the apical membrane of rumen epithelium via SCFA − /

{HCO}_{3}^{-}

exchange (Kramer et al . , Aschenbach et al .…”

Section: Resultsmentioning

confidence: 99%

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Bicarbonate‐dependent transport of acetate and butyrate across the basolateral membrane of sheep rumen epithelium

et al. 2013

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Inhibition of Chloride Absorption from the Sheep Rumen by Nitrate

Cited by 20 publications

References 9 publications

Mechanism of electrically silent Na and Cl transport across the rumen epithelium of sheep

Mechanism of electrically silent Na and Cl transport across the rumen epithelium of sheep

Transport of cations and anions across forestomach epithelia: conclusions from in vitro studies

Bicarbonate‐dependent transport of acetate and butyrate across the basolateral membrane of sheep rumen epithelium

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