Oertzenweg 19 b
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Fermentational processes in the rumen release large amounts of short chain fatty acids (SCFA) that are absorbed locally and enter the portal blood. Absorption is transcellular and increases with decreasing mucosal pH and increasing chain length. Current models suggest both diffusive uptake as HSCFA and as the anion in exchange for HCO3-, with modulation by a pH-microclimate within the stratum corneum. Protons taken up with SCFA are rapidly recycled to the rumen via NHE in exchange for Na+, which leaves basolaterally via the Na+-K+-ATPase. The potential generated across the basolateral membrane drives efflux through a large conductance anion channel with high permeability for chloride, acetate and propionate. The permeability for butyrate is poor and thus, this SCFA is largely metabolized into substrates that leave via basolateral monocarboxylate transport (MCT).