Publikationsdatenbank

Luminal hyperosmolarity decreases Na transport and impairs barrier function of sheep rumen epithelium (2005)

Art

Zeitschriftenartikel / wissenschaftlicher Beitrag

Autoren

Schweigel, Monika

Freyer, Markus

Leclercq, Sabine

Etschmann, Benjamin

Lodemann, Ulrike

Böttcher, Almut

Martens, Holger

Quelle

Journal of Comparative Physiology B, Biochemical, Systemic, and Environmental Physiology

Bandzählung: 175

Heftzählung: 8

Seiten: 575 – 591

ISSN: 0174-1578

Sprache

Englisch

Verweise

Pubmed: 16177895

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

The effects of luminal hyperosmolarity on Na and Cl transport were studied in rumen epithelium of sheep. An increase of luminal osmotic pressure with mannitol (350 and 450 mosm/l) caused a significant increase of tissue conductance, G (T), which is linearly correlated with flux rates of (51)Cr-EDTA and indicates an increase of passive permeability. Studies with microelectrodes revealed, that an increase of the osmotic pressure caused a significant increase of the conductance of the shunt pathway from 1.23 +/- 0.10 (control) to 1.92 +/- 0.14 mS cm(-2) (450 mosm/l) without a change of fractional resistance. Hyperosmolarity significantly increased J (sm) and reduced J (net) Na. The effect of hyperosmolarity on J (ms) Na is explained by two independent and opposed effects: increase of passive permeability and inhibition of the Na(+)/H(+) exchanger. Hypertonic buffer solution induced a decrease of the intracellular pH (pH(i)) of isolated ruminal cells, which is consistent with an inhibition of Na(+)/H(+) exchange, probably isoform NHE-3, because NHE-3-mRNA was detectable in rumen epithelium. These data are in contrast to previous reports and reveal a disturbed Na transport and an impaired barrier function of the rumen epithelium, which predisposes translocation of rumen endotoxins and penetration of bacteria.