Fachbereich Veterinärmedizin



    Molecular identification, immunolocalization, and functional activity of vacuolar-type H+-ATPase in bovine rumen epithelium (2008)

    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Albrecht, E.
    Kolisk, M.
    Viergutz, T.
    Zitnan, R.
    Schweigel, M.
    Journal of Comparative Physiology B, Biochemical, Systemic, and Environmental Physiology; 178(3) — S. 285–295
    ISSN: 0174-1578
    Pubmed: 17989983
    Institut für Veterinär-Physiologie

    Oertzenweg 19 b
    14163 Berlin
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    Abstract / Zusammenfassung

    In this study, we have studied the expression, localization, and functionality of vacuolar-type H(+)-ATPase (vH(+)-ATPase) and Na(+)/K(+)-ATPase in the bovine rumen epithelium. Compared with the intracellular pH (pH(i)) of control rumen epithelial cells (REC; 7.06 +/- 0.07), application of inhibitors selective for vH(+)-ATPase (foliomycin) and Na(+)/K(+)-ATPase (ouabain) reduced pH(i) by 0.10 +/- 0.03 and 0.18 +/- 0.03 pH-units, respectively, thereby verifying the existence of both functional proteins. Results from qRT-PCR and immunoblotting clearly confirm the expression of vH(+)-ATPase B subunit in REC. However, the amount of Na(+)/K(+)-ATPase mRNA and protein is tenfold and 11-fold of those of vH(+)-ATPase subunit B, respectively, reflecting a lower overall abundance of the latter in REC. Na(+)/K(+)-ATPase immunostaining has revealed the protein in the plasma membrane of all REC from the stratum basale to stratum granulosum, with the highest abundance in basal cells. In contrast, the vH(+)-ATPase B subunit has been detected in groups of cells only, mainly localized in the stratum spinosum and stratum granulosum of the epithelium. Furthermore, vH(+)-ATPase has been detected in the cell membrane and in intracellular pools. Thus, functional vacuolar-type H(+) pumps are expressed in REC and probably play a role in the adaptation of epithelial transport processes.