ULTRASTRUCTURAL LOCALIZATION OF TRANSPORT ATPASE IN THE RAT-LIVER AT NON-BILE CANALICULAR PLASMA-MEMBRANES

  • 1 January 1979
    • journal article
    • research article
    • Vol. 76  (5) , 988-996
Abstract
Na,K-ATPase in rat livers was localized cytochemically at the ultrastructural level. The Ernst technique, a method using p-nitrophenylphosphate (pNPP) substrate, was used to demonstrate ouabain-sensitive, K-dependent phosphatase, an enzyme of the Na,K-ATPase reaction sequence. Reaction product was localized predominantly on the sinusoidal and non-bile canalicular (intercellular) surfaces. This localization contrasts with previous histochemical studies using ATP substrate and with models that have considered the transport enzyme to be localized at the canalicular surface. If Na,K-ATPase is of importance in bile salt independent flow, a significant presence of the enzyme at sites other than the canalicular membrane suggests that a paracellular movement of Na and water into the canaliculus must be considered.