Taurocholat-Transport in isolierten proximalen Tubuluszellen der Ratte : Einfluss einer extrahepatischen Cholestase

In the kidneys, the non-protein bound fractions of plasma bile acids are filtered in the glomeruli. The bile acids reaching the tubular fluid are nearly completely reabsorbed by the apical sodium-dependent bile salt transporter (asbt). Hence, with normal conditions, urinary excretion of bile acids is negligible low. During extrahepatic cholestasis, when bile acid concentrations in the plasma are enhanced, there is, according to our studies, an adaptive renal mechanism facilitating urinary excretion of bile acids. The aim of the study was to elucidate whether this adaptive mechanism is due to an altered transport capacity of the tubular asbt. The experiments were performed on proximal tubular cells which were freshly isolated from rat kidneys. These cells were enriched by density gradient centrifugation of the renal cortex. By this method more than 90% of pure proximal tubular cells could be obtained. Cellular 3H-taurocholate uptake was investigated with control conditions and after 24 h bile duct ligation. With control conditions, there was a concentration dependent cellular uptake of 3H-taurocholate. A maximum cell water/medium accumulation ratio of more than 4 could be determined. The kinetic data revealed an apparent Km value of 143.25 µM and a Vmax value of 66.44 µM/ l cell water/ 20 min. After 24 h bile duct ligation the Km value for 3H-taurocholate uptake was not significantly altered (139.22 µM) whereas Vmax was significantly (p< 0.05) decreased to 41.52 µM/ l cell water/ 20 min. The data show that there is a downregulation of the transport capacity of the proximal tubular asbt during bile duct ligation which may be related to our finding that renal 3H-taurocholate clearance is markedly enhanced with these conditions.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Winter, Christian Henrik

Contributors dc:contributor

• Greven, Joachim

• info:eu-repo/classification/ddc/610
• Medizin
• glomeruläre Filtrationsrate
• apikaler natriumabhängiger Gallensäure-Transporter (ASBT)
• Taurocholat
• proximale Tubuluszellen
• Cholestase
• glomerular filtration rate
• apical sodium-dependent bile salt transporter
• taurocholate
• proximal tubular cells
• cholestasis

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123786%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62202