Vol. 283, Issue 6, F1281-F1289, December 2002
Increase in renal glutathione in cholestatic liver disease is
due to a direct effect of bile acids
Edmund
Purucker1,
Hanns-Ulrich
Marschall2,
Andreas
Geier1,
Carsten
Gartung1, and
Siegfried
Matern1
1 Department of Internal Medicine III, Medical
Faculty, Aachen University of Technology, D-52057 Aachen,
Germany; and 2 Department of Medicine,
Division of Gastroenterology and Hepatology, Karolinska Institute,
Huddinge University Hospital, S-14186 Stockholm, Sweden
Hepatic synthesis and plasma
levels of glutathione are markedly decreased in chronic liver
disease. Because glutathione turnover is highest in kidneys, we
examined whether changes in kidney glutathione occur in chronic
cholestasis and whether they are related to kidney dysfunction in liver
disease. Kidney and plasma GSH and GSSG were measured 1) in
bile duct-ligated (BDL) rats; 2) in healthy rats after bile
acid loading to mimic cholestasis; and 3) after irreversible inhibition of glutathione synthetase with buthionine-sulfoximine (BSO),
where glutathione consumption, urinary volume, and sodium excretion
were also estimated. In addition,
-glutamylcysteine synthetase
(
-GCS) mRNA, protein, and enzymatic specific activity were measured
in kidney tissue after BDL. After BDL, kidney GSH and GSSG increased
within hours by 67 and 66%, respectively. The increases were not
related to plasma glutathione, which decreased below control values.
Intravenous bile acid loading caused identical increases in GSH and
GSSG as occurred after BDL, when glycine- or taurine-conjugated
dihydroxy bile acids were administered. Glutathione consumption, as
estimated after blocking of de novo synthesis with BSO, was
significantly increased after BDL (127 vs. 44 nmol · g
1 · min
1).
-GCS mRNA and enzymatic specific activity were significantly reduced
5 days after BDL, whereas protein concentrations did not change. The
urinary sodium concentration was 70% lower in BDL than in control
rats. Depletion of renal glutathione normalized sodium excretion by
increasing urinary sodium concentration and urinary volume. The
increase in kidney glutathione after BDL seems to be mediated by an
increase in plasma bile acids and is critically related to sodium
retention. The increase in GSH consumption despite reduced
-GCS
activity indicates a decreased GSH turnover tentatively due to reduced
renal GSH efflux by competition with organic anions at membrane
transport proteins.
bile duct ligation; sodium excretion; glutathione depletion;
-glutamylcysteine synthetase