Abstract
We examined the role of chronic aldosterone receptor blockade on the altered furosemide-sensitive sodium reabsorption in rats with liver cirrhosis induced by common bile duct ligation. CBL and sham-operated control animals were treated with the aldosterone receptor antagonist canrenoate (20 mg/day i.v.) for 4 weeks. Untreated CBL and sham-CBL served as control groups. The plasma concentration of aldosterone was within the normal range in all groups. Sodium balance studies showed that aldosterone receptor blockade prevented sodium retention in cirrhotic rats. Clearance studies showed that the glomerular filtration rate was unchanged, whereas the renal plasma flow was increased in CBL rats. A test dose of furosemide (7.5 mg/kg b.wt. i.v.) produced significantly greater diuretic (+59%) and natriuretic (+56%) responses in CBL rats than in sham-operated controls. The urinary furosemide excretion rate (UFURV) reflects delivery of furosemide to the thick ascending limb. When the natriuresis was expressed relative to UFURV (i.e., the natriuretic efficiency), we found that natriuretic efficiency of furosemide was significantly increased in untreated CBL rats (+59%). However, the natriuretic efficiency of furosemide was normalized in CBL rats treated with canrenoate. The urinary excretion of furosemide was unchanged in untreated CBL rats, but it was significantly increased in cirrhotic rats treated with canrenoate (+43%). This suggests that in CBL rats, chronic canrenoate treatment increases the renal elimination of furosemide as a consequence of reduced metabolism. These data suggest that chronic aldosterone receptor blockade with canrenoate prevents sodium retention in cirrhotic rats partly by inhibition of increased sodium reabsorption in the thick ascending limb.
Footnotes
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Send reprint requests to: Thomas E. N. Jonassen, M.D., Department of Pharmacology, The Panum Institute, University of Copenhagen, 3 Blegdamsvej, Building 18.6, DK-2200 Copenhagen N, Denmark. E-mail: fitj{at}farmakol.ku.dk
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↵1 This work received financial support from the Danish Medical Research Council, The Eva and Robert Voss Hansen Foundation, The Ruth Kønig-Petersen Foundation, The Knud Øster-Jørgensen Foundation and The Helen and Ejnar Bjørnow Foundation.
- Abbreviations:
- TAL
- thick ascending limb of Henle’s loop
- CD
- collecting duct
- CBL
- common bile duct ligation
- GFR
- glomerular filtration rate
- ERPF
- effective renal plasma flow
- EFF
- effective filtration fraction
- ERVR
- effective renal vascular resistance
- MAP
- mean arterial pressure
- HR
- heart rate
- C
- renal clearance
- FE
- fractional excretion
- V
- urine flow rate
- UNaV
- urinary sodium excretion rate
- UFURV
- urinary furosemide excretion rate
- ALAT
- alanine aminotransaminase
- Received November 4, 1997.
- Accepted June 25, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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