Effects of bile duct ligation and captopril on salt appetite and renin-aldosterone axis in rats

A ligation of the common bile duct (BDL) produces cholestasis and hypotensi on and increases the daily ingestion of sodium chloride solutions in rats. Low-dose captopril (CAP) treatment also modifies the ingestion of water and sodium in naive rats, and may do so in cholestatic rats. This study examin ed whether the elevated ingestion of saline by Long-Evans rats after BDL is associated with increased plasma renin activity (PRA), and whether treatme nt with a low dose of the angiotensin converting-enzyme inhibitor CAP furth er exacerbates fluid intake and PRA after BDL. In these experiments water a nd 0.3 M saline intake and PRA and plasma aldosterone (PA) were measured in naive and CAP-treated BDL and sham-ligated rats. We found that BDL elevate d rats' daily saline intake 2 weeks after the ligation procedure but had no effect on PRA. CAP (0.1 mg/mL) placed in the drinking water of some BDL ra ts further increased saline intake. Both PA and hematocrits tended to be re duced in BDL rats, whereas PRA was elevated in both BDL and sham-ligated ra ts receiving CAP in the drinking water or by gavage (0.1 mg/mL in 10 mL/kg) . The data suggest that the ingestion of saline by rats can be modified by BDL and CAP administration, but that exaggerated saline intake in BDL rats is not associated with excessive renin secretion. (C) 1999 Elsevier Science Inc.