Reduced water and sodium intakes associated with high levels of natriuretic factor following common bile duct ligation in the rabbit

Abstract

Renal failure complicating obstructive jaundice (OJ) is probably linked to reduction of the extracellular water compartment. To elucidate the mechanism by which OJ leads to isotonic water depletion we studied a group of rabbits with OJ after common bile duct ligation (n = 17) and another group of sham operated rabbits (n = 14) for 10 days. Water intake and balance for two study periods (1-4 and 7-10 days after operation) were calculated. Renal function, sodium balance and plasma atrial natriuretic factor were determined on the fourth and tenth days after operation. Water intake and balance were lower in the OJ group both in the first study period (230 versus 519 ml/days 1-4, P less than 0.001; and -2.4 versus 219 ml/days 1-4, P less than 0.0001 respectively) and in the second study period (260 versus 865 ml/days 7-10, P less than 0.0001; and 11 versus 379 ml/days 7-10, P less than 0.0001 respectively). Sodium intake was negligible in the OJ group both on day four (0.73 versus 7.15 mM/24 h, P less than 0.0001) and on day 10 (0.78 versus 15.78 mM/24 h, P less than 0.0001). As a result plasma osmolality did not change. Day 10 urine osmolality and osmolar clearance were reduced in the OJ group (653 versus 1103 mOsm/kg, P less than 0.0001 and 0.09 versus 0.25 ml/min, P less than 0.0001 respectively) together with a decreased creatinine clearance (3 versus 11 ml/min, P less than 0.0001). Atrial natriuretic factor was increased in jaundiced rabbits (day 4, 22.7 versus 7.5 fmol/ml, P less than 0.0001; and day 10, 26.5 versus 11.2 fmol/ml, P less than 0.02). These findings suggest that OJ leads to an isotonic volume depletion resulting from abnormalities of the extracellular volume regulating mechanisms. These appear to be secondary to an inappropriate elevation of the atrial natriuretic factor plasma concentration.