Rat renal functions during the first days post-bile duct ligation.

Renal functions during the early stage of hepatic damage before ascites formation were studied in adult female rats. Tubular and hemodynamic parameters were analyzed for 12 days after common bile duct ligation. The fractional excretion of water, sodium, and potassium increased from control values at every day studied. Glomerular filtration rate and renal plasma flow were found to be diminished on the fourth day. Renal plasma flow remained decreased while glomerular filtration rate was recovered on the sixth day after common bile duct ligation. Filtration fraction in both experimental groups (4 and 6 days) was higher than in control animals. These observations suggested a preferential efferent arteriole vasoconstriction that could be responsible for a blood flow redistribution to the medulla. This fact might cause the sodium diuresis with diminished urine-to-plasma osmolalities ratio. The onset of cortical vasoconstriction was confirmed by dopamine infusion to bile duct-ligated rats 4 days postsurgery. Hemodynamic and tubular parameters recovered to control values during dopamine administration. All the data point out diuresis and natriuresis as the earliest renal abnormalities in bile duct-ligated rats. This phenomenon could be associated not only to the cortical vasoconstriction proposed but also to another systemic modification associated to liver damage.