A micropuncture study of salt and water retention in chronic experimental cirrhosis.

The object of this study was to localize increased sodium resorption in rats with chronic hepatic cirrhosis. Cirrhosis was induced by the administration of phenobarbital and carbon tetrachloride. The animals retained salt and water after loading and showed edema and ascites. Salt and water balance, clearance, and micropuncture tests were performed. Five or six weeks after the start of procedures to induce injury, the rats were unable to excrete salt and water loads promptly. Urine flow and sodium concentration were significantly less in cirrhotic rats with edema and ascites than in the normal controls. The glomerular filtration rate was slightly lower in the right, nonmicropunctured kidney but was the same in the left. The nephron glomerular filtration rates of surface nephrons were equal in both the experimental and control rats. The fractional proximal resorption rate was notably greater in cirrhotic rats, as was the total proximal nephron resorption rate. That increased proximal resorption alone might account for diminished sodium and water excretion cannot be demonstrated from this study, although we believe that major evidence is provided of the importance of proximal resorption in this phenomenon.