Pathogenesis of edema in cirrhosis of the liver is still incompletely understood. The present study was designed to examine interstitial fluid dynamics in cirrhotic, non-ascitic rats, measuring interstitial fluid pressure by means of a subcutaneous plastic capsule in basal conditions during extracellular fluid volume expansion with Ringer solution and during albumin infusion. Urine flow and sodium excretion and plasma and interstitial fluid volumes were simultaneously measured. Cirrhotic rats exhibited reduced urine flow and sodium excretion, both in basal conditions and in response to expansion maneuvers. Plasma and interstitial fluid volumes were higher in cirrhotic than in control animals. Remarkable alterations were present in capsular pressures in cirrhotic rats. In the control rats, basal capsular pressure values were negative, and they increased after Ringer infusion and markedly decreased with albumin infusion. In contrast, in cirrhotic rats, basal capsular pressures were in the positive range and they remained nearly constant during ringer infusion and albumin administration. These results suggest that in cirrhotic rats there are significant alterations in systemic interstitial dynamics, even before ascites formation. Altered systemic capillary dynamics may therefore be important early changes that precede and thus contribute to the formation of edema in cirrhosis.
