Exclusion phenomenon in the liver interstitium.

Measurements were made of hepatic interstitial fluid volume and the proportion of that space occupied by 125I-labeled lactoglobulin, albumin, and gamma-globulin in anesthetized cats. 51Cr-red blood cells and 99mTc-diethylenetriaminepentaacetic acid were used to estimate tissue blood volume and extracellular volume, respectively. Hepatic lymph was assumed to represent the interstitial fluid of the liver. The degree of exclusion of each protein increased with increasing molecular size. At normal hepatic venous pressures, the excluded volume fraction for cat albumin was 0.41. Elevation of hepatic venous pressure by 12.5 mmHg caused a fourfold increase in hepatic lymph flow with an increase in interstitial volume and a reduction in albumin exclusion. When the exclusion of heterologous (human) albumin was studied in the cat liver, much higher values were obtained than with homologous albumin. This effect may be due to polymerization of commercial human albumin on storage.