Increased transvascular escape rate of albumin during experimental portal and hepatic venous hypertension in the pig. Relation to findings in patients with cirrhosis of the liver

Abstract

Transvascular escape rate of albumin [TER_alb, i.e. the fraction of the intra-vascular mass of albumin (IVM_alb) passing to the extravascular space per unit time] was determined from the disappearance of i. v. injected radioiodinated serum albumin in anaesthetized pigs during control conditions and during regional venous congestion in the infradiaphragmatic area. Balloon catheters were placed in the portal vein (infrahepatic portal congestion) and in the inferior vena cava above (suprahepatic caval congestion) and below (infrahepatic caval congestion) the outlets of the hepatic veins. TER_alb was on the average 13% 1VM_alb.h^−l under basal pressure conditions. TER_alb rose significantly (P<0.01) during suprahepatic caval and infrahepatic portal congestion to an average of 29 and 19 % IVM_alb * h^−l, respectively. TER_alb was positively correlated to the portal pressure (r = 0.75, P<0.001). Only a minor increment in TER_alb was found during infrahepatic caval congestion. The hepatic share of the increased TER_alb during stasis above the hepatic veins was estimated to be threefold that of the extrahepatic splanchnic area. Our results point to filtration of protein, pre-dominantely through the lining of the sinusoids and perisinusoidal space of the liver into the interstitial space around the portal vessels and further into the lymphatics, as the main mechanism of the previously demonstrated marked increase in TER_alb in patients with portal venous hypertension due to cirrhosis of the liver.

Key Words:

• albumin transport kinetics
• cirrhosis
• hepatic venous congestion
• lymph flow
• macromolecular filtration
• portal venous hypertension
• protein extravasation
• transvascular escape rate of albumin