Experimental portal hypertension in the rat

Area of Science:

• Physiology
• Surgical Research
• Animal Models

Background:

• Previous attempts to induce sustained portal hypertension in animal models via portal venous obstruction were unsuccessful.
• Understanding the pathophysiology of portal hypertension requires reliable experimental models.

Purpose of the Study:

• To develop and characterize a novel rat model of sustained extrahepatic portal hypertension.
• To investigate the effects of gradual portal venous occlusion combined with hepatic lymphatic ligation.

Main Methods:

• Adult male Lewis rats were divided into sham-operated, hepatic lymphatic ligation only, and portal vein ameroid constrictor plus hepatic lymphatic ligation groups.
• Portal venous pressure and portovenograms were monitored over time.
• Development and characteristics of collateral circulation were assessed quantitatively.

Main Results:

• The combined portal vein occlusion and lymphatic ligation model induced a sustained doubling of portal venous pressure for up to 2 months, remaining elevated for 1 year.
• Three distinct collateral circulation systems rapidly developed: direct hepatopetal flow restoration, early splenorenal shunts, and late-developing retroperitoneal/esophageal veins.
• Submucosal esophageal veins showed significant lumen enlargement in both intervention groups compared to controls.

Conclusions:

• This novel rat model effectively replicates sustained extrahepatic portal hypertension and the development of portosystemic collaterals.
• The model's similarities to human pediatric extrahepatic portal hypertension suggest its utility for future research.
• The study highlights the dynamic nature of collateral formation in response to portal venous obstruction.