BACKGROUND: The normal adult liver is quiescent and only a small percentage of its cells is subjected to cell division at any time, but can quickly initiate cell proliferation in response to a stimulus. This process can be triggered by partial hepatectomy. AIM: To evaluate the effect of portal hypertension caused by partial occlusion of hepatic venous drainage on regeneration of remnant liver of rats after partial hepatectomy. METHODS: It was performed two-thirds hepatectomy in 50 adult male Wistar rats. The animals were divided into five groups: a control group and four study groups were subjected to different degrees of plication of inferior vena cava-hepatic above. After 240 hours of the stimulus for regeneration took place relaparotomy with measurement of portal pressure and inferior vena cava, and liver biopsy. Fragments were analyzed by immunohistochemistry for the markers Ki-67 and von Willebrand factor. The collagen deposition was evaluated by Masson's trichrome staining and liver function using serological markers. RESULTS: Cell proliferation in animals subjected to partial hepatectomy and portal hypertension persisted in varying degrees higher when compared to the control group. The proliferation index for Ki-67 was higher in the groups submitted to the elevation of portal pressure. The expression of von Willebrand factor was markedly elevated after partial hepatectomy in groups with higher degree of portal hypertension. There was little collagen deposition in liver tissue in animals of the four groups with partial plication of the inferior vena cava above-liver, but the deposition was more intense in the group with lower portal pressure. CONCLUSIONS: Rats underwent 70% partial hepatectomy and portal hypertension, after 240 hours, presented: 1. delay in the regenerative process directly proportional to pressure levels in the portal system; 2. after ten days, there was the proliferation of hepatocytes proportionally more intense the higher the elevation of pressure in the porta, but extreme levels of portal pressure inhibit proliferation and liver regeneration; it has also been shown delayed angiogenesis influenced by the values portal pressure; 3. extreme portal hypertension produces an elevation of expression of factor VIII, suggesting sinusoid capillarization; 4. the higher levels of portal pressure, the lower the amount of collagen deposited, it can be inferred that the increased portal pressure leads to delay in restoration of the extracellular matrix; 5. analysis of liver function showed that 70% partial hepatectomy after ten days, did not interfere with the physiology of the liver, which remained within normal limits; but, with portal hypertension, can happens functional impairment of the remnant liver during the regenerative process.
Hepatic regeneration; Portal hypertension; Immunohystochemistry; Rats
