Evaluation of hepatocyte injury following partial ligation of the left portal vein

Background/Aims: Total ligation of the left portal vein is thought to induce both hepatocyte apoptosis and necrosis. The pathological impact of partial ligation of a branch of the portal vein has not yet been evaluated. Methods: We studied the degree of hepatocyte injury following 0, 43, 48, 59, 68, 72, 78 and 100% left portal vein stenosis in 200-g Sprague-Dawley male rats. Serum alanine aminotransferase levels, total body weight, and left and right liver lobe weights were measured at 2 and 7 days. Mitosis and ³H- thymidine labelling indices were measured as markers of proliferation; the apoptotic index and TUNEL stain were used as markers to measure apoptotic cell death. Necrosis was assessed morphologically. All these parameters were evaluated 2 days after ligation. Results: There was a direct relation between the increase in weight of the right lobes and the reduction in weight of the left lobes. The degree of weight change correlated significantly with the degree of stenosis. In the right lobes, mitosis and ³H-thymidine labelling were increased in proportion to the degree of stenosis. In the left lobes, the decrease in volume of hepatocytes correlated with the degree of ligation, especially in the pericentral areas. Necrosis was identified only when ligation was ≥68%, this being associated with an increase in alanine aminotransferase levels. On the other hand, apoptotic cells were identified in increasing numbers, starting from the lowest degree of ligation to 100% ligation. This was found both morphologically and with TUNEL stain. Conclusions: Partial ligation of the left portal vein induces left liver atrophy through hepatocyte volume loss and apoptosis. Necrosis is found only when the degree of ligation is severe.