Protective effect of intermittent clamping of the portal triad in the rat liver on liver ischemia-reperfusion injury

Background: intermittent clamping (ic) of the portal triad is an effective method of protecting the liver from ischemia-reperfusion injury (ir). in clinical practice, this method is employed during a resection, but its mechanism is still not clear.objectives: to evaluate the effect of ic on rat liver and determine its mechanisms.materials and methods: wistar rats were submitted to 60-min ic (cycles of 12-min clamping followed by 4-min reperfusion), and the samples were collected after 1, 6, and 72 hrs of reperfusion. we determined the serum activity of alanine aminotransferase (alt), and measured the concentration of tnf-?, malondialdehyde (mda) and myeloperoxidase (mpo) in liver homogenates. the apoptosis of hepatocytes was evaluated immunohistochemically.results: when compared to the ir rats, the activity of alt decreased in the ic group in all periods of observation (the highest decrease of ~48% after 1 hr of reperfusion). when compared to the ir group, a statistically significant decrease (p < 0.05) in the tnf-? concentration (~33%) in the ic rats occurred only after 1 hr of reperfusion, and it was accompanied by a decrease in the mpo concentration after 1 and 6 hrs of reperfusion. ic reduces the effects of reactive oxygen species (ros) activity, which has been confirmed by a statistically significant decrease in mda concentration by 25%-35% in all studied periods. the limitation of hepatocytes apoptosis due to ic occurs in the early (~26%; p < 0.05) and late (~45%; p < 0.01) phases of reperfusion.conclusions: the use of ic in early phase of reperfusion brings about a decrease in tnf-? release, which can be related to liver injury due to neutrophil infiltration and apoptotic cell reduction. it seems that the reduction of lipid peroxidation may also limit the liver injury.