The impact of transient elevation of intra-abdominal pressure on liver regeneration in the rat.

ABSTRACT

Transient increased intra-abdominal pressure (IIAP) due to carbon dioxide insufflation is suspected to cause a form of ischemia-reperfusion injury. Considering this, a study was designed to assess the effect of transient IIAP on liver regeneration in a rat model. Six groups of animals (each n = 6) were studied. While experiments in Group 1 (IIAP+PHR) were subjected to IIAP, following partial hepatic resection (PHR), those in Group 2 (IIAP) experiments were subjected to IIAP. Animals in Group 3 (IR+PHR) were subjected to liver ischemia-reperfusion (IR) following PHR, and those in Group 4 (IR) underwent only IR. Group 5 (PHR) and Group 6 (healthy) served as controls. Blood was taken for assessment of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 with enzyme-linked immunosorbent assay (ELISA) at day 5 postoperatively. Each rat was then given a lethal injection of pentobarbital. Gravimetric analysis and immunohistochemistry staining for proliferating cell nuclear antigen (PCNA) were used for assessments of liver regeneration. Apoptosis was assessed by immunohistochemical TUNEL index, expressed as the number of positive cells/per total number of cells at the same time. Although mean liver regeneration rates of Group 1 and Group 3 were the same, that of Group 5 was the highest (p = .04). Serum TNF-alpha levels of Group 1 versus Group 3 were 340 pg/ml versus 352 pg/ml. Serum IL-l levels of Group 1 versus Group 3 were 124 pg/ml versus 135 pg/ml. Serum TNl-alpha and IL-6 levels of Group 1 and Group 3 were the same at the first day of surgical procedure (p > .05). Mean serum TNF-alpha levels of Group 5 (387 pg/ml) were significantly higher than those of both Group 1 and Group 3 at 24 h of operation. Serum IL-6 levels of Group 5 (174 pg/ml) at the same time was higher than those of Group 1 and Group 3 at the same time (p = .01). Proliferating cell nuclear antigen indices of Group 1, Group 2, Group 3, Group 4, and Group 6 were the same; however, the mean PCNA-labeling index of Group 5 was higher than those of the others. There were no significant differences between the groups (p > .05). Liver regeneration is suppressed by transient IIAP. However, the effect of IIAP on liver apoptosis needs to be clarified.