Beneficial effects of hyperbaric oxygen pretreatment on massive hepatectomy model in rats

Background. The purpose of this study was to investigate the impact of hyperbaric oxygen (HBO) pretreatment in massive hepatectomy model, a surrogate model of small-for-size graft, using rats. Methods. (Experiment I) Rats were divided into the following four groups: HBO (-), HBO-1D (day), HBO-3D, and HBO-5D. Samples were taken after the completion of HBO pretreatment, and the following parameters were evaluated: reverse transcription polymerase chain reaction and immunohistochemical staining for HSP 70 and HO-1; biochemical parameters; and liver weight to body weight ratio (Lw/Bw ratio). (Experiment II) Rats were divided into four groups as follows; 70% hepatectomy (Hx), 70% Hx-HBO, 90% Hx, and 90% Hx-HBO group. Samples were taken 12, 24, 48, and 72 hr after hepatectomy and the following parameters were investigated: biochemical analysis; Lw/Bw ratio; PCNA labeling index; and survival. Results. (Experiment 1) The expression of HSP70 mRNA was significantly increased in the HBO-3D group compared with the HBO (-) group (P < 0.05). HSP70- and HO-1-positive hepatocytes were significantly increased in the HBO-3D group compared with the HBO (-) group (P < 0.05). (Experiment II) Transaminases were significantly decreased in both 70% and 90% Hx-HBO groups compared with Hx alone group (P < 0.05). The Lw/Bw ratio and PCNA labeling index of the 90% Hx-HBO group were significantly increased compared with the 90% Hx group, 24, 48 and 72 hr after hepatectomy (P < 0.05). The survival rate in the 90% Hx-HBO group was significantly higher than that in the 90% Hx group (P=0.01). Conclusions. HBO pretreatment had beneficial effects in a massive hepatectomy model in rats via the induction of HSP70 and HO-1.