The Study Of CO₂ As Gas Source In Laparoscopy With Tumor Volume, Apoptosis And Proliferation In HCC Rat Model

Objective: In this study, we evaluated and compared effect of differentgas sources used in the laparoscopy with tumor growth, apoptosis andproliferation of tumor cells in HCC model. Methods: 1) A transplantedhepatic carcinoma rat model was set up. The Walker256 cell linesuspensions were subcutaneously injected into the limb of Wistar malerat (weight 60-80g). The mass (approximately 1 ×1 ×1 mm3) wastransplanted into the rat liver on the day 6 after the mass appeared.2) The operation in the rats was performed. On the day 10 after modelwas established, total 100 HCC rats (weight 200-250 g) were randomizedinto the carbon dioxide, helium, nitrogen, laparotomy, and anesthesiacontrol groups. The insuflation groups underwent CO2, He, and N2pneumoperitoneum(8mmHg), respectively, for 60 min via an angiocatheter.The laparotomy group only underwent a midline incision from xiphoidto pubis and closed 60 min later. The anesthesia control group was justinserted with an angiocatheter. 3) Tumor volume and apoptosis as wellas proliferation of tumor cells were determined. Tumors were excisedfrom half the survival rats in each group on the day 1 and 7postoperation respectively. The tumor volumes were measured, and thensections of the tumor tissues were made for detecting the apoptosiswith TUNEL and proliferation by cyclin-PCNA index withImmunohistochemistry. Result: Either on the day 1 or 7 postoperation ,there was no statistical significant difference between the groups inthe tumor volume (Kruskal-Wallis test: χ2=2.642 P=0.619;χ2=0.209P=0.995). Also no significant difference was found in proliferativeindex (ANOVA: F=0.554 P=0.697;F=1.236 P=0.323) and in apoptotic rateon the day 1 postoperation(ANOVA: F=0.413 P=0.798). However, there wassignificant difference in apoptotic rate on the day 7 postoperation(F=5.698 P=0.002). Conclusion: Our data demonstrated that CO2 as gassource in pneumoperitoneum did not play role in enhancing the tumorgrowth and affecting the biological features of tumor in this HCC ratmodel; He as gas source can induce the apoptosis of tumor in this model.