Effects of Different Pressures of CO2 on P33 Tumor Inhibitor Gene in Liver and Spleen Tissues During CO2 Pneumoperitoneum in Adult Rats

Introduction: We aimed to study the effects of different CO2 pressures on expression of P33 gene and apoptosis in liver and spleen cells during CO2 pneumoperitoneum. Methods: This study was performed on 30 male Sprague-Dawley rats, weighing between 280 and 340 g (procured from Tehran Pasteur Institute’s animal house). They were randomly divided into 3 equal groups. Groups 1 and 2 received 10 and 20 mm Hg CO2 pressures during pneumoperitoneum, respectively, and group 3 was the control group. CO2 gas was insufflated through a cannula into abdominal cavity of rats in groups 1 and 2 for one hour; then perfusion was performed for half an hour. In group 3, cannula was put into the rats’ abdominal cavities without releasing any gas. Then the rats were killed, and their livers and spleens were removed after laparotomy to study expression of gene P33 and apoptosis using RT-PCR and TUNEL techniques. Results: The TUNEL technique revealed a significant rise in apoptosis in liver cells of rats that received 20 mm Hg pressure of gas compared to rats that received 10 mm Hg pressure of gas and the control group (P<0.001). Similarly, the increase in apoptosis in spleen cells was also significant in rats that received 20 mmHg gas pressure compared to rats in 10 mmHg gas pressure and control groups (P<0.006). Furthermore, RT-PCR revealed a significant decrease in P33 gene mRNA in liver and spleen cells in 20 mmHg group compared to other two groups (P<0.001). Conclusion: Pressure level and duration of CO2 gas administration affect viability of liver and spleen cells. Too high a pressure or too long a duration may release cytokines and free radicals from cells of these organs, which can lead to transient or serious dysfunction.