Experimental study on effects of different gas on peritoneum

Abstract

Objective Electron microscopic studies have shown significant morphologic changes of peritoneum after CO2 pneumoperitoneum in vivo. This experiment was to assess the effect of different gas on the morphology of peritoneum and the underlying mechanism of CO2 pneumoperitoneum on tumor cells. Methods In vivo, fourteen piglets (2-4 kilogram in weight, 7-14 days of age) were equally divided into the CO2 group(n = 7) and N2O group(n = 7). 100% CO2 or 100% N2O pneumoperitoneum was infused for 4 hours. Pneumoperitoneum pressure was 12 mmHg. At the end of the experiment, the samples of peritoneum were collected. In vitro, primary murine peritoneal mesothelial cells were36 collected by peritoneal lavage from ten C57BL/6 mice (4 weeks of age) after 0. 125% trypsin pretreatment. Isolated cells were divided into three groups: control group (5% CO2),100% CO2 group and 8 cm H2O pressure &. 100% CO2 group. After monolayers of mesothelial cells were established, cells were cultured with 5%CO2, 100% CO2 and 100% CO2 with 8 cm H2O pressure for 4 hours. Peritoneum and isolated mesothelial cells were examined by scanning electron microscopy. Results Scanning electron microscopy investigation suggested in vivo, 12 mmHg 100% CO2 pneumoperitoneum for 4 hours destroyed mesothelial cells layer of peritoneum, exposing the basal lamina. In contrast, 100% N2O pneumoperitoneum leaded to an increase of intercellular gaps and the basal lamina was exposed in part areas under same pressure and duration. In vitro, 100% CO2 exposition was associated with a significant destruction of the microvilli formation of isolated mesothelial cells. 100% CO2 with 8 cm H2O pressure had more significant impact on mesothelial cells. Conclusions The peritoneal mesothelial cells lose their typical cell morphology when exposed to 100% CO2. Thus, the increased neuroblastoma metastasis observed after CO2 pneumoperitoneum in mice might be related to an impaired mesothelial barrier function. Key words: Nitrous oxide; Carbon dioxide; Peritoneum