The effect of low pH on oxidative status of human peritoneal mesothelial cell induced by in vitro exposure to carbon dioxide

• Grant number: 07/02986-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2007
• End date: January 31, 2009
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Ângela Mara Bentes de Souza van Nimwegen
• Grantee: Ângela Mara Bentes de Souza van Nimwegen
• Host Institution: Faculdade de Medicina do ABC (FMABC). Organização Social de Saúde. Fundação do ABC. Santo André , SP, Brazil

Abstract

Laparoscopic surgery represents an attractive approach that offers many advantages when compared to open surgery. However, laparoscopy has peculiar effects as it is usually performed in a different environment, the pneumoperitoneum. Carbon dioxide (CO2) is the most common gas used to create the pneumoperitoneum during laparoscopy, and the standards set for its use as an insufflation agent require 99% purity with relative humidity of 0.0002%.1 This environment produces intricate effects in the abdominal cavity, including: (1) a drop in the abdominal cavity pH with transient impairment of the release of inflammatory mediators by macrophages in peritoneal fluid2; (2) dissecation of tissue surfaces causing loss of integrity, cellular compromise, and exposure of the sub-mesothelial layer4; and peritoneal oxidative stress5. The cause of oxidative stress during laparoscopy may be multifactorial, resulting from elevated intra-abdominal pressure6, and/or from changes induced directly by CO2 contact7. Abdominal pressure induces oxidative stress through disturbance of the splanchnic microcirculation. Oxidative stress induced by CO2 exposure is related to its high partial pressures of CO2 (99%) displacing oxygen to produce a hypoxic condition. However, it is not clear whether its acidification properties augment this process.Direct measurement of ROS generation in vivo has proven problematic. The conventional approach has been to measure products of free radical activity. 8-iso-PGF2α is a member of a complex family of compounds produced in-situ in cell membranes by direct free-radical action on arachidonic acid. It can be quantified as a reliable patho-physiological marker of free radical activity8.The objective of this study is to investigate the effect of low pH induced by in vitro exposure to CO2 on 8-iso-PGF2α levels in human peritoneal mesothelial cells. (AU)