Preparation of parietal peritoneum for measurements of in vitro permeability

An experimental method for in vitro studies of permeability of parietal peritoneal membrane was developed in rats. Sodium and potassium fluxes across the peritoneum lining two different regions (the diaphragm and the anterior abdominal wall) were estimated and electrical resistance of the isolated membranes were determined. A significant reciprocal correlation was observed between the two indices. Quantitative differences between the two types of membranes were found, the diaphragmatic region being more permeable than the other. It is suggested that a monolayer of mesothelial cells covering the membranes is partially responsible for these differences. The parietal peritoneum was found to be less permeable than visceral peritoneum (mesentery) studied under identical conditions.