 Peritoneal fibrosis is one of the major causes of technical failure in patients on peritoneal dialysis PD for long period of time. Although the exact mechanisms of peritoneal damage during PD still remain unclear, generation of Endoplasmic reticulum ER stress may be responsible for progressive membrane dysfunction. Ursodeoxycholic acid URSA is a powerful inhibitor of ER stress to protect peritoneal fibrosis in peritoneal dialysis in the investigators in-vitro study. In this study the researchers investigated the hypothesis that URSA protect peritoneal membrane damage. 