ObjectiveTo investigate the effect of sulodexide on the peritoneal morphology and function of long-term peritoneal dialysis rats. MethodsAdult male Sprague-Dawley rats were randomly divided into the following four groups: control group(n=6),model group(n=10), low-dose sulodexide group (n=10) and high-dose sulodexide group(n=10).A 1 hour peritoneal equilibration test was performed after an eight-week peritoneal dialysis in each group. The dialysate samples were subjected to examination by hemocytometer for determination of 1 h dialysate urea(Durea), dialysate protein(Dtp), initial dialysate glucose(D0) and 1 h dialysate glucose(D1),plasma urea nitrogen(Purea)and total plasma protein(Ptp); and the D/Purea(parameter for clearance rate of urea nitrogen), D/Ptp(parameter for total protein loss in dialysate), and D1/D0(parameter for peritoneal ultrafiltration)were calculated. The parietal peritoneum tissues of rats were harvested and stained by Hematoxylin-eosin and Masson trichrome for observation of the peritoneal structure.The vessels and leukocytes in peritoneum tissue were counted (n/mm2) using stained sections.Leukocytes in dialysate samples were evaluated using hemocytometer. The levels of inflammatory cytokine (MCP-1, TNFα) in dialysate samples were measured by enzyme-linked immunosorbent assay(ELISA) and the expression of TGF-β1 in parietal peritoneum was detected by immunohistochemistry assay. ResultsCompared with the control group, rats in the model group had decreased peritoneal mesothelial cells, thickened sub-mesothelial matrix, increased inflammatory cells, and angiogenesis (P＜0.05). The ultrafilitration volume (UF) and glucose reabsorption (D1/D0) were significantly lower and the dialysate-to-plasma urea ratio (D/Purea) and dialysate-to-plasma total protein ratio(D/Ptp) were significantly higher in model group than those in the control group (P＜0.05). Counts of leukocytes and levels of MCP-1 and TNFα in dialysate samples were significantly increased (P＜0.05) and TGF-β1 expression in parietal peritoneum was also significantly increased in the model group.Administration of sulodexide greatly improved the structure changes of the peritoneum, decreased the inflammatory cell infiltration and angiogenesis, greatly improved peritoneal function, significantly decreased the levels of MCP-1 and TNF-α in dialysate samples (P＜0.05), and decreased the expression of TGF-β1 in parietal peritoneum. ConclusionSulodexide may improve the peritoneal morphology and function by inhibiting pertioneal chronic inflammation.