Does enalapril prevent peritoneal fibrosis induced by hypertonic (3.86%) peritoneal dialysis solution?

Objective: Peritoneal fibrosis (PF) is one of the most serious causes of failure in continuous ambulatory peritoneal dialysis (PD). Although the underlying mechanism responsible for the genesis of PF is still unknown, transforming growth factor beta (TGF beta (1)) has been shown to be associated with PF. Angiotensin converting enzyme inhibitors have been shown to prevent the stimulating effect of growth factors. The aim of the present study was to investigate the effect of enalapril on peritoneal function and morphology in a rat model of experimental PF. Methods: Twenty-one albino Wistar rats were divided into three groups: (1) the control group (C) received 10 mt isotonic saline Intraperitoneally (IP), (2) the dextrose (Dx) group 10 mt 3.86% dextrose PD solution IF, and (3) the enalapril-treated group (ENA) 10 cc 3.86% dextrose PD solution IP plus 100 mg/L enalapril in drinking water. After 4 weeks, a 1-hour peritoneal equilibration test was performed with 20 mt 2.27% dextrose PD solution. Dialysate-to-plasma urea ratio (D/P urea), glucose reabsorption (D-1/D-0 glucose), ultrafiltration (UF) volume, and levels of dialysate protein, TGF beta (1), and cancer antigen 125 (CA125) were determined. The parietal peritoneum was evaluated histologically by light microscopy. Results: Administration of enalapril resulted in preserved UF (-0.2 +/- 0.7 mt vs 1.7 +/- 0.3 mt, p<0.05), protein loss (2.3 +/- 0.5 g/L vs 1.6 +/- 0.2 g/L, p < 0.05), and peritoneal thickness (77 +/- 7 mu vs 38 +/- 5 mu, p < 0.001). D/P urea increased significantly in the Dr group (p < 0.05). Both higher levels of TGF beta (1) (undetectable vs 298 +/- 43 pg/mL, p< 0.001) and lower levels of CA125 in dialysate effluent (0.94 +/- 0.5 U/L vs 0.11 +/- 0.1 U/L, p > 0.05) were determined in the Dx group. Conclusion:These findings show that peritoneal morphology and function tests were dramatically deranged in the Dr group. The same properties were partially preserved in the ENA group. The production of TGF beta (1) was significantly reduced but peritoneal thickness was not completely inhibited. In conclusion, by inhibiting the production of TGF beta (1), enalapril can preserve peritoneal histology, peritoneal function, and remodeling of mesothelial cells.