Improvement of a chronic rat model for peritoneal dialysis by using heparin-coated catheters.

The use of silicone peritoneal catheters, connected to implanted subcutaneous mini vascular access ports, was an essential step in the development of a widely used rat model for peritoneal dialysis (PD). Despite the model's many advantages, it has one major disadvantage: a high drop-out rate because of omental wrapping of the silicone catheter. To investigate whether heparinization of the peritoneal catheter reduces the high drop-out rate in the model, we infused rats with conventional PD fluid through either a regular silicone catheter (PDF, n = 14) or a heparin-coated catheter (PDF-h, n = 15) daily for 5 weeks. Untreated rats served as a control group (control, n = 7). We used various peritoneal tissues for cellular and morphologic analysis by light and electron microscopy. We found a statistically significant, lower rate of drop-out in rats implanted with heparin-coated catheters (20%) than in rats implanted with regular silicone catheters (57%, p < 0.05). No significant differences were seen between the two treated groups with regard to the PD fluid-induced angiogenic response in omentum and mesentery. Likewise, instillation of PD fluid resulted in a similar cellular response (increased numbers of mast cells and milky spots in the omentum and mesothelial regeneration on the liver) in both groups regardless of heparin coating. Based on our results, we recommend the use of heparin-coated catheters for instillation of dialysis solutions in the chronic PD model in the rat.