Ultrastructure of basement membranes of peritoneal capillaries in a chronic peritoneal infusion model in the rat.

BACKGROUND Long-term peritoneal dialysis with glucose- based dialysis solutions has been associated with diabetiform alterations of peritoneal tissue. A peritoneal infusion model in the rat was developed to study the effect of chronic infusion of a glucose-based dialysis solution and an isotonic non-glucose solution on the ultrastructure of the basement membranes of peritoneal capillaries. The effect of ageing was also studied in an untreated control group. METHODS A vascular access port (Rat-o-Port) with attached peritoneal catheter was implanted subcutaneously in the neck of nine male Wistar rats. The rats were divided randomly into three groups: the glucose group (n = 3) was infused daily for 20 weeks with 60 ml/kg body weight 3.86% glucose solution. A control group (n = 2) was infused daily for 20 weeks with 60 ml/kg body weight Ringer's lactate. The untreated control group (n = 4) was studied at the onset of the experiment and after 20 weeks. Omental tissue was obtained from each rat at the end of the experimental period for ultrastructural examination. RESULTS Extensive lamination of basement membranes of omental capillaries was found in the glucose group. This was in contrast to the untreated control group where clear, single basement membranes were seen at the onset of the experiment and after 20 weeks. These latter findings were similar to those in the Ringer's lactate group. CONCLUSIONS The chronic infusion model in the rat is suitable for the investigation of the effects on the ultrastructure of peritoneal capillaries of chronic exposure to dialysis fluids. The duplications of basement membranes of omental capillaries found in the glucose group show a striking resemblance to those found in long-term peritoneal dialysis patients. This suggests a role for glucose in the development of peritoneal ultrastructural alterations found in long-term peritoneal dialysis.