Effect of peritoneal dialysis on renal morphology and function

Background. Results of clinical studies suggest that peritoneal dialysis (PD) is less harmful to the residual renal function than haemodialysis. However, we have no objective data describing the potential injuring effect of PD to kidney. We studied in rats after unilateral nephrectomy changes in renal structure and function after 12 weeks exposure to standard, glucose-based PD fluid. Methods. One month after removing one kidney PD catheters were implanted in rats and during the following 12 weeks, twice a day, animals were infused with 20 ml of 3.9% glucose dialysis fluid containing high concentration of glucose degradation products. Rats not infused with the dialysis fluid served as control (CON). At the beginning and after 12 weeks of the study renal creatinine clearance, urinary excretion of albumin, N-acetyl-beta-glucosaminidase (NAG) and cytokines were measured. Concentration of malondialdehyde (MDA), advanced glycation end products (AGEs) and monocyte chemoattractant protein-1 (MCP-1) were measured in serum samples. Morphology of the kidneys was evaluated in the light microscope. Results. After 12 weeks exposure to the dialysis fluid serum MDA, AGEs and MCP levels were increased as compared with CON by 80%, P < 0.002, 29%, P < 0.05 and 71%, P < 0.005, respectively. Renal clearance of creatinine was comparable in both groups, but urinary excretion of albumin was increased by 55% in control group and by 160% in the studied group, P < 0.001; whereas urinary excretion of NAG was not changed in control group but increased by 125% in the studied group, P < 0.01. Increase of the remnant kidney's weight was higher (+77%, P < 0.01) in the CON group, but accumulation of the extramesangial matrix in glomeruli and collagen in the peritubular space was stronger in the studied group by 69%, P < 0.0001 and 274%, P < 0.0001, respectively. Conclusion. Chronic exposure of rats to the glucose-based dialysis fluid causes morphological changes in the renal glomeruli similar to diabetic nephropathy. Albuminuria increases what may accelerate progression of the kidney damage.