Biochemical validation of a rat model for polycystic kidney disease: Comparison of guanidino compound profile with the human condition

Polycystic kidney disease (PKD) accounts for 7–10% of all dialyzed renal insufficient patients. Accumulation of specific guanidino compounds (GCs) has been related to neurological, cardiovascular, hematological, and immunological complications of renal failure. In this study, we investigate whether the PKD/Mhm rat model can be used as a biochemical model for human PKD. For the validation of the rat model, we performed the first detailed evaluation of the concentrations of GCs in serum and urine of patients with PKD in addition to the GC patterns in the plasma, urine, and tissues of the PKD/Mhm rat model. The GCs were determined after separation on a cation exchange resin and fluorescence detection. The GC levels and changes observed in blood and urine of patients with PKD are comparable with those found in patients with renal insufficiency due to different etiologies. The PKD/Mhm rat model can be used as a biochemical model for human PKD as the obvious increases of urea, guanidinosuccinic acid, creatinine, guanidine, methylguanidine, and NGNG-dimethylarginine (symmetrical dimethylarginine) seen in blood of oldest heterozygous and younger homozygous PKD rats were largely within the same range as those found in the studied human PKD population, especially in patients with a glomerular filtration rate below 60 ml/min/1.73 m2. The decreased levels of plasma guanidinoacetic acid seen at end-stage renal disease in homozygous and oldest heterozygous rats were also observed in serum of patients with a glomerular filtration rate below 20 ml/min/1.73 m2. The PKD/Mhm rat model has, besides similar disease characteristics with human PKD, comparable GC alterations.