Activation of L-arginine transport in undialysed chronic renal failure and continuous ambulatory peritoneal dialysis patients.

1. Treatment with haemodialysis and continuous ambulatory peritoneal dialysis (CAPD) presents different pathophysiological profiles and it has been suggested that clinical outcome in chronic renal failure may depend on the mode of dialysis. The transport of L-arginine, a precursor of nitric oxide, into blood cells is increased in uraemic patients on haemodialysis. The present study was designed to investigate L-arginine transport into red blood cells (RBC) in uraemic patients not yet on dialysis and on CAPD therapy. 2. Eleven uraemic patients not yet on dialysis and 17 on CAPD were included in the study. L-Arginine transport into RBC and plasma and RBC amino acid profiles were analysed in these sets of patients. 3. L-Arginine transport via system y(+), but not y(+)L, into RBC, was significantly increased in undialysed uraemic patients (459 +/- 40 micromol/L per cell per h) and CAPD patients (539 +/- 61 micromol/L per cell per h) compared with controls (251 +/- 39 micromol/L per cell per h). High-pressure liquid chromatography measurements demonstrated low levels of plasma L-arginine in uraemic patients both on CAPD (54 +/- 3 micromol/L) and not yet on dialysis (80 +/- 6 micromol/L) compared with control subjects (146 +/- 14 micromol/L). 4. Our findings provide the first evidence that uraemic patients not yet on dialysis and on CAPD present with an activation of L-arginine transport via system y(+) into RBC associated with reduced plasma levels of L-arginine.