PLASMA AND PERITONEAL ENDOTHELIN LEVELS AND BLOOD-PRESSURE IN CAPD PATIENTS WITH OR WITHOUT ERYTHROPOIETIN REPLACEMENT THERAPY

The aim of the study was to determine the ET-1 concentration in perito neal dialysate fluid and to investigate the relationship between perit oneal and plasma ET-1 levels and blood pressure in stable continuous a mbulatory peritoneal dialysis (CAPD) patients with and without human r ecombinant erythropoietin (r-HuEPO) replacement therapy. Twenty-seven stable CAPD patients were investigated. They completed their overnight exchange at the Dialysis Centre. Blood pressure was recorded and a bl ood sample was drawn. Biochemical parameters and ET-1 were measured in plasma and peritoneal dialysate fluid. Mean plasma ET-1 levels were i ncreased by about four-fold in CAPD patients. ET-1 was detectable in p eritoneal dialysate fluid and a significant correlation was observed b etween plasma and peritoneal ET-1 concentrations (r = 0.65, p <0.01). The peritoneal clearance of ET-1 was lower than the creatinine clearan ce (1.69 +/- 0.08 ml/min vs. 3.96 +/- 0.15 ml/min, p <0.01). There was also a significant correlation between the time (months) on dialysis and plasma (r = 0.68, p < 0.01) or peritoneal dialysate ET-1 levels (r = 0.46, p < 0.05). Mean blood pressure was higher in patients treated with r-HuEPO than in untreated patients (97 +/- 4 mmHg vs. 81 +/- 4 m mHg, p <0.01). Plasma and peritoneal dialysate ET-1 concentrations wer e comparable in the two groups with or without r-HuEPO replacement the rapy and plasma ET-1 values correlated significantly with mean blood p ressure only in r-HuEPO-treated patients (r = 0.63, p <0.05 vs. r = 0. 10, N. S. in untreated patients). In conclusion, plasma ET-1 concentra tions are elevated in CAPD patients and the levels appear to increase with time on dialysis. ET-1 is cleared by the peritoneal membrane but at a much lower rate than creatinine. Blood pressure is higher in CAPD patients on r-HuEPO replacement therapy and blood pressure correlates with plasma ET-1 levels in these patients.