Endothelin-1In Continuous Ambulatory Peritoneal Dialysis and Hemodialysis Patients: A Preliminary Study

Objective To determine the effects of continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) on endothelin-1 (ET-1) levels in patients with endstage renal disease (ESRD) and to assess the relationship between plasma ET-1 levels and selected patient parameters.Design Prospective, non randomized comparison study.Setting Outpatient CAPD and HD units of a university medical center.Participants Twelve ESRD patients (6 on CAPD and 6 on HD) and 5 healthy normotensive subjects.Interventions CAPD patients had blood and peritoneal dialysate samples collected and measurements made following an overnight exchange. HD patients had blood collected and measurements made at 0 hours (basal) and again at 3 hours during a midweek HD session. Blood samples were also collected from normal subjects and served as ET-1 controls.Measurements ET-1 and patient parameters (creatinine, peritoneal dialysate volume, blood pressure, bodyweight, age, and treatment duration) were determined. Data are reported as the mean ± one standard deviation.Results Plasma and dialysate ET-1 levels in the CAPD group were 19.5±4.2 pglmL and 9.2±4.2 pglmL, respectively. The control group plasma and unused dialysate contained no detectable ET-1 «3.0 pg/mL, the limit of detection). The peritoneal clearance of ET-1 was less than that of creatinine (2. 29±0.69 mL/minute vs 4.22±0.66 mL/minute, p=0.005). The basal (0 hour) plasma ET-1 level in the HD group (16.5±7.8 pg/mL) did not differ from that of the CAPD group, p=0.423. Furthermore, no differences in patient parameters were detected between the CAPD and basal HD groups. Although the mean arterial pressure (MAP) decreased during HD, the plasma ET-1 level at 3 hours (13.5±5.4 pg/mL) remained unchanged from the basal level, p=0.307. An analysis of pooled data from the CAPD and HD groups revealed no significant correlation between plasma ET-1 and MAP, body weight, creatinine, or treatment duration. There was, however, a positive correlation between plasma ET-1 and age (r=0.643, p=0.024).Conclusions Plasma ET-1 levels are elevated in both CAPD and HD patients. Despite the clearance of ET-1 by the peritoneal membrane, plasma ET-1 levels in CAPD patients are elevated to the same extent as levels observed in HD patients. Preliminary results show a positive correlation between plasma ET-1 and age in the absence of renal function. This finding remains to be examined in a larger ESRD population.