Acute Changes of Endothelin 1 in Children on

Amira Peco-Antić, University Children’s Hospital, 10 Tiršova Street, SER-11000 Belgrade (Serbia) Dear Sir, In uremic patients, hemodialysis (HD) may change plasma endothelin 1 (ET-1) levels [1, 2], but, at present, little is known about its causes and consequences. The aims of this study were to estimate the effect of volume depletion and blood depuration on plasma ET-1 concentration during HD and to evaluate the potential importance of ET-1 as the modulating cardiovascular hormone in blood pressure control and myocardial hypertrophy. Plasma levels of ET-1 were measured in 10 children with terminal renal failure (mean age 14.7 ± 5.1 years) studied 1-157 months (mean 40.6 ± 52.6), undergoing chronic HD with acetate or bicarbonate dialysis fluid and cuprophane suitable hollow disposable dialyzers. The clinical characteristics of the patients are summarized in table 1. Six patients were treated with nifedi-pine and captopril due to arterial hypertension. Blood samples were taken during a single dialysis session: before ultrafiltration, after ultrafiltration and after HD without fluid removal. Initially, the patients were only on ultrafiltration without dialysis until they achieved ‘dry weight’ or until symptoms of hypotension appeared. After that they continued dialysis without ultrafiltration for at least 2 h. For ET-1 measurements, blood samples were collected in tubes containing aprotinin (Bayer, Leverkusen, Germany; Trasylol, 500 KlU/ml of blood) and EDTA (7.5 mmoy∏il of blood) and immediately centrifuged at +4°C. The plasma samples were stored at -80 °C until assayed. Plasma ET-1 concentrations were measured by radioimmunoas-say (RIA) using a commercially available kit (Biomedica, Vienna, Austria), after extraction with Amprep C 18 columns that were preequilibrated with methanol and water. Plasma renin activity was measured by an angiotensin I RIA kit (SB REN 2, Cis bio international). M mode echocardiography was used to determine left ventricle dimensions. Left ventricle mass was calculated according to the Penn convention [3]. The left ventricular mass index was obtained by normalization of left ventricle mass to body surface.