RENAL EXCRETION OF ENDOTHELIN IN CHILDREN IS INFLUENCED BY AGE AND DIURESIS

Endothelin is a peptide with vasoactive and diuretic potential. Its re lease has been demonstrated from endothelial and renal epithelial cell s. Urinary excretion of endothelin, as shown by others, is thought to reflect intrarenal production. We measured endothelin by RIA in a popu lation of healthy children from Germany and Hungary (group 1), neonate s (group 3) and children before and during forced diuresis (groups 2a and 2b). Group 1 consisted of 24 children living in Germany and 13 chi ldren resident in Hungary. The age range in this group was 2.9-17 year s. Daily excretion correlated significantly with age (r = 0.48,p < 0.0 01), but endothelin excretion corrected for body surface area remained constant with regard to the age group studied. This indicates that bo dy or kidney size may influence endothelin excretion, respectively. Th ere was no difference in endothelin excretion between the two countrie s. In premature infants and neonates (group 3), daily excretion of end othelin was highest in infants with very low gestational ages and decr eased in full-term neonates to values not significantly different to t he group of older children. The high values in premature infants may h ave been influenced by mechanical ventilation of physical stress, whic h cannot be differentiated in this study, however. In contrast to repo rted results in adults, renal excretion of endothelin was correlated p ositively to urine flow in all groups. Furthermore, the influence of f orced diuresis was evaluated in 10 children with oncological disease b efore (group 2a) and during (group 2b) forced diuresis with fluid load (3 1/m(2); n = 4) and fluid load with furosemide injection (0.3-1.0 m g/kg body weight; n = 6). During this diuretic state, endothelin excre tion was enhanced significantly.