Renal excretion of endothelin in children is influenced by age and diuresis

Abstract

Endothelin is a peptide with vasoactive and diuretic potential. Its release has been demonstrated from endothelial and renal epithelial cells. Urinary excretion of endothelin, as shown by others, is thought to reflect intrarenal production. We measured endothelin by RIA in a population of healthy children from Germany and Hungary (group 1), neonates (group 3) and children before and during forced diuresis (groups 2a and 2b). Group 1 consisted of 24 children living in Germany and 13 children resident in Hungary. The age range in this group was 2.9-17 years. Daily excretion correlated significantly with age (r = 0.48, p < 0.001), but endothelin excretion corrected for body surface area remained constant with regard to the age group studied. This indicates that body or kidney size may influence endothelin excretion, respectively. There was no difference in endothelin excretion between the two countries. In premature infants and neonates (group 3), daily excretion of endothelin was highest in infants with very low gestational ages and decreased in full-term neonates to values not significantly different to the group of older children. The high values in premature infants may have been influenced by mechanical ventilation of physical stress, which cannot be differentiated in this study, however. In contrast to reported results in adults, renal excretion of endothelin was correlated positively to urine flow in all groups. Furthermore, the influence of forced diuresis was evaluated in 10 children with oncological disease before (group 2a) and during (group 2b) forced diuresis with fluid load (3 l/m2; n = 4) and fluid load with furosemide injection (0.3-1.0 mg/kg body weight; n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Renal excretion of endothelin in children

“…Little information is available on urinary ET excretion in children, either under pathological or normal conditions. In our investigations [55], the range of urinary ET excretion in healthy children between 2.9 and 17 years of age was 59.3 + 3.68 ng/24 h ×1.73 m 2 body surface area (mean+SEM), which is within the normal range measured in adults and by others [45].…”

“…In premature neonates we found elevated urinary excretion [55], with a lower concentration of urinary ET. The very low-birth-weight neonates of less than 28 weeks' gestational age were on mechanical ventilation.…”

“…It correlated significantly with age and the values corrected for body surface area remained constant [55,56]. These data suggest that there is a difference in secretion of ET between the various age groups, which is predominantly due to body size and thus to dif-516 (Table 3).…”

“…We demonstrated that forced diuresis significantly enhanced urinary excretion of ET, while the amount of creatinine excreted remained unchanged [55]. Urinary ET not only correlated with forced but normal diuresis.…”

“…These data suggest that ET might have a growth-promoting effect in developing kidneys and may mediate some of the changes in glomerular and tubular functions observed in the first days of extrauterine life. ET excreted in the urine is mostly synthesized by renal cells [4,55,63]. The elevated urinary excretion may indicate a higher synthesis in developing renal tissue, mainly in tubular epithelial cells.…”