Effect of sodium chloride supplementation on urinary endothelin-1 excretion in premature infants

Area of Science:

• Nephrology
• Neonatology
• Physiology

Background:

• Endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in renal function.
• Sodium balance is critical for fluid homeostasis, particularly in premature infants.
• The role of renal ET-1 in adapting to sodium fluctuations in neonates remains incompletely understood.

Purpose of the Study:

• To investigate the role of endothelin-1 in the renal adaptation to altered sodium balance in premature infants.
• To compare urinary ET-1 excretion in premature infants with low versus high sodium intake.
• To elucidate the interplay between angiotensin II and ET-1 in maintaining sodium balance.

Main Methods:

• Prospective study comparing urinary endothelin-1 excretion in premature infants on low (1.5-2.5 mmol/kg/day) versus high (3-5 mmol/kg/day) sodium intake.
• Measurements of sodium balance and urinary endothelin-1 (normalized to creatinine or body surface area) were performed weekly up to 5 weeks of age.
• Statistical analysis was used to compare urinary ET-1 levels between the two sodium intake groups.

Main Results:

• Urinary endothelin-1 concentration and excretion were significantly lower in infants receiving high sodium intake compared to those on low sodium intake (p < 0.001) from weeks 2 through 5.
• This suggests that renal endothelin-1 production is suppressed by adequate sodium intake.
• The findings indicate a compensatory increase in renal endothelin-1 production in sodium-depleted infants.

Conclusions:

• In sodium-depleted premature infants with high urinary sodium excretion, an angiotensin II-mediated increase in renal endothelin-1 production occurs.
• Renal endothelin-1 acts in concert with angiotensin II to restore sodium balance in these infants.
• These findings highlight the crucial role of the endothelin system in neonatal renal sodium homeostasis.