Effect on maturation of kidney function in newborn infants of repeated administration of water and electrolytes.

In newborn infants of various ages, the influence of repeated administration of water and electrolytes on renal excretion of urine, sodium, potassium, free and bound hydrogen ions and on urine osmolarity was studied. In 14- and 21-day-old infants the repeated administration of water and electrolytes was followed by diminution of renal excretion of hydrogen ions and potassium, possibly caused by stimulation of hormonal regulation of ion exchange in the kidney. In animal studies performed with a larger water and electrolyte load, stimulation of renal excretion of sodium was caused by the pretreatment.