Functional renal maturation in rat neonates after prenatal exposure to furosemide.

We investigated the pattern of functional renal maturation and electrolyte handling on postnatal day 1, (PD1), day 5 (PD5), and day 12 (PD12) in rat neonates, after mothers were given furosemide during pregnancy. The drug was administered (75 mg/kg per day i.p.) on day 7-11 (organogenesis) and 14-18 (nephrogenesis) of gestation. On PD1 and PD5, there was a disturbance of the urinary concentrating ability with a hyperdiuresis and an over-stimulated ionic exchange, mainly the distal sodium reabsorption. From PD1 to PD12, a progressive functional recovery in electrolyte handling appeared. However, on PD12, when nephrogenesis was achieved, the renal concentrating defect remained. We discuss the possibility of a drug-induced delay in the development of the loop of Henle, leading to functional and morphological adaptations of already developed parts of the nephron.