The Effects of Early Postnatal Diuretics Treatment on Kidney Development and Long-Term Kidney Function in Wistar Rats

Diuretics are administered to neonates to control fluid balance. We studied whether clinical doses affected kidney development and function and whether extrauterine growth retardation (EUGR) could be a modulator. Wistar rats were cross-fostered in normal food or food restricted litters at postnatal day (PND) 2 and treated daily with 0.9% NaCl, 5 mg/kg furosemide or 5 mg/kg hydrochlorothiazide (HCTZ) up to PND 8. Kidneys were evaluated on proliferation, apoptosis and a set of mRNA target genes at PND 8, glomerular- and glomerular generation count at PND 35, clinical pathology parameters at 3- and 9 months, neutrophil gelatinase-associated lipocalin at PND 8, 3 and 6 months, monthly blood pressure from 3 months onward and histopathology at study end. Treatment with furosemide or HCTZ did not have relevant effects on measured parameters. EUGR resulted in lower body weight from day 3 onwards (-29% at weaning; p < 0.001, -10% at necropsy; p < 0.001), less glomerular generations (4.4 ± 0.32 vs. 5.0 ± 0.423; p = 0.025, males only), decreased glomerular numbers (27,861 ± 3,468 vs. 30,527 ± 4,096; p = 0.026), higher creatinine clearance (0.84 ± 0.1 vs. 0.77 ± 0.09 ml/min/kg; p = 0.047) at 3 months and lower plasma creatinine (25.7 ± 1.8 vs. 27.5 ± 2.8 µmol/l; p = 0.043) at 9 months. Furosemide and HCTZ did not influence kidney development or function when administered in a clinically relevant dose to rat pups at a stage of ongoing nephrogenesis. EUGR led to impaired kidney development but did not modify furosemide or HCTZ findings