Acceleration of p-aminohippurate excretion in immature rats by dexamethasone treatment

In 5-, 10- and 15-day-old rats repeated administration of dexamethasone caused a dose-dependent increase of p-aminohippurate (PAH) excretion. Remarkably, dexamethasone has no influence on PAH excretion in adult rats. The effect of treatment in young rats cannot be explained by an increase in the glomerular filtration rate. In 10-day-old rats GFR shows a tendency to increase. In renal cortical slices from 5-day-old rats PAH transport is increased following dexamethasone treatment, whereas in 10- and 15-day-old rats an increase of kidney mass seems to be responsible for acceleration of renal excretion of PAH after administration of dexamethasone. In 5-day-old rats only the protein content is statistically significantly increased after dexamethasone treatment.