p-Aminohippurate (PAH) transport and Na-K-ATPase activity in rat renal cortical slices during postnatal maturation and drug-induced stimulation.

ABSTRACT

PAH transport and Na-K-ATPase activity markedly increase during the first month of postnatal life. Pretreatment of rats with PAH or cyclopenthiazide induces a stimulation of in vitro PAH accumulation in renal cortical slices, whereas Na-K-ATPase activity is unchanged in comparison to saline-pretreated controls. 5 mM ouabain in the incubation medium reduces PAH accumulation. Developmental pattern and stimulation effects are pronounced as in controls. The ouabain-insensitive component of net PAH accumulation progressively increases with age and is significantly enhanced following drug pretreatment, whereas the ouabain-sensitive component of net PAH accumulation shows relatively slight modifications. Consequently, Na-K-ATPase seems not to be linked with postnatal maturation or drug-induced stimulation in tubular PAH transport.