Relation between renal and hepatic excretion of drugs: VI. Influence of pretreatment with phenol red on renal excretion and accumulation capacity of kidney or liver slices of immature and adult rats

Abstract

Pretreatment with phenol red causes a significant increase in renal excretion of p-amino-hippurate (PAH) in adult rats. In vitro experiments have shown that phenol red pretreatment significantly enhances the accumulation of PAH in renal tubular cells of adult rats. Thus the stimulation of active renal tubular PAH transport is at least in part responsible for its accelerated excretion via urine. A similar phenol red administration does not enhance the renal excretion of this dye, neither in adult nor in immature rats. In accordance with these in vivo findings the renal accumulation of phenol red is not increased after pretreatment with this dye. Remarkably the repeated administration of phenol red causes a distinct reduction of phenol red accumulation capacity in liver tissue. The rate of accumulation of both PAH and phenol red in renal cortical slices increases significantly during maturation; in liver tissue slices such an intensification does not occur. Under anaerobic conditions an active energy requiring uptake of phenol red does not take place and an accumulation by active transport of the dye can also be excluded. Therefore a passive uptake of phenol red and a binding of the dye in renal tubular cells could explain the distinct accumulation of phenol red in tissue slices from the kidney under nitrogen atmosphere. In 55-day-old rats the anaerobic phenol red accumulation in the liver is diminished after pretreatment with this dye.