Relation between renal and hepatic excretion of drugs:: IX. Acceleration of phenol red excretion via kidney and liver in rats of different ages by dexamethasone treatment

Abstract

Experiments were performed on 10-, 20-, and 55-day-old female rats. After treatment with dexamethasone (60 or 80 micrograms/100 g b.wt. for 3 days, once daily) there is a significant increase in renal phenol red excretion only in 10-day-old rats. In contrast, the stimulatory effect of dexamethasone treatment on the hepatic excretion of this dye occurs exclusively in mature, 55-day-old rats. After repeated administration of this hormone in nephrectomized rats there is an increase of hepatic phenol red excretion, and maximal transport capacity increases from 6-8 to 12 mg/100g b.wt. X hour. In renal cortical slices there is no significant influence of dexamethasone on phenol red accumulation in vitro, whereas accumulation of the dye in liver tissue seems to be diminished. In rats of all groups kidney and liver weights increased significantly after dexamethasone treatment. Calculation of total accumulation capacity (= accumulation per 1 g X organ wet weight) also results in unchanged accumulation capacity in the kidney, but transported phenol red amounts in the liver are distinctly diminished. This is in contrast to the in vivo findings. Possible reasons are discussed.