Sex-related differences in the hepatobiliary transport of phenolsulfonphthalein in the rat.

Sex-related differences in the hepatobiliary transport of phenolsulfonphthalein (PSP) were investigated in male and female Wistar rats. Maximal biliary excretion of unconjugated PSP was significantly higher in females while the excretion of the conjugated dye and liver UDP-glucuronosyltransferase activity toward PSP were higher in male animals. Orchidectomy decreased enzyme activity and excretion of the conjugate, whereas ovariectomy produced the opposite effect. Both in gonadectomized males and females maximal biliary excretion of the unconjugated dye was significantly reduced. Testosterone treatment increased the excretion of both conjugated and unconjugated PSP and transferase activity in orchidectomized males. Combined treatment of gonadectomized females with estradiol plus progesterone led to excretions of both conjugated and unconjugated PSP and UDP-glucoronosyltransferase activities similar to those found in control rats. These data indicate the existence of sex-related differences in the conjugation and biliary excretion of PSP in the rat and its modulation by sex hormones.