The effect of oral contraceptive steroids on bile secretion and bilirubin Tm in rats

Abstract

1 . The effect of oestrogens and progestogens and their 17α-ethinyl derivatives on bile flow, maximum rate of bilirubin secretion, serum and liver bilirubin has been studied. 2 . Both 17α-ethinyl substituted oestrogens and progestogens greatly reduced the basal bile flow. The parent compounds, oestradiol-17β and 19-nortestosterone had little or no effect. 3 . A much larger dose of progestogens (40 mg/kg) than oestrogens (5 mg/kg) was needed. 4 . Between 12 and 48 h were required for 17α-ethinyloestradiol to produce the effect. 5 . Bilirubin maximum secretion rate (Tm) was little affected, the only significant reduction being produced by the 3-methyl ether of 17α-ethinyloestradiol (mestranol). 6 . Rises in serum conjugated bilirubin following infusion of bilirubin were produced by 17α-ethinyloestradiol and mestranol but not by the progestogens.