Ethinyl estradiol cholestasis involves alterations in expression of liver sinusoidal transporters

Am J Physiol. 1996 Dec;271(6 Pt 1):G1043-52. doi: 10.1152/ajpgi.1996.271.6.G1043.


The mechanisms involved in ethinyl estradiol-induced cholestasis are controversial. Basal bile flow was reduced by ethinyl estradiol administration, with a half time (t1/2) of 12.5 +/- 0.6 h. In contrast, initial taurocholate uptake was not significantly reduced until 3 days to 59% of control and to 13 and 10% of control at 5 and 7 days, respectively. The t1/2 was 4.3 +/- 0.1 days. These physiological changes were correlated with measurement of protein mass and steady-state mRNA for Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase), Na(+)-dependent taurocholate transporter, organic anion transporters, and membrane lipid fluidity. Ethinyl estradiol significantly decreased Na(+)-K(+)-ATPase activity and membrane fluidity. However, neither Na(+)-K(+)-ATPase alpha-subunit nor beta-subunit mass was altered by ethinyl estradiol administration. In contrast, protein content of the Na(+)-dependent taurocholate transporter was significantly reduced to 21% of control (P < 0.001) at 5 days. The Na(+)-dependent taurocholate transporter was identified in sinusoidal membrane fractions as a doublet with a molecular size estimated to be 51 and 56 kDa. Although both bands were reduced with ethinyl estradiol treatment, the 56-kDa band was decreased more rapidly and to a greater extent than the 51-kDa band. The estimated t1/2 of 4.8 +/- 0.6 days for the doublet was similar to that for Na(+)-dependent taurocholate uptake. The organic anion transporter protein mass was similarly reduced with time of ethinyl estradiol administration to 21% of control (P < 0.01) at 5 days. Ethinyl estradiol also rapidly decreased the steady-state mRNA levels of Na(+)-dependent and organic anion transporters to approximately 50% and 15% of control at 5 days, respectively. These studies indicate early generalized abnormalities of the sinusoidal membrane lipid fluidity, Na(+)-K(+)-ATPase activity, and bile acid transport protein content.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carrier Proteins / metabolism*
  • Cell Membrane / drug effects
  • Cholestasis / chemically induced
  • Cholestasis / metabolism*
  • Ethinyl Estradiol / administration & dosage*
  • Liver / metabolism
  • Liver / physiopathology*
  • Liver / ultrastructure
  • Male
  • Membrane Fluidity / drug effects
  • Organic Anion Transporters, Sodium-Dependent*
  • Rats
  • Rats, Sprague-Dawley
  • Sodium-Potassium-Exchanging ATPase / metabolism*
  • Symporters*


  • Carrier Proteins
  • Organic Anion Transporters, Sodium-Dependent
  • Symporters
  • sodium-bile acid cotransporter
  • Ethinyl Estradiol
  • Sodium-Potassium-Exchanging ATPase