Influence of new estrogens on liver transport function in rats.

Ethinylestradiol (EE), administered to male Wistar rats for 5 or 14 days, decreased bile flow and biliary excretion of ICG in bile fistula rats in dependence on dose. The bile acid excretion rate was not constantly influenced. EE pretreatment of rats also diminished the in vitro accumulation of eosine in liver slices. The new estrogens STS 651 and STS 661 decreased bile flow, ICG excretion and in vitro eosine accumulation to nearly the same extent as did EE pretreatment; bile acid excretion was not influenced significantly. Evidently the 14 alpha-15 alpha-methylen structure in STS 651 and STS 661 as well as the additional methoxygroup in C3 position did not protect against cholestatic effects of estrogens. The new 17 beta-trimethyl-silyloxy-estrogen J 303 did not show cholestatic effects in rats. This structure is able to prevent the formation of toxic estrogen metabolites in rats.