Effects of ethinyl estradiol and phenobarbital on bile acid synthesis and biliary bile acid and cholesterol excretion.

摘要: Bile acid synthesis calculated from respiratory 14CO2 derived the catabolism of[26 or 27-14C ]cholesterol to bile acids in rats with intact enterohepatic circulations decreased 50% after 5 days of ethinyl estradiol treatment (5 mg per kg day). Maximal derepressed synthesis, measured as biliary excretion pool depletion, was also reduced by treatment. Because did not alter cholesterol excretion, contained less relative cholesterol. Hepatic concentration increased inhibitory effect on required it is concluded that probably negative feedback repression 7 α-hydroxylase, rate-limiting enzyme which has a half-life 2 3 hr. During first 14 hr duct cannulation, before estradiol-treated excreted than one-half much and same amount controls. The ratio therefore decreased. Rats treated simultaneously phenobarbital significantly more alone, but increased. proportion thereby restored control value. In contrast, drainage depletion pool, those phenobarbital-ethinyl acid. Thus, when administered estradiol, increases size does increase synthesis. might be due phenobarbital-induced ileal absorption acids.