Enhancing effects of vasoconstrictors on bile flow and bile acid excretion in the isolated perfused rat liver

Abstract

The effects of vasoconstrictors on bile flow and bile acid excretion were examined in single-pass isolated perfused rat livers. Administration of norepinephrine (NE), 4 nmol/min, plus continuous infusion of taurocholate (TC) (1.0 μmol/min) rapidly increased bile flow in 1 min, and from min 5 until the end of NE administration (late period) bile flow remained above the basal level (111.7 ± 2.2%), as did bile acid output (114.6 ± 1.8%). Without TC infusion, administration of NE produced no increase in the late period. Administration of NE plus taurochenodeoxycholate (1.0 μmol/min) increased bile flow and bile acid output in the late period to 121.9 ± 7.0 and 137.1 ± 6.8%, respectively. With NE plus taurodehydrocholate, the respective values were only 105.4 ± 1.6 and 104.1 ± 4.0%. When horseradish peroxidase (HRP) (25 mg) was infused over 1 min with continuous NE, the late peak (20–25 min) of HRP elimination into bile significantly exceeded that of untreated controls (P < 0.01). These observations suggest that vasoconstrictors enhance biliary excretion of more hydrophobic bile acids, in part by stimulating vesicular transport.