흰쥐 간의 Carboxylesterase 활성에 미치는 고부하 Taurocholate의 영향

Abstract

Background/Aims: We have investigated the effect of bile acid load on the carboxylesterase activity in cholestatic rat liver and serum in order to elucidate the possible mechanism of decrease of carboxylesterase activity under cholestasis. Methods: Rats were divided into eight groups- Normal sham operated control bile duct obstruction (BDO) alone (BDO group)BDO plus taurocholic acid (TCA) injection (BDO plus TCA group) BDO plus tauroursodeoxycholic acid (TUDCA) injection (BDO plus TUDCA group)choledocho-caval shunt (CCS) operation alone (CCS group)CCS plus TCA injection (CCS plus TCA group)and CCS plus TUDCA injection (CCS plus TUDCA group). Carboxylesterase activity was determined in the serum and liver cytosolic mitochondrial and microsomal preparations from above experimental rats. The values of Km and Vmax in this hepatic enzyme were measured. Results: The activity of liver microsomal carboxylesterase showed a significant decrease in both CCS and BDO group. And the activity of serum carboxylesterase showed a marked decrease in both CCS and BDO group. However carboxylesterase activity in the serum and liver microsomal preparation fell more rapidly in the BDO group than CCS. Carboxylesterase activity in liver cytosolic mitochondrial and microsomal preparations and its Vmax value decreased significantly in both CCS plus TCA group and its Vmax value decreased significantly in both CCS plus TCA group and BDO plus TCA group than each control group. On the other hand the values of Km of the hepatic subcellular carboxylesterase did not change in all the experimental group. Serumcarboxylesterase activity decreased significantly in both CCS plus TCA group and BDO plus TCA group than each control group. However these serum and hepatic enzyme activity did not change in both CCS plus TUDCA group and BDO plus TUDCA group. Summary: The above results suggest that TCA repress biosynthesis of the carboxylesterase in the liver. And the lowering of the serum enzyme activity thought to be caused by decrease of biosynthesis of this hepatic enzyme which cause the enzyme to leak into the blood in small quantities.