• Biomedical Science Letters
• /
• v.10 no.4
• /
• pp.429-434
• /
• 2004

The effects of intravenous administration of high concentration of taurocholic acid (TCA) on cathepsin B and D, and acid phosphatase activities in rat liver lysosome were studied. These liver lysosomal enzymes were determined from the experimental rats with choledocho-caval shunt (CCS). The activities of liver lysosomal cathepsin B and D, and acid phosphatase were found to be significantly increased in the CCS plus TCA injection group than in control group, such as group of CCS alone group. However, these hepatic enzyme activities did not change in the CCS plus tauroursodeoxycholic acid injection group. The above results suggest that TCA stimulates the biosynthesis of the lysosomal cathepsin B and D, and acid phosphatase in the liver.

• Biomedical Science Letters
• /
• v.12 no.2
• /
• pp.91-97
• /
• 2006

The effects of intravenous administration of high concentration of taurocholic acid (TCA) on monoamine oxidase (MAO) A and B activities in rat liver mitochondria and microsomes were studied. These liver subcellular organelles and serum MAO activities were determined from the experimental rats with choledocho-caval shunt (CCS). The Michaelis-Menten constants in these hepatic enzymes were also measured. The activities of mitochondrial MAO A and B, and microsomal MAO B as well as their $V_{max}$ values were found to be decreased significantly in CCS plus TCA injected group then in the control group, such as CCS alone groups. However their $K_m$ values in the experimental groups did not vary. MAO of serum appeared in the CCS plus TCA injected groups only. The above results suggest that TCA represses biosynthesis of the MAO in the liver. The MAO of serum is believed to be caused by the increment of membrane permeability of hepatocytes upon TCA mediated liver cell necrosis.

• Biomedical Science Letters
• /
• v.13 no.2
• /
• pp.135-140
• /
• 2007

The possible mechanism of decreased catechol-O-methyltransferase (COMT) activity in cholestatic rat liver was studied. Hepatic and serum COMT activities were determined from the experimental rats with choledocho-caval shunt (CCS). The Michaelis-Menten constants in this hepatic enzyme was also measured. The activities of cytosolic, mitochondrial and mircosomal COMT as well as their $V_{max}$ values were found to be decreased significantly in CCS plus taurocholic acid (TCA) injected group than in the control group, such as CCS alone groups. However, their $K_m$ values in the experimental groups did not vary. Seru4m COMT activity increased slightly in the CCS plus TCA injerted group than in the control group. The above results suggest that TCA represses biosynthesis of the COMT in the liver, The elevated activity of the serum COMT is believed to be caused by the increment of membrane permeability of hepatocytes upon TCA mediated liver cell necrosis.

• Biomedical Science Letters
• /
• v.11 no.4
• /
• pp.503-508
• /
• 2005

Possible mechanisms of increased serum aryl sulfotransferase (AST) isozyme activities in cholestatic rats were studied. Serum AST-I, II and -III, IV isozymes activities were determined from the experimental rats with common bile duct ligation (CBDL) or choledocho-caval shunt (CCS). The activities of serum AST-I, II and -III, IV isozymes were found to be increased significantly in both the CCS plus taurocholic acid (TCA) injected group, and the CBDL plus TCA group than those in each control group, such as CCS or CBDL alone groups. The above results suggest that the elevated serum AST most likely due to increased hepatocyte membrane permeability caused by TCA mediated liver cell necrosis.