Dynamics of the Conjugate Pattern during the Infusion of Bile Acids into Isolated Rat Liver

Ogura, Yoshio; Ogura, Michio; YAMAMOTO, Yoritoshi

doi:10.1515/bchm3.1986.367.1.495

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Accordingly, the dietary conditions which expand the bile acid pool or synthesis in the rat (bile acid, cholesterol and pectin feeding; Myant & Mitropoulous, 1977;Ide et al 1990) all increased the bile acid G : T ratio accompanying a decrease in hepatic concentration of taurine. However, Ogura & Ogura (1986) reported that the concentration of taurine in rat liver perfused with cholic or chenodeoxycholic acids was similar to that of glycine at the end of the perfusion. Moreover, they also showed that simultaneous infusion of taurine or cysteine greatly suppressed the increase in the glycine-conjugation without influencing taurine concentration in the liver.…”

Section: Discussionmentioning

confidence: 97%

“…The current observation that neither substrate specificity of bile acid-CoA: amino acid Nacyltransferase nor the availability of amino acid substrates could account for the dietary manipulation of the bile acid G :T ratio indicates the existence of an alternative mechanism that regulates the G:T ratio at a cellular level. Experiments using perfused rat liver (Hardison & Proffitt, 1977;Ogura & Ogura, 1986;Sweeney et al 1991) have demonstrated that infusion of bile acids evokes a marked increase in glycine-conjugation of biliary bile acids accompanying a decrease in hepatic taurine concentrations. This situation resembles that in the present study where glycine-conjugation was increased.…”

Section: Discussionmentioning

confidence: 99%

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Dietary modifications of the biliary bile acid glycine: taurine ratio and activity of hepatic bile acid-CoA:amino acidN-acyltransferase (EC2.3.1) in the rat

et al. 1994

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Effects of dietary manipulations on the biliary bile acid glycine: taurine (G: T) ratio and the activity of hepatic bile acid-Co A: amino acidN-acyltransferase (EC 2.3.1) in the post-mitochondrial fraction of liver homogenates were examined in the rat. The G:T ratio in rats fed on the diet containing 100 g pectin/kg (2.18) was markedly higher than that in the animals fed on the diet containing 100 g cellulose/kg (0.09). The diets containing either 10 g cholesterol/kg or 5 g sodium cholate/kg, especially the latter, also increased the G:T ratio (0.77 and 2.33 respectively) compared with a control diet free of these steroids (0.34). When the saturating concentrations of taurine (20 mM) and glycine (100 mM) were the substrates, dietary pectin relative to cellulose significantly increased the activity of both taurine- and glycine-dependent bile acid-CoA: amino acidN-acyltransferase, but neither dietary bile acid nor cholesterol influenced it. In spite of the marked difference in the G:T ratio among the rats given various types of experimental diet, the bile acid-CoA: amino acid N-acyltransferase reaction produced taurine- but little glycine-conjugated bile acid when both taurine and glycine coexisted at physiological concentration ranges in the assay media. Dietary manipulations modified the hepatic taurine concentrations and the changes were inversely correlated with those in the G: T ratio. However, hepatic concentration of taurine (1.67–4.82 μmol/g) in rats given various types of experimental diet was comparable with or even higher than the reported Michaelis constant (Km) value ofN-acyltransferase for this compound (0.8–2.5 mM). In contrast, glycine concentrations (1.81–2.58 μmol/g) were much lower than the Km value for this amino acid (35–40 mM) under various dietary conditions. Thus, neither the substrate specificity of the bile acid conjugation enzyme nor the alteration in the hepatic concentration of taurine or glycine accounted for the change in the G: T ratio in the present study.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Dietary modifications of the biliary bile acid glycine: taurine ratio and activity of hepatic bile acid-CoA:amino acidN-acyltransferase (EC2.3.1) in the rat

et al. 1994

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Bile Acid Conjugation Pattern in the Isolated Perfused Rat Liver During Infusion of an Amino Acid Formulation

Sweeny

Barnes

Diasio

1991

J Parenter Enteral Nutr

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The influence of the taurine-containing amino acid mixture Trophamine on the pattern of bile acid conjugation was examined in the isolated perfused rat liver using cholic acid as the bile acid substrate. In all experiments, greater than 97% of the cholic acid appearing in bile was conjugated with taurine or glycine. The pattern of taurine and glycine bile acid conjugation, however, was dependent on the availability of taurine in the perfusate medium. Thus, in the absence of Trophamine infusion, the percentage of cholic acid conjugated with taurine (ie, taurocholate) declined throughout the course of the cholic acid infusion. Trophamine infusion increased the ratio of biliary taurocholate/glycocholate by 4.5-fold over that observed in the absence of the amino acid infusion. Increasing the amount of taurine in Trophamine by 2- or 5-fold resulted in a 1.8- and 4.3-fold increase, respectively, in the taurocholate/glycocholate ratio over that observed during the Trophamine infusion. Infusion of taurine alone, at an equimolar concentration of taurine as that in Trophamine, resulted in a similar taurocholate/glycocholate ratio as that observed during the Trophamine infusion. These data indicate that taurine availability, even in the presence of high concentrations of glycine and other amino acids in Trophamine, appears to be the most important factor in determining the pattern of bile acid conjugation in the isolated perfused rat liver.

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Effect of Diabetes on the Metabolism of Chenodeoxycholic Acid in Isolated Perfused Rat Liver

Ogura¹,

Ayaki²

1987

Biological Chemistry Hoppe-Seyler

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Dynamics of the Conjugate Pattern during the Infusion of Bile Acids into Isolated Rat Liver

Cited by 3 publications

References 5 publications

Dietary modifications of the biliary bile acid glycine: taurine ratio and activity of hepatic bile acid-CoA:amino acidN-acyltransferase (EC2.3.1) in the rat

Dietary modifications of the biliary bile acid glycine: taurine ratio and activity of hepatic bile acid-CoA:amino acidN-acyltransferase (EC2.3.1) in the rat

Bile Acid Conjugation Pattern in the Isolated Perfused Rat Liver During Infusion of an Amino Acid Formulation

Effect of Diabetes on the Metabolism of Chenodeoxycholic Acid in Isolated Perfused Rat Liver

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