Uptake of bile acids by perfused rat liver

The uptake of 14C-labeled cholic, taurocholic, and chenodeoxycholic acid by the perfused rat liver was studied to characterize the mechanism responsible for hepatic uptake of bile acids. A rapid-injection multiple indicator-dilution technique and the three-compartment model of Goresky were employed. The kinetics of hepatic uptake of the three bile acids could be described by the Michaelis-Menten equation. The maximal uptake velocities (Vmax) were 24.9 +/- 2.2 (mean +/- SD), 20.8 +/- 1.2, 1.2, and 11.4 +/- 0.9 nmol/s-g liver for cholic, taurocholic, and chenodeoxycholic acid, respectively. The corresponding apparent half-saturation constants (Km) were 526 +/- 125, 258 +/- 43, and 236 +/- 48 nmol/g liver. Competitive inhibition could be demonstrated between cholate and taurocholate as well as between cholate and chenodeoxycholate. Substitution of 94% of the Na+ in the perfusion medium decreased the Vmax and the apparent Km of taurocholate uptake by 68 and 55%, respectively. These findings are consistent with the hypothesis that bile acids are taken up into the hepatocyte by Na+-dependent carrier-mediated transport.

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Hepatic uptake of hippurate: a multiple-indicator dilution, perfused rat liver study

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.274.1.g10 ◽

1998 ◽

Vol 274 (1) ◽

pp. G10-G20 ◽

Cited By ~ 4

Author(s):

Tsutomu Yoshimura ◽

Andreas J. Schwab ◽

Lei Tao ◽

Ford Barker ◽

K. Sandy Pang

Keyword(s):

Benzoic Acid ◽

Rat Liver ◽

Hepatic Uptake ◽

Indicator Dilution ◽

Monocarboxylate Transporter ◽

Maximal Velocity ◽

Perfused Rat Liver ◽

Hepatic Transport ◽

Multiple Indicator Dilution ◽

Multiple Indicator

The hepatic transport of hippuric acid (HA), a glycine-conjugated metabolite of benzoic acid that exhibits only modest plasma albumin binding (binding association constant of 2.1 × 103M−1), was studied in the single-pass perfused rat liver (12 ml/min), using the multiple indicator dilution (MID) technique. The venous recovery of [3H]HA on portal venous injection of a MID dose containing a mixture of a set of noneliminated reference indicators and [3H]HA revealed a survival fraction of unity, corroborating the lack of disappearance of bulk HA from plasma. When the outflow recovery was fitted to the barrier-limited model of Goresky et al. (C. A. Goresky, G. G. Bach, and B. E. Nadeau. J. Clin. Invest. 52: 991–1009, 1973), the derived influx ( P in S ) and efflux ( P out S ) permeability-surface area products were found to be dependent on the concentration of HA (1–930 μM); P in S and P out S were ∼3.5 times the plasma flow rate at low HA concentration, but decreased with increasing HA concentration. All values, however, greatly exceeded the expected contribution from passive diffusion, because the equilibrium distribution ratio of chloroform to buffer for HA was extremely low (0.0001 at pH 7.4). The tissue equilibrium partition coefficient ( P in/ P out, or ratio of influx to efflux rate constants, k 1/ k −1) was less than unity and decreased with concentration. The optimized apparent Michaelis-Menten constant and maximal velocity were 182 ± 60 μM and 12 ± 4 nmol ⋅ s−1 ⋅ g−1, respectively, for influx and 390 ± 190 μM and 29 ± 13 nmol ⋅ s−1 ⋅ g−1, respectively, for efflux. In the presence ofl-lactate (20 mM), however, P in S for the uptake of HA (174 ± 3 μM) was reduced. Benzoic acid (10–873 μM) was also effective in reducing hepatic uptake of HA (5.3 ± 0.9 μM). These interactions suggest that MCT2, the monocarboxylate transporter that mediates the hepatic uptake of lactate and other monocarboxylic acids, may be involved in HA transport.

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Metabolism of 4-C14-cholesterol in the isolated perfused rat liver

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1962.202.4.699 ◽

1962 ◽

Vol 202 (4) ◽

pp. 699-703 ◽

Cited By ~ 9

Author(s):

Henry Danielsson ◽

William Insull ◽

Paul Jordan ◽

Ove Strand

Keyword(s):

Bile Acids ◽

Rat Liver ◽

Chenodeoxycholic Acid ◽

Liver Cholesterol ◽

Tween 20 ◽

Isolated Perfused Rat Liver ◽

Perfused Rat Liver ◽

Mode Of Administration ◽

Ethanol Extracts

The influence of the mode of administration on the distribution and oxidation of 4-C14-cholesterol in the isolated perfused rat liver has been studied. When labeled cholesterol was added to the perfusate as an emulsion with Tween 20 only about 1% of the labeled liver cholesterol was oxidized to bile acids. Approximately the same oxidation (1–2%) was obtained in perfusions of livers from animals injected with emulsions of 4-C14-cholesterol 1 hr before operation. When livers were perfused with blood withdrawn from animals injected with emulsions of 4-C14-cholesterol 24 hr prior to sacrifice the amount of labeled liver cholesterol converted to bile acids was about 10%, i.e., five to ten times more than in the above-mentioned sets of experiments, indicating the advisability of using physiological solutions of cholesterol rather than artificial emulsions. The main labeled acidic products were identified as cholic and chenodeoxycholic acid. The only labeled product isolated from ethanol extracts of the liver was found to be identical with cholesterol.

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Hepatic uptake and biliary secretion of bile acids in the perfused rat liver

Pharmacological Research ◽

10.1016/s1043-6618(05)80064-7 ◽

1992 ◽

Vol 25 (1) ◽

pp. 51-61 ◽

Cited By ~ 3

Author(s):

R ALDINI ◽

A RODA ◽

P LENZI ◽

D CALCATERRA ◽

C VACCARI ◽

...

Keyword(s):

Bile Acids ◽

Rat Liver ◽

Hepatic Uptake ◽

Biliary Secretion ◽

Perfused Rat Liver

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Kinetics of Hepatic Uptake of Unconjugated Bilirubin

Clinical Science ◽

10.1042/cs0510169 ◽

1976 ◽

Vol 51 (2) ◽

pp. 169-176 ◽

Cited By ~ 4

Author(s):

G. Paumgartner ◽

J. Reichen

Keyword(s):

Sodium Taurocholate ◽

Compartment Model ◽

Hepatic Uptake ◽

Uptake System ◽

Multiple Indicator Dilution ◽

Half Saturation Constant ◽

Carrier Mediated Transport ◽

Multiple Indicator ◽

Uptake Velocity ◽

Kinetics Of

1. The uptake of bilirubin was studied in the perfused rat liver by a multiple-indicator dilution technique employing the three-compartment model of Goresky. 2. The kinetics of hepatic bilirubin uptake could be described by the Michaelis—Menten equation. 3. The maximal uptake velocity (Vmax.) and the apparent half-saturation constant (Km) were 4·4 ± 0·5 nmol s−1 g−1 of liver and 58 ±16 nmol/g of liver respectively, indicating that the hepatic uptake system for bilirubin under normal conditions is operating far below saturation. 4. Sodium taurocholate did not compete with bilirubin for hepatic uptake. 5. These findings are consistent with the concept that carrier-mediated transport is responsible for hepatocellular uptake of bilirubin and that bilirubin and bile acids enter the hepatocyte via separate pathways.

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Hepatic uptake and metabolism of benzoate: a multiple indicator dilution, perfused rat liver study

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2001.280.6.g1124 ◽

2001 ◽

Vol 280 (6) ◽

pp. G1124-G1136 ◽

Cited By ~ 16

Author(s):

Andreas J. Schwab ◽

Lei Tao ◽

Tsutomu Yoshimura ◽

André Simard ◽

Ford Barker ◽

...

Keyword(s):

Rat Liver ◽

Hepatic Uptake ◽

Distributed Model ◽

Perfused Rat Liver ◽

Rate Determining Step ◽

Multiple Indicator Dilution ◽

Formation Kinetics ◽

Permeability Surface ◽

Multiple Indicator ◽

Best Fit

Multiple, noneliminated references (51Cr-labeled erythrocytes,125I-albumin, [14C]- or [3H]sucrose, and [2H]2O), together with [3H]hippurate or [14C]benzoate, were injected simultaneously into the portal vein of the perfused rat liver during single-pass delivery of benzoate (5–1,000 μM) and hippurate (5 μM) to investigate hippurate formation kinetics and transport. The outflow dilution data best fit a space-distributed model comprising vascular and cellular pools for benzoate and hippurate; there was further need to segregate the cellular pool of benzoate into shallow (cytosolic) and deep (mitochondrial) pools. Fitted values of the membrane permeability-surface area products for sinusoidal entry of unbound benzoate were fast and concentration independent (0.89 ± 0.17 ml · s−1 · g−1) and greatly exceeded the plasma flow rate (0.0169 ± 0.0018 ml · s−1 · g−1), whereas both the influx of benzoate into the deep pool and the formation of hippurate occurring therein appeared to be saturable. Results of the fit to the dilution data suggest rapid uptake of benzoate, with glycination occurring within the deep and not the shallow pool as the rate-determining step.

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Sex differences in hepatic uptake of long chain fatty acids in single-pass perfused rat liver

The Journal of Lipid Research ◽

10.1016/s0022-2275(20)34956-7 ◽

1981 ◽

Vol 22 (3) ◽

pp. 431-436

Author(s):

M C Kushlan ◽

J L Gollan ◽

W L Ma ◽

R K Ockner

Keyword(s):

Fatty Acids ◽

Sex Differences ◽

Rat Liver ◽

Hepatic Uptake ◽

Long Chain Fatty Acids ◽

Perfused Rat Liver ◽

Single Pass ◽

Long Chain ◽

Chain Fatty Acids

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Endogenous ET-1 contributes to liver injury induced by galactosamine and endotoxin in isolated perfused rat liver

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1995.268.6.g997 ◽

1995 ◽

Vol 268 (6) ◽

pp. G997-G1003 ◽

Cited By ~ 3

Author(s):

T. Ohuchi ◽

K. Tada ◽

K. Akamatsu

Keyword(s):

Liver Injury ◽

Rat Liver ◽

Early Event ◽

Isolated Perfused Rat Liver ◽

Perfused Rat Liver ◽

Hepatic Microcirculation ◽

Nonparenchymal Cells ◽

Multiple Indicator Dilution ◽

Microcirculatory Disturbances ◽

Hepatocyte Damage

Injury to hepatocytes most likely occurs via disturbances in the microcirculation. The role of vasoconstriction due to the effect of endogenous endothelin-1 (ET-1) in the development of galactosamine (GalN)- and lipopolysaccharide (LPS)-induced liver injury was investigated. Using the multiple indicator dilution technique, we measured the volume of the hepatic sinusoids and the apparent Disse space as indicators of overall hepatic microcirculation. Serum purine nucleoside phosphorylase activity as a marker of damage to nonparenchymal cells increased and the volume of the sinusoids and the Disse space decreased prior to hepatocyte damage in rats treated intraperitoneally with GalN and LPS. Moreover, the amount of ET-1 release was elevated. When livers from untreated rats were perfused with ET-1 in a recirculating system, hepatocyte damage was observed similar to experiments with GalN and LPS. A monoclonal anti-endothelin antibody, AwETN40, diminished the extent of liver injury caused by GalN and LPS in isolated perfused rat liver. The present study suggests that vasoconstriction is an early event in GalN- and LPS-induced liver injury and that the development of hepatocyte damage is mediated via microcirculatory disturbances due to endogenous ET-1.

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