Effect of albumin on taurocholate uptake kinetics in rat liver

1987 ◽  
Vol 72 (1) ◽  
pp. 11-17 ◽  
Author(s):  
Rita Aldini ◽  
Aldo Roda ◽  
Antonio Maria Morselli-Labate ◽  
Patrizia Simoni ◽  
Enrico Roda ◽  
...  
Keyword(s):  
Rat Liver ◽  
Uptake Kinetics ◽  
The Other ◽  
Molar Ratio ◽  
Albumin Concentration ◽  
Single Pass ◽  
Rat Livers ◽  
Kinetics Of ◽  
Isolated Rat

1. Isolated rat livers were perfused in a single pass with increasing doses of taurocholate with and without albumin in the perfusion media. 2. The kinetics of taurocholate uptake were thus evaluated. 3. In all the experiments, taurocholate uptake showed Michaelis-Menten kinetics. Increasing the albumin concentration in the medium resulted in an increase in the Km, without effect on the Vmax. When taurocholate and albumin were kept constant (20:1 molar ratio), the Vmax was significantly lower than in the other experiments. 4. These data suggest that taurocholate uptake shows saturation in the absence of albumin and that albumin reduces taurocholate uptake.

scholarly journals Genistein inhibits glucose and sulphate transport in isolated rat liver lysosomes

2009 ◽  
Vol 103 (2) ◽  
pp. 197-205 ◽  
Author(s):  
Hsu-Fang Chou ◽  
Kun-Hung Chuang ◽  
Yi-Shan Tsai ◽  
Yi-Ju Chen
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Rat Liver ◽  
Uptake Kinetics ◽  
Isolated Rat Liver ◽  
Sulphate Transport ◽  
Genistein Treatment ◽  
Liver Lysosomes ◽  
Rat Liver Lysosomes ◽  
Isolated Rat

Genistein and daidzein are known to have both beneficial and adverse effects on human health due to their many biological actions at the cellular level. Both isoflavones have been shown to inhibit GLUT-mediated glucose transport across the plasma membrane of mammalian cells. Since lysosomal membrane transport is essential for maintaining cellular homeostasis, the present study examined the effects of genistein and daidzein on glucose and sulphate transport in isolated rat liver lysosomes. Both genistein and daidzein significantly inhibited lysosomal glucose uptake. Genistein was a more potent glucose transport inhibitor than daidzein, with a half-maximum inhibitory concentration (IC50) of 45 μmol/l compared with 71 μmol/l for daidzein. Uptake kinetics of d-glucose showed a significant decrease in Vmax (control:genistein treat = 1489 (sem 91):507 (sem 76) pmol/unit of β-hexosaminidase per 15 s) without a change in Km. The presence of 50 μm-genistein in the medium also reduced glucose efflux from lysosomes preloaded with 100 mm-d-glucose. Genistein also inhibited lysosomal sulphate transport. Similar to its effects on glucose uptake kinetics, genistein treatment caused a significant decrease in sulphate uptake Vmax (control:genistein treat = 87 (sem 4):59 (sem 5) pmol/unit of β-hexosaminidase per 30 s), while the Km was not affected. The evidence provided by the present study suggests that the most likely mechanism of lysosomal glucose transport inhibition by genistein is via direct interaction between genistein and the transporter, rather than mediation by tyrosine kinase inactivation. Genistein likely has a similar mechanism of directly inhibiting sulphate transporter.

Propranolol metabolism by isolated hepatocytes from normal and cirrhotic rat livers: the effect of albumin

1990 ◽  
Vol 68 (6) ◽  
pp. 657-662 ◽  
Author(s):  
Louise Gariepy ◽  
Daphna Fenyves ◽  
Jean-Luc Petit ◽  
Ginette Raymond ◽  
Jean-Pierre Villeneuve
Keyword(s):  
Free Fraction ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Hepatic Uptake ◽  
Albumin Concentration ◽  
Isolated Rat Hepatocytes ◽  
Subsequent Elimination ◽  
Rat Livers ◽  
Mediated Catalysis ◽  
Isolated Rat

Several recent reports have shown that the hepatic uptake and subsequent elimination of some substrates is faster in the presence of albumin than in its absence, as if some of the substrate bound to albumin was also available for uptake. In the present study, we examined the effect of albumin on the clearance of propranolol by isolated rat hepatocyte suspensions. The clearance of total drug decreased progressively as albumin concentration increased. There was also a progressive decrease in the free fraction of propranolol and the net result was an increase in the clearance of unbound drug (+50% at 40 g/L albumin). This increase was not due to an oncotic pressure effect of albumin, nor to the presence of fatty acids bound to albumin. The clearance of propranolol by isolated hepatocytes from cirrhotic rats was decreased compared with controls (−50%), and albumin also increased propranolol free clearance, albeit to a lesser extent than in control animals. Our results indicate that albumin facilitates the elimination of propranolol by hepatocytes, possibly because of surface-mediated catalysis of the albumin–propranolol complexes.Key words: propranolol clearance, albumin, isolated rat hepatocytes, cirrhosis.

scholarly journals Impedimetric Detection of Albumin-Bound Fatty Acids Using Graphene Oxide Electrode

Chemosensors ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 240
Author(s):  
Zihni Onur Uygun ◽  
Soner Duman ◽  
Ismail Oran
Keyword(s):  
Graphene Oxide ◽  
Adsorption Kinetics ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Single Frequency ◽  
Molar Ratio ◽  
Albumin Concentration ◽  
Limit Of Quantification ◽  
Faradaic Impedance ◽  
Kinetics Of

The fatty acid/albumin (FA/Alb) molar ratio is ≤1 in healthy subjects; this ratio can reach 3–4 in patients with acute myocardial ischemia. We describe the spontaneous desorption–adsorption kinetics of FAs from albumin to a graphene electrode at neutral pH. Albumin-depleted human serum was prepared via ultrafiltration and then mixed with defatted human albumin and sodium oleate at different FA/Alb molar ratios, at a final albumin concentration of 0.6 mM. A commercially available screen-printed graphene oxide (GO)-modified carbon electrode was used for the electrochemical experiments. Frequency-ranged Faradaic electrochemical impedance spectroscopy (EIS) and a single-frequency non-Faradaic impedance measure (chronoimpedance) were used to derive the desorption–adsorption kinetics. The surface of the GO electrode was finally evaluated with the aid of X-ray photoelectron spectroscopy (XPS). With the chronoimpedance experiment, the measured impedance increased accordingly to the FA/Alb ratios. The frequency-ranged EIS showed good linearity between the impedance and the FA/Alb ratio, with a limit of quantification value of 1.06. XPS surface analysis revealed that the FA was adsorbed onto the electrode, with the amount of the adsorbed FA proportional to the FA/Alb ratio. The electrochemical method applied on this peculiar desorption–adsorption kinetics of FAs has the ability to differentiate serum having excess FAs.

Kinetics of Distribution of D2O and Antipyrine in Isolated Perfused Rat Liver

1958 ◽  
Vol 192 (3) ◽  
pp. 531-537 ◽  
Author(s):  
Alan M. Thompson ◽  
H. Mead Cavert ◽  
Nathan Lifson
Keyword(s):  
Rat Liver ◽  
Early Period ◽  
Tissue Perfusion ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Rate Of Increase ◽  
The Difference ◽  
Rat Livers ◽  
Kinetics Of

Isolated rat livers were perfused via the portal vein with a blood-Ringer mixture containing a constant inflow concentration of D2O and, in some cases, antipyrine. The rate of increase of outflow concentration was studied, comparisons being made between D2O, antipyrine and a theoretical outflow curve based on completely flow-limited distribution. The effect of flow rate on the deviation of D2O from theoretical was also studied. The results indicate that exchange of D2O and antipyrine between blood and tissue in the perfused rat liver is extremely rapid relative to the rate of blood supply of these substances to the organ, even at flows several times that occurring in vivo. In the average experiment the average D2O concentration in the liver during the early period of the perfusion was about 90% of the mixed venous concentration. The factors responsible for the failure of D2O to distribute maximally, particularly tissue perfusion heterogeneity and diffusion limitation, are discussed. Although quantitation of the difference is difficult, antipyrine appears to distribute somewhat more rapidly than D2O due to its greater solubility in cell membranes.

scholarly journals Purification from rat liver of an enzyme that catalyses the sulphurylation of phenols

1971 ◽  
Vol 123 (5) ◽  
pp. 901-906 ◽  
Author(s):  
F. A. McEvoy ◽  
J. Carroll
Keyword(s):  
Enzyme Activity ◽  
Methyl Ester ◽  
Rat Liver ◽  
The Other ◽  
Male Rat ◽  
Thiol Compounds ◽  
Km Value ◽  
Rat Livers

1. An enzyme (EC 2.8.2.1) that catalyses the transfer of sulphate from adenosine 3′-phosphate 5′-sulphatophosphate to phenols was purified approx. 2000-fold from male rat livers. 2. The purified preparation did not catalyse the sulphurylation of dehydroepiandrosterone, butan-1-ol, l-tyrosine methyl ester, 1-naphthylamine or serotonin. 3. At pH8.0 and 37°C the Km values of the enzyme for p-nitrophenol and adenosine 3′-phosphate 5′-sulphatophosphate are 51 and 14μm respectively. The Km value for either substrate is independent of the concentration of the other. 4. The sulphurylation of phenol is inhibited by thiol compounds and glutathione at a concentration of 3mm caused an approx. 50% decrease in enzyme activity. 5. The Km of the enzyme for adenosine 3′-phosphate 5′-sulphatophosphate is unaffected by the presence of added glutathione but at a concentration of 5mm-glutathione the Km of the enzyme for its phenolic substrate is decreased.

Sign in / Sign up

Export Citation Format

Share Document