scholarly journals Uptake of phospholipid-depleted chylomicrons by the perfused rat liver

1980 ◽  
Vol 192 (3) ◽  
pp. 845-851 ◽  
Author(s):  
J Borensztajn ◽  
T J Kotlar ◽  
B J McNeill
Keyword(s):  
Phospholipase A2 ◽  
Neutral Lipid ◽  
Rat Liver ◽  
Lipid Composition ◽  
Hepatic Uptake ◽  
Perfused Rat Liver ◽  
Apparent Effect ◽  
Isolated Rat Liver ◽  
Chylomicron Remnants ◽  
Isolated Rat

1. Rat lymph chylomicrons were depleted of their surface phospholipids by treatment with pure phospholipase A2 from Crotalus adamanteus venom. 2. About 80% of the phospholipids could be removed from the chylomicrons without any apparent effect on their size, neutral lipid composition or qualitative profile of their tetramethylurea-soluble apoproteins. 3. Phospholipid-depleted chylomicrons were rapidly taken up whole by liver cells when perfused through isolated rat liver preparations. The rate of uptake was dependent on the extent of phospholipid depletion and reached a maximum (4-6.5-fold greater than control chylomicrons) when 80% of the phospholipids had been removed. 4. It is speculated that the hepatic uptake of phospholipid-depleted chylomicrons occurs by a mechanism to that of chylomicron-remnants uptake.

scholarly journals Apoprotein-independent binding of chylomicron remnants to rat liver membranes

1991 ◽  
Vol 279 (3) ◽  
pp. 769-773 ◽  
Author(s):  
J Borensztajn ◽  
T J Kotlar ◽  
S Y Chang
Keyword(s):  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Hepatic Differentiation ◽  
Direct Role ◽  
Isolated Rat Liver ◽  
Liver Membranes ◽  
Chylomicron Remnants ◽  
Isolated Rat

Rat lymph chylomicrons and chylomicron remnants were treated with trypsin or Pronase. The ability of the resulting apoprotein-free lipoproteins to be taken up by the isolated perfused rat liver, and to bind to isolated rat liver membranes, was examined. Compared with control lipoproteins, the apoprotein-free chylomicrons and remnants retained unaltered their capacity to be differentiated by the intact liver and by the isolated membranes. Further, control remnants and apoprotein-free remnants competed for binding to the isolated membranes. We conclude that apoproteins are not required for the hepatic differentiation between chylomicrons and remnants, and suggest that the lipoprotein phospholipids may play a direct role in this process.

Removal of Excess Cholesterol and Cholate by the Isolated Rat Liver From its Perfusate

1956 ◽  
Vol 184 (2) ◽  
pp. 412-414 ◽  
Author(s):  
Meyer Friedman ◽  
René Bine ◽  
Tad Ishida
Keyword(s):  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Isolated Rat Liver ◽  
Almost All ◽  
Isolated Liver ◽  
Isolated Rat

Perfusion of the isolated perfused rat liver with a perfusate containing hypercholesteremic and hypercholatemic blood results in the removal of some of the cholesterol and almost all of the excess cholate. The withdrawn cholesterol is deposited almost completely in the liver, whereas the withdrawn cholate is excreted promptly in the bile. It is concluded that the isolated liver behaves qualitatively similar to the liver of the intact rat in respect to cholesterol and cholate metabolism.

Effect of Varying Pco2 on Intracellular pH and Lactate Consumption in the Isolated Perfused Rat Liver

1978 ◽  
Vol 55 (2) ◽  
pp. 175-181 ◽  
Author(s):  
P. G. Baron ◽  
R. A. Iles ◽  
R. D. Cohen
Keyword(s):  
Intracellular Ph ◽  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Lactate Metabolism ◽  
Isolated Rat Liver ◽  
Buffering Effect ◽  
Lactate Uptake ◽  
Lactate Consumption ◽  
Isolated Rat

1. The effects of varying Pco2 on lactate uptake and intracellular pH (pHl) were studied in the isolated rat liver perfused with differing concentrations of lactate. 2. In general, pHl and lactate uptake are inversely related to Pco2, and pHl and lactate uptake are directly related to each other, but the quantitative aspects and significance of these relationships vary with the availability of lactate. A model of hepatic lactate metabolism is proposed which may account for the quantitative variation. 3. The metabolism of lactate within the hepatocyte exerts a destabilizing effect on hepatocyte cell pH, in contrast to the buffering effect seen in predominantly glycolytic tissues. 4. An attempt is made to relate the findings to the disturbances of lactate metabolism in clinical respiratory failure.

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16α-monoglucuronide through the isolated rat liver

1982 ◽  
Vol 100 (2) ◽  
pp. 274-278
Author(s):  
M. Höller ◽  
H. Weber ◽  
H. Breuer
Keyword(s):  
Rat Liver ◽  
Small Extent ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Perfusion Medium ◽  
Isolated Rat Liver ◽  
Isolated Rat

Abstract. The uptake of [4-14C]oestriol by the isolated perfused rat liver is 3.8 times faster as compared to that of simultaneously perfused [6,9-3H2]oestriol 16α-monoglucuronide. During perfusion the concentration of both radioactive oestrogens decreased exponentially in perfusion medium (apparent kel: 0.061 min−1 and 0.016 min−1, respectively). [6,9−3H2]Oestriol 16α-monoglucuronide was metabolized only to a small extent; more than 92% was secreted unchanged into the bile where it was highly concentrated (1800 nmol/g). In contrast [4-14C]oestriol was extensively metabolized; it was mainly hydroxylated at C-atom 2, leading to a rapid increase in the concentration of 2-hydroxyoestriol in the perfused medium. This metabolite was quickly taken up by the liver during recirculation and subsequently either methylated or sulphated. 2-Hydroxyoestriol monosulphate was glucuronated to 2-hydroxyoestriol 16α-monoglucuronide 3-sulphate, which was rapidly excreted into the bile. No double conjugate was formed when [6,9-3H2]oestriol 16α-monoglucuronide was perfused; this is additional evidence for the correctness of the assumption that monoglucuronides cannot serve as precursors of sulphoglucuronides.

scholarly journals Sustained oscillations in extracellular calcium concentrations upon hormonal stimulation of perfused rat liver

1987 ◽  
Vol 241 (3) ◽  
pp. 933-936 ◽  
Author(s):  
P Graf ◽  
S vom Dahl ◽  
H Sies
Keyword(s):  
Angiotensin Ii ◽  
Rat Liver ◽  
Perfused Rat Liver ◽  
Hormone Concentration ◽  
Oscillatory Behaviour ◽  
Hormonal Stimulation ◽  
Isolated Rat Liver ◽  
Sustained Oscillations ◽  
Isolated Rat ◽  
Stimulation Of

Sustained oscillations in extracellular free Ca2+ were shown to occur on addition of vasopressin, phenylephrine or angiotensin II in isolated rat liver perfused with low (10 microM)-Ca2+ medium. The amplitude and frequency of oscillation depend on hormone concentration. In contrast, Ca2+ releases on addition of ATP, t-butyl hydroperoxide or arachidonate do not exhibit oscillatory behaviour. The vasopressin-induced oscillations were suppressed by glucagon and dibutyryl 3′,5′-cyclic AMP, but not by dibutyryl 3′,5′-cyclic GMP. These observations in the extracellular space complement observations by Woods, Cuthbertson & Cobbold [(1986) Nature (London) 319, 600-602] on oscillations in intracellular free Ca2+ in single liver cells.

Effect of intestinal factors on extraction of insulin in perfused rat liver

1987 ◽  
Vol 253 (6) ◽  
pp. E603-E607
Author(s):  
T. Ikeda ◽  
T. Yoshida ◽  
M. Honda ◽  
Y. Ito ◽  
I. Murakami ◽  
...  
Keyword(s):  
Direct Effect ◽  
Rat Liver ◽  
Untreated Control ◽  
Oral Glucose ◽  
Perfused Rat Liver ◽  
Hepatic Extraction ◽  
Rat Intestine ◽  
Isolated Rat Liver ◽  
Glucose Ingestion ◽  
Isolated Rat

To study the direct effect of intestinal factors on hepatic extraction of insulin, an investigation was made into the extraction of insulin from isolated rat liver perfused with portal venous effluent (PVE) obtained from the isolated perfused rat intestine. Rat intestine was perfused with Krebs-Ringer bicarbonate medium for 45 min, and the PVE was collected from glucose-, lipid-, or NaCl-treated and untreated control intestines. The PVE, after adjustment of its glucose (180 mg/dl) and insulin (200 microU/ml) concentrations, was used as the perfusing medium for the liver of a different rat. The liver was perfused without recirculation with the PVE not containing insulin for 15 min and then perfused with the PVE containing insulin for the next 30 min. Insulin removal from liver perfused with PVE from lipid- or NaCl-treated intestine (52.6 +/- 5.4 or 46.6 +/- 4.1%) was similar to that from comparable controls (49.7 +/- 2.8 or 48.2 +/- 2.9%), respectively. However, that from glucose-treated intestine (39.7 +/- 6.2%) was significantly (P less than 0.01) lower than that from control intestine (51.1 +/- 2.5%). These results indicate that an intestinal factor secreted after glucose ingestion significantly reduces hepatic extraction of insulin and that at least a part of the incretin phenomenon is due to a decreased hepatic extraction of insulin after oral glucose administration.

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