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.

scholarly journals Sub-micromolar concentrations of extramitochondrial Ca2+ stimulate the rate of citrulline synthesis by rat liver mitochondria

1989 ◽  
Vol 257 (1) ◽  
pp. 285-288 ◽  
Author(s):  
J D Johnston ◽  
M D Brand
Keyword(s):  
Rat Liver ◽  
Urea Cycle ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Hormonal Stimulation ◽  
Isolated Rat Liver ◽  
Citrulline Synthesis ◽  
Isolated Rat ◽  
Stimulation Of

1. In the presence of physiological concentrations of Na+ and Mg2+, the rate of citrulline synthesis by isolated rat liver mitochondria respiring on a range of substrates was stimulated by up to 60% when the extramitochondrial Ca2+ concentration was raised from 130 pM to 770 nM. 2. Our findings suggest that hormonal stimulation of the urea cycle may be mediated by Ca2+.

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.

scholarly journals Hepatic inositol release upon hormonal stimulation of perfused rat liver

1988 ◽  
Vol 251 (3) ◽  
pp. 843-848 ◽  
Author(s):  
S vom Dahl ◽  
P Graf ◽  
H Sies
Keyword(s):  
Cyclic Amp ◽  
Rat Liver ◽  
Radioactive Material ◽  
Perfused Rat Liver ◽  
Dibutyryl Cyclic Amp ◽  
Hormonal Stimulation ◽  
Metabolic Difference ◽  
Basal Release ◽  
Stimulation Of ◽  
Sustained Increase

A sustained increase in the hepatic release of 3H radioactivity was shown to occur upon hormonal stimulation of perfused rat liver 15-20 h after intraperitoneal injection of 100 microCi of myo-[2-3H]inositol. Hormone-released radioactive material was analysed by t.l.c. and was found to consist predominantly of [3H]inositol, without further metabolites. Vasopressin (14 nM), phenylephrine (1.7 microM), angiotensin II (15 nM), glucagon (0.5 nM) and dibutyryl cyclic AMP (5 microM) exert maximal effects on hepatic inositol efflux after 10-15 min of stimulation. Omission of Ca2+ from the perfusion medium abolishes the hormone-dependent inositol release. LiCl (10 mM) does not significantly affect the basal release of [3H]inositol, but suppresses vasopressin- and angiotensin-triggered inositol release. Inositol efflux induced by glucagon, dibutyryl cyclic AMP and phenylephrine, however, remains essentially unchanged by LiCl infusion. This establishes a further metabolic difference between these two groups of agonists in that stimuli that act through cyclic AMP produce a stimulated outflow of inositol, but apparently without a Li+-sensitive phosphatase being involved in the overall process.

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.

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