The Immunogenicity of Isolated Liver Cells: Comparison of Complete Liver Cell Suspensions (LCS) versus Liver Parenchymal Cell Suspensions (LPS) in Two Different Allogeneic Inbred Rat Strain Combinations

Isolated liver parenchymal cells from rats fed a 65% sucrose diet for 14 days were incubated in the presence and absence of 10(-6) M glucagon. The pyruvate kinase obtained from homogenates of the glucagon-treated cells displayed and increased Ks 0.5 for phosphoenolpyruvate (P-enolpyruvate), as well as an increased Ka 0.5 for 6-phosphogluconate (6-P-gluconate), compared to pyruvate kinase from untreated cells. Additionally, glucagon treatment decreased the maximal stimulation of pyruvate kinase by 6-P-gluconate by approximately two-thirds and decreased the Hill coefficient value of pyruvate kinase for 6-P-gluconate from 1.76 to 1.56. 6-Aminonicotinamide, an inhibitor of 6-P-gluconate dehydrogenase, increased 6-P-gluconate levels in isolated liver parenchymal cells three- to sevenfold, depending on the substrates present. The flux of P-enolpyruvate through pyruvate kinase was increased from 18 to 40% in these preparations and was highly correlated with the increase in 6-P-gluconate levels. The results suggest that 6-P-gluconate could regulate pyruvate kinase activity in the intact liver parenchymal cell. Furthermore, the activator would be of greatest importance in the lipogenic animal.

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l-Thyroxine enters the rat liver cell by simple diffusion

Journal of Endocrinology ◽

10.1677/joe.0.0970277 ◽

1983 ◽

Vol 97 (2) ◽

pp. 277-282 ◽

Cited By ~ 11

Author(s):

G. S. Rao ◽

M. L. Rao

Keyword(s):

Rat Liver ◽

Arrhenius Plot ◽

Parenchymal Cell ◽

Liver Cells ◽

Liver Parenchymal Cell ◽

Simple Diffusion ◽

Liver Parenchymal ◽

Isolated Rat Liver ◽

Centrifugation Technique ◽

Parenchymal Cells

The mode of uptake of l-[125I]thyroxine by freshly isolated rat liver parenchymal cells was studied by a rapid centrifugation technique. Using conditions for measuring initial rates of uptake, uptake by liver cells was not saturable when exposed to hormone concentrations in the incubation medium ranging from 2 pmol/l to 10 μmol/l. The Arrhenius plot was linear from 2 to 37°C; the temperature coefficient was 1·4. The uptake of l-[125I]thyroxine by liver cells was 35% when compared with that of l-[125I]tri-iodothyronine. In the presence of 2·8% bovine serum albumin the rate of uptake of l-[125I]thyroxine by liver cells was reduced by 90%. These results suggest that l-[125I]thyroxine enters the rat liver parenchymal cell by simple diffusion and only the free hormone crosses the plasma membrane.

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Characterization of the binding of diadenosine 5′,5‴-P1,P4-tetraphosphate (Ap4A) to rat liver cell membranes

Biochemical Journal ◽

10.1042/bj3140687 ◽

1996 ◽

Vol 314 (2) ◽

pp. 687-693 ◽

Cited By ~ 17

Author(s):

Mandy EDGECOMBE ◽

Alexander G. McLENNAN ◽

Michael J. FISHER

Keyword(s):

Plasma Membrane ◽

Rat Liver ◽

Liver Cell ◽

Plasma Membranes ◽

Rank Order ◽

Liver Cells ◽

Diadenosine Polyphosphates ◽

Cell Plasma ◽

Isolated Liver Cells ◽

Isolated Liver

Diadenosine polyphosphates present in the extracellular environment can, through interaction with appropriate purinoceptors, influence a range of cellular activities. Here we have investigated the nature of the ligand:receptor interactions involved in diadenosine 5′,5″-P1,P4-tetraphosphate (Ap4A)-mediated stimulation of glycogen breakdown in isolated rat liver cells. [2-3H]Ap4A showed specific binding to both intact isolated liver cells and plasma membrane fractions prepared from isolated liver cells. HPLC analysis confirmed that binding was mediated by intact Ap4A and not by potential breakdown products (e.g. ATP, adenosine etc). Binding of [2-3H]Ap4A, to isolated liver cell plasma membrane preparations, was successfully displaced by a range of both naturally occurring and synthetic diadenosine polyphosphates with the rank order potency Ap4A ⩾Ap5A > Ap6A > Ap3A > Ap2A. [2-3H]Ap4A binding was not displaced by P1 effectors but was successfully displaced by a range of P2 effectors with the rank order potency 2-methylthio-ATP > ATP > ADP ⩾adenosine 5′-[αβ-methylene]triphosphate > adenosine 5′-[βγ-methylene]triphosphate. These findings are consistent with the interaction of Ap4A with a P2y-like subclass of purinoceptor and are discussed in relation to (1) the known purinoceptor populations in liver cell plasma membranes and (2) observations concerning the binding of diadenosine polyphosphates to purinoceptors in other tissues.

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