HORMONAL CONTROL OF PHENYLALANINE HYDROXYLASE ACTIVITY IN ISOLATED RAT HEPATOCYTES

1981 ◽  
Vol 9 (2) ◽  
pp. 233P-233P
Author(s):  
Jean-Pierre ABITA
Keyword(s):  
Phenylalanine Hydroxylase ◽  
Rat Hepatocytes ◽  
Hormonal Control ◽  
Hydroxylase Activity ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals Immunocytochemical identification of phenylalanine hydroxylase and albumin in cultured hepatoma cells and isolated rat hepatocytes.

1981 ◽  
Vol 90 (1) ◽  
pp. 145-152 ◽  
Author(s):  
R E Baker ◽  
L S Jefferson ◽  
R Shiman
Keyword(s):  
Phenylalanine Hydroxylase ◽  
Fluorescent Antibody ◽  
Rat Hepatocytes ◽  
Cell Types ◽  
Isolated Hepatocytes ◽  
Hepatoma Cells ◽  
Isolated Rat Hepatocytes ◽  
Analogous Data ◽  
Almost All ◽  
Isolated Rat

Rhodamine-conjugated antibodies specific for phenylalanine hydroxylase and serum albumin were employed as cytochemical probes to identify these two proteins in H4 hepatoma cells and in isolated rat hepatocytes. Each fluorescent antibody stained the cells specifically and in a distinctive manner. In both cell types, albumin staining was discretely localized in cytoplasmic and in H4 cultures varied somewhat from cell to cell. Evidence from cultures of REB15 cells, a strain derived by cloning H4 cells in tyrosine-free medium, suggested that the staining variability of H4 cells could reflect a variability in phenylalanine hydroxylase content. Hydrocortisone-treated H4 cells and REB15 cultures contain increased amounts of phenylalanine hydroxylase; and all cells in the culture appear to be induced by the hormone. Evidence was presented to show that the albumin visualized within the isolated hepatocytes had been synthesized by these cells, and, furthermore, that quantitatively nearly all intracellular albumin in the isolated rat hepatocytes appeared to be entrained in the secretion pathway (analogous data already exist for H4 cells [Baker, R.E., and R. Shiman. 1979. J. Biol. Chem. 254:9633-9639]). By scoring specific fluorescence, 86 and 98% of the H4 cells and 89 and 98% of the isolated hepatocytes were found to contain phenylalanine hydroxylase and albumin, respectively. Therefore, almost all cells in each population appeared to synthesize both proteins. An implication of these findings is that in rat virtually all liver parenchymal cells must synthesize both phenylalanine hydroxylase and albumin.

scholarly journals Responsiveness to glucagon by isolated rat hepatocytes controlled by the redox state of the cytosolic nicotinamide—adenine dinucleotide couple acting on adenosine 3′:5′-cyclic monophosphate phosphodiesterase

1978 ◽  
Vol 176 (3) ◽  
pp. 805-816 ◽  
Author(s):  
M G Clark ◽  
I G Jarrett
Keyword(s):  
Cyclic Amp ◽  
Redox State ◽  
Rat Hepatocytes ◽  
Hormonal Control ◽  
Maximal Velocity ◽  
Isolated Rat Hepatocytes ◽  
Cyclic Amp Phosphodiesterase ◽  
Membrane Bound ◽  
Glucose Output ◽  
Isolated Rat

1. The effects of changes in the cytoplasmic [NADH]/[NAD+] ratio on the efficacy of glucagon to alter rates of metabolism in isolated rat hepatocytes were examined. 2. Under reduced conditions (with 10mM-lactate), 10nM-glucagon stimulated both gluconeogenesis and urea synthesis in isolated hepatocytes from 48h-starved rats; under oxidized conditions (with 10mM-pyruvate), 10nM-glucagon had no effect on either of these rates. 3. The ability of glucagon to alter the concentration of 3′:5′-cyclic AMP and the rates of glucose output, glycogen breakdown and glycolysis in cells from fed rats were each affected by a change in the extracellular [lactate]/[pyruvate] ratio; minimal effects of glucagon occurred at low [lactate]/[pyruvate] ratios. 4. Dose-response curves for glucagon-mediated changes in cyclic AMP concentration and glucose output indicated that under oxidized conditions the ability of glucagon to alter each parameter was decreased without affecting the concentration of hormone at which half-maximal effects occurred. 5. The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.05 mM) significantly reversed the inhibitory effects of pyruvate on glucagon-stimulated glucose output. 6. For exogenously added cyclic [3H]AMP(0.1 mM), oxidized conditions decreased the stimulatory effect on glucose output as well as the intracellular concentration of cyclic AMP attained, but did not alter the amount of cyclic [3H]AMP taken up. 7. The effects of lactate, pyruvate, NAD+ and NADH on cyclic AMP phosphodiesterase activities of rat hepatocytes were examined. 8. NADH (0.01–1 MM) inhibited the low-Km enzyme, particularly that which was associated with the plasma membrane. 9. The inhibition of membrane-bound cyclic AMP phosphodiesterase by NADH was specific, reversible and resulted in a decrease in the maximal velocity of the enzyme. 10. It is proposed that regulation of the membrane-bound low-Km cyclic AMP phosphodiesterase by nicotinamide nucleotides provides the molecular basis for the effect of redox state on the hormonal control of hepatocyte metabolism by glucagon.

Hormonal control of cholesterogenesis and related enzymes in isolated rat hepatocytes during pre- and postnatal development

1985 ◽  
Vol 125 (3) ◽  
pp. 507-511 ◽  
Author(s):  
S. Leoni ◽  
S. Spagnuolo ◽  
L. Conti Devirgiliis ◽  
L. Dini ◽  
M. T. Mangiantini ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Rat Hepatocytes ◽  
Hormonal Control ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals Lysosomal triacylglycerol lipase and lipolysis in isolated rat hepatocytes.

1979 ◽  
Vol 254 (18) ◽  
pp. 8841-8846
Author(s):  
L.J. Debeer ◽  
J. Thomas ◽  
P.J. De Schepper ◽  
G.P. Mannaerts
Keyword(s):  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Triacylglycerol Lipase ◽  
Isolated Rat
Sign in / Sign up

Export Citation Format

Share Document