scholarly journals Synthesis of renin substrate by rat liver

1979 ◽  
Vol 184 (1) ◽  
pp. 7-12 ◽  
Author(s):  
A T Chiu ◽  
J W Ryan ◽  
F T Bryan ◽  
R E Niemeyer ◽  
D R Schultz
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Salt Solution ◽  
Molecular Sieve ◽  
Radioactive Substance ◽  
Converting Enzyme ◽  
Renin Substrate ◽  
Isolated Rat Liver ◽  
Extensive Evaluation ◽  
Isolated Rat

The present study attempts to determine if the isolated rat liver is capable of synthesizing renin substrate from 14C-labelled amino acids added in the perfusate. The renin substrate is characterized via reaction with renin, forming a substance that is subsequently identified as proangiotensin. Extensive evaluation of the reaction product is carried out by using molecular-sieve chromatography, countercurrent distribution, reactivity with converting enzyme, radioimmunological technique and bioassay. The results demonstrate that isolated rat liver perfused with artificial salt solution is capable of synthesizing a protein that reacts with renin to form a radioactive substance indistinguishable from proangiotensin.

scholarly journals The effects L-leucine on the synthesis of urea, glutamate and glutamine by isolated rat liver cells

1975 ◽  
Vol 146 (2) ◽  
pp. 457-464 ◽  
Author(s):  
J M Mourão ◽  
J D McGivan ◽  
J B Chappell
Keyword(s):  
Amino Acids ◽  
Nitrogen Source ◽  
Glutamate Dehydrogenase ◽  
Rat Liver ◽  
Liver Cells ◽  
Carbamoyl Phosphate ◽  
Isolated Cells ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat

With either alanine or a mixture of 15 different amino acids as nitrogen source, the addition of L-leucine inhibited the synthesis of urea by isolated rat liver cells. With alanine present leucine promoted the production of glutamate and glutamine. Comparison of effects of leucine on soluble glutamate dehydrogenase, mitochondria and isolated cells supports the postulate that leucine exerts its effect through activation of glutamate dehydrogenase. It is suggested that this latter enzyme may not be as important for the production of NH3 for carbamoyl phosphate synthesis as has been considered hitherto.

EFFECTS OF INSULIN AND GLUCAGON ON PRODUCTION OF RENIN SUBSTRATE BY THE ISOLATED RAT LIVER

1980 ◽  
Vol 85 (1) ◽  
pp. 151-153 ◽  
Author(s):  
EIKI MURAKAMI ◽  
KUNIO HIWADA ◽  
TATSUO KOKUBU
Keyword(s):  
Normal Control ◽  
Rat Liver ◽  
Liver Perfusion ◽  
Perfusion System ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Isolated Rat Liver ◽  
Rat Liver Perfusion ◽  
Isolated Rat

SUMMARY An isolated rat liver perfusion system was used to study the effects of insulin and glucagon on renin substrate production. Normal livers synthesized renin substrate at a rate of 28·3 ± 3·8 (s.e.m.) ng angiotensin I equiv./g liver each h (n = 8). The addition of insulin (more than 0·1 i.u.) to the perfusion significantly enhanced the production of renin substrate which was about twofold higher than normal control values (P< 0·001). However, glucagon (20 μg) did not affect the synthesis of renin substrate. These results indicated that insulin promoted the synthesis of renin substrate by the isolated rat liver.

Transport of the aromatic amino acids into isolated rat liver cells by a ‘T’ system

1985 ◽  
Vol 13 (4) ◽  
pp. 693-694
Author(s):  
MARK SALTER ◽  
RICHARD G. KNOWLES ◽  
CHRISTOPHER I. POGSON
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Aromatic Amino Acids ◽  
Liver Cells ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat ◽  
T System

scholarly journals Transport of the aromatic amino acids into isolated rat liver cells. Properties of uptake by two distinct systems

1986 ◽  
Vol 233 (2) ◽  
pp. 499-506 ◽  
Author(s):  
M Salter ◽  
R G Knowles ◽  
C I Pogson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Transport System ◽  
Aromatic Amino Acids ◽  
Liver Cells ◽  
Transport Systems ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat

The transport of the aromatic amino acids into isolated rat liver cells was studied. There was a rapid and substantial binding of the aromatic amino acids, L-alanine and L-leucine to the plasma membrane. This has important consequences for the determination of rates of transport and intracellular concentrations of the amino acids. Inhibition studies with a variety of substrates of various transport systems gave results consistent with aromatic amino acid transport being catalysed by two systems: a 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH)-insensitive aromatic D- and L-amino acid-specific system, and the L-type system (BCH-sensitive). The BCH-insensitive component of transport was Na+-independent and facilitated non-concentrative transport of the aromatic amino acids; it was unaffected by culture of liver cells for 24 h, by 48 h starvation, dexamethasone phosphate or glucagon. Kinetic properties of the BCH-inhibitable component were similar to those previously reported for the L2-system in liver cells. The BCH-insensitive component was a comparatively low-Km low-Vmax. transport system that we suggest is similar to the T-transport system previously seen only in human red blood cells. The results are discussed with reference to the importance of the T- and L-systems in the control of aromatic L-amino acid degradation in the liver.

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