Free Amino Acids In Liver Research Articles

Free amino acids in liver of patients with homocystinuria due to cystathionine synthase deficiency: Effects of vitamin B 6

Patients with homocystinuria due to cystathionine synthase deficiency do not have free homocystine in the liver when it is present in high concentrations in the plasma and the urine. The liver of these patients is capable of maintaining normal concentrations of cystine at a time when the plasma cystine concentration is severely reduced. There is an increase in the methionine concentration of the liver which is reduced to normal concentrations during pyridoxine therapy.

Relation between Liver Amino Acid-Catabolizing Enzymes and Free Amino Acids of Liver and Plasma in Adult Cockerels Fed Diets Containing Graded Levels of Protein

Activities of liver amino acid-catabolizing enzymes and liver and plasma free amino acid concentrations in adult cockerels fed diets containing 3% to 21% casein were determined 2 hours after a meal. Liver tryptophan pyrrolase activity and liver tryptophan increased with an increase in dietary casein level, but plasma tryptophan decreased with the increase dietary casein level. As the dietary casein level increased, liver lysine-ketoglutarate reductase activity decreased, but liver and plasma lysine increased proportionally, and the rate of increase was larger in the plasma than in the liver. Liver phenylalanine hydroxylase activity increased with the increase in dietary casein level from 3% to 12%, and thereafter remained unchanged. Reflecting the change of this enzyme, phenylalanine increased in the liver and decreased in the plasma with the increase in dietary casein level from 3% to 12%, and thereafter the rate of increase in liver phenylalanine became small and plasms phenylalanine increased. Liver tyrosine was not influenced by the dietary casein level, whereas plasma tyrosine increased sharply from 3% to 12%, and thereafter the rate of increase decreased. Thus, the difference between liver and plasma free amino acid responses might be due to the changes in the activities of liver amino acid-catabolizing enzymes.

L-dihydroxyphenylalanine: effect on levels of free amino acids in rat liver.

SummaryThe concentrations of liver free amino acids in l-Dopa-treated and control rats were assayed by a Jeol amino acid analyzer. Subcutaneous injections of 500 mg/kg l-Dopa daily for 8 days incre...

The influence of excess methionine on the free amino acids of brain and liver of the weanling rat.

Abstract— —High circulating levels of l‐methionine produced by inclusion in the diet or parenteral injection of the amino acid caused alterations in the free amino acid pattern of liver and brain tissues. Acute effects following l‐methionine injection were more pronounced than those following long term feeding where adaptation played a role. The net effect following parenteral injection was to increase the total free amino acids of liver while decreasing those of brain.Individually, hepatic levels of aspartic acid, threonine, serine, glutamine, glutamic acid, glycine, and alanine were depressed while levels of taurine, cystathionine, methionine, lysine, and ornithine were markedly elevated. Brain levels of aspartic acid, threonine, serine, glutamic acid, glycine, alanine, and γ‐aminobutyric acid were markedly depressed and increased levels of cystathionine, methionine, lysine, and glutamine were observed.A generalized aminoaciduria occurred shortly after excessive methionine intake.Disruption of the free amino acid pools was of two kinds. The first depended on the continued presence of excess l‐methionine, the second did not.

Modification by 8-Azaguanine of the Effects of Hydrocortisone on the Induction and Inactivation of Tyrosine Transaminase of Rat Liver

Abstract Although the hydrocortisone-mediated induction of hepatic tyrosine transaminase (l-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) is not inhibited by the administration of 8-azaguanine with the hormone, the later phases of the induction cycle are drastically modified. Within 6 hours after administering hydrocortisone to adrenalectomized rats (controls), the enzyme activity begins to return from the induced to the basal level. In contrast, the activity rises to approximately 30% above the induced level of the controls (i.e. is superinduced) in animals treated simultaneously with hydrocortisone and 8-azaguanine. The activity is maintained at this superinduced level for approximately 3 hours before falling to the induced level of the controls. There follows another phase in animals receiving both hydrocortisone and 8-azaguanine during which the activity is maintained at or near the induced level until approximately 18 hours after hormone administration (i.e. 12 hours later than in the controls). The delay in the fall of enzyme activity, but not the superinduction phenomenon, is observed when the analogue is administered 4 hours after hydrocortisone. Results of experiments in which 8-azaguanine was given 4 or 5.5 hours after the hormone indicate that there is a lag of approximately 2 hours before the analogue becomes effective in this system. Other bases having primary amino groups (guanine, cytosine, or adenine), when given in conjunction with hydrocortisone, elicit the superinduction but not the maintenance of enzyme activity. Bases without primary amino groups (uracil or 8-azaxanthine) do not alter the induction cycle. Preliminary treatment of rats receiving 8-azaguanine and hydrocortisone, with 4-amino-5-imidazolecarboxamide, abolishes the superinduction phase but not the prolonged maintenance of enzyme activity at or near the induced level. The data indicate that the superinduction and the maintenance phenomena can be dissociated. It appears that the superinduction is due to an increase in free amino acids in liver following ammonia production by deamination of the bases; on the other hand, the delay in the fall of tyrosine transaminase activity, which is restricted to 8-azaguanine-treated rats, appears to be a consequence of the incorporation of the analogue into RNA.

Free amino acids in liver, plasma, and muscle of patients with cirrhosis of the liver

A significant decrease in concentration of branched-chain amino acids in skeletal muscle of cirrhotic patients has been observed. These data are presented in further support of the concept that a relative deficiency of these amino acids may be present in cirrhotic patients.

Nature of the free amino-acid pool in avian tissues.

IN an earlier report from these laboratories1 we demonstrated significant diurnal changes in protein, nucleic and seven free amino-acids of liver during the active involvement stage of a mild Newcastle disease virus (NDV) infection in chicks. The investigations have now been extended to include a comparison of liver and serum levels of these parameters during the incubation stage of NDV.

Free amino-acids in liver and blood after partial hepatectomy in normal and adrenalectomized rats.

The Journal of PhysiologyVolume 124, Issue 3 p. 443-463 ArticleFree Access Free amino-acids in liver and blood after partial hepatectomy in normal and adrenalectomized rats V. Ferrari, V. FerrariSearch for more papers by this authorR. D. Harkness, R. D. HarknessSearch for more papers by this author V. Ferrari, V. FerrariSearch for more papers by this authorR. D. Harkness, R. D. HarknessSearch for more papers by this author First published: 28 June 1954 https://doi.org/10.1113/jphysiol.1954.sp005120Citations: 37AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume124, Issue3June 28, 1954Pages 443-463 RelatedInformation