Amino Acid Regulation of Albumin Synthesis

Rothschild, Marcus A.; Oratz, Murray; Mongelli, Joseph; Fishman, Louis; Schreiber, S. S.

doi:10.1093/jn/98.4.395

Cited by 128 publications

(46 citation statements)

References 19 publications

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“…It lately has been recognized that specific amino acids may stimulate synthesis or secretion, or both, of other polypeptides and protein. Leucine stimulates insulin release (28), arginine stimulates growth hormone secretion (29), and tryptophan and isoleucine stimulate albumin synthesis (30). Amino acids with these properties all are of the "essential" variety, a connotation which may come to include an essential function in metabolic control as well as in the regulation of normal growth.…”

Section: Discussionmentioning

confidence: 99%

Pancreozymin bioassay in man based on pancreatic enzyme secretion: potency of specific amino acids and other digestive products

Go¹,

Hofmann²,

Summerskill³

1970

J. Clin. Invest.

239

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AB S T R A C T The ability of products of digestion to stimulate pancreozymin secretion in man was investigated using a bioassay procedure, based on duodenal perfusion, which quantified the total outputs of pancreatic enzymes evoked by intraduodenal stimuli under steady-state conditions. Patterns of response resulting from physiologic intraduodenal concentrations of test material were basal output (with isotonic saline), washout of enzymes (with dextrose, micellar fatty acid, and amino acids), and sustained output of enzymes (with amino acids and micellar fatty acid). The sustained secretion of pancreatic enzymes found during the 2nd hr of perfusion and subsequently was characteristic of pancreozymin-induced secretion. The enzyme output in response to a mixture of essential and nonessential amino acids was significantly higher than that evoked by micellar fatty acid and was comparable with that resulting from the maximally tolerated dose of pancreozymin given by vein.Perfusion with essential amino acids caused enzyme outputs comparable to those induced by perfusion with the original amino acid mixture, whereas perfusion with nonessential amino acids had no effect. When the essential amino acids were tested individually, only phenylalanine, methionine, and valine caused significant increases in pancreatic enzyme output; the effect of tryptophan was indeterminate. However, the pancreatic enzyme output was less in response to these three essential amino acids than to mixtures containing all of them.

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Section: Discussionmentioning

confidence: 99%

Pancreozymin bioassay in man based on pancreatic enzyme secretion: potency of specific amino acids and other digestive products

Go¹,

Hofmann²,

Summerskill³

1970

J. Clin. Invest.

239

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“…Tubes were read at 278 m/A. The fraction of the first peak, from the midpoint of the ascending slope to the peak of this slope were pooled and portions examined by qualitative polyacrylamide electrophoresis (8) and immunoelectrophoresis (12) at a 6% protein level.…”

Section: Methodsmentioning

confidence: 99%

“…Since arginine is the immediate precursor not only of the arginine residue in albumin but also of urea, a direct product precursor relationship exists as has been described by Swick (4), Reeve, Pearson, and Martz (5), and McFarlane (6). This technique has been examined in detail in numerous publications (3)(4)(5)(6)(7)(8). After 30 min of perfusion (control and experimental) 100 /ACi of carbonate-"C (specific activity 5 mCi/mmole) was injected directly into the inflow tube to the portal vein and the perfusion continued for 2.5 hr.…”

Section: Introductionmentioning

confidence: 99%

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Alcohol-induced depression of albumin synthesis: reversal by tryptophan

Rothschild¹,

Oratz²,

Mongelli³

et al. 1971

J. Clin. Invest.

121

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A B S T R A C T The influence of alcohol on albumin synthesis was studied in the isolated perfused rabbit liver. Carbonate-"C was used to label the intracellular arginine pool which serves as the precursor of both the carbon of urea and the guanido carbon of arginine in albumin. The control group synthesized albumin at a rate of 33 mg/100 g of wet liver weight during 2.5 hr of perfusion. When alcohol, 220 mg/100 ml, was added to the perfusate, albumin synthesis decreased to between 7 and 11 mg, less than one-third the control rate. The addition of 10 mm tryptophan to perfusates containing alcohol prevented most of the inhibitory effects and albumin synthesis increased to average 24 mg. Further, the addition of alcohol to the perfusate decreased the hepatic protein/DNA ratio from 70 to 54 and the RNA/DNA ratio from 2.3 to 1.8, changes equivalent to those seen after a 24 hr fast. The addition of tryptophan to the perfusate prevented these findings in both instances.Endoplasmic membrane-bound polysomes were examined for aggregation. Alcohol decreased the quantity of heavier aggregates. Reaggregation occurred when tryptophan was added but quantitative changes in albumin synthesis could not be related to the degree of reaggregation.

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“…The administration of tryptophan alone to mice or rats rapidly induced enhanced hepatic protein synthesis, whereas no other single amino acid had such an effect (29). Others have confirmed the stimulatory effect of tryptophan on hepatic protein synthesis (3,13,(19)(20)(21)(22)24). Subsequently, many studies concerned with the mechanism of the unique effect of tryptophan have revealed the following findings, which they claim are attributable to tryptophan: increased cytoplasmic mRNA(poly[A]mRNA) (15,16), probably related to increased translocation of mRNA from nuclei to cytoplasm (17,18,28); stimulation of the activities of enzymes associated with nuclear efflux of mRNA (14) and of nuclear poly(A)polymerase (10); and nuclear-envelope tryptophan binding and stimulation of poly(A)polymerase activity (10), which appeared to be related to increased nuclear mRNA efflux (28).…”

Section: Introductionmentioning

confidence: 99%