PHENYLALANINE METABOLISM IN SHEEP INFUSED WITH GLUCOSE PLUS INSULIN. II. EFFECTS ON IN VIVO AND IN VITRO PROTEIN SYNTHESIS AND RELATED ENERGY EXPENDITURES

1988 ◽  
Vol 68 (3) ◽  
pp. 721-730 ◽  
Author(s):  
RICHARD J. EARLY ◽  
BRIAN W. McBRIDE ◽  
RONALD O. BALL
Keyword(s):  
Protein Synthesis ◽  
Gastrocnemius Muscle ◽  
Specific Radioactivity ◽  
Intercostal Muscle ◽  
Energy Expenditures ◽  
Phenylalanine Metabolism ◽  
Arterial Plasma ◽  
Vitro Protein

In vivo fractional rates of protein synthesis (FSR), based on both intracellular fluid (ICF) and arterial plasma specific radioactivity (SRA), were determined for the external intercostal muscle (EIC), gastrocnemius muscle, liver and kidneys of growing sheep during infusions of either saline or glucose (2 g h−1) plus insulin (1.2 U h−1; G+I). In vitro FSR and energy expenditures associated with protein synthesis (cycloheximide-sensitive respiration) and Na+, K+ transport (ouabain-sensitive respiration) were also determined in EIC muscle. In vivo FSR based on ICF SRA in muscle were not significantly different between G+I and S infused sheep (5.2 vs. 4.2% d−1 and 5.0 vs. 3.2% d−1 for EIC and gastrocnemius, respectively). In vivo FSR in the liver (54 vs. 61% d−1) and kidneys (38 vs. 55% d−1) were also not significantly different between G+I versus S infused sheep. Based on plasma SRA, FSR in all tissues were unaffected by treatments and were less (P < 0.05) than those calculated from ICF SRA. In vitro FSR and the energy expenditures associated with protein synthesis and Na+, K+ transport were not affected by G+I infusions. The average in vitro FSR in isolated EIC muscle (2.7% d−1) was 53% and 81% of the average in vivo FSR calculated from ICF and plasma SRA, respectively. Compared to data reported for nonruminants, these data suggest that rates of protein synthesis and energy expenditures associated with protein synthesis in ruminants are less influenced by insulin and glucose. Key words: Sheep, protein synthesis, insulin, glucose, Na+, K+ transport

Use of an in Vitro Protein Synthesizing System to Test the Mode of Action of Chloracetamides

Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Luanne M. Deal ◽  
J. T. Reeves ◽  
B. A. Larkins ◽  
F. D. Hess
Keyword(s):  
Protein Synthesis ◽  
Sand Culture ◽  
Leucine Incorporation ◽  
Insoluble Protein ◽  
In Vitro System ◽  
A Cell ◽  
Protein Incorporation ◽  
Vitro Protein

The effects of chloracetamides on protein synthesis were studied both in vivo and in vitro. Four chloracetamide herbicides, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], CDAA (N–N-diallyl-2-chloroacetamide), and propachlor (2-chloro-N-isopropylacetanilide) were tested for inhibition of [3H]-leucine incorporation into protein. Incorporation of3H-leucine into trichloroacetic acid (TCA)-insoluble protein was inhibited in oat (Avena sativaL. ‘Victory’) seedlings grown in sand culture and treated 12 h at 1 × 10−4M with these chloracetamides. The herbicides were also tested in a cell-free protein synthesizing system containing polyribosomes purified from oat root cytoplasm. These herbicides had no effect on the rates of polypeptide elongation nor on the synthesis of specific polypeptides when herbicides (1 × 10−4M) were added directly to the system. Polypeptide formation was inhibited 89% when 1 × 10−4M cycloheximide was added during translation. Cytoplasmic polyribosomes were isolated from oat roots treated 12 h with 1 × 10−4M herbicide. Translation rates and products were not altered when these polyribosomes were added to the in vitro system. Protein synthesis is inhibited when tested in an in vivo system; however, the inhibition does not occur during the translation of mRNA into protein.

Extreme hyperinsulinemia unmasks insulin’s effect to stimulate protein synthesis in the human forearm

1998 ◽  
Vol 274 (6) ◽  
pp. E1067-E1074 ◽  
Author(s):  
Teresa A. Hillier ◽  
David A. Fryburg ◽  
Linda A. Jahn ◽  
Eugene J. Barrett
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
In Vivo Studies ◽  
Skeletal Muscle Protein ◽  
High Concentrations ◽  
Arterial Plasma ◽  
Stimulation Of

Insulin clearly stimulates skeletal muscle protein synthesis in vitro. Surprisingly, this effect has been difficult to reproduce in vivo. As in vitro studies have typically used much higher insulin concentrations than in vivo studies, we examined whether these concentration differences could explain the discrepancy between in vitro and in vivo observations. In 14 healthy volunteers, we raised forearm insulin concentrations 1,000-fold above basal levels while maintaining euglycemia for 4 h. Amino acids (AA) were given to either maintain basal arterial ( n = 4) or venous plasma ( n = 6) AA or increment arterial plasma AA by 100% ( n = 4) in the forearm. We measured forearm muscle glucose, lactate, oxygen, phenylalanine balance, and [3H]phenylalanine kinetics at baseline and at 4 h of insulin infusion. Extreme hyperinsulinemia strongly reversed postabsorptive muscle’s phenylalanine balance from a net release to an uptake ( P < 0.001). This marked anabolic effect resulted from a dramatic stimulation of protein synthesis ( P < 0.01) and a modest decline in protein degradation. Furthermore, this effect was seen even when basal arterial or venous aminoacidemia was maintained. With marked hyperinsulinemia, protein synthesis increased further when plasma AA concentrations were also increased ( P< 0.05). Forearm blood flow rose at least twofold with the combined insulin and AA infusion ( P< 0.01), and this was consistent in all groups. These results demonstrate an effect of high concentrations of insulin to markedly stimulate muscle protein synthesis in vivo in adults, even when AA concentrations are not increased. This is similar to prior in vitro reports but distinct from physiological hyperinsulinemia in vivo where stimulation of protein synthesis does not occur. Therefore, the current findings suggest that the differences in insulin concentrations used in prior studies may largely explain the previously reported discrepancy between insulin action on protein synthesis in adult muscle in vivo vs. in vitro.

Protein metabolism by rat lung: influence of fasting, glucose, and insulin

1977 ◽  
Vol 43 (3) ◽  
pp. 463-467 ◽  
Author(s):  
L. A. Thet ◽  
M. D. Delaney ◽  
C. A. Gregorio ◽  
D. Massaro
Keyword(s):  
Protein Synthesis ◽  
Protein Content ◽  
Protein Metabolism ◽  
Specific Radioactivity ◽  
Rat Lung ◽  
Synthetic Process ◽  
In Vitro System ◽  
Other Substances

We studied protein metabolism by rat lung slices. We found that phenylalanine is not metabolized to other substances by the lung and that the rate of incorporation of L-[U-14C]phenylalanine into protein, calculated using its intracellular specific radioactivity, reached a maximum within 20 min and remained stable for the rest of a 3-h incubation. The rate of protein degradation, determined using [12C]phenylalanine as a marker, was linear over a 3-h incubation. Fasting for 3 days slowed the increase in lung protein content of fasted compared to nonfasted rats; there was also a decrease in protein synthesis and an increase in proteolysis. In fed rats, glucose, insulin, and glucose plus insulin did not alter protein synthesis. Glucose, insulin alone, and glucose plus insulin decreased proteolysis. We conclude that the in vitro system reflected changes in the in vivo protein content of the lung. Fasting decreases protein synthesis and increases proteolysis. Glucose and insulin alone modulate protein metabolism in the lung by acting on the degradative rather than the synthetic process.

In vivo and In vitro protein synthesis of oviducal pars recta by estradiol effect

1992 ◽  
Vol 102 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Zulema C. Mansilla-Whitacre ◽  
Silvia N. FernÁndez ◽  
Dora C. Miceli
Keyword(s):  
Protein Synthesis ◽  
In Vitro Protein Synthesis ◽  
Pars Recta ◽  
Vitro Protein

Action of synergimycins and macrolides on in vivo and in vitro protein synthesis in archaebacteria

1985 ◽  
Vol 199 (2) ◽  
pp. 323-329 ◽  
Author(s):  
M. Di Giambattista ◽  
H. Hummel ◽  
A. Böck ◽  
C. Cocito
Keyword(s):  
Protein Synthesis ◽  
In Vitro Protein Synthesis ◽  
Vitro Protein

Antimalarials: Effects on in vivo and in vitro Protein Synthesis

Science ◽  
1970 ◽  
Vol 170 (3963) ◽  
pp. 1213-1214 ◽  
Author(s):  
K. A. Conklin ◽  
S. C. Chou
Keyword(s):  
Protein Synthesis ◽  
In Vitro Protein Synthesis ◽  
Vitro Protein

scholarly journals The specific radioactivity of the tissue free amino acid pool as a basis for measuring the rate of protein synthesis in the rat in vivo

1974 ◽  
Vol 142 (2) ◽  
pp. 413-419 ◽  
Author(s):  
Edward B. Fern ◽  
Peter J. Garlick
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Gastrocnemius Muscle ◽  
Specific Radioactivity ◽  
Amino Acid Pool ◽  
Free Amino Acid Pool ◽  
Acid Pool

1. Rats were infused in vivo with [U-14C]glycine for periods of 2–6h, during which time the specific radioactivity of the free glycine in plasma and tissue approached a constant value. 2. Free serine also became labelled. The ratio of specific radioactivity of serine to that of glycine in the protein of liver, kidney, brain, jejunum, heart, diaphragm and gastrocnemius muscle was closer to the ratio in the free amino acid pool of the tissue than that of the plasma. 3. The kinetics of incorporation of [14C]glycine and [14C]serine into the protein of gastrocnemius muscle further suggested that the plasma free amino acids were not the immediate precursors of protein. 4. Infusion of rats with [U-14C]serine resulted in labelling of free glycine. The ratio of specific radioactivity of glycine to serine in the protein of liver, kidney, brain, jejunum and heart again suggested incorporation from a pool similar to the free amino acid pool of the tissue. 5. Rates of tissue protein synthesis calculated from the incorporation into protein of both radioactive glycine and serine, either infused or derived, were very similar when the precursor specific radioactivity was taken to be that in the total free amino acids of the tissue. Except for gastrocnemius muscle and diaphragm during the infusion of radioactive serine, the rates of tissue protein synthesis calculated from the specific radioactivity of the free glycine and serine in plasma differed markedly.

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