Extensive changes in collagen synthesis and degradation during compensatory lung growth

1988 ◽  
Vol 255 (6) ◽  
pp. C754-C759 ◽  
Author(s):  
R. J. McAnulty ◽  
L. H. Staple ◽  
D. Guerreiro ◽  
G. J. Laurent
Keyword(s):  
Protein Synthesis ◽  
Collagen Synthesis ◽  
Collagen Degradation ◽  
Lung Growth ◽  
Compensatory Lung Growth ◽  
Fractional Rate ◽  
Degradation Rates ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Unilateral pneumonectomy in rats causes compensatory growth of the remaining lung. This growth involves rapid production of collagen and noncollagen proteins, but the mechanisms for these changes have not been fully investigated. Rates of collagen metabolism were measured using previously validated in vivo methods. Six days after pneumonectomy, a threefold increase in the fractional rate of collagen synthesis was observed (control 11.8 +/- 0.9%/day, pneumonectomy 30.0 +/- 4.6%/day). Collagen degradation rates also increased but returned to normal more rapidly than the synthesis rates. These changes in synthesis and degradation resulted in a 75% increase in collagen content by 28 days. Although degradation of extracellular collagens was apparently increased, the fraction degraded intracellularly decreased by approximately 30%. Noncollagen protein synthesis and degradation rates both increased by approximately 80% (control 44.3 +/- 3.4%/day, pneumonectomy 80.3 +/- 10.2%/day) with a slightly greater increase in synthesis that led to an 85% increase in noncollagen protein content 28 days after pneumonectomy. The data obtained show dramatic changes in protein synthesis and degradation during compensatory lung growth and indicate extensive remodeling of structural elements in lung tissue. The changes for intracellular collagen degradation provide further evidence that this pathway may have an important role in regulating collagen deposition.

scholarly journals Effect of hypophysectomy on the rates of protein synthesis and degradation in rat liver

1979 ◽  
Vol 178 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R D Conde
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Rat Liver ◽  
Protein Metabolism ◽  
Plasma Proteins ◽  
Degradation Rates ◽  
Hypophysectomized Rats ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of hypophysectomy on the protein metabolism of the liver in vivo was studied. Fractional rates of protein synthesis and degradation were determined in the livers of normal and hypophysectomized rats. Synthesis was measured after the injection of massive amounts of radioactive leucine. Degradation was estimated either as the balance between synthesis and accumulation of stable liver proteins or from the disappearance of radioactivity from the proteins previously labelled by the injection of NaH14CO3. The results indicate that: (1) hypophysectomy diminishes the capacity of the liver to synthesize proteins in vivo, mainly of those that are exported as plasma proteins; (2) livers of both normal and hypophysectomized rats show identical protein-degradation rates, whereas plasma proteins are degraded slowly after hypophysectomy.

scholarly journals A comparison of rates of protein turnover in rat diaphragm in vivo and in vitro

1986 ◽  
Vol 233 (1) ◽  
pp. 279-282 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Rat Diaphragm ◽  
Degradation Rates ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Protein synthesis and degradation rates in diaphragms from fed or starved rats were compared in vivo and in vitro. For fed rats, synthesis rates in vivo were approximately twice those in vitro, but for starved rats rates were similar. Degradation rates were less in vivo than in vitro in diaphragms from either fed or starved rats.

Human protein metabolism: its measurement and regulation

2002 ◽  
Vol 283 (6) ◽  
pp. E1105-E1112 ◽  
Author(s):  
Zhenqi Liu ◽  
Eugene J. Barrett
Keyword(s):  
Protein Synthesis ◽  
Whole Body ◽  
Body Protein ◽  
Architectural Support ◽  
Protein Mass ◽  
Protein Pool ◽  
Tracer Kinetic ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The body's protein mass not only provides architectural support for cells but also serves vital roles in maintaining their function and survival. The whole body protein pool, as well as that of individual tissues, is determined by the balance between the processes of protein synthesis and degradation. These in turn are regulated by interactions among hormonal, nutritional, neural, inflammatory, and other influences. Prolonged changes in either the synthetic or degradative processes (or both) that cause protein wasting increase morbidity and mortality. The application of tracer kinetic methods, combined with measurements of the activity of components of the cellular signaling pathways involved in protein synthesis and degradation, affords new insights into the regulation of both protein synthesis and breakdown in vivo. These insights, including those from studies of insulin, insulin-like growth factor I, growth hormone, and amino acid-mediated regulation of muscle and whole body protein turnover, provide opportunities to develop and test therapeutic approaches with promise to minimize or prevent these adverse health consequences.

scholarly journals Contribution of whole-body protein synthesis to basal metabolism in layer and broiler chickens

1987 ◽  
Vol 57 (2) ◽  
pp. 269-277 ◽  
Author(s):  
T. Muramatsu ◽  
Y. Aoyagi ◽  
J. Okumura ◽  
I. Tasaki
Keyword(s):  
Protein Synthesis ◽  
Broiler Chickens ◽  
Whole Body ◽  
Synthesis Rate ◽  
Body Protein ◽  
Fractional Synthesis Rate ◽  
Degradation Rates ◽  
Fractional Synthesis ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

1. The effect of starvation on whole-body protein synthesis and on the contribution of protein synthesis to basal metabolic rate was investigated in young chickens (Expt 1). Strain differences between layer and broiler chickens in whole-body protein synthesis and degradation rates were examined when the birds were starved (Expt 2).2. In Expt 1, 15-d-old White Leghorn male chickens were used, while in Expt 2 Hubbard (broiler) and White Leghorn (layer) male chickens at 14 d of age were used. They were starved for 4 d, and heat production was determined by carcass analysis after 2 and 4 d of starvation. Whole-body protein synthesis rates were measured on 0, 2 and 4 d of starvation (Expt 1), and on 0 and 4 d of starvation (Expt 2).3. The results showed that starving reduced whole-body protein synthesis in terms of fractional synthesis rate and the amount synthesized. Whole-body protein degradation was increased by starvation both in terms of fractional synthesis rate and the amount degraded on a per kg body-weight basis.4. Reduced fractional synthesis rate of protein in the whole body was accounted for by reductions in both protein synthesis per unit RNA and RNA:protein ratio.5. In the fed state, whole-body protein synthesis and degradation rates, whether expressed as fractional rates or amounts per unit body-weight, tended to be higher in layer than in broiler chickens. In the starved state, the difference in the rate of protein synthesis between the two strains virtually disappeared, while the degradation rates were higher in layer than in broiler birds.6. Based on the assumed value of 3.56 kJ/g protein synthesized (Waterlow et al. 1978), the heat associated with whole-body protein synthesis in the starved state was calculated to range from 14 to 17% of the basal metabolic rate with no strain difference between layer and broiler chickens.

scholarly journals The effect of insulin and intermittent mechanical stretching on rates of protein synthesis and degradation in isolated rabbit muscle

1985 ◽  
Vol 230 (1) ◽  
pp. 117-123 ◽  
Author(s):  
R M Palmer ◽  
P A Bain ◽  
P J Reeds
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Suppressive Effect ◽  
Rabbit Muscle ◽  
Degradation Rates ◽  
Forelimb Muscles ◽  
Amino Acid Balance ◽  
Mechanical Stretching ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Tyrosine balance and protein synthesis were studied during the same incubation in isolated rabbit forelimb muscles. From these measurements, protein degradation was calculated. Isolated muscles were usually in a state of negative amino acid balance, principally as a result of the 75% decrease in protein synthesis. Muscles from rabbits starved for 18 h had lower rates of both protein synthesis and degradation compared with muscles from normally fed rabbits. Intermittent mechanical stretching and the addition of insulin at 100 microunits/ml increased rates of both protein synthesis and degradation. Increases in the rate of protein synthesis were proportionately greater in the muscles from starved animals. In muscles from both fed and starved donors, increases in protein-synthesis rates owing to intermittent stretching and insulin were proportionately greater than the increases in degradation rates. For example, insulin increased the rate of protein synthesis in the muscles from starved donors by 111% and the rate of degradation by 31%. Insulin also increased the rate of protein synthesis when added at a higher concentration (100 munits/ml); at this concentration, however, the rate of protein degradation was not increased. The suppressive effect of insulin on high rates of protein degradation in other skeletal-muscle preparations may reflect a non-physiological action of the hormone.

Cardiac protein synthesis and degradation during thyroxine-induced left ventricular hypertrophy

1986 ◽  
Vol 251 (5) ◽  
pp. C727-C736 ◽  
Author(s):  
M. S. Parmacek ◽  
N. M. Magid ◽  
M. Lesch ◽  
R. S. Decker ◽  
A. M. Samarel
Keyword(s):  
Protein Synthesis ◽  
Left Ventricular Hypertrophy ◽  
Total Protein ◽  
Ventricular Hypertrophy ◽  
Left Ventricular ◽  
Protein Accumulation ◽  
The Difference ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Assessment of cardiac protein metabolism in thyroxine-induced left ventricular hypertrophy requires measurements of both protein synthesis and degradation. In vivo protein degradative rates can best be measured as the difference between rates of protein synthesis and growth. Accordingly, rates of left ventricular protein accumulation were determined in growing rabbits, and in animals administered intravenous L-thyroxine (200 micrograms X kg-1 X day-1) for up to 15 days. Left ventricular protein fractional synthetic rates in euthyroid and thyroxine-treated rabbits were measured by continuous infusion of [3H]leucine (200 mu Ci/h X 6 h), and results converted to milligrams protein synthesized and degraded per day. Thyroxine administration produced left ventricular hypertrophy by increasing the rate of total protein synthesis (35.7 +/- 2.0, 71.0 +/- 7.0, and 62.6 +/- 4.0 mg of left ventricular protein synthesized per day for 0-, 3-, and 9-day, thyroxine-treated rabbits, respectively). However, the increased rate of total protein synthesis was greater than the measured rate of total protein accumulation (8.1 vs. 15.9 mg protein/day for euthyroid and thyroxine-treated animals), indicating that left ventricular protein degradative rates were increased as well. These studies indicate that accelerated proteolysis may be important in the molecular and architectural remodeling of the rapidly hypertrophying heart during thyrotoxicosis.

scholarly journals Atrophic Remodeling of the Heart In Vivo Simultaneously Activates Pathways of Protein Synthesis and Degradation

Circulation ◽  
2003 ◽  
Vol 108 (20) ◽  
pp. 2536-2541 ◽  
Author(s):  
Peter Razeghi ◽  
Saumya Sharma ◽  
Jun Ying ◽  
Yi-Ping Li ◽  
Stanislaw Stepkowski ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation
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