Effect of insulin on protein turnover in heart muscle.

The rate of myocardial protein synthesis was studied in hearts of normal rabbits and in hearts of animals with experimentally produced cardiac hypertrophy and with acute and chronic myocardial failure. Cardiac hypertrophy was accompanied by an increase in protein synthesis; however, there was no increased myocardial protein turnover rate. In acute heart failure the rate of myocardial protein synthesis was diminished as compared to protein synthesis during the development of cardiac hypertrophy. In chronic heart failure the relative incorporation of glycine-2-C14 into heart muscle protein was diminished. The turnover rate of myocardial proteins during cardiac hypertrophy was not altered.

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Use of aromatic amino acids as monitors of protein turnover

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1981.240.6.e677 ◽

1981 ◽

Vol 240 (6) ◽

pp. E677-E681 ◽

Cited By ~ 4

Author(s):

I. H. Williams ◽

P. H. Sugden ◽

H. E. Morgan

Keyword(s):

Amino Acids ◽

Aspartate Aminotransferase ◽

Heart Muscle ◽

Protein Turnover ◽

Rat Heart ◽

Aromatic Amino Acids ◽

Mitochondrial Enzyme ◽

Perfused Rat Heart ◽

Net Production

Phenylalanine and tyrosine were metabolized by the perfused rat heart via a mitochondrial aminotransferase. When L-[alanyl-2,3-3H]phenylalanine and L-[alanyl-2,3-3H]tyrosine were used, release of 3H2O was progressive over 2 h of perfusion. Metabolism of L-[U-14C]phenylalanine to 14CO2 or production of 3H2O from L-[ring-2,6–3H]phenylalanine or L-[ring-2,6-3H]tyrosine was not detected. Although 3H2O production from L-[alanyl-2,3-3H]phenylalanine was rapid, net production of phenylpyruvate or other metabolites of phenylalanine was negligible. As a result, use of aromatic amino acids as monitors of protein turnover in heart muscle was validated. Production of 3H2O from L-[alanyl-2,3-3H]phenylalanine was catalyzed by a mitochondrial enzyme, which is thought to be aspartate aminotransferase (EC 2.6.1.1). The rate of 3H2O production by both intact and detergent-treated mitochondria exceeded that of phenylpyruvate by a factor of 10 and occurred in the absence of alpha-ketoglutarate. These data provide an explanation for the production of 3H2O from L-[alanyl-2,3-3H]phenylalanine by perfused rat heart without the concomitant production of [3H]phenylpyruvate.

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Factors Controlling Protein Turnover in Heart Muscle

Circulation Research ◽

10.1161/res.35.3_supplement.iii-22 ◽

1974 ◽

Vol 35 (3_supplement) ◽

Author(s):

H. E. Morgan ◽

D. E. Rannels ◽

R. L. Kao

Keyword(s):

Heart Muscle ◽

Protein Turnover

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Effects of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle as measured by [14C]tyrosine infusion

Biochemical Journal ◽

10.1042/bj2040069 ◽

1982 ◽

Vol 204 (1) ◽

pp. 69-74 ◽

Cited By ~ 24

Author(s):

W J Carter ◽

W S V W Benjamin ◽

F H Faas

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Cardiac Muscle ◽

Heart Muscle ◽

Protein Turnover ◽

Cardiac Myocyte ◽

Muscle Protein ◽

Muscle Growth ◽

Protein Breakdown ◽

Fractional Rate

The effect of T3 (3,3′,5-tri-iodothyronine) on protein turnover in skeletal and cardiac muscle was measured in intact rats by means of a 6 h [14C]tyrosine-infusion technique. Treatment with 25-30 micrograms of T3/100 g body wt. daily for 4-7 days increased the fractional rate of protein synthesis in skeletal muscle. Since the fractional growth rate of the muscle was decreased or unchanged, T3 treatment increased the rate of muscle protein breakdown. These findings suggest that increased protein degradation is an important factor in decreasing skeletal-muscle mass in hyperthyroidism. In contrast with skeletal muscle, T3 treatment for 7 days caused an equivalent increase in the rate of cardiac muscle growth and protein synthesis. This suggests that hyperthyroidism does not increase protein breakdown in heart muscle as it does in skeletal muscle. The failure of T3 to increase proteolysis in heart muscle may be due to a different action on the cardiac myocyte or to systemic effects of T3 which increase cardiac work.

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The Quantitative Ultrastructure of the Heart Muscle of Japanese Quail by Hypergravitation, Hypodynamy and Combination

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100158480 ◽

1990 ◽

Vol 48 (3) ◽

pp. 188-189

Author(s):

Anton Bózner ◽

Mikuláš Gažo ◽

Jozef Dostál

Keyword(s):

Japanese Quail ◽

Heart Muscle ◽

Relative Size ◽

Combination Group ◽

Control Group ◽

Group V ◽

Group Iii ◽

Space Flights ◽

Group I ◽

Quantitative Ultrastructure

It is anticipated that Japanese quail /Coturnix coturnix japonica/ will provide animal proteins in long term space flights. Consequently this species of birds is of research interest of international space program INTERCOSMOS. In the year 1987 we reported on an experiment /2/ in which the effect of chronic acceleration of 2 G hypergravitation, the hypodynamy and the simultaneous effect of chronic acceleration and the location in the centre of the turntable of the centrifuge on the protein fractions in skeletal muscles was studied. The ultrastructure of the heart muscle was now in this experiments examined as well.Japanese quail cockerels, aged 48 days were exposed to 2 G hypergravitation /group IV/ in a 6,4 m diameter centrifuge, to hypodynamy /group III/ and their combination /group V/, respectively for 6 days / Fig.1/. The hypodynamy in group III was achieved by suspending the birds in jackets without contact the floor. The group II was located in the centre ofthe turntable of the centrifuge. The control group I. was kept under normal conditions. The quantitative ultrastructure of myocard was evaluated by the methods of Weibel/3/ - this enables to determine the number, relative size and volume of mitochondria volume of single mitochondria, defficiency of mitochondrial cristae and volume of myofibrils.

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