Effects of thyroxine on protein turnover in rat skeletal muscle

K. E. Flaim, J. B. Li, Leonard "Jim" Jefferson

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The effects of thyroxine (T4) on protein turnover in skeletal muscle were studied using normal, thyroidectomized (thyrex), and hypophysectomized (hypox) rats. Thyrex rats had a depressed growth rate that was accompanied by 50% reductions in the levels of RNA and the rate of protein synthesis in gastrocnemius muscle, as determined in the perfused hemicorpus. Protein synthetic efficiency (protein synthesis per unit RNA) was decreased by 18%. Daily treatment of thyrex rats with T4 at different dose levels for up to 16 days led to improved growth rates, elevated RNA concentrations, and increased protein synthesis rates. The primary effect of T4 was to increase the protein synthetic capacity of muscle. Protein degradation, determined in the perfused hemicorpus, and activity of a lysosomal protease, determined in unperfused muscle, were reduced in the thyrex condition. Treatment of thyrex rats with T4 increased protein degradative rates, but not protease activity. Hypox rats, which also exhibited depressed skeletal muscle protein synthesis, responded to T4 and combined T4 and growth hormone with marked improvements in protein synthesis.

Original languageEnglish (US)
JournalAmerican Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology
Volume4
Issue number2
StatePublished - Jan 1 1978

Fingerprint

Thyroxine
Skeletal Muscle
Proteins
RNA
Peptide Hydrolases
Muscles
Muscle Proteins
Growth
Proteolysis
Growth Hormone

All Science Journal Classification (ASJC) codes

  • Medicine(all)

Cite this

@article{984ecfccf7684f8a92625b85257b0546,
title = "Effects of thyroxine on protein turnover in rat skeletal muscle",
abstract = "The effects of thyroxine (T4) on protein turnover in skeletal muscle were studied using normal, thyroidectomized (thyrex), and hypophysectomized (hypox) rats. Thyrex rats had a depressed growth rate that was accompanied by 50{\%} reductions in the levels of RNA and the rate of protein synthesis in gastrocnemius muscle, as determined in the perfused hemicorpus. Protein synthetic efficiency (protein synthesis per unit RNA) was decreased by 18{\%}. Daily treatment of thyrex rats with T4 at different dose levels for up to 16 days led to improved growth rates, elevated RNA concentrations, and increased protein synthesis rates. The primary effect of T4 was to increase the protein synthetic capacity of muscle. Protein degradation, determined in the perfused hemicorpus, and activity of a lysosomal protease, determined in unperfused muscle, were reduced in the thyrex condition. Treatment of thyrex rats with T4 increased protein degradative rates, but not protease activity. Hypox rats, which also exhibited depressed skeletal muscle protein synthesis, responded to T4 and combined T4 and growth hormone with marked improvements in protein synthesis.",
author = "Flaim, {K. E.} and Li, {J. B.} and Jefferson, {Leonard {"}Jim{"}}",
year = "1978",
month = "1",
day = "1",
language = "English (US)",
volume = "4",
journal = "American Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology",
issn = "0363-6100",
publisher = "American Physiological Society",
number = "2",

}

TY - JOUR

T1 - Effects of thyroxine on protein turnover in rat skeletal muscle

AU - Flaim, K. E.

AU - Li, J. B.

AU - Jefferson, Leonard "Jim"

PY - 1978/1/1

Y1 - 1978/1/1

N2 - The effects of thyroxine (T4) on protein turnover in skeletal muscle were studied using normal, thyroidectomized (thyrex), and hypophysectomized (hypox) rats. Thyrex rats had a depressed growth rate that was accompanied by 50% reductions in the levels of RNA and the rate of protein synthesis in gastrocnemius muscle, as determined in the perfused hemicorpus. Protein synthetic efficiency (protein synthesis per unit RNA) was decreased by 18%. Daily treatment of thyrex rats with T4 at different dose levels for up to 16 days led to improved growth rates, elevated RNA concentrations, and increased protein synthesis rates. The primary effect of T4 was to increase the protein synthetic capacity of muscle. Protein degradation, determined in the perfused hemicorpus, and activity of a lysosomal protease, determined in unperfused muscle, were reduced in the thyrex condition. Treatment of thyrex rats with T4 increased protein degradative rates, but not protease activity. Hypox rats, which also exhibited depressed skeletal muscle protein synthesis, responded to T4 and combined T4 and growth hormone with marked improvements in protein synthesis.

AB - The effects of thyroxine (T4) on protein turnover in skeletal muscle were studied using normal, thyroidectomized (thyrex), and hypophysectomized (hypox) rats. Thyrex rats had a depressed growth rate that was accompanied by 50% reductions in the levels of RNA and the rate of protein synthesis in gastrocnemius muscle, as determined in the perfused hemicorpus. Protein synthetic efficiency (protein synthesis per unit RNA) was decreased by 18%. Daily treatment of thyrex rats with T4 at different dose levels for up to 16 days led to improved growth rates, elevated RNA concentrations, and increased protein synthesis rates. The primary effect of T4 was to increase the protein synthetic capacity of muscle. Protein degradation, determined in the perfused hemicorpus, and activity of a lysosomal protease, determined in unperfused muscle, were reduced in the thyrex condition. Treatment of thyrex rats with T4 increased protein degradative rates, but not protease activity. Hypox rats, which also exhibited depressed skeletal muscle protein synthesis, responded to T4 and combined T4 and growth hormone with marked improvements in protein synthesis.

UR - http://www.scopus.com/inward/record.url?scp=0018253117&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0018253117&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0018253117

VL - 4

JO - American Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology

JF - American Journal of Physiology Endocrinology Metabolism and Gastrointestinal Physiology

SN - 0363-6100

IS - 2

ER -