Myosin heavy chain turnover during cardiac mass changes by glucocorticoids

S. M. Czerwinski, T. T. Kurowski, E. E. McKee, R. Zak, R. C. Hickson

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

One aim of this investigation was to determine whether the cardiac enlargement observed with glucocorticoid treatment is temporary or remains a permanent adaptation if steroid treatment is prolonged. A second aim was to study whether myosin heavy chain (MHC) synthesis rates are coordinated with the cardiac mass responses. Female rats received either a vehicle (1% aqueous carboxymethyl cellulose in saline) or hydrocortisone 21-acetate for 1, 3, 7, 11, and 15 days. Peak cardiac enlargement (10-15%) was observed after 7 days of hormone treatment in two separate series of experiments. The enlargement was maintained through 11 days of steroid injections but by 15 days had declined toward control levels. MHC synthesis measurements were performed by constant infusion of [3H]leucine. Leucine specific activities were similar among precursor pools (intracellular, extracellular, and leucyl-tRNA) and did not vary with steroid treatments. Fractional synthesis rates of ventricular MHC (%/day) did not change during the period of increase in ventricular mass but were reduced to 56-59% of controls (-11/19.5) at 7 and 11 days of treatment, when ventricular mass increases were highest. MHC breakdown (%/day) was reduced to ~ 60% (-11.5/18.7) of controls at 7 and 11 days. Changes in total protein synthesis, which was measured in isolated perfused hearts, were similar to the MHC responses and indicated that the alterations in MHC synthesis are synchronized with the hormonal effects on total protein metabolism. These results demonstrate that peak cardiac enlargement is not maintained with long-term glucocorticoid treatment. The downregulation of total protein and MHC synthesis by 7 treatment days may represent one of the early events in an anabolic-to-catabolic transition, because the decreased synthesis rates preceded the muscle mass loss by > 1 wk.

Original languageEnglish (US)
Pages (from-to)300-305
Number of pages6
JournalJournal of Applied Physiology
Volume70
Issue number1
StatePublished - 1991
Externally publishedYes

Fingerprint

Myosin Heavy Chains
Glucocorticoids
hydrocortisone acetate
Steroids
Leucine
Therapeutics
Ventricular Myosins
Carboxymethylcellulose Sodium
Proteins
Transfer RNA
Down-Regulation
Hormones
Muscles
Injections

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Czerwinski, S. M., Kurowski, T. T., McKee, E. E., Zak, R., & Hickson, R. C. (1991). Myosin heavy chain turnover during cardiac mass changes by glucocorticoids. Journal of Applied Physiology, 70(1), 300-305.

Myosin heavy chain turnover during cardiac mass changes by glucocorticoids. / Czerwinski, S. M.; Kurowski, T. T.; McKee, E. E.; Zak, R.; Hickson, R. C.

In: Journal of Applied Physiology, Vol. 70, No. 1, 1991, p. 300-305.

Research output: Contribution to journalArticle

Czerwinski, SM, Kurowski, TT, McKee, EE, Zak, R & Hickson, RC 1991, 'Myosin heavy chain turnover during cardiac mass changes by glucocorticoids', Journal of Applied Physiology, vol. 70, no. 1, pp. 300-305.
Czerwinski SM, Kurowski TT, McKee EE, Zak R, Hickson RC. Myosin heavy chain turnover during cardiac mass changes by glucocorticoids. Journal of Applied Physiology. 1991;70(1):300-305.
Czerwinski, S. M. ; Kurowski, T. T. ; McKee, E. E. ; Zak, R. ; Hickson, R. C. / Myosin heavy chain turnover during cardiac mass changes by glucocorticoids. In: Journal of Applied Physiology. 1991 ; Vol. 70, No. 1. pp. 300-305.
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