Congestive heart failure: Differential adaptation of the diaphragm and latissimus dorsi

S. Howell, J. M.I. Maarek, M. Fournier, K. Sullivan, W. Z. Zhan, G. C. Sieck

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Diaphragm and latissimus dorsi muscle functions, histochemistries, and morphometries were studied in anesthetized male Yucatan minipigs with congestive heart failure (CHF) induced by supraventricular tachycardia (n = 5). Sham-operated animals served as a control group (n = 5). In CHF animals, transdiaphragmatic pressure measured during supramaximal phrenic stimulation was reduced by 40% at low frequencies (≤20 Hz) and by 60% at higher frequencies. Twitch amplitude and half-relaxation time were also decreased. The cross-sectional areas of type I, IIa, and IIb fibers were reduced in the diaphragm. The proportion of type I fibers increased, whereas type IIa fibers decreased. Succinate dehydrogenase activity was elevated in type IIa and lib fibers, but diaphragmatic fatigability was not altered. CHF reduced latissimus dorsi isometric force by 40% for stimulation frequencies ≥ 30 Hz. The cross-sectional area of latissimus dorsi type IIb fibers was decreased, but twitch characteristics, fiber type composition, succinate dehydrogenase activity, and fatigability were unchanged. Experimental CHF appears to cause greater intrinsic adaptive changes in the diaphragm compared with those in the latissimus dorsi in the minipig. For both muscles, reduced contractile function was associated with atrophy. Impaired performance of the diaphragm may also be attributed to an increase in the relative contribution of type I fibers to the total tension-generating capacity of the muscle and to the pathophysiological mechanisms underlying the shortened relaxation time of the twitch response.

Original languageEnglish (US)
Pages (from-to)389-397
Number of pages9
JournalJournal of applied physiology
Volume79
Issue number2
DOIs
StatePublished - Jan 1 1995

Keywords

  • atrophy
  • exercise intolerance
  • minipig
  • skeletal muscle dysfunction

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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    Howell, S., Maarek, J. M. I., Fournier, M., Sullivan, K., Zhan, W. Z., & Sieck, G. C. (1995). Congestive heart failure: Differential adaptation of the diaphragm and latissimus dorsi. Journal of applied physiology, 79(2), 389-397. https://doi.org/10.1152/jappl.1995.79.2.389