Salbutamol enhances isotonic contractile properties of rat diaphragm muscle

H. F.M. Van Der Heijden, W. Z. Zhan, Y. S. Prakash, P. N.R. Dekhuijzen, G. C. Sieck

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Abstract

The effects of the β2-adrenoceptor agonist salbutamol (Slb) on isometric and isotonic contractile properties of the rat diaphragm muscle (Dia(mus)) were examined. A loading dose of 25 μg/kg Slb was administered intracardially before Dia(mus) excision to ensure adequate diffusion. Studies were then performed with 0.05 μM Slb in the in vitro tissue chamber. cAMP levels were determined by radioimmunoassay. Compared with controls (Ctl), cAMP levels were elevated after Slb treatment. In Slb-treated rats, isometric twitch and maximum tetanic force were increased by ~40 and ~20%, respectively. Maximum shortening velocity increased by ~15% after Slb treatment, and maximum power output increased by ~25%. During repeated isotonic activation, the rate of fatigue was faster in the Slb-treated Dia(mus), but both Slb-treated and Ctl Dia(mus) fatigued to the same maximum power output. Still, endurance time during repetitive isotonic contractions was ~10% shorter in the Slb-treated Dia(mus). These results are consistent with the hypothesis that β-adrenoceptor stimulation by Slb enhances Dia(mus) contractility and that these effects of Slb are likely mediated, at least in part, by elevated cAMP.

Original languageEnglish (US)
Pages (from-to)525-529
Number of pages5
JournalJournal of applied physiology
Volume85
Issue number2
StatePublished - Aug 1 1998

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Keywords

  • Fatigue
  • Skeletal muscle
  • Velocity of shortening
  • cAMP
  • β-adrenoceptor agonist

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Van Der Heijden, H. F. M., Zhan, W. Z., Prakash, Y. S., Dekhuijzen, P. N. R., & Sieck, G. C. (1998). Salbutamol enhances isotonic contractile properties of rat diaphragm muscle. Journal of applied physiology, 85(2), 525-529.