Effects of halothane on Ca2+-activated tension development in mechanically disrupted rabbit myocardial fibers

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The effect of halothane on maximal and submaximal Ca2+-activated tension in mechanically disrupted right ventricular papillary muscle from rabbits was studied. Steady-state isometric tension generation was measured in the muscle bundle. The relaxing solution contained (in mM) [mg2+]=1, [K+]=70, [MgATP̈-]=2, [creatine phosphatë-]=15, [EGTA total]=7 and imidazole proprionate. The contracting solution contained in addition Ca2+ in various concentrations. In all solutions ionic strength was maintained at 0.15 and pH at 7.00±0.02 at 20°C. Each fiber bundle was immersed in control solutions equilibrated with 100% N2 and test solutions equilibrated with various concentrations of halothane-N2 mixture. Increasing doses of halothane (1-4%) significantly shifted the relationship between Ca2+ and tension towards higher [Ca2+] and depressed the maximum Ca2+-activated tension. The maximum tension generated at pCa=3.8 was depressed 5% per 1% increase in halothane concentration. The percentage of maximum tension at submaximum Ca2+ concentrations (pCa=5.6-5.0) was not significantly decreased until halothane concentration was greater than 2%. It is concluded that halothane slightly but significantly depressed the interactions of contractile proteins and to a lesser degree Ca2+-activation of the regulatory proteins. The halothane-induced depression was completely reversible.

Original languageEnglish (US)
Pages (from-to)111-117
Number of pages7
JournalPflügers Archiv European Journal of Physiology
Issue number2
StatePublished - Jul 1 1978
Externally publishedYes


  • Cardiac muscle
  • Contractile proteins
  • Halothane
  • Regulatory proteins
  • Skinned fibers

ASJC Scopus subject areas

  • Physiology


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