Fluorescence changes from single striated muscle fibres injected with labelled troponin C (TnCDANZ)

P. J. Griffiths, J. D. Potter, B. Coles, P. Strang, C. C. Ashley

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

A fluorescently labelled derivative of the calcium binding subunit of troponin, TnC, has been injected into isolated striated muscle fibres from the barnacle Balanus nubilus. The Ca2+ affinity of isolated TnC is close to that of intact troponin when located in the thin filament. Excitation of the TnCDANZ within the muscle cell (325nm) revealed a marked fluorescence at 510 nm and was similar to that observed in vitro, which was absent at 400 or 600 nm after subtraction of the fibre autofluorescence. High Ca2+ salines increased the fluorescence at 510 nm by roughly 2 times. Single voltage clamp pulses produced a rapid rise in fluorescence at 510 nm after allowing for any non-specific changes at 400 nm, and this signal preceded force development by approx. 55 ms at 22° C. It reached a maximum at the same time as force and subsequently decayed more slowly. The fluorescence signal increased in magnitude with increase in stimulus intensity. These results suggest that Ca2+ attaches rapidly to the contractile filament, but is lost relatively slowly and imply a slow decay of the activation process.

Original languageEnglish (US)
Pages (from-to)144-150
Number of pages7
JournalFEBS letters
Volume176
Issue number1
DOIs
StatePublished - Oct 15 1984

Keywords

  • Ca
  • Contraction
  • Fluorescence
  • Muscle
  • Troponin C

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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