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Myotonic dystrophy kinase modulates skeletal muscle but not cardiac voltage-gated sodium channels

M Chahine1, A L George

  • 1Centre de Recherche, Hôpital Laval, Sainte-Foy, Quebec, Canada.

FEBS Letters
|August 4, 1997
PubMed

Insights

Myotonic dystrophy kinase (DMPK) significantly reduces skeletal muscle sodium channel function but not cardiac channels. This suggests DMPK

Area of Science:

  • Molecular biology
  • Neuroscience
  • Genetics

Background:

  • Myotonic dystrophy is linked to altered skeletal muscle sodium channel function.
  • Myotonic dystrophy kinase (DMPK) is implicated in this channel modulation.

Purpose of the Study:

  • To investigate the effect of DMPK on human skeletal (hSkM1) and cardiac (hH1) sodium channels.
  • To determine if DMPK's effect on sodium channels is isoform-specific.

Main Methods:

  • Xenopus oocyte expression system used.
  • Co-expression of mouse DMPK with hSkM1 and hH1 sodium channels.
  • Functional properties of sodium channels were analyzed.

Main Results:

  • DMPK significantly reduced peak sodium current in hSkM1 channels.
  • DMPK had no effect on hH1 sodium channel current amplitude.
  • No significant changes in channel kinetics or gating were observed for either isoform.

Conclusions:

  • DMPK's inhibitory effect on sodium channels is specific to the skeletal muscle isoform.
  • This isoform specificity may contribute to myotonia in myotonic dystrophy.
  • Findings support previous studies on rat muscle sodium channels.

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