Document Detail

Potassium contractures and asymmetric charge movement in extensor digitorum longus and soleus muscles from thyrotoxic rats.
MedLine Citation:
PMID:  3654955     Owner:  NLM     Status:  MEDLINE    
Potassium contractures and asymmetric charge movement were recorded from extensor digitorum longus (EDL) and soleus muscle from normal rats and rats that had been made thyrotoxic by daily intraperitoneal injections of triiodothyronine (150 micrograms kg-1) for two to three weeks. Potassium contracture tension (relative to tetanic tension) in thyrotoxic rats was greater in EDL muscles and smaller in soleus muscles than in normal rats. As the relationship between membrane potential and potassium concentration was unaltered by thyroid treatment, it was concluded that the changes in potassium contracture tension were due to changes in excitation-contraction coupling. In thyrotoxic rats there was an average negative shift of -5 mV in the voltage sensitivity of tension in EDL fibres and a positive shift of 5 mV in soleus. As a result, the tension-membrane potential curves for EDL and soleus fibres essentially coincided. There was a corresponding average negative shift of -4 mV in the voltage sensitivity of asymmetric charge in EDL fibres, and a positive shift of 4 mV in soleus fibres from thyrotoxic rats. The dependence of asymmetric charge movement on membrane potential became essentially the same in EDL and soleus fibres from thyrotoxic rats. The maximum asymmetric charge in soleus fibres increased from an average value of 6.5 nC microF-1 in normal rats (n = 33) to 8.9 nC microF-1 in thyrotoxic rats (n = 32; p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
A F Dulhunty; P W Gage; G D Lamb
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of muscle research and cell motility     Volume:  8     ISSN:  0142-4319     ISO Abbreviation:  J. Muscle Res. Cell. Motil.     Publication Date:  1987 Aug 
Date Detail:
Created Date:  1987-11-18     Completed Date:  1987-11-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8006298     Medline TA:  J Muscle Res Cell Motil     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  289-96     Citation Subset:  IM    
Department of Physiology, John Curtin School of Medical Research, Australian National University, Canberra, A.C.T.
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MeSH Terms
Contracture / physiopathology*
Membrane Potentials
Potassium / physiology*
Thyrotoxicosis / physiopathology*
Triiodothyronine / toxicity
Reg. No./Substance:
6893-02-3/Triiodothyronine; 7440-09-7/Potassium

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