Effects of external cadmium ions on excitation-contraction coupling in rat soleus fibres
Date
1999
Authors
Mould, Jeremy
Dulhunty, Angela
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Publisher
Springer
Abstract
The actions of external Cd2+ on the twitch and tetanic contractions, action potentials and potassium (K+) contractures of rat soleus muscle fibre bundles have been investigated. Cd2+ at 1-1.5 mM did not significantly alter tetanic tension, but increased twitch tension and increased the duration and overshoot of action potentials. At ≥3 mM, Cd2+ (1) depressed tetanic contractions and initially potentiated but later depressed twitches, (2) abolished the action potential overshoot, and (3) shifted peak K+ contracture tension to more positive membrane potentials. Twitch and tetanic contractions, and action potentials remained depressed when Cd2+ was washed out of the bath. The effects of Cd2+ on the twitch, tetanus and action potential were mimicked by Zn2+, while La3+ and Co2+ at 3 mM - or Mg2+ and Ca2+ at 30 mM - depressed peak twitch and tetanic tension, but did not potentiate twitches. The results suggest that: (1) Cd2+ and Zn2+ potentiate twitch tension by prolonging action potential depolarisation; (2) Cd2+ depresses twitch and tetanic tension by reducing the action potential overshoot, and causing a positive shift in the voltage dependence of contraction; and (3) the irreversible depression of action potential amplitude in rat soleus muscle is a specific property of Cd2+ and Zn2+ that is not shared by Co2+, Mg2+ or Ca2+.
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Keywords: animal experiment; article; depolarization; excitation contraction coupling; male; muscle action potential; muscle twitch; nonhuman; potassium current; priority journal; rat; soleus muscle; tetanus; Action Potentials; Animals; Cadmium; Cations; Electric S Action potentials; Cadmium; Excitation-contraction coupling; Potassium contractures; Rat soleus muscle; Skeletal muscle
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Source
Pflugers Archives European Journal of Physiology
Type
Journal article
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2037-12-31
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