Inhibition of Na+, K+-ATPase of intact mouse soleus muscle by Mg++

The effect of 10 mM MgCl₂ on the inhibition of respiration by ouabain was investigated with intact mouse soleus muscle preparations. Although ouabain caused a 19.7% inhibition of respiration of soleus muscle incubated in 1 mM MgCl₂ buffer, the response of respiration to ouabain was abolished upon incubation in buffer containing 10 mM MgCl₂. Initial respiration rates were significantly decreased in soleus muscle exposed to 10 mM, as contrasted to 1 mM, MgCl₂.