Figure 6. Mean change in mitochondrial [Ca²⁺] before, during and after a series of repeated tetani.

A, mean data (± S.E.M.) from 10 soleus fibres (•) and eight EDL fibres (▵) showing the changes in the mitochondrial Rhod-2 F/F₀ during and for 30 min after a series of up to 1000 tetani. The mitochondrial [Ca²⁺] is clearly increased after 10 tetani, reaches its maximum at 50 tetani, and thereafter falls steadily during the remaining period of stimulation. B, after stimulation was stopped, the mitochondrial [Ca²⁺] falls relatively rapidly, with a decline to 50 % of its final value within 3 min.