Figure 3.

Representative examples of [Ca^{2 +} ]_i measurements in C57 muscle fibers. Fibers were incubated for 5 min in potassium aspartate (10 mM EGTA) solution in the presence or absence of 1 μM thapsigargin. Next, they were repolarized for 5 min in a Krebs solution (50 μM EGTA). Finally, depolarization in potassium aspartate solution induced a [Ca²⁺]_i transient that was taken as an index of the amount of releasable Ca.