Figure 5.

Local Ca²⁺ release transients elicited at individual t-tubular-SR junctional sites in the presence of 10 μM FPL. (A) Confocal line-scan image (Upper) and Ca²⁺ spikes (Lower) elicited by a single depolarizing pulse to +30 mV for 50 ms, followed by repolarization to −60 mV. Numbers in the image indicate the spatial locations of the six individual release sites at which the Ca²⁺ spikes displayed in the Lower panel were recorded. (B) Scatter plot of amplitudes of depolarization-induced Ca²⁺ spikes vs. amplitudes of those triggered by the subsequent repolarization. The straight line is the least square linear regression of the data, r is the correlation coefficient, and n = 170.