FIGURE 4.

Example of Ca²⁺ transients used to calculate buffer power. SR function was blocked with 1 μM thapsigargin and 100 μM ryanodine. Shown are Ca²⁺ transients from five consecutive 200-ms voltage-clamp pulses to +10 mV from a holding potential of −80 mV at 5-s intervals. In some instances the Ca²⁺ channel agonist Bay k 8644 was added to increase the size of the Ca²⁺ current as in the examples for ED11 and 15 shown here. These data were used to calculate [Ca²⁺]_m as described in the text and illustrated in Fig. 5.