Baseline Isolated Heart Function.

Isolated heart performance at baseline 7 Hz pacing frequency. Values shown, other than time to 50% rise, are also presented with other pacing frequencies in Figures 3, 4, and 5. Values represent mean and SEM of each group's isolated heart performance; values for each heart were determined by averaging 5–10 pressure peaks at each pacing frequency after the heart's performance at that step had stabilized. *: P<0.05; **:P<0.01; ***: P<0.001 for FL vs. KO at either 1 week or 4 weeks post-tamoxifen injection, as determined by unpaired two-tailed t test.