Fig. 1.

A: representative tracing of pressure during ischemia, wild-type (WT) female mouse, 8 Hz, 37^°C, experiment no. 110311e. B: left ventricular developed pressure (LVDP) in WT and p21-activated kinase 1 (Pak1)-knockout (KO) ex vivo hearts is significantly reduced after 20 min ischemia and 30 min reperfusion relative to baseline values in each group. Statistics were performed by 2-way ANOVA followed by Student's t-test using JMP statistical software. C: the rate-pressure product, calculated as heart rate multiplied by left ventricular developed pressure, in WT and Pak1-KO ex vivo hearts is significantly reduced after 20 min ischemia and 30 min reperfusion relative to baseline values in each group. Statistics were performed by 2-way ANOVA followed by Student's t-test using JMP statistical software. bpm, Beats/min. D: %recovery of left ventricular developed pressure after ischemia-reperfusion (I/R) injury, as calculated by left ventricular developed pressure after I/R divided by left ventricular developed pressure at baseline, is significantly less in Pak1-KO hearts compared with WT controls. Statistics were performed by t-test using JMP statistical software. E: change in left ventricular end diastolic pressure during reperfusion is increased in Pak1-KO hearts compared with WT. Data were statistically analyzed by an independent-samples t-test (ANOVA with 2 groups) using JMP statistical software to determine if there is a difference for the two groups WT and Pak1-KO over the entire reperfusion phase (but not at any particular time point). Data collected at 2.5 mM extracellular Ca²⁺ concentration, 37^°C, n = 9 for WT, n = 16 for Pak1-KO. Data are reported as means ± SE. *P < 0.05 considered significant.