Fig 3. VO_2max achieved with the GXT_m, but not the PXT_m, identifies impaired cardiovascular fitness in mouse models of cardiovascular dysfunction.

(A) Averaged VO₂ kinetics obtained from WT (dashed line), Casq2^-/- (solid thick line), and obese (solid line) mice that performed the PXT_m and GXT_m. VO₂ is indicated for each group from the beginning of the test until the end (Minute 2, after the 2 minute warm, to point of exhaustion). Of note, during the PXT_m, the largest increase in VO₂ occurred with the first stage, and leveled off as the test continued in dysfunctional models. (B) Relative VO_2max values and (C) change from baseline to maximal oxygen consumption (VO_2delta) are compared (mean±SD, MANOVA, Tukey HSD Multiple Comparisons, alpha = .007) in WT-healthy (white bar), WT-obese (hashed bar), and Casq2^-/- (black bar) mice. Asterisks indicate significance at the alpha = .007 level (MANOVA, multiple comparisons Tukey HSD for the PXT_m and GXT_m of WT v. obese and WT v. Casq2^-/-), hash indicates significant difference at the alpha = .05 level between tests for the same genotypes (Student’s t-Test), and diamond indicates significance at the alpha = .007 level (MANOVA, multiple comparisons Tukey HSD for the PXT_m and GXT_m of obese v. Casq2^-/-).