Cardiomyocyte contractile properties in WT and KD transgenic mice treated with or without paraquat (45 mg/kg, i.p.) or vehicle for 48 h. (A) Representative traces from cardiomyocytes isolated from WT mice treated with paraquat (45 mg/kg, i.p.) or vehicle for 48 h. (B) Representative traces from cardiomyocytes isolated from KD mice treated with paraquat (45 mg/kg, i.p.) or vehicle for 48 h. (C) Resting cell length; (D) peak shortening (normalized to cell length); (E) maximal velocity of shortening (+ dL/dt); (F) maximal velocity of relengthening (− dL/dt); (G) time-to-peak shortening (TPS); (H) time-to-90% relengthening (TR90). Mean ± SEM, n = 114–141 cells per group; *p < 0.05 versus WT group, #p < 0.05 versus WT-paraquat group.