FIG. 4.

Mitochondrial catalase prevents contractile dysfunction in isolated perfused HFHS hearts. LV contractile function was assessed at four levels of progressively increasing myocardial work demand. Hearts were paced at HR 450 bpm at baseline, and paced at 600 bpm and/or Ca²⁺ was raised (4 mM) to increase work demand. With increased work demand, the LVEDP increased more in hearts from HFHS-fed (vs. CD-fed) mice (A). Mitochondrially expressed catalase prevented the increase: LVEDP in the mCAT HFHS group remained similar to CD. ESP (B), DevP (C), and the RPP (D) failed to increase appropriately in HFHS during high work demand and increased normally in mCAT HFHS hearts. For all panels, data are shown as mean ± SEM; open circles = CD-fed mice; filled circles = HFHS-fed mice; triangles = mCAT HFHS mice; n = 8 in each group; *p < 0.05 versus CD-fed mice. bpm, beats per minute; DevP, developed pressure; ESP, end-systolic pressure; HR, heart rate; LV, left ventricle; LVEDP, left ventricular end-diastolic pressure; RPP, rate × pressure product.