Application of 10 μM rotenone, a mitochondrial complex I inhibitor, led to a significant decrease in ΔΨm in WT sham from 1516 ± 89 to 858 ± 43 a.u., n = 39, p < 0.001 but not in WT TAC myocytes where basal level was already at 911 ± 24 a.u., n = 17 (not shown), confirming that the inability of mitochondria to maintain ΔΨm in HF was related to impairment of the mitochondrial complex I. In TSPO-KO TAC mice, basal levels of ΔΨm were significantly closer (1404 ± 72 a.u., n = 24) to that observed in sham controls (1567 ± 81 a.u., n = 39). Here, TSPO is linked to hydrops fetalis.