Chagas Disease (CD) is one of the leading causes of heart failure and sudden death in Latin America. Treatments with antioxidants have provided promising alternatives to ameliorate CD. However, the specific roles of major reactive oxygen species (ROS) sources, including NADPH-oxidase 2 (NOX2), mitochondrial-derived ROS and nitric oxide (NO) in the progression or resolution of CD are yet to be elucidated. We used C57BL/6 (WT) and a gp91^PHOX knockout mice (PHOX^-/-), lacking functional NOX2, to investigate the effects of ablation of NOX2-derived ROS production on the outcome of acute chagasic cardiomyopathy. Infected PHOX^-/- cardiomyocytes displayed an overall pro-arrhythmic phenotype, notably with higher arrhythmia incidence on ECG that was followed by higher number of early afterdepolarizations (EAD) and 2.5-fold increase in action potential (AP) duration alternans, compared to AP from infected WT mice. Furthermore, infected PHOX^-/- cardiomyocytes display increased diastolic [Ca²⁺], aberrant Ca²⁺ transient and reduced Ca²⁺ transient amplitude. Cardiomyocyte contraction is reduced in infected WT and PHOX^-/- mice, to a similar extent. Nevertheless, only infected PHOX^-/- isolated cardiomyocytes displayed significant increase in non-triggered extra contractions (appearing in ~75% of cells). Electro-mechanical remodeling of infected PHOX^-/—cardiomyocytes is associated with increase in NO and mitochondria-derived ROS production. Notably, EADs, AP duration alternans and in vivo arrhythmias were reverted by pre-incubation with nitric oxide synthase inhibitor L-NAME. Overall our data show for the first time that lack of NOX2-derived ROS promoted a pro-arrhythmic phenotype in the heart, in which the crosstalk between ROS and NO could play an important role in regulating cardiomyocyte electro-mechanical function during acute CD. Future studies designed to evaluate the potential role of NOX2-derived ROS in the chronic phase of CD could open new and more specific therapeutic strategies to treat CD and prevent deaths due to heart complications.

恰加斯病（CD）是拉丁美洲心力衰竭和猝死的主要原因之一。用抗氧化剂治疗已经为改善CD提供了有希望的替代方法。但是，主要的活性氧物质（ROS）来源，包括NADPH-氧化酶2（NOX2），线粒体衍生的ROS和一氧化氮（NO）在CD的进展或消退中的具体作用尚待阐明。我们使用了C57BL / 6（WT）和gp91 ^PHOX基因敲除小鼠（PHOX ^-/-），它们缺乏功能性NOX2 ，来研究消融NOX2引起的ROS产生对急性chagasic心肌病的影响。感染的PHOX ^-/-与感染的WT小鼠的AP相比，心肌细胞表现出整体的前心律失常表型，尤其是ECG的心律失常发生率更高，其后的去极化（EAD）次数增加，动作电位（AP）持续时间增加了2.5倍。此外，感染的PHOX ^-/-心肌细胞显示出舒张性[Ca ²⁺ ]增加，异常的Ca ²⁺瞬变和降低的Ca ²⁺瞬变幅度。在感染的WT和PHOX ^-/-小鼠中，心肌细胞的收缩减少了相似的程度。尽管如此，只有被感染的PHOX ^-/-分离的心肌细胞在未触发的额外收缩中显示出显着增加（出现在约75％的细胞中）。感染的PHOX ^-/-心肌细胞的机电重塑与NO和线粒体来源的ROS产生增加有关。值得注意的是，EAD，AP持续时间和体内通过与一氧化氮合酶抑制剂L-NAME进行预温育，可恢复心律失常。总的来说，我们的数据首次显示出缺乏NOX2的ROS会促进心脏的心律失常表型，其中ROS和NO之间的串扰可能在急性CD期间调节心肌细胞的机电功能中起重要作用。旨在评估源自NOX2的ROS在CD慢性期中的潜在作用的未来研究可能会开辟新的，更具体的治疗策略，以治疗CD并防止因心脏并发症而死亡。