Nitric oxide supplementation during extracorporeal resuscitation drives oxidative–inflammatory signaling and metabolic suppression in the post–cardiac arrest heart

Myocardial dysfunction is a major determinant of mortality after cardiac arrest, yet the molecular events driving post-resuscitation injury remain incompletely understood. Nitric oxide (NO) has been proposed as a cardioprotective adjunct during extracorporeal life support (ECLS), but its mechanistic impact on myocardial recovery is unclear. We investigated whether NO supplementation during ECLS modulates oxidative stress, metabolic pathways, and apoptotic signaling in the post–cardiac arrest heart. Male Sprague Dawley rats underwent hypothermic cardiac arrest followed by ECLS resuscitation with or without NO supplementation (20 ppm). Myocardial tissue was analyzed using bulk RNA sequencing, quantitative RT-PCR, oxidative stress assays (MDA, 3-nitrotyrosine, total oxidant/antioxidant status), and TUNEL staining to characterize pathway-level alterations. NO supplementation markedly increased cardiomyocyte apoptosis (46%±3 vs. 27%±2; p 550 differentially expressed genes, highlighting upregulation of inflammatory and apoptotic cascades (MAPK, TNF, NF-κB, proteasome/TLR pathways) and profound suppression of metabolic programs essential for myocardial recovery, including fatty acid oxidation, branched-chain amino acid metabolism, and oxidative phosphorylation. NO induced a striking oxidative–nitrosative imbalance, with elevated MDA, 3-nitrotyrosine, and total oxidant status and reduced total antioxidant capacity, resulting in a threefold increase in the oxidative stress index. NO administration during ECLS drives a coordinated oxidative–inflammatory–apoptotic response and disrupts metabolic pathways necessary for myocardial recovery, suggesting a mechanistic basis for worsened post-arrest myocardial injury. These findings have direct implications for optimizing resuscitation strategies in human ECLS and may inform future therapeutic modulation of NO signaling.