['Oxidative stress (oxidant-antioxidant imbalance) plays an important role in the pathophysiology of neonatal sepsis. This study evaluated whether an antisense peptide endothelin receptor antagonist, ETR-P1/fl, could attenuate oxidative stress in a neonatal sepsis model.', 'A total of 18 3-d-old piglets were anesthetized and mechanically ventilated. Six piglets received cecal ligation and perforation (CLP group) for induction of sepsis. Six piglets also received continuous infusion (0.05\u2009mg/kg/h) of ETR-P1/fl 30\u2009min after CLP (ETR-P1/fl group). Six piglets received a sham operation. Serum total hydroperoxide (TH), biological antioxidant potentials (BAPs), oxidative stress index (OSI, calculated as TH/BAP), interleukin (IL)-6, serum glutamic oxaloacetic transaminase (GOT), and creatinine were measured before CLP and at 1, 3, and 6\u2009h after CLP.', 'CLP evoked a state of shock resulting in elevated TH, OSI, and IL-6 levels. ETR-P1/fl administration after CLP resulted in lower serum TH at 1 and 3\u2009h after CLP, OSI at 1 and 3\u2009h after CLP, IL-6 at 1 and 3\u2009h after CLP, and GOT at 3 and 6\u2009h after CLP as compared with the CLP group.'] Does endothelin receptor antagonist attenuate oxidative stress in a neonatal sepsis piglet model?