ONO-1714, a Nitric Oxide Synthase Inhibitor, Attenuates Endotoxin-Induced Acute Lung Injury in Rabbits

UNLABELLED: Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) expressed in the lung is thought to play a crucial role in the pathogenesis of endotoxin-induced acute lung injury (ALI). In this two-part study, we determined whether ONO-1714, a new selective iNOS inhibitor, attenuates endotoxin-induced ALI in rabbits. For Part I of the study, a control group received IV saline and ALI was induced by IV infusion of endotoxin 5 mg/kg over 30 min in 4 groups. Three groups received either 0.1, 0.03, or 0.01 mg/kg of ONO-1714 10 min before the start of endotoxin and the fourth group received saline. For Part II of the study, ALI was induced by endotoxin infusion in all 6 groups. One group was treated with saline. The other 5 groups received ONO-1714 0.1 mg/kg at various timings (10 min before or 1, 2, 3, or 4 h after ALI induction). The lungs were mechanically ventilated with 40% oxygen for 6 h after induction of ALI. In Part I, pretreatment with 0.1 mg/kg ONO-1714 mitigated endotoxin-induced ALI. In Part II, early posttreatment (within 2 h after the insult) with ONO-1714 was as effective as pretreatment in improving oxygenation, lung mechanics, lung leukosequestration, pulmonary edema, and histological change. However, lung damage was not improved in rabbits receiving the drug 3 or 4 h after endotoxin. These data suggest that the current study is a basis for future clinical trials to elucidate whether ONO-1714 can be a promising therapeutic approach in patients with acute respiratory distress syndrome induced by endotoxin/sepsis. IMPLICATIONS: An excess of nitric oxide is thought to play a crucial role in the pathogenesis of acute organ injury in endotoxemia. Early posttreatment with ONO-1714, a nitric oxide synthase inhibitor, attenuated physiological, biochemical, and pathological changes in endotoxin-induced acute lung injury in rabbits.