Objective To investigate the effect of
ketamine on iNOS activity and NO content in the lungs of rats with LPS-induced ARDS.
Methods The rat model of ARDS was produced by intratracheal
instillation of endotoxine (LPS, 3.0 mg/kg) 16 h after intraperitoneal injection of LPS 1.0 mg/kg. 32 male rats were randomly divided into 4 groups to proceed with different experiments: in control group (group C), norml saline was instilled into the trachea; in LPS group (group L), was made the ARDS model; in LPS +
ketamine group (group L+K), ketamine 5 mg·kg -1·h -1 iv gtt was given along with intratracheal LPS; in ketamin control group (group K), ketamin iv was given the same way 2.5 h after the intatracheal instillation of LPS. Oxygenation index (PaO 2/FiO 2), MAP and CVP were measured before instillation of LPS (baseline) and 0 h, 1 h, 2 h and 3 h after the ARDS was established. The rats were sacrificed after 3 h of ARDS. Histological examination was made with the right lung. The left lung was used to determine the wet/dry weight ratio (W/D), the activity of iNOS and the content of NO. Results The PaO 2/FiO 2 after ARDS was significantly lower than the baseline in group L and group L+K. The W/D, iNOS activity and NO content were much higher in group L than in group C, but they were significantly lower in group L+K than in group L. Histological examination showed ketamine treatment attenuated the lung injury in ARDS rats. Conclusion Ketamine can attenuate LPS-induced ARDS in rats by inhibiting iNOS activity and decreasing NO production.