Effects of N~G-nitro-L-arginine on LPS-induced lung injury in rats

AIM: To investigate the effects of nitric oxide (NO) and NO synthase (NOS) inhibitor NG-nitro-L arginine (L-NA) on LPS induced-lung injury in rats. METHODS: Forty healthy male SD rats, weighing 300±20 g, were used. The animals were anesthetized with 20% urethane 1 g·kg -1. Common carotid artery (CAA) and jugular vein were exposed through a median incision in the neck. Mean arterial pressure (MAP) was measured through a pressure transducer connected with intubation of CAA. The animals were randomly divided into five groups: group 1: control; group 2: LPS (5 mg·kg -1, iv); group 3: high dose L-NA (20 mg·kg -1 intraperitoneal injection, ip); gropu 4: middle dose L-NA (10 mg·kg -1, ip); group 5: low dose L-NA (5 mg·kg -1, ip). Group1 : 0.9% saline solution was given and the animals were killed 6 h after the saline solution. Gruop 2: saline solution was given 3 h after LPS and the animals were killed 3 h after administration. Group 3, 4 and 5: L-NA was given 3 h after LPS iv and the animals were killed 3 h after administration, respectively. The pulmonary was removed immediately. The pulmonary coefficient and water content in pulmonary tissue were calculated (%). The NO 2-/NO 3- content in plasma, MDA content and NOS, SOD activity in the pulmonary tissue were measured. RESULTS: L-NA significantly decreased pulmonary coefficient and water content in pulmonary tissue and ameliorated LPS induced lung injury. The effect in high dose group was better than that in low dose group. L-NA significantly decreased NO 2-/NO 3- content in plasm, decreased MDA content and inhibited NOS activity and enhanced SOD activity in the pulmonary tissue. CONCLUSION: It may be concluded that L-NA has a beneficial effect on lung injury induced by LPS.