Protective effects of S-methylisothiourea sulfate on different aspiration materials-induced lung injury in rats.

Objectives: The aim of this study was to evaluate the efficiency of inducible nitric oxide synthase (iNOS) specific inhibitor, S-methylisothiourea sulfate (SMT) in preventing lung injury after different pulmonary aspiration materials in rats.

Material And Methods: The experiments were performed in 80 Sprague-Dawley rats, ranging in weight from 220 to 250 g, randomly allotted into one of the eight groups (n=10): normal saline (NS, control), Biosorb Energy Plus (BIO), sucralfate (SUC), hydrochloric acid (HCl), NS+SMT treated, BIO+SMT treated, SUC+SMT treated, and HCl+SMT treated. NS, BIO, SUC, HCl were injected in to the lungs in a volume of 2 ml/kg. The rats received twice daily intraperitoneal injections of 20 mg(kg day) SMT (Sigma Chemical Co.) for 7 days. Seven days later, rats were killed, and both lungs in all groups were examined immunohistochemically and histopathologically.

Results: Our data show that SMT inhibits the inflammatory response significantly reducing (p<0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation in different pulmonary aspiration models. Furthermore, our data suggest that there is a significant reduction in the activity of iNOS and arise in the expression of surfactant protein D in lung tissue of different pulmonary aspiration models with SMT therapy.

Conclusion: It was concluded that SMT treatment might be beneficial in lung injury, therefore shows potential for clinical use.