ABSTRACT
Objective To investigate the effects of a-melanocyte stimulating hormone (?MSH) on serum cytokine levels in rats with acute respiratory distress syndrome (ARDS) induced by acute hemorrhagic shock and intratracheal lipopolysaccharide (LPS) administration (two-hit model) .Methods Thirty male SD rats weighing (337? 25) g were randomly assigned to six groups of five animals in each group: group A normal control; group B ARDS control; group C-F treatment groups in which ?MSH 1.7 mg/kg was given at different time points - Ih before LPS(C), at the time as LPS was administratered (D), 1h after LPS (E) or together with and 3 h and 6 h after LPS (F) . The animals were anesthetized with intravenous thiopental 30 mg?kg-1 and tracheotomized and mechanically ventilated (FiO2 : 0.5, RR 100 bpm, VT12ml, I: E = 1:1.5) . Right common carotid artery was cannulated for BP monitoring, removal of blood and blood sampling. Acute hemorrhagic shock was induced by removal of blood and MAP was maintained at 45 mm Hg for 1 h, then the animals were resuscitated with reinfusion of removed blood and lactated Ringer's solution, then endotoxin (LPS 200 ?g/kg in 500 ?l normal saline). The criterion for ARDS was PaO2/FiO2