Effects of pretreatment with exogenous insulin-like growth factors-1 on lung injury in rats undergoing cardiopulmonary bypass

Objective To evaluate the effects of pretreatment with exogenous insulin-like growth factor-1 (IGF-1) on lung injury in rats undergoing cardiopulmonary bypass(CPB). Methods Seventy-two SPF healthy male Sprague-Dawley rats, weighing 350-500 g, were divided into 4 groups (n=18 each) using a random number table: sham operation group (group S), CPB group, CPB plus left lung ischemia-reperfusion group (group LI) and IGF-1 group.The chest was only opened, and the rats underwent no CPB in group S. Only the CPB model was established in group CPB.The model of left lung ischemia-reperfusion injury was established based on the CPB model in group LI.The model of CPB and left lung ischemia-reperfusion injury was established, and IGF-1 30 μg/kg was intravenously injected at 10 min before clamping the hilum of lung and immediately after opening the hilum of lung in group IGF-1.Six rats were selected before operation (T1), 10 min after opening the left hilum (T2) and at the end of operation (T3), and blood samples were collected from the femoral artery for blood gas analysis.The oxygenation index (OI) and respiratory index (RI) were calculated.Serum was obtained from blood, and the concentrations of interleukin-6 (IL-6), IL-1β and tumor necrosis factor-alpha (TNF-α) in serum were measured using enzyme-linked immunosorbent assay.The left upper lung tissues were removed for examination of the pathological changes which were scored with a light microscope. Results Compared with the baseline at T1, OI was significantly decreased, and RI, concentrations of IL-6, IL-1β and TNF-α in serum and pathological scores of lung tissues were increased at T3 in CPB, LI and IGF-1 groups (P<0.05). Compared with group S, OI was significantly decreased, and RI, concentrations of IL-6, IL-1β and TNF-α in serum and pathological scores of lung tissues were increased at T3 in CPB, LI and IGF-1 groups (P<0.05). Compared with group CPB, OI was significantly decreased, and RI, concentrations of IL-6, IL-1β and TNF-α in serum and pathological scores of lung tissues were increased at T3 in group LI (P<0.05). Compared with group LI, OI was significantly increased, RI, concentrations of IL-6 and IL-1β in serum and pathological scores of lung tissues were decreased at T3, and the concentration of serum TNF-α was increased at T3 in group IGF-1 (P<0.05). Conclusion IGF-1 pretreatment can reduce lung injury in rats undergoing CPB, and the mechanism is related to inhibiting inflammatory responses. Key words: Insulin-like growth factor Ⅰ; Cardiopulmonary bypass; Respiratory distress syndrome, adult