Expressions Of Endothelin Receptors And Endothelin Converting Enzyme-1 In Pulmonary Hemorrhage In Newborn Rats

Objective To investigate the expressions of endothelin A receptor, endothelin B receptor, endothelin converting enzyme-1 in pulmonary tissue of newborn rats developing pulmonary hemorrhage by establishing pulmonary hemorrhage model in different phases induced by hypothermia-hypoxia/rewarming-reoxygenating.Methords 75 Wistar newborn rats were randomly divided into control group(group C, n=15) and four experimental groups: group H1 (n=15),group H2 (n=15), group H3 (n=15), group H4:(n=15). Group C were exposed to normothermia and normoxia and, group H1 to hypoxia (FiO2 5~6%) for 6 hours,group H2 to hypothermia (10±1℃) for 6 hours, group H3 to hypothermia and hypoxia for 6 hours, group H4 to hypothermia and hypoxia for 6 hours and followed by hyperthermia(37℃) and hyperoxia (FiO2>95%) for 2 hours. The gross anatomical and histological changes (HE staining) in lungs were observed. Expressions of endothelin A receptor mRNA(ETAmRNA), endothelin B receptor mRNA(ETBmRNA), endothelin converting enzyme-1 mRNA (ECE-1mRNA) were measured by real-time reverse transcription polymerase chain reaction.Results 1.11 rats in experimental groups died while none in group C and the mortality rate of experimental groups was 18.33%. Gross anatomical in experimental groups included edema, spotty pulmonary hemorrhage, local pulmonary hemorrhage and diffuse pulmonary hemorrhage. 2. Expression of ETAmRNA increased significantly in group H1, H2 and H3 (P<0.01), and decreased significantly in group H4 and even less than that in group C(P<0.01).3. Expression of ETBmRNA elevated significantly in group H1, H2, H3 and H4 (P<0.01 in group H1, H2, H3 and P<0.05 in group H4). 4. Expression of ECE-1mRNA raised significantly in group H1, H2 and H3 (P<0.01), and decreased significantly after rewarming-reoxygenating compared with other groups (P<0.01 in group H1, H2, H3 and P<0.05 in group C).Conclusion 1.Pulmonary hemorrahge model can be established successfully in newborn rats subjected hypothermia-hypoxia/rewarming- reoxygenating. Hypoxia,hypothermia and rewarming/ reoxygenating are factors contributing to lung injury. 2.Hypoxia and hypothermia may promote the expressions of ETAmRNA, ETBmRNA and ECE-1mRNA ; Rewarming/ reoxygenating may reduce the expressions of ETAmRNA and ECE-1mRNA ; 3. ETA, ETB, ECE-1 may contribute to the development of pulmonary hemorrhage by altering the expression and biological function of ET-1.