Objective To explore the effects of calcitonin gene - related peptide( CGRF) on type II alveolar epithelial cell( AEC II ) exposed to hyperoxia and whether the mechanism is mediated by extracellular signal - regulated kinase ( ERK) pathway. Methods AEC II were isolated from 21 d fetal rat lung and grew for 12 h to attach. Then AEC II were randomly divided into six groups;air group,CGRP/air group,CGRP8 -37/air group,hyperoxia group,CGRP/O2 and CGRP8 - 37/O2 group. Air or hyperoxia environment was achieved by exposing AEC1I into 210 mL · L-1oxygen or 850 mL · L-1 oxygen for 18 h. CGRP group or CGRP8 - 37 group was carried out by adding 10-1 mol · L-1 CGRP or both CGRP and CGRP8 -37(10-1 mol · L-1) ,a receptor antagonist against CGRP,into medium before cultured in air or 850 mL · I-1 oxygen. Lactate dehydrogenase (LDH) ,alkaline phosphatase (AKP) and malondialdehyde (MDA) were measured by immune tur-bidimetry and reactive oxygen species( ROS) by flow cytometry. Immunofluorescence microscopy was used to analyze the expression of surfactant protein C( SP - C) and Western blot was taken to detect the content of p - ERK1/2. Results The levels of MDA,LDH,AKP,ROS and p-ERKl/2 were markedly increased in hyperoxia group than those in air group [(2. 29 ±0.10) μmol · L-1 vs (1.06±0.14) μmol · L-1, (58.79 ±5.01) U ·L-1 vs (25.92 ±3.68) U · L-1,(24.63 ±2.92) U · L-1 vs (10. 34 ±1.78) U · L-1,47.74 ±3.35 vs 25.96 ±5.04, 1.21 ±0.06 vs 0.45 ±0.05 ,P, <0.01] .whereas expression of SP -C was decreased in hyperoxia group compared with air group (22.75 ±3.31 vs 43. 50 ± 4.42 ). Levels of MDA, LDH, AKP and ROS were reduced with an elevated expression of p - ERK1 /2 and SP - C in CGRP/O2 group compared with those in hyperoxia group and CGRP8 - 37/O2 group (Pa < 0. 01). There were no significant differences about the levels of MDA,LDH,AKP,ROS and SP- C among three groups cultured in air condition. The expression of p - ERK1/2 in CGRP/air group was also higher than that in air group or CGRP8 - 37/air group(P. < 0.01). Conclusion CGRP can protect lung epithelium cells against hyperoxic insult and its effects can mediate by ERK pathway.%目的 探讨降钙素基因相关肽(CGRP)对高体积分数氧(高氧)暴露下胎鼠肺泡Ⅱ型上皮细胞( AECⅡ)氧化损伤的影响,及其作用是否由细胞外信号调节激酶(ERK)所介导.方法 原代分离培养孕21 d胎鼠AECⅡ,培养12 h待细胞贴壁后分为6组:空气组、空气CGRP组、空气CGRP拮抗剂组、高氧组、高氧CGRP组、高氧CGRP拮抗剂组.空气组和高氧组分别在氧体积分数为210 mL·L-1的空气或850 mL·L-1的氧气中培养18 h.CGRP组和CGRP拮抗剂组分别在空气或高氧暴露前加入CGRP或同时加入CGRP和其受体拮抗剂CGRPS-37,终浓度分别为10-8 mol·L-1和10-7 mol·L-1.用免疫比浊法测定培养液LDH、AKP和丙二醛(MDA)水平,流式细胞术测定细胞内活性氧(RoS)水平,荧光显微镜检测胞质表面活性蛋白C(SP-C)的表达情况,Western blot检测磷酸化ERK1,2(p-ERK1/2)的表达水平.结果 高氧组MDA、LDH、AKP、ROS及p-ERK1/2水平均明显高于空气组[(2.29±0.10) μmol ·L-1 vs (1.06 ±0.14)μmol·L-1,( 58.79±5.01)U·L-1 vs(25.92±3.68)U·L-1,(24.63±2.92)U·L-1 vs (10.34±1.78)U·L-1,47.74±3.35 vs 25.96±5.04,1.21±0.06 vs 0.45±0.05,Pa＜0.01],而细胞内SP-C表达则明显低于空气组(22.75±3.31 vs 43.50±4.42)；与高氧组及高氧CGRP拮抗剂组比较,高氧CGRP组MDA、LDH、ROS及AKP水平显著降低,而p-ERK1/2及SP-C的表达水平则明显增高(Pa＜0.01).空气组、空气CGRP组、空气CGRP拮抗剂组组间MDA、LDH、ROS、AKP及SP-C表达水平比较差异均无统计学意义；空气CGRP组p-ERK1/2表达水平明显高于空气组及空气CGRP拮抗剂组(Pa＜0.01).结论 CGRP可减轻高氧对AECⅡ的氧化损伤,其作用机制可能是通过ERK的活化来介导.
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