慢性阻塞性肺疾病大鼠肺组织中表面活性蛋白C表达与呼吸参数的关系

Relationship between surfactant protein C expression in lung tissues and respiratory parameters in rats with chronic obstructive pulmonary disease

目的探讨慢性阻塞性肺疾病(COPD)大鼠肺组织中表面活性蛋白C(SP-C)表达与呼吸功能的关系。方法将20只Sprague Dawley大鼠随机分为COPD组和对照组,每组10只。COPD组大鼠每日香烟烟雾暴露2次,每次30 min,持续暴露28 d,第1、14天气管内滴注脂多糖1 mg·kg^-1。对照组大鼠正常饲养,不做任何处理。第29天,2组大鼠腹腔注射40 g·L^-1水合氯醛(10 mL·kg^-1)麻醉,暴露膈肌,使用2个针式电极连接膈肌和BL-420生物信号采集处理系统,采集呼吸曲线,记录吸气时间、呼气时间、呼吸幅度、呼吸频率。呼吸曲线参数采集后处死大鼠,完整取出双侧肺脏;采用免疫组织化学染色观察肺组织中SP-C蛋白表达,酶联免疫吸附试验检测肺组织中SP-C蛋白水平,反转录-聚合酶链反应检测肺组织中SP-C mRNA表达。结果COPD组大鼠吸气时间、呼气时间、呼吸幅度、呼吸频率分别为(263.29±14.01)ms、(429.32±13.52)ms、(3.79±1.02)g、(82.39±7.15)次·min^-1,对照组大鼠吸气时间、呼气时间、呼吸幅度、呼吸频率分别为(290.51±17.24)ms、(371.45±12.19)ms、(4.93±1.27)g、(71.21±5.04)次·min^-1;与对照组比较,COPD组大鼠吸气时间缩短,呼气时间延长,呼吸幅度变小,呼吸频率升高(P<0.05)。COPD组和对照组大鼠肺组织匀浆中SP-C蛋白表达水平分别为(346.19±17.03)、(465.82±21.60)μg·L^-1,COPD组大鼠肺组织匀浆中SP-C蛋白表达水平低于对照组(P<0.05)。COPD组和对照组大鼠肺组织中SP-C mRNA相对表达量分别为0.141±0.012、0.224±0.003,COPD组大鼠肺组织中SP-C mRNA相对表达量显著低于对照组(P<0.05)。结论香烟烟雾和脂多糖可损伤大鼠肺泡上皮,使SP-C释放减少,肺顺应性降低,导致肺通气及肺换气不足,呼吸功能下降。

Objective To investigate the relationship between the expression of surfactant protein C(SP-C)in lung tissues and respiratory function in rats with chronic obstructive pulmonary disease(COPD).Methods Twenty Sprague Dawley rats were randomly divided into COPD group and control group,with 10 rats in each group.The rats in the COPD group were exposed to cigarette smoke for 28 days(twice a day,30 minutes each time),and lipopolysaccharide(1 mg·kg^-1)was infused into trachea of rats on the 1 st and and 14 th day.The rats in the control group were fed normally without any treatment.On the 29 th day,all rats in the two groups were anesthetized by intraperitoneal injection of 40 g·L^-1 chloral hydrate(10 mL·kg^-1),and the diaphragm of rats was exposed.The diaphragm and BL-420 biological signal acquisition and processing system were connected by two needle electrodes to collect the respiratory curve,including inspiratory time,expiratory time,respiratory amplitude and respiratory frequency.The rats were killed after the acquisition of respiratory curve parameters,and the bilateral lungs were removed completely.The expression of SP-C protein in lung tissues was observed by immunohistoche-mical staining,the level of SP-C protein in lung tissues was detected by enzyme linked immunosorbent assay,and the expression of SP-C mRNA was detected by reverse transcription polymerase chain reaction.Results The inspiratory time,expiratory time,respiratory amplitude and respiratory rate of rats in the COPD group were(263.29±14.01)ms,(429.32±13.52)ms,(3.79±1.02)g,(82.39±7.15)times·min^-1,respectively;while those in the control group were(290.51±17.24)ms,(371.45±12.19)ms,(4.93±1.27)g,(71.21±5.04)times·min^-1.Compared with the control group,the inspiratory time was shortened,the expiratory time was prolonged,the respiratory amplitude was decreased and the respiratory rate was increased in the COPD group(P<0.05).The expression level of SP-C protein in lung homogenate of rats in the COPD group and the control group was(346.19±17.03)μg·L^-1 and(465.82±21.60)μg·L^-1,respectively.The expression of SP-C protein in lung homogenate of rats in the COPD group was lower than that in the control group(P<0.05).The relative expression of SP-C mRNA in lung tissues of rats in the COPD group and the control group was 0.141±0.012 and 0.224±0.003,respectively.The relative expression of SP-C mRNA in lung tissues of rats in the COPD group was significantly lower than that in the control group(P<0.05).Conclusion Cigarette smoke and lipopolysaccharide can damage the alveolar epithelium of rats,and reduce the release of SP-C,which can lead to the decrease of lung compliance,pulmonary ventilation and ventilation disorders,and decreased respiratory function.