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目的探讨机械通气产生的气道压力对大鼠气道黏液高分泌的影响及机制。方法 48只SD大鼠分为4组,实施麻醉和气管切开后接小动物呼吸机进行机械通气。①对照组(8只):大鼠气管插管后自主呼吸;②机械通气组:对大鼠采用压力控制通气模式机械通气,根据气道压力水平再分10、20、30 cmH2O 3个亚组,每个亚组8只大鼠,机械通气6 h;③钌红干预组(8只):施加机械通气前鼠尾静脉注射瞬时感受器电位香草酸受体4型通道蛋白(transient receptorpotential vanilloid 4,TRPV4)非特异性阻断剂钌红(ruthenium red,RR)进行预处理;④4α-PDD干预组(8只):机械通气前鼠尾静脉注射4-α-佛波醇-12,13-二癸酸(4-α-Phorbol-12,13-didecanoate,4α-PDD)进行预处理。实验完毕后收集大鼠支气管肺泡灌洗液(BALF)和肺组织标本。采用ELISA法检测BALF中MUC5AC蛋白含量,RT-PCR法检测大鼠肺组织MUC5ACmRNA的表达水平。结果与对照组相比,机械通气组MUC5AC在蛋白及转录水平表达均增加,呈压力依赖性。30 cmH2O亚组MUC5AC蛋白及mRNA转录水平分别为[(0.71±0.10)、(6.23±0.54)]明显高于对照组[(0.29±0.05)、(1.68±0.35)](P<0.01)。在30 cmH2 O压力水平下MUC5AC的表达增加可被RR干预减弱[(0.41±0.06)、(4.15±0.22)](P<0.05),被4α-PDD干预增强[(1.12±0.09)、(8.47±0.35)](P<0.05)。结论 机械通气产生的气道压力可以通过作用于TRPV4诱导MUC5AC表达增加,这可能是压力诱导气道黏液高分泌的调节机制之一。
Objective To investigate the effect and mechanism of airway pressure induced by mechanical ventilation on airway mucus hypersecretion in rats. Methods 48 SD rats were divided into 4 groups. After anesthesia and tracheotomy, they were ventilated by small animal ventilator. ① Control group (8 rats): spontaneous respiration after tracheal intubation in rats; ②Mechanical ventilation group: rats were ventilated by pressure-controlled ventilation and sub-divided into 10, 20, 30 cmH2O subgroups according to airway pressure , 8 rats in each subgroup were given mechanical ventilation for 6 h. ③ Ruthenium red intervention group (n = 8): transient receptor potential vanilloid 4 TRPV4) was pretreated with ruthenium red (RR) .④The 4α-PDD intervention group (n = 8): 4-α-phorbol-12,13- Acid (4-α-Phorbol-12,13-didecanoate, 4α-PDD). After the experiment, bronchoalveolar lavage fluid (BALF) and lung tissue samples were collected. The content of MUC5AC in BALF was detected by ELISA, and the expression of MUC5AC mRNA in lung tissue was detected by RT-PCR. Results Compared with the control group, the expression of MUC5AC in the mechanical ventilation group was increased at a protein and transcription level, showing a pressure-dependent manner. The transcription level of MUC5AC protein and mRNA in the 30 cmH2O subgroup was significantly higher than that in the control group [(0.71 ± 0.10), (6.23 ± 0.54), respectively] (0.29 ± 0.05, 1.68 ± 0.35, P <0.01). The increased expression of MUC5AC at 30 cmH2O pressure was attenuated by RR intervention [(0.41 ± 0.06), (4.15 ± 0.22)] (P <0.05), and was enhanced by 4α-PDD intervention [(1.12 ± 0.09), ± 0.35)] (P <0.05). Conclusions Airway pressure induced by mechanical ventilation can induce MUC5AC expression through TRPV4, which may be one of the mechanisms of pressure-induced mucus hypersecretion.