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目的观察氯胺酮对哮喘模型大鼠气道高反应性及炎症的影响。方法 56只 BrownNorway 大鼠随机分成阴性对照组(A 组)、哮喘模型组(B 组)和不同浓度氯胺酮雾化吸入预处理组(C组、D 组和 E 组)及不同剂量氯胺酮腹腔用药预处理组(F 和 G 组)。采用卵蛋白(OVA)辅以百日咳杆菌菌苗和氢氧化铝为佐剂注射致敏大鼠。雾化吸入10 mg/ml OVA 激发。氯胺酮预处理组大鼠在激发前分别给予12.5 mg/ml、25 mg/ml 或50 mg/ml 浓度的氯胺酮雾化吸入或50μg/kg,100μg/kg剂量的氯胺酮腹腔注射。A 组采用磷酸盐缓冲液替代 OVA 进行雾化吸入。最后1次激发后24 h,测定气道反应性。并取肺组织作诱导性一氧化氮合酶(iNOS)的基囚和蛋白表达,一氧化氮(NO)生成量及病理组织学检测。结果 (1)B 组的呼气阻力(Re)增长百分率的剂量反应曲线向左上移位,而且PC100(Re 增长达100%幅度时所需乙酰胆碱的激发剂量),PC200及 PC400值显著低于 A 组(分别为14.65±1.19vs32.28±1.43,15.17±1.19vs38.91±1.39及16.28±1.18vs56.53±1.38)差异有统计学意义(P<0.01)。氯胺酮预处理组的 Re 剂量反应曲线向右下移位,而 PC100,PC200及PC400值均明显高于 B 组(P<0.05)。(2)B 组可见明显的气道炎症性病理改变。氯胺酮治疗组炎症细胞浸润及上皮细胞损伤程度明显减轻,肺间质水肿改善。(3)B 组 iNOS 基因表达与 A 组相比明显增强(1.00±0.07vs0.48±0.07,P<0.01)。与 B 组相比,iNOS 基因的表达在 C 组(0.65±0.07),D 组(0.58±0.09),E 组(0.56±1.00)及 F 组(0.66±0.06)均减低,差异有统计学意义(P<0.05)。(4)与 A 组相比,B 组 iNOS 蛋白表达(0.54±0.08)明显增强(P<0.05),而与 B 组相比,iNOS 蛋白表达量在 C 组(0.20±0.03),D 组(0.18±0.03)及 F 组(0.21±0.04)均减低,差异有统计学意义(P<0.05)。(5)B 组肺组织 NO 产量[(0.39±0.04)μmol/g 蛋白]显著高于 A 组(P<0.01)。肺组织 NO 产量在 C 组[(0.19±0.03)μmol/g 蛋白],D 组[(0.17±0.03)μmol/g 蛋白]及F组[0.16±0.04)μmol/g 蛋白]明显低于 B 组,差异有统计学意义(P<0.05)。结论氯胺酮明显抑制致敏原诱发的肺 iNOS 的高表达,降低 NO 的过度产生,从而减轻炎性损伤,抑制气道高反应性,对哮喘模型大鼠具有肺保护作用。
Objective To observe the effects of ketamine on airway hyperresponsiveness and inflammation in asthmatic rats. Methods Fifty-six BrownNorway rats were randomly divided into three groups: control group (group A), asthma model group (group B) and different concentrations of ketamine inhalation pretreatment group (group C, group D and group E) Treatment groups (Groups F and G). Sensitized rats were injected with OVA supplemented with Bordetella pertussis vaccine and aluminum hydroxide as an adjuvant. Inhalation 10 mg / ml OVA challenge. Ketamine preconditioning rats were given ketamine at doses of 12.5 mg / ml, 25 mg / ml or 50 mg / ml by nebulized inhalation or 50 μg / kg and 100 μg / kg doses of ketamine intraperitoneally before challenge. Group A used phosphate buffer instead of OVA for inhalation. 24 h after the last challenge, airway responsiveness was measured. The lung tissue was used as the substrate and protein expression of inducible nitric oxide synthase (iNOS), nitric oxide (NO) production and histopathological examination. Results (1) The dose-response curve of the percentage of increase of expiratory flow (Re) in group B shifted to the upper left, and PC100 (the dose of acetylcholine required for increasing Re to 100% amplitude), PC200 and PC400 values were significantly lower than that of A (14.65 ± 1.19 vs 32.28 ± 1.43, 15.17 ± 1.19 vs. 38.91 ± 1.39 and 16.28 ± 1.18 vs 56.53 ± 1.38, respectively) (P <0.01). Re dose response curve of Ketamine pretreatment group shifted to the right downward while PC100, PC200 and PC400 values were significantly higher than that of B group (P <0.05). (2) In group B, obvious airway inflammatory pathological changes were observed. Ketamine treatment group inflammatory cell infiltration and epithelial cell damage was significantly reduced, interstitial edema improved. (3) The expression of iNOS gene in group B was significantly higher than that in group A (1.00 ± 0.07 vs 0.48 ± 0.07, P <0.01). Compared with group B, the expression of iNOS gene was decreased in group C (0.65 ± 0.07), group D (0.58 ± 0.09), group E (0.56 ± 1.00) and group F (0.66 ± 0.06), the difference was statistically significant (P <0.05). (4) Compared with group A, the expression of iNOS protein in group B (0.54 ± 0.08) was significantly increased (P <0.05), while the expression of iNOS protein in group B was significantly lower than that in group C 0.18 ± 0.03) and F (0.21 ± 0.04), respectively. The difference was statistically significant (P <0.05). (5) NO production in group B was significantly higher than that in group A ([(0.39 ± 0.04) μmol / g protein, P <0.01). NO production in lung tissue was significantly lower in group C than that in group B ([(0.19 ± 0.03) μmol / g protein, [0.17 ± 0.03] μmol / g protein in group D] and 0.16 ± 0.04 μmol / g protein in group F , The difference was statistically significant (P <0.05). Conclusions Ketamine significantly inhibits the allergen-induced lung iNOS overexpression, reduces the overproduction of NO, thus alleviates inflammatory injury, inhibits airway hyperresponsiveness and has lung protection in asthmatic rats.