吸入低浓度异氟烷对肺感染大鼠气血屏障的影响

The effects of inhalation of low concentration isoflurane on pulmonary air-blood barriers in rats with pulmonary infection

目的探讨低浓度异氟烷对肺感染大鼠气血屏障的影响。方法健康清洁级Wistar大鼠32只,体重240～300g,随机分为4组：盐水正常组（C组）、异氟烷正常组（Ⅰ组）、内毒素组（L组）和给内毒素后吸入异氟烷组（T组）。气管内注入内毒素（LPS,10mg/kg溶于0．5ml生理盐水）或等量生理盐水15min后,T组、I组吸入0．68%异氟烷2h后再机械通气2h；L组、C组单纯机械通气4h。监测平均动脉压（MAP）,分别于机械通气20min（T0）、气管内注入内毒素或生理盐水后15min（T1）、吸入异氟烷1h（T2）、2h（T3）、停止异氟烷吸入1h（T4）、2h（T5）采集动脉血行血气分析；于T2、T3、T4时点进行气管内吸引,抽取气道内液体并计算其总重量,随后处死动物,测定肺湿/干重比（W/D）、支气管肺泡灌洗液（BALF）中性粒细胞百分比和蛋白浓度,并行肺组织病理学检查。结果与L组相比,T组在T2、T5时点动脉血氧分压升高（P＜0．05）,在T4、T5时点动脉血二氧化碳分压降低（P＜0．05）；T组气道内液体总重量、BALF中性粒细胞百分比和蛋白浓度均降低（P＜0．05）；T组肺脏病理改变减轻。虽然T组指标有改善,但尚未恢复到C组水平。结论吸入低浓度异氟烷对肺感染大鼠气血屏障具有一定的保护作用,可能与抑制中性粒细胞在肺内积聚有关。

Objective To investigate the effects of low concentration isoflurane on pulmonary air-blood barriers in rats with pulmonary infection.Methods Thirty-two healthy Wistar rats weighing 240-300 g were randomly divided into 4 groups： saline group （group C）, isoflurane group （group Ⅰ）, LPS group （group L） and LPS-isoflurane group （group T）. At 15 min after intratracheal instillation of lipopolysaccharide （10 mg/kg LPS was dissolved in 0.5 ml normal saline） or equivalent volume of normal saline, group T or group Ⅰ inhaled isoflttrane at the end-expired concentration of 0.68% for 2 h and then were ventilated for 2 h, and group L or group C were ventilated alone for 4 h. The mean arterial pressure （MAP） was monitored. Arterial blood gases were analyzed respectively at 20 min of ventilation （ T0 ）, 15 min after intratracheal instillation （ W1 ） , 1h and 2 h following inhalation of isoflurane（T2 , T3 ）, 1 h and 2 h after stopping inhalation of isoflurane （T4, T5 ） . The total weight of the airway fluid sucked at T2 , T3 and T4 was recorded. The rats were sacrificed for determination of the lung wet to dry weight ratio （W/D）, neutrophil percentage and protein level in bronchoalveolar lavage fluid （BALF）, and for microscopic examinations of the lung tissue. Results PaO2 was significantly increased at T2 and T5 , PaCO2 was decreased at T4 and T5 in group T as compared with group L. The neutrophil percentage and protein concentration in BALF and the total weight of fluid in airway were significantly lower in group T than in group L. Pathological changes of the lung were obviously alleviated in group T as compared with group L, but there were significant differences in the above parameters between group T and group C. Conclusion Inhalation of low concentration isoflurane can protect pulmonary air-blood barriers in rats against pulmonary infection-induced injury. The inhibition of neutrophil accumulation in the lung is involved in the underlying mechanism.