【作者】 赵晖；

【导师】 徐礼鲜； 张惠；

【作者基本信息】 第四军医大学 ， 麻醉学， 2009， 博士

【摘要】 目的利用低压舱模拟高原技术,建立家兔急性高原低压缺氧模型,观察高氧液对急性高原低压缺氧的防治作用,并初步探讨其相关机理,以期为进一步积极探讨和研究急性高原低压缺氧损伤及其防治机制找到一种新的方法和途径。方法1.高氧液的制备:以气密包装的500ml医用生理盐水为高氧液基液,医用氧气瓶为气源,以3 L/min氧流量通过连接管道输入高氧医用液体治疗仪,氧气经过反应室输出端通入基液进行溶氧活化处理,经15min溶氧后制备成高氧液。2.低压舱模拟高原急性低压缺氧动物模型的建立:选择雄性健康家兔,体重2.5±0.2 kg,静脉注射3%戊巴比妥钠20mg/kg麻醉动物,颈部正中切开,右侧颈总动脉穿刺置管后,逐层严密缝合关闭伤口。除常压(平原)对照组外,其余低压缺氧组在实验中均分别暴露于预设模拟海拔高度的实验动物低压舱内3h,低压舱海拔高度上升速度为10m/s。所有模拟高原缺氧的实验组动物入低压舱后,将肝素化的动脉穿刺延长导管经过舱壁上的气密通道连接于舱外。实验过程中,分别采集入舱前以及到达预设的模拟海拔高度后30 min、1、2、和3h的血样进行动脉血气分析,记录PaO2和SaO2。当3h的模拟低压缺氧暴露过程完成后,低压舱以20m/s的减压速率降低到平原状态,迅速开舱取出动物并立即处死进行解剖,取出相应器官组织进行组织含水量、生物化学以及病理学检测与观察。3.动物分组:实验动物根据不同的实验目的与研究指标分为三个大组(注:各大组中的常压平原对照组和后两大组中低压缺氧对照组,即C组和H组为同一组动物),具体情况如下:①低压舱模拟高原急性低压缺氧损伤动物模型海拔高度的确定:健康雄性家兔40只,随机分为4组,每组10只,除其中一组为常压(平原)对照组(C组)外,其余3组均为模拟高原急性低压缺氧损伤暴露组,模拟海拔高度分别为3,000m(H1组)、5,000m(H2组)、8500m(H3组)。动物实验和相关指标检测与观察完成后,根据实验结果数据,确定后续研究所需的合适模拟海拔高度。②急性低压缺氧暴露前高氧液预处理:50只健康雄性家兔,随机分为5组(C、H、HIP、HVP和HOSP组),每组10只。除C组为常压(平原)对照组外,其余四组在实验中均分别暴露于模拟海拔8,500 m的实验动物低压舱内3h。其中,H组作为低压缺氧对照组,在入舱前不做任何处理;HIP组在入舱前30min给予持续面罩吸氧,氧流量为0.2-0.4L/min;HVP组入舱前30min内静脉匀速输注完毕10ml/kg高氧液基液-0.9%生理盐水;HOSP组则在入舱前静脉输注相同剂量的新鲜制备高氧液。所有组动物在实验结束后均立即处死进行解剖,取出相关的器官和组织进行组织含水量、生物化学以及病理学检测与观察。③急性低压缺氧暴露过程中静脉输注高氧液:50只健康雄性家兔,随机分为5组(C、H、HI、HV和HOS组),每组10只。除C组为常压(平原)对照组外,其余四组在实验中均分别暴露于模拟海拔8,500 m的实验动物低压舱内3h。其中,H组作为低压缺氧对照组,在舱内不做任何处理;HI组为低压缺氧面罩吸氧组,氧流量为0.2-0.4L/min;HV组静脉恒速输注10ml/kg/h高氧液基液-0.9%生理盐水;HOS组则以相同的方式静脉输注新鲜制备的高氧液。所有组动物在实验结束后均立即处死,提取标本进行相关检测与观察。4.检测指标:所有模拟高原缺氧的实验组动物分别采集入低压舱前以及到达预设的模拟海拔高度后30 min、1、2、和3h的血样进行动脉血气分析,记录PaO2和SaO2。动物在处死前抽取静脉血10ml,低温离心,分离血清,取不溶血血清样品-70℃冰箱保存,用来检测心肌酶谱乳酸脱氢酶(LDH)、肌酸激酶(CK)、心肌型肌酸激酶同功酶(CK-MB)活性,以及血清中TNF-α、乳酸(D-lactate)、MDA和SOD、CAT、GSH-Px活性。实验动物完成急性低压缺氧暴露处死后,立即解剖摘取右侧肺脏,行支气管肺泡灌洗,从气管注入30ml生理盐水,反复三次,得到支气管肺泡灌洗液(BALF);采用考马斯亮蓝法测定BALF与血清中蛋白浓度之比,即为肺通透性指数。另取左肺与左侧大脑半球,滤纸吸干水分后称重(湿重),并将其置于60℃干燥箱内烘烤72h后再次称重,计算肺、脑含水量。取少许心、脑、肺脏相同部位组织,生理盐水清洗干净,分别置于10%中性福尔马林液或5%戊二醛中固定,制作光镜病理切片和制备电镜标本,用来观察各器官的组织病理学改变。另取家兔心、脑、肺脏相同部位组织,用生理盐水洗三次,清除残血,之后用滤纸吸干,各取0.5克制备10%组织匀浆,用于检测组织中MDA含量和SOD、CAT、GSH-Px活性以及脑、肺组织髓过氧化物酶(MPO)活力、NO含量、脑和心肌组织Na+ K+-ATPase活力以及肺组织的TXB2和6-keto-PGF1α含量。结果1.动物在不同模拟海拔高度急性低压缺氧暴露的过程中动脉血PaO2和SaO2与平原状态相比均有显著地下降。其中海拔8,500m急性低压缺氧暴露组PaO2和SaO2呈现出最为降低的水平,且该组动物的肺和脑组织含水率、组织病理损伤、MDA含量和SOD、CAT、GSH-Px活力的伤害性改变水平显著高于处于平原对照组、海拔3,000m和5,000m组。2.高氧液预处理,显著改善了模拟海拔8,500m急性低压缺氧暴露30min时PaO2和SaO2降低的水平。但在完成急性低压缺氧暴露3h后,高氧液预处理组、面罩吸氧预处理和其他低压缺氧暴露组,在肺和脑组织含水率、组织病理损伤、TNF-α、乳酸、MDA含量及SOD、CAT和GSH-Px活性、MPO活力、NO含量、脑和心肌组织Na+ K+-ATPase活力、肺组织的TXB2和6-keto-PGF1α含量及其释放比值和心肌酶谱等方面均出现了伤害性改变,且各组之间以上检测指标相互比较没有显著的统计学差异。3.模拟海拔8,500m急性低压缺氧暴露过程中静脉输注高氧液,显著改善了PaO2和SaO2降低的水平,明显降低了肺和脑组织含水量、组织病理损伤、TNF-α、乳酸、MDA含量及SOD、CAT和GSH-Px活性、MPO活力、脑和心肌组织Na+ K+-ATPase活力以及肺组织的TXB2/6-keto-PGF1α释放比值和心肌酶谱等指标出现的有害性变化,提示暴露在急性低压缺氧条件下静脉输注高氧液,对机体组织器官的缺氧损伤均具有一定程度的保护作用。结论1.模拟急性高原缺氧暴露前高氧液预处理,对急性低压缺氧造成的机体损伤没有明显的保护作用,其原因可能与高氧液在体内有效作用持续时间的局限性有关。2.模拟急性高原缺氧暴露过程中静脉输注高氧液,能够明显减轻急性低压缺氧所致机体氧化性伤害,并且对肺、脑、以及心肌组织的急性低压缺氧损伤具有一定的保护作用。3.高氧液减轻急性低压缺氧所致机体损伤的可能机制在于高氧液能够不依赖于肺的气体交换功能,通过血液循环系统直接地向组织供氧,改善PaO2和SaO2水平的下降;提高机体内抗氧化酶的活性,降低脂质过氧化反应程度;调节组织微血管收缩/舒张因子的释放比例,从而缓解急性低压缺氧下造成的细胞毒性和血管源性组织渗出与水肿。4.高氧液可有效减轻与改善急性低压缺氧造成的机体损伤,但在应用高氧液防治高原急性低压缺氧损伤时,不但要注意治疗剂量,还要重视给药的方法以及给药时机,才能达到满意与有效的治疗效果。更多还原

【Abstract】 AIMS: A rabbit simulated acute high altitude (HA) exposure model was established by using an animal decompression chamber to observe tissues and organs injury induced by acute hybobaric hypoxia, and to investigate the protective effects and potential mechanisms of hyperoxygenated solution (HOS) intravenous infusion and HOS preconditioning on these injuries.METHODS:1. Preparation of HOS: Airtight normal saline solution (0.9%, 500 mL/dose) serves as the base solution. Medical oxygen (from an oxygen bomb) is introduced into the‘medical hyperoxygenated solution apparatus’at an inflow of 3 L/min. Treatment with ultraviolet light (wavelength = 180–240 nm) in the reaction chamber results in rapid transformation of O2 into O3, after which the O2/O3 mixture flows into the airtight base solution from the outlet end of the apparatus. The nitrogen (N2) dissolved as 70% by volume in the fluid will be replaced by O3 and O2. The preparation process takes 15 min to complete. The PO2 can reach 795±58.5 mmHg during the preparation of HOS, and the base solution transforms into HOS. The concentration of O3 in freshly made HOS was 13.4±2.6μg/mL, but fell to zero after 20 min. 2. Rabbit simulated acute HA exposure model: Male New Zealand white rabbits with a mean body weight of 2.5±0.2 kg were used in this study. After a six hours fasting with unrestricted access to water, the animals were anesthetized intravenously with 3% pentobarbital sodium (30mg/kg). After making an incision in the neck, a heparinized catheter was introduced into the right common carotid artery. The catheter was extended from the decompression chamber through a gas-tight channel during a simulated altitude of 8,500 m exposure for 3 hours in an animal decompression chamber, and the heparinized catheter was used to obtain specimens for blood gas analysis (before and 30 min; and 1, 2 and 3 hours after HA 8,500 m exposure). The incision was sutured and covered with plastic wrap. When the stipulated period of HA exposure was over, the chamber was returned to the local altitude level (rate of descent: 20 m/sec). The animals were rapidly sacrificed and the following assessments were made.3. Grouping: Experimental animals were divided randamly into three large groups according to different experimental design(Notes:the three large group share the same C and H group)a. The altitude level Determination of the simulated acute HA exposure model: Fourty rabbits were randomly divided into four groups: control group (C group) in which animals were kept at normal atmospheric pressure (local altitude level = 477 m). The remaining three groups were exposed respectively to a simulated altitude of 3,000 m ( H1 group ), 5,000 m ( H2 group ) and 8,500 m (H3 group ) for 3 hours in an animal decompression chamber.b. HOS preconditioning before HA exposure: Fifty rabbits were randomly divided into five groups: Except control group (C group), the remaining four groups were exposed to a simulated altitude of 8,500 m for 3 hours, H group served as the hypobaric hypoxia control group which received no treatment during HA exposure, the animals in HIP group were treated with continued mask oxygen inhalation (0.2–0.4 L/min) in 30min before HA exposure, HVP group and HOSP group were received i.v. infusions of either 0.9% normal saline solution (HVP group) or freshly made HOS (HOSP group), respectively, by an infusion pump, with an infusion dose of 10 mL/kg in 30 min before HA exposure.c. HOS intravenous infusion during HA exposure: Fifty rabbits were randomly divided into five groups: Except control group (C group), the remaining four groups were exposed to a simulated altitude of 8,500 m for 3 hours. During the period of HA exposure, H group served as the hypobaric hypoxia control group which received no treatment, HI group were treated with continued mask oxygen inhalation (0.2–0.4 L/min), the animals in HV group and HOS group were received i.v. infusions of either 0.9% normal saline solution (HV group) or freshly made HOS (HOS group), respectively, by an infusion pump, with an infusion dose of 10 mL/kg per hour during HA exposure.4. Observation items: During HA exposure, blood gas analysis was made to observe the changes of PaO2 and SaO2. After HA exposure, peripheral vein blood samples were obtained, and lung, brain and myocardium tissues were harvested for further study. Plasma concentrations of TNF-α, D-lactate, LDH, CK, CK-MB, MDA contents, activities of SOD, CAT and GSH-Px were measured respectively. Lung and brain water contents; NO, MDA contents, activities of SOD, CAT and GSH-Px in lung, brain and myocardium tissues; MPO activities in lung and brain; activities of Na+ K+-ATPase in brain and myocardium tissues and contents of TXB2 and 6-keto-PGF1αin lung tissues were also detected, respectively.RESULTS:1. During exposure to the simulated altitude of different levels for 3 hours, PaO2 and SaO2 of the HA exposure groups were markedly decreased, and the levels of PaO2 and SaO2 in the 8,500m simulated altitude group were lowest among the HA exposure groups. We also find the most severity degree of tissues and organs injury in the 8,500m simulated altitude group, to draw assistance from analysising the negatively changes of following measurement data: lung and brain water contents, MDA contents, activities of SOD, CAT and GSH-Px in Plasma, lung, brain and myocardium tissues.2. HOS preconditioning before HA exposure can significantly increased the levels of PaO2 and SaO2 at 30 min after 8,500m simulated altitude exposure. But, HOS preconditioning before HA exposure did not attenuated the tissues and organs injury induce by acute hypobaric hypoxia, to draw assistance from analysising the anomalies of following detected parameters: lung and brain water contents; plasma concentrations of TNF-α, D-lactate, LDH, CK, CK-MB; NO, MDA contents, activities of SOD, CAT and GSH-Px in blood, lung, brain and myocardium tissues; MPO activities in lung and brain; activities of Na+ K+-ATPase in brain and myocardium tissues and contents of TXB2 and 6-keto-PGF1αin lung tissues.3. HOS intravenous infusion during HA exposure shows the protective effects of HOS on acute hypobaric hypoxia induced tissues and organs injury , by attenuate the anomalies of following monitored datas and biochemical parameters: the levels of PaO2 and SaO2; lung and brain water contents; plasma concentrations of TNF-α, D-lactate, LDH, CK, CK-MB; MDA contents, activities of SOD, CAT and GSH-Px in blood, lung, brain and myocardium tissues; MPO activities in lung and brain; activities of Na+ K+-ATPase in brain and myocardium tissues and contents of TXB2 and 6-keto-PGF1αin lung tissues.CONCLUSIONS:1. HOS preconditioning before simulated HA exposure did not attenuated the tissues and organs injury induce by acute hypobaric hypoxia, and that may be the limitations of the effective time of HOS intravenous infusion.2. HOS intravenous infusion during HA exposure can attenuates acute hypobaric hypoxia-induced oxidative damage, and have the protective effects on lung, brain and myocardium tissues injuries induced by acute hypobaric hypoxia.3. The mechanisms of HOS treatment on acute hypobaric hypoxia induced injury: HOS can supply oxygen directly to hypoxic tissues without depending on airway ventilation, and increasing PaO2 and SaO2 levels; improvement of the activities of antioxidase and inhibition of lipid peroxidation; adjustment the delivery proportionality of vasoconstriction and vasorelaxation cytokines; attenuates cytotoxic and vasogenic edema.更多还原