缺血预适应在大鼠肢体缺血再灌注后胃黏膜损伤中的作用

背景:肢体缺血再灌注作为应激原而引起胃黏膜损伤,导致应激性溃疡的发生。目的:观察肢体缺血再灌注对胃黏膜的损伤,了解肢体缺血再灌注对胃黏膜损伤的作用及其部分机制,以及短暂多次肢体缺血在胃黏膜损伤发生中的作用。设计:随机分组设计、对照动物实验。单位:华北煤炭医学院病理生理学教研室。材料:实验于2002-01/06在华北煤炭医学院病理生理学实验室完成。选择健康成年的雄性Wistar大鼠54只随机数字表法分为3组,每组18只。缺血再灌注组:按Rosenthal方法复制模型,乙醚浅麻醉下以橡皮带环绕结扎大鼠双后肢根部,阻断血流4h后松解,恢复血流灌注4h后自腹主动脉放血处死。缺血预适应组:如上法预先阻断双后肢血流5min,然后恢复血流灌注5min,反复4次,其后操作同缺血再灌注组。对照组:操作同缺血再灌注组,但松弛结扎双后肢,不阻断血流。方法:取各组胃黏膜制作切片于光学显微镜和电子显微镜下进行观察,按Guth标准测定各组胃黏膜损伤指数,在721型分光光度计上于650nm波长比色,计算胃结合黏液量,同时测定胃黏膜血流量、胃黏液中磷脂、氨基己糖的含量、血浆和胃组织一氧化氮含量及胃黏膜一氧化氮合酶活性。主要观察指标:胃黏膜损伤指数、胃结合黏液量、胃黏膜血流量、胃黏液中磷脂、氨基己糖的含量、血浆和胃组织一氧化氮含量及胃黏膜一氧化氮合酶活性。结果:纳入动物54只,均进入结果分析。①缺血再灌注组大鼠胃黏膜损伤严重,光镜下可见黏膜腺体水肿、充血,糜烂、解体,在黏膜基底部及黏膜下层可见炎细胞浸润,即溃疡形成。缺血预适应组胃黏膜较完整,损伤程度较缺血再灌注组轻;电镜下缺血再灌注组胃壁细胞、主细胞细胞器结构不完整,遭到破坏。同样缺血预适应组各类细胞损伤轻于缺血再灌注组损伤指数分别为18.00±10.71,34.00±15.01,P<0.01]。②缺血再灌注组和缺血预适应组大鼠胃黏膜血流量及胃结合黏液量、胃黏液中磷脂、氨基己糖的含量均明显低于对照组分别为(2.12±0.56),(10.84±2.56),(25.52±2.97)mL/(kg·h);(2.01±0.91),(2.79±0.73),(3.99±0.87)mg;(7.68±1.95),(9.74±1.04),(11.98±1.98)mg/g;(3.83±1.18),(5.42±0.47),(5.76±1.21)mg/g,P<0.05,0.01]。缺血预适应组胃黏膜血流量及胃结合黏液量、胃黏液中磷脂、氨基己糖的含量均高于缺血再灌注组。③缺血再灌注组和缺血预适应组血浆与胃黏膜组织一氧化氮含量及一氧化氮合酶活性显著高于对照组分别为(250.0±5.6),(270.0±11.3),(210.0±7.4)μmol/L;(9.34±0.67),(11.34±1.00),(7.50±0.67)μkat/g,P<0.01],缺血预适应组血浆与胃黏膜组织一氧化氮含量和胃黏膜的一氧化氮合酶活性又显著高于缺血再灌注组。结论:肢体缺血再灌注作为应激原可导致胃黏膜损伤,引起应激性溃疡;缺血预适应可减轻肢体缺血再灌注后的胃黏膜损伤。

Effect of ischemic preconditioning on gastric mucosal injury following limb ischemia reperfusion in rats

BACKGROUND: Limb ischemia reperfusion (LIR) as a stressor leads to gastric mucosal injury, and then results in the occurrence of stress ulcer.OBJECTIVE: To observe the effects of LIR on gastric mucosal injury, investigate part of the mechanism, and the role of several transient limb ischemia in the occurrence of gastric mucosal injury.DESIGN: A randomized grouping design and controlled animal experiment.SETTING: Department of Pathophysiology of North China Coal Medical College.MATERIALS: The experiment was carried out in the pathophysiological laboratory of North China Coal Medical College from January to June 2002. Fifty-four healthy adult male Wistar rats were randomly divided into three groups with 18 rats in each group. Ischemia reperfusion (I/R) group: The rats were duplicated into models according to the Rosenthal method that under superficial anesthesia with ether, the roots of both hindlimbs were ligated by wrapping with rubber strap, blood flow was blocked for 4 hours and then recovered to perfusion for 4 hours, and finally killed by bleeding from abdominal aorta. Ischemic preconditioning group: Before model establishment, blood flow of both hindlimbs was blocked for 5 minutes, and then recovered to perfusion for 5 minutes, which was repeated for four times, and the following operations were the same as those in the I/R group. Control group: The operations were the same as those in the I/R group,but both hindlimbs were ligated at relaxation without blocking the blood flow.METHODS: Sections of gastric mucosa were prepared, and then observed under light microscope and electron microscope, and the index of gastric mucosal injury was determined according to the Guth standard. The colorimetric assay was performed with 721 spectrophotometer at 650 nm, and the amount of gastric combining mucus was calculated.Meanwhile, the blood flow of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus, content of nitric oxide in plasma and gastric tissue and activity of nitric oxide synthase (NOS) in gastric mucosa were determined.MAIN OUTCOME MEASURES: Index of gastric mucosal injury, amount of gastric combining mucus, blood flow of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus, contents of nitric oxide in plasma and gastric tissue and NOS activity in gastric mucosa.RESULTS: All the 54 rats were involved in the analysis of results. ① In the I/R group, gastric mucosal injury was serious, edema, hyperemia, erosion and disintegration of gland of mucosal glands were observed, infiltration of inflammatory cells (formation of ulcer) was observed in basal and inferior mucosa. In the ischemic preconditioning group, the gastric mucosa was complete, and the damaged severity was milder than that in the I/R group; Under electron microscope, the organell structures of gastric parietal and chief cells were incomplete and destroyed. The cell injuries in the ischemic preconditioning group were milder than those in the I/R group (index of injury: 18.00±10.71, 34.00±15.01, P＜ 0.01). ② The blood flow and combining mucosal amount of gastric mucosa, contents of phospholipid and hexosamine in gastric mucus in the ischemic preconditioning group and I/R group were all obviously lower than those in the control group (2.12±0.56), (10.84±2.56), (25.52±2.97) mL/(kg·h); (2.01±0.91), (2.79±0.73), (3.99±0.87) mg;(7.68±1.95), (9.74±1.04), (11.98±1.98) mg/g; (3.83±1.18), (5.42±0.47), (5.76±1.21) mg/g, P ＜ 0.05, 0.01], those the above indexes were all higher in the ischemic preconditioning group than in the I/R group. ③ The contents of nitric oxide in plasma and gastric tissue and NOS activity in gastric mucosa in the ischemic preconditioning group and I/R group were significantly lower than those in the control group (250.0±5.6), (270.0±11.3), (210.0±7.4) μmol/L; (9.34±0.67), (11.34±1.00), (7.50±0.67) μ kat/g, P ＜ 0.01], those were also signficantly higher in the ischemic preconditioning group than in the I/R group.CONCLUSION: As a stressor, LIR can lead to gastric mucosal injury, and cause stress ulcer.Ischemic preconditioning can alleviate the gastric mucosal injury following LIR