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[摘要] 目的 觀察不同频率间歇低氧对大鼠血压的影响及其血管内皮功能的变化。 方法 将40只Wistar雄性大鼠随机分为常氧对照组（NC组）及4个间歇低氧组（IH1，IH2，IH3，IH4），其低氧频率分别为10次/h、20次/h、30次/h、40次/h。测定实验前后大鼠动脉收缩压、血清内皮素-1、一氧化氮水平。 结果 ①各组大鼠实验前SBP比较差异无统计学意义。6周实验结束后，各 IH组SBP较实验前和NC组均显著升高（P<0.05或P<0.01）；随着间歇低氧频率的增加，各IH组大鼠血压逐渐升高，但IH4组较IH3组比较差异无统计学意义。NC组SBP较实验前差异无统计学意义。②各IH组血清ET-1水平较NC组相比明显增高（P<0.05），血清NO水平显著降低（P均<0.01）。随着间歇低氧频率的增加，血清ET-1水平升高，NO水平显著降低（P<0.05或P<0.01）。IH4组与IH3组相比，各指标差异无统计学意义。结论 血管内皮功能障碍在慢性间歇低氧致高血压过程中起着重要的作用。随着间歇低氧频率增高，血压升高及内皮损伤加重，但并非频率越高，损伤越重。
[关键词] 阻塞性睡眠呼吸暂停；血压；内皮功能；间歇低氧频率
[中图分类号] R544.1 [文献标识码] A [文章编号] 1673-9701（2017）29-0031-04
Effects of different intermittent hypoxia frequency on blood pressure and vascular endothelial function in rats
LIN Hui1 CHEN Yihe2 XIA Xiaodong1
1.Department of Respiratory Medicine， the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University， Wenzhou 325000， China； 2.Department of Cardiovascular Medicine，the First Affiliated Hospital of Wenzhou Medical University， Wenzhou 325000，China
[Abstract] Objective To observe the effect of intermittent hypoxia with different frequencies on blood pressure and the changes of vascular endothelial function in rats. Methods 40 Wistar male rats were randomly divided into normoxic control group（NC group） and 4 intermittent hypoxia group（IH1， IH2， IH3， IH4）. The frequency of hypoxia was 10 times/h， 20 times/h， 30 times/h， and 40 times/h. The arterial systolic blood pressure， serum endothelin-1 and nitric oxide levels were measured before and after the experiment. Results （1）There were no statistically significant differences in SBP between the two groups before the experiment. After 6 weeks of experiment， SBP in each IH group was significantly higher than that before experiment and that in NC group（P<0.05 or P<0.01）； with the increase of intermittent hypoxia frequency， the blood pressure of each IH group of rats was increased gradually， but there was no statistically significant difference between IH4 group and IH3 group. SBP in NC group was not statistically significant compared with that before experiment. （2） Compared with NC group， the levels of serum ET-1 in each IH group were significantly higher（P<0.05）. Serum NO level was significantly decreased（all P<0.01）. With the increase of intermittent hypoxia frequency， serum ET-1 level was increased， and NO level was significantly decreased（P<0.05 or P<0.01）. There was no statistically significant difference in each index between IH4 group and IH3 group. Conclusion Vascular endothelial dysfunction plays an important role in the process of hypertension caused by chronic intermittent hypoxia. With the increase of intermittent hypoxia frequency， the blood pressure is increased and the endothelial injury becomes severe. But it is not the case that the higher the frequency， the more severe the injury [Key words] Obstructive sleep apnea； Blood pressure； Endothelial function； Intermittent hypoxia frequency
阻塞性睡眠呼吸暂停综合征（obstructive sleep apnea syndrome，OSAS）是一种常见的睡眠呼吸障碍性疾病，可以导致OSAS患者各系统损伤，尤其是心血管系统[1，2]。文献表明，OSAS与高血压有很强的相关性，是高血压发生的独立危险因素之一[3，4]。不断有研究证明OSAS患者夜间频繁的间歇低氧血症可导致血管内皮功能障碍，从而引起OSAS合并高血压的发生[5]。关于不同间歇低氧程度和间歇低氧持续时间对大鼠高血压的严重程度影响已有文献报道，但动物模型方面有关低氧频率的研究较少。因此我们通过建立OSAS模式不同频率间歇低氧（intermittent hypoxia，IH）大鼠模型，测定鼠尾动脉收缩压（systolic arterial pressure，SBP）以及大鼠血清中一氧化氮（nitric oxide，NO）和内皮素-1（endothelin-1，ET-1），探讨睡眠呼吸暂停模式不同频率间歇低氧下大鼠血管内皮功能的变化以及对血压的影响机制。
1 材料与方法
1.1 实验动物
健康成年雄性Wistar大鼠40只，合格证号：SCXK-（军）2009-003，体重（202±15）g。给予普通饲料喂养。
1.2 实验方法
1.2.1 實验分组 按照随机排列表法，将大鼠分为5组，每组8只，分别为NC组（常氧对照组）及IH1组、IH2组、IH3组、IH4组，其间歇低氧频率分别为10次/h、20次/h、30次/h、40次/h。
1.2.2 模型制作 建立OSAS模式间歇低氧模型，将各组大鼠置于自制的相同密闭低氧舱，通过电脑控制程序设定压缩空气和氮气的释放时间及流量，使低氧舱内氧气浓度循环维持在5%～21%，达到预置的低氧/复氧条件。即首先低氧舱内充入纯氮气 30 s，使舱内氧浓度降至最低5%，随后充入压缩空气（IH1：330 s，IH2：150 s，IH3：90 s，IH4：60 s），使舱内氧浓度从低氧状态5%恢复至 21%。NC组舱内氧浓度始终维持在21%。每日低氧暴露时间为9：00～17：00，共6周。其余时间自由摄食，实验过程中无大鼠死亡。
1.2.3 大鼠血压测定 应用无创鼠尾动脉血压仪测量大鼠SBP，分别于实验开始前1 d早晨8：00、实验结束后第2天早晨8：00测量收缩压。连续测量三次取平均值。仪器BP-6，购自成都泰盟科技有限公司。
1.2.4 血清标本采集及各指标测定 于6周实验结束后采取大鼠动脉血，4 000 r/min离心15 min，取上清液，-80℃保存待测。血清ET-测定采用酶联免疫吸附试验（ELI SA），血清NO测定采用硝酸还原酶法，试剂盒分别购于R
[关键词] 阻塞性睡眠呼吸暂停；血压；内皮功能；间歇低氧频率
[中图分类号] R544.1 [文献标识码] A [文章编号] 1673-9701（2017）29-0031-04
Effects of different intermittent hypoxia frequency on blood pressure and vascular endothelial function in rats
LIN Hui1 CHEN Yihe2 XIA Xiaodong1
1.Department of Respiratory Medicine， the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University， Wenzhou 325000， China； 2.Department of Cardiovascular Medicine，the First Affiliated Hospital of Wenzhou Medical University， Wenzhou 325000，China
[Abstract] Objective To observe the effect of intermittent hypoxia with different frequencies on blood pressure and the changes of vascular endothelial function in rats. Methods 40 Wistar male rats were randomly divided into normoxic control group（NC group） and 4 intermittent hypoxia group（IH1， IH2， IH3， IH4）. The frequency of hypoxia was 10 times/h， 20 times/h， 30 times/h， and 40 times/h. The arterial systolic blood pressure， serum endothelin-1 and nitric oxide levels were measured before and after the experiment. Results （1）There were no statistically significant differences in SBP between the two groups before the experiment. After 6 weeks of experiment， SBP in each IH group was significantly higher than that before experiment and that in NC group（P<0.05 or P<0.01）； with the increase of intermittent hypoxia frequency， the blood pressure of each IH group of rats was increased gradually， but there was no statistically significant difference between IH4 group and IH3 group. SBP in NC group was not statistically significant compared with that before experiment. （2） Compared with NC group， the levels of serum ET-1 in each IH group were significantly higher（P<0.05）. Serum NO level was significantly decreased（all P<0.01）. With the increase of intermittent hypoxia frequency， serum ET-1 level was increased， and NO level was significantly decreased（P<0.05 or P<0.01）. There was no statistically significant difference in each index between IH4 group and IH3 group. Conclusion Vascular endothelial dysfunction plays an important role in the process of hypertension caused by chronic intermittent hypoxia. With the increase of intermittent hypoxia frequency， the blood pressure is increased and the endothelial injury becomes severe. But it is not the case that the higher the frequency， the more severe the injury [Key words] Obstructive sleep apnea； Blood pressure； Endothelial function； Intermittent hypoxia frequency
阻塞性睡眠呼吸暂停综合征（obstructive sleep apnea syndrome，OSAS）是一种常见的睡眠呼吸障碍性疾病，可以导致OSAS患者各系统损伤，尤其是心血管系统[1，2]。文献表明，OSAS与高血压有很强的相关性，是高血压发生的独立危险因素之一[3，4]。不断有研究证明OSAS患者夜间频繁的间歇低氧血症可导致血管内皮功能障碍，从而引起OSAS合并高血压的发生[5]。关于不同间歇低氧程度和间歇低氧持续时间对大鼠高血压的严重程度影响已有文献报道，但动物模型方面有关低氧频率的研究较少。因此我们通过建立OSAS模式不同频率间歇低氧（intermittent hypoxia，IH）大鼠模型，测定鼠尾动脉收缩压（systolic arterial pressure，SBP）以及大鼠血清中一氧化氮（nitric oxide，NO）和内皮素-1（endothelin-1，ET-1），探讨睡眠呼吸暂停模式不同频率间歇低氧下大鼠血管内皮功能的变化以及对血压的影响机制。
1 材料与方法
1.1 实验动物
健康成年雄性Wistar大鼠40只，合格证号：SCXK-（军）2009-003，体重（202±15）g。给予普通饲料喂养。
1.2 实验方法
1.2.1 實验分组 按照随机排列表法，将大鼠分为5组，每组8只，分别为NC组（常氧对照组）及IH1组、IH2组、IH3组、IH4组，其间歇低氧频率分别为10次/h、20次/h、30次/h、40次/h。
1.2.2 模型制作 建立OSAS模式间歇低氧模型，将各组大鼠置于自制的相同密闭低氧舱，通过电脑控制程序设定压缩空气和氮气的释放时间及流量，使低氧舱内氧气浓度循环维持在5%～21%，达到预置的低氧/复氧条件。即首先低氧舱内充入纯氮气 30 s，使舱内氧浓度降至最低5%，随后充入压缩空气（IH1：330 s，IH2：150 s，IH3：90 s，IH4：60 s），使舱内氧浓度从低氧状态5%恢复至 21%。NC组舱内氧浓度始终维持在21%。每日低氧暴露时间为9：00～17：00，共6周。其余时间自由摄食，实验过程中无大鼠死亡。
1.2.3 大鼠血压测定 应用无创鼠尾动脉血压仪测量大鼠SBP，分别于实验开始前1 d早晨8：00、实验结束后第2天早晨8：00测量收缩压。连续测量三次取平均值。仪器BP-6，购自成都泰盟科技有限公司。
1.2.4 血清标本采集及各指标测定 于6周实验结束后采取大鼠动脉血，4 000 r/min离心15 min，取上清液，-80℃保存待测。血清ET-测定采用酶联免疫吸附试验（ELI SA），血清NO测定采用硝酸还原酶法，试剂盒分别购于R