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Differential effect of simulated microgravity on myogenic tone of middle cerebral and mesenteric small arteries in rats
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- Author:
- No author available
- Journal Title:
- ACTA PHYSIOLOGICA SINICA
- Issue:
- 1
- DOI:
- 10.3321/j.issn:0371-0874.2009.01.005
- Key Word:
- 微重力;血管肌源性紧张度;血管收缩反应性;大鼠
Abstract： 本实验观察模拟失重对大鼠大脑中动脉和肠系膜三级小动脉血管的肌源性紧张度和缩血管反应的影响,以及每日1 h的-Gx重力(矢量方向为由背向胸)对其是否具有防止作用.以3天尾部悬吊模拟失重模型;以恢复正常站立体位模拟-Gx重力;采用压力型小动脉测量仪在含Ca2+(2.5 mmol/L)或无Ca2+生理盐溶液中,测量不同管腔压力下血管的主动态管径(active diameter,Da)和被动态管径(passive diameter,Dp).肌源性紧张度(Dp-Da)/Dpx 100%表示.大脑中动脉与肠系膜三级小动脉对5-羟色胺(5-hydroxytryptamine,5-HT)和苯肾上腺素(phenylephrine,PE)的收缩反应性,在含Ca2+生理盐溶液,管腔内压力为40 mmHg条件下进行测定.结果显示:模拟失重3天可引起大脑中动脉的肌源性紧张度以及对5-HT的收缩反应性增强,引起肠系膜三级小动脉的肌源性紧张度显著降低以及对PE的缩血管反应性减弱;每日1 h的-Gx重力只能防止肠系膜三级小动脉肌源性紧张度下降及血管收缩反应性减弱,而对于大脑中动脉两种反应性的增强均无影响.上述结果表明:短期模拟失重可引起人脑中动脉与肠系膜小动脉血管的肌源性紧张度和收缩反应性发生不同方向的改变;每日短时-Gx重力负荷只对肠系膜小动脉功能下调有防止作用.
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