过刊浏览

模拟失重大鼠大脑中动脉与肠系膜小动脉生物力学行为的比较

程九华, BOSCOLO Marco, 林乐健, 白云刚, 张向, 马进, 张立藩

第四军医大学航空航天医学教育部重点实验室，航空航天生理学教研室，西安 710032； 克兰菲尔德大学航空工程系， 克兰菲尔德，MK43 0AL 英国

摘要

为进一步阐明短期失重下血管的适应性改变及其重力性对抗措施的机理，本文对3 d 模拟失重组(SUS)、对抗措施组(STD，每日恢复正常站立体位1 h 模拟-Gx 重力)及对照组(CON)大鼠大脑中动脉和肠系膜第三级小动脉的被动和主动生物力学特性进行了分析。所研究的生物力学参数包括：被动血管的表观刚度(β)、被动和主动血管的周向应力(σθ)- 应变(εθ)关系及其增量弹性模量(Einc,p)，和平滑肌收缩活动所致的激活增量弹性模量(Einc,a)。主动血管生物力学特性分析结果显示，肌源性紧张度的调节对失重下血管的适应具有重要意义：(1) SUS 组肠系膜第三级小动脉的主动σθ -εθ 曲线与其被动态曲线基本一致，表明通过肌紧张度调节使σθ 恢复正常的功能基本丧失；但每日1 h 的-Gx 重力暴露则可完全防止此功能减退；(2) SUS 组大脑中动脉的主动σθ -εθ 曲线较其被动曲线明显左移，不同压力下εθ 始终相对稳定，σθ 也趋于正常；且每日短时-Gx 重力不能防止这种功能亢进。另一方面，对被动血管生物力学特性的分析则提示，不同血管的间质成分可能有不同重塑(remodeling)变化，如失重暴露时间进一步延长，将可能观察到有显著意义的重要变化。总之，本文血管生物力学特性分析对阐明失重环境下血管适应机理及其重力性对抗措施具有重要意义。

关键词： 微重力; 应力- 应变关系; 增量弹性模量; 刚度; 肌源性紧张度; 大脑中动脉; 肠系膜小动脉

分类号：R318.01；R852.22

[Comparison of biomechanical behavior of cerebral and mesenteric small arteries of simulated microgravity rats.] [Ariticle in Chinese]

CHENG Jiu-Hua, BOSCOLO Marco, LIN Le-Jian, BAI Yun-Gang, ZHANG Xiang, MA Jin, ZHANG Li-Fan

Key Laboratory of Aerospace Medicine of Ministry of Education, Department of Aerospace Physiology, the Fourth Military Medical University, Xi’an 710032, China； Department of Aerospace Engineering, Cranfield University, Cranfield, MK43 0AL,UK

Abstract

The aim of the present study was to further elucidate the mechanisms of vascular adaptation to microgravity and its gravitybased countermeasure by a biomechanical approach. Active (the dissected vessel segment was superfused with PPS) and passive (while it was superfused with Ca2+-free PPS) biomechanical properties of mesenteric third-order small arteries and middle cerebral arteries isolated from 3-day simulated microgravity (SUS), countermeasure (STD, daily 1 h of -Gx gravitation), and control (CON) groups of rats were studied. The following mechanical parameters were calculated: the overall stiffness parameter of passive vessels (β), circumferential stress (σθ)-strain (εθ) relationship, and pressure-dependent incremental elastic modulus (Einc,p) of both active and passive vessels, and vascular smooth muscle (VSM) activity-dependent incremental modulus (Einc,a). Results from the analysis of active biomechanical properties revealed the contribution of vascular smooth muscle (VSM) tone during the early adaptation to microgravity: (1) For mesenteric small arteries, active circumferential σθ-εθ curve of SUS group was comparable with that of the passive vessels, indicating that the function of VSM to restore the normal stress distribution is compromised; however, this mal-adaptation was fully prevented by the countermeasure of daily 1 h of -Gx gravitation; (2) For the middle cerebral arteries, active circumferential σθ -εθ relation of SUS group was shifted to the left side of the passive curve and εθ was kept at a nearly constant level with the corresponding σθ being at its normal range; furthermore, the enhanced myogenic tone responsiveness was not prevented by daily short-duration -Gx. Analysis of the passive biomechanical properties has suggested remodeling changes in matrix components of different types of vessels, which might be significant if the exposure duration was further prolonged. In brief, studies of vascular biomechanics are of particular importance in elucidating the mechanisms underlying vascular adaptation to microgravity and its gravity-based countermeasure.

Key words: Microgravity; stress-strain relationship; incremental elastic modulus; stiffness; myogenic tone; middle cerebral artery; mesenteric small artery

收稿日期：2008-12-17　　录用日期：2009-05-15

通讯作者：张立藩　　E-mail: zhanglf@fmmu.edu.cn

引用本文：

程九华, BOSCOLO Marco, 林乐健, 白云刚, 张向, 马进, 张立藩. 模拟失重大鼠大脑中动脉与肠系膜小动脉生物力学行为的比较[J]. 生理学报 2009; 61 (4): 386-394.

CHENG Jiu-Hua, BOSCOLO Marco, LIN Le-Jian, BAI Yun-Gang, ZHANG Xiang, MA Jin, ZHANG Li-Fan. [Comparison of biomechanical behavior of cerebral and mesenteric small arteries of simulated microgravity rats.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (4): 386-394 (in Chinese with English abstract).