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[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

Received: 2008-12-17　　Accepted: 2009-05-15

Corresponding author: 张立藩　　E-mail: zhanglf@fmmu.edu.cn

Citing This Article：

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).