Effects of hindlimb unweighting on the mechanical and structure properties of the rat abdominal aorta.
Effects of hindlimb unweighting on the mechanical and structure properties of the rat abdominal aorta.
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DOI：
10.1152/japplphysiol.00734.2002
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发表时间：
2003-02
影响因子：
3.3
通讯作者：
A. Papadopoulos;M. Delp
中科院分区：
文献类型：
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作者：
A. Papadopoulos;M. Delp
先前的研究表明，作为微重力的一种模型，大鼠的后肢减重可以降低外周管道动脉诱发的收缩张力。据推测，这种收缩张力的降低是这些动脉的机械特性(例如，主动和被动力学)改变的结果。因此，本研究的目的是确定2wk后肢失重(HU)大鼠腹主动脉收缩力的降低是否源于结构血管改变或材料特性变化导致的机械功能缺陷。从对照组(C)和HU大鼠分离主动脉，体外测定去甲肾上腺素(10(-9)-10(-4)M)和AVP(10(-9)-10(-5)M)对血管的收缩反应。在第二系列测试中，通过递增主动脉环的单轴位移来确定主动和被动柯西应力-拉伸关系。HU大鼠的主动脉环对去甲肾上腺素和AVP的最大柯西应激反应较小。主动柯西应力-拉伸反应表明，虽然HU大鼠的主动脉最大应力较低(C，8.1+/-0.2kPa；HU，7.0+/-0.4kPa)，但在类似的环状拉伸下也能达到最大应力。两组在被动柯西应力-拉伸反应和大体血管形态(如内侧横截面积：C，0.30+/-0.02 mm(2)；HU，0.32+/-0.01 mm(2))方面也没有差异，在引起最大张力处的静息或基础血管张力方面，两组之间也没有差异(静息张力：C，1.71+/-0.06g；HU，1.78+/-0.14g)。这些结果表明，HU不改变导管动脉的功能力学特性。然而，HU大鼠主动脉的主动柯西应力显著降低，表明这些动脉存在真正的收缩缺陷。
Previous studies have shown that hindlimb unweighting of rats, a model of microgravity, reduces evoked contractile tension of peripheral conduit arteries. It has been hypothesized that this diminished contractile tension is the result of alterations in the mechanical properties of these arteries (e.g., active and passive mechanics). Therefore, the purpose of this study was to determine whether the reduced contractile force of the abdominal aorta from 2-wk hindlimb-unweighted (HU) rats results from a mechanical function deficit resulting from structural vascular alterations or material property changes. Aortas were isolated from control (C) and HU rats, and vasoconstrictor responses to norepinephrine (10(-9)-10(-4) M) and AVP (10(-9)-10(-5) M) were tested in vitro. In a second series of tests, the active and passive Cauchy stress-stretch relations were determined by incrementally increasing the uniaxial displacement of the aortic rings. Maximal Cauchy stress in response to norepinephrine and AVP were less in aortic rings from HU rats. The active Cauchy stress-stretch response indicated that, although maximum stress was lower in aortas from HU rats (C, 8.1 +/- 0.2 kPa; HU, 7.0 +/- 0.4 kPa), it was achieved at a similar hoop stretch. There were also no differences in the passive Cauchy stress-stretch response or the gross vascular morphology (e.g., medial cross-sectional area: C, 0.30 +/- 0.02 mm(2); HU, 0.32 +/- 0.01 mm(2)) between groups and no differences in resting or basal vascular tone at the displacement that elicits peak developed tension between groups (resting tension: C, 1.71 +/- 0.06 g; HU, 1.78 +/- 0.14 g). These results indicate that HU does not alter the functional mechanical properties of conduit arteries. However, the significantly lower active Cauchy stress of aortas from HU rats demonstrates a true contractile deficit in these arteries.