Contrasting effects of simulated microgravity with and without daily -Gx gravitation on structure and function of cerebral and mesenteric small arteries in rats
Contrasting effects of simulated microgravity with and without daily -Gx gravitation on structure and function of cerebral and mesenteric small arteries in rats
复制标题
模拟微重力与每日-Gx重力对大鼠大脑和肠系膜小动脉结构和功能的影响对比。
DOI：
10.1152/japplphysiol.00493.2009
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发表时间：
2009-12-01
影响因子：
3.3
通讯作者：
Zhang, Li-Fan
中科院分区：
文献类型：
--
作者：
Lin, Le-Jian;Gao, Fang;Zhang, Li-Fan
本研究旨在验证以下假设：28天的尾部悬吊（SUS）可诱导大脑中动脉（MCA）肥大，肌源性和血管收缩反应增强，而肠系膜三级小动脉（MSA）萎缩，肌源性和血管收缩反应降低。此外，除了在MCA的功能增强，在这两种动脉的结构变化和功能递减的MSA都可以防止每天1小时的背腹（-G（x））重力的干预恢复到站立姿势。为了检验这一假设，血管直径的压力变化和非受体和受体介导的激动剂，确定使用压力动脉造影的程序，以测量在体内的长度和减少滞后的血管段和纵向middlemost部分固定在最大扩张状态的血管进行了检查，使用电子显微镜和组织形态学。功能研究表明，28天的尾部悬吊，头向下倾斜（SUS）导致增强和降低肌张力和血管收缩反应，分别在MCA和MSA。组织形态学数据显示，SUS诱导的肥大性变化的特点是增加中膜厚度（T）和横截面积（CSA）和血管平滑肌细胞层（N（CL））的数量，而在MSA中，它引起减少中膜CSA和T和N（CL）。每日1-h-G（x）28天可完全防止两种小动脉的这些差异性结构变化和MSAs的功能减退，但不能防止MCAs的肌源性张力增加和血管反应性增加。这些研究结果揭示了小阻力动脉在有和没有重力对策的适应微重力过程中的特殊特征。
This study was designed to test the hypothesis that a 28-day tail suspension (SUS) could induce hypertrophy and enhanced myogenic and vasoconstrictor reactivity in middle cerebral arteries (MCAs), whereas atrophy and decreased myogenic and vasoconstrictor responses in mesenteric third-order arterioles (MSAs). Also, in addition to the functional enhancement in MCAs, structural changes in both kinds of arteries and functional decrement in MSAs could all be prevented by the intervention of daily 1-h dorsoventral (-G(x)) gravitation by restoring to standing posture. To test this hypothesis, vessel diameters to pressure alterations and nonreceptor- and receptor-mediated agonists were determined using a pressure arteriograph with a procedure to measure in vivo length and decrease hysteresis of vessel segments and longitudinal middlemost sections of vessels fixed at maximally dilated state were examined using electron microscopy and histomorphometry. Functional studies showed that 28-day tail-suspended, head-down tilt (SUS) resulted in enhanced and decreased myogenic tone and vasoconstrictor responses, respectively, in MCAs and MSAs. Histomorphometric data revealed that SUS-induced hypertrophic changes in MCAs characterized by increases in thickness (T) and cross-sectional area (CSA) of the media and the number of vascular smooth-muscle-cell layers (N(CL)), whereas in MSAs, it induced decreases in medial CSA and T and N(CL). Daily 1-h -G(x) over 28 days can fully prevent these differential structural changes in both kinds of small arteries and the functional decrement in MSAs, but not the augmented myogenic tone and increased vasoreactivity in the MCAs. These findings have revealed special features of small resistance arteries during adaptation to microgravity with and without gravity-based countermeasure.