Tarasova Olga S, Kalenchuk Vjatcheslav U, Borovik Anatoly S, Golubinskaya Veronika O, Delp Michael D, Vinogradova Olga L
State Research Center of the Russian Federation, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia.
Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia.
Front Physiol. 2020 Jun 30;11:675. doi: 10.3389/fphys.2020.00675. eCollection 2020.
: Mechanical forces and sympathetic influences are key determinants of vascular structure and function. This study tested the hypothesis that hindlimb unloading (HU) exerts diverse effects on forelimb and hindlimb small arteries of rats in functionally different regions of the skeletal muscle and skin. : Male Wistar rats were subjected to HU for 2 weeks, then skeletal muscle arteries (deep brachial and sural) and skin arteries (median and saphenous) were examined using wire myography or isobaric perfusion and glyoxylic acid staining. : HU increased lumen diameter of both forelimb arteries but decreased diameter of the sural artery; the saphenous artery diameter was not affected. Following HU, maximal contractile responses to noradrenaline and serotonin increased in the forelimb but decreased in the hindlimb skeletal muscle feed arteries with no change in skin arteries; all region-specific alterations persisted after endothelium removal. HU increased the sensitivity to vasoconstrictors in the saphenous artery but not in the sural artery. In the saphenous artery, initially high sympathetic innervation density was reduced by HU, sparse innervation in the sural artery was not affected. Electrical stimulation of periarterial sympathetic nerves in isobarically perfused segments of the saphenous artery demonstrated a two-fold decrease of the contractile responses in HU rats compared to that of controls. : HU induces contrasting structural and functional adaptations in forelimb and hindlimb skeletal muscle arteries. Additionally, HU had diverse effects in two hindlimb vascular regions. Hyper-sensitivity of the saphenous artery to vasoconstrictors appears to result from the shortage of trophic sympathetic influence. Importantly, HU impaired sympathetically induced arterial vasoconstriction, consistent with the decreased sympathetic constrictor response in humans following space flight.
机械力和交感神经影响是血管结构和功能的关键决定因素。本研究检验了以下假设：后肢卸载（HU）对大鼠前肢和后肢不同功能区域骨骼肌和皮肤的小动脉产生不同影响。雄性Wistar大鼠接受2周的HU处理，然后使用线肌描记法或等压灌注及乙醛酸染色检查骨骼肌动脉（肱深动脉和腓肠动脉）和皮肤动脉（正中动脉和隐动脉）。HU增加了前肢动脉的管腔直径，但减小了腓肠动脉的直径；隐动脉直径未受影响。HU处理后，前肢对去甲肾上腺素和5-羟色胺的最大收缩反应增加，而后肢骨骼肌供血动脉的反应降低，皮肤动脉无变化；去除内皮后，所有区域特异性改变仍然存在。HU增加了隐动脉对血管收缩剂的敏感性，但腓肠动脉未增加。在隐动脉中，最初较高的交感神经支配密度因HU而降低，腓肠动脉中稀疏的神经支配未受影响。对等压灌注的隐动脉节段进行动脉周围交感神经电刺激显示，与对照组相比，HU大鼠的收缩反应降低了两倍。HU在前肢和后肢骨骼肌动脉中诱导出相反的结构和功能适应性变化。此外，HU在两个后肢血管区域产生了不同影响。隐动脉对血管收缩剂的高敏感性似乎是由于营养性交感神经影响不足所致。重要的是，HU损害了交感神经诱导的动脉血管收缩，这与人类太空飞行后交感神经收缩反应降低一致。
