Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
Department of Engineering Science, University of Electro-communications, Tokyo, Japan.
J Physiol. 2018 May 15;596(10):1903-1917. doi: 10.1113/JP275459. Epub 2018 Apr 5.
In aged rats, daily muscle stretching increases blood flow to skeletal muscle during exercise. Daily muscle stretching enhanced endothelium-dependent vasodilatation of skeletal muscle resistance arterioles of aged rats. Angiogenic markers and capillarity increased in response to daily stretching in muscles of aged rats. Muscle stretching performed with a splint could provide a feasible means of improving muscle blood flow and function in elderly patients who cannot perform regular aerobic exercise.
Mechanical stretch stimuli alter the morphology and function of cultured endothelial cells; however, little is known about the effects of daily muscle stretching on adaptations of endothelial function and muscle blood flow. The present study aimed to determine the effects of daily muscle stretching on endothelium-dependent vasodilatation and muscle blood flow in aged rats. The lower hindlimb muscles of aged Fischer rats were passively stretched by placing an ankle dorsiflexion splint for 30 min day , 5 days week , for 4 weeks. Blood flow to the stretched limb and the non-stretched contralateral limb was determined at rest and during treadmill exercise. Endothelium-dependent/independent vasodilatation was evaluated in soleus muscle arterioles. Levels of hypoxia-induced factor-1α, vascular endothelial growth factor A and neuronal nitric oxide synthase were determined in soleus muscle fibres. Levels of endothelial nitric oxide synthase and superoxide dismutase were determined in soleus muscle arterioles, and microvascular volume and capillarity were evaluated by microcomputed tomography and lectin staining, respectively. During exercise, blood flow to plantar flexor muscles was significantly higher in the stretched limb. Endothelium-dependent vasodilatation was enhanced in arterioles from the soleus muscle from the stretched limb. Microvascular volume, number of capillaries per muscle fibre, and levels of hypoxia-induced factor-1α, vascular endothelial growth factor and endothelial nitric oxide synthase were significantly higher in the stretched limb. These results indicate that daily passive stretching of muscle enhances endothelium-dependent vasodilatation and induces angiogenesis. These microvascular adaptations may contribute to increased muscle blood flow during exercise in muscles that have undergone daily passive stretch.
在老年大鼠中，每天进行肌肉拉伸可增加运动时骨骼肌的血流量。每天的肌肉拉伸增强了老年大鼠骨骼肌阻力小动脉的内皮依赖性血管舒张作用。对老年大鼠肌肉进行日常拉伸会引起血管生成标记物和毛细血管增加。使用夹板进行肌肉拉伸可能为无法进行常规有氧运动的老年患者提供一种可行的改善肌肉血流和功能的方法。
机械拉伸刺激改变了培养的内皮细胞的形态和功能；然而，对于日常肌肉拉伸对内皮功能和肌肉血流适应性的影响知之甚少。本研究旨在确定日常肌肉拉伸对老年大鼠内皮依赖性血管舒张和肌肉血流的影响。将 Fischer 老年大鼠的后肢下肢肌肉通过放置踝关节背屈夹板被动拉伸 30 分钟/天，每周 5 天，持续 4 周。在休息和跑步机运动期间测定拉伸肢体和未拉伸的对侧肢体的血流。在比目鱼肌小动脉中评估内皮依赖性/非依赖性血管舒张作用。在比目鱼肌纤维中测定缺氧诱导因子-1α、血管内皮生长因子 A 和神经元型一氧化氮合酶的水平。在比目鱼肌小动脉中测定内皮型一氧化氮合酶和超氧化物歧化酶的水平，并通过微计算机断层扫描和凝集素染色分别评估微血管体积和毛细血管密度。在运动过程中，跖屈肌的血流在拉伸肢体中明显更高。拉伸肢体比目鱼肌小动脉的内皮依赖性血管舒张作用增强。拉伸肢体的微血管体积、每根肌纤维的毛细血管数以及缺氧诱导因子-1α、血管内皮生长因子和内皮型一氧化氮合酶的水平均显著升高。这些结果表明，每天被动拉伸肌肉可增强内皮依赖性血管舒张作用并诱导血管生成。这些微血管适应性可能有助于在接受日常被动拉伸的肌肉中增加运动时的肌肉血流量。
