Role of α-adrenergic vasoconstriction in regulating skeletal muscle blood flow and vascular conductance during forearm exercise in ageing humans.
Role of α-adrenergic vasoconstriction in regulating skeletal muscle blood flow and vascular conductance during forearm exercise in ageing humans.
复制标题
α-肾上腺素能血管收缩在调节老年人前臂运动过程中骨骼肌血流和血管电导中的作用。
DOI：
10.1113/jphysiol.2014.278358
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Dinenno,FrankA
中科院分区：
文献类型：
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作者：
Richards,JenniferC;Luckasen,GaryJ;Larson,DennisG;Dinenno,FrankA
关键点人类衰老与运动时骨骼肌血流减弱有关。尚不清楚随着年龄的增长交感神经系统活动的增加是否会限制运动时骨骼肌的血流量。确定交感神经系统在健康老龄化中调节血流量的作用具有临床意义，因为交感神经系统中与年龄相关的变化会随着与组织灌注受损相关的许多疾病而加剧。在本研究中，与年轻人相比，老年人在分级握力运动期间表现出骨骼肌血流量受损，这是由于血管传导减少。在去除交感神经α肾上腺素能血管收缩张力后，老年人在运动过程中肌肉血流量和血管传导的增加低于年轻人，与对照条件下观察到的情况相似。因此，在局部肾上腺素受体阻滞期间，运动肌肉血流量和血管传导的年龄相关损伤持续存在。摘要在健康人中，衰老通常与运动期间骨骼肌血流量和血管传导性的降低有关。此外，静息交感神经系统（SNS）活动随年龄增长而显著增加，但SNS介导的α肾上腺素能血管收缩增强是否会导致人体运动肌肉血流量和血管张力的年龄相关损伤尚不清楚。我们测试了SNS介导的血管收缩在老年人中比年轻人更大的假设，并在分级握力运动（5，15，25%最大随意收缩（MVC））期间限制肌肉（前臂）血流量（FBF）。在对照条件下以及分别通过动脉内输注酚妥拉明和普萘洛尔进行局部α-和β-肾上腺素受体联合阻滞期间，测量11名年轻人（21 ± 1岁）和12名老年人（62 ± 2岁）的FBF（多普勒超声）并计算前臂血管传导性（FVC）。在对照条件下，老年人在15%MVC运动时的FBF和FVC显著低于对照组（22.6 ± 1.3vs. 29 ± 3.3 ml min-1100 g前臂无脂肪质量（FFM）-1和21.7 ± 1.2vs. 33.6± 4.0 ml min−1100 g FFM−1100 mmHg−1;P< 0.05）和25% MVC运动（37.4 ± 1.4vs. 46.0± 4.9 ml min−1100 g FFM− 1和33.7 ± 1.4vs. 49.0± 5.7 ml min−1100 g FFM−1100 mmHg−1;P< 0.05），而在5%MVC运动时没有年龄组差异。局部肾上腺素受体阻滞剂增加了两组静息和运动时的FBF和FVC，尽管在不同运动强度的年轻人和老年人中，从静息到稳态运动的FBF和FVC增加相似，因此FBF和FVC的年龄相关性损害持续存在。我们的数据表明，在分级强度的握力运动中，老年健康成人的FVC降低和随后的骨骼肌血流量降低不是由于交感神经血管收缩增强，而是由于随着年龄的增长，局部信号传导受损或外周血管结构限制。
Key pointsHuman ageing is associated with attenuated skeletal muscle blood flow during exercise. It is unknown whether elevated sympathetic nervous system activity with ageing limits skeletal muscle blood flow during exercise. Determining the role of the sympathetic nervous system in regulating blood flow in healthy ageing is clinically relevant as age‐related changes in the sympathetic nervous system are exacerbated with many diseases associated with impaired tissue perfusion.In the present study, compared to young adults, older adults demonstrate impaired skeletal muscle blood flow during graded handgrip exercise, and this is due to reductions in vascular conductance.Second, the increase in muscle blood flow and vascular conductance during exercise after removal of sympathetic α‐adrenergic vasoconstrictor tone in older adults was lower compared to young adults, similar to what was observed under control conditions.As such, the age‐associated impairment in exercising muscle blood flow and vascular conductance persisted during local adrenoreceptor blockade.AbstractIn healthy humans, ageing is typically associated with reduced skeletal muscle blood flow and vascular conductance during exercise. Further, there is a marked increase in resting sympathetic nervous system (SNS) activity with age, yet whether augmented SNS‐mediated α‐adrenergic vasoconstriction contributes to the age‐associated impairment in exercising muscle blood flow and vascular tone in humans is unknown. We tested the hypothesis that SNS‐mediated vasoconstriction is greater in older than young adults and limits muscle (forearm) blood flow (FBF) during graded handgrip exercise (5, 15, 25% maximal voluntary contraction (MVC)). FBF was measured (Doppler ultrasound) and forearm vascular conductance (FVC) was calculated in 11 young (21 ± 1 years) and 12 older (62 ± 2 years) adults in control conditions and during combined local α‐ and β‐adrenoreceptor blockade via intra‐arterial infusions of phentolamine and propranolol, respectively. Under control conditions, older adults exhibited significantly lower FBF and FVC at 15% MVC exercise (22.6 ± 1.3vs. 29 ± 3.3 ml min−1100 g forearm fat‐free mass (FFM)−1and 21.7 ± 1.2vs. 33.6 ± 4.0 ml min−1100 g FFM−1100 mmHg−1;P< 0.05) and 25% MVC exercise (37.4 ± 1.4vs. 46.0 ± 4.9 ml min−1100 g FFM−1and 33.7 ± 1.4vs. 49.0 ± 5.7 ml min−1100 g FFM−1100 mmHg−1;P< 0.05), whereas there was no age group difference at 5% MVC exercise. Local adrenoreceptor blockade increased FBF and FVC at rest and during exercise in both groups, although the increase in FBF and FVC from rest to steady‐state exercise was similar in young and older adults across exercise intensities, and thus the age‐associated impairment in FBF and FVC persisted. Our data indicate that during graded intensity handgrip exercise, the reduced FVC and subsequently lower skeletal muscle blood flow in older healthy adults is not due to augmented sympathetic vasoconstriction, but rather due to impairments in local signalling or structural limitations in the peripheral vasculature with advancing age.