VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia.
Department of Cardiology, Sunshine Coast University Hospital, Birtinya, QLD, Australia.
Physiol Rep. 2020 Oct;8(19):e14580. doi: 10.14814/phy2.14580.
Impairments in skeletal muscle microvascular function are frequently reported in patients with various cardiometabolic conditions for which older age is a risk factor. Whether aging per se predisposes the skeletal muscle to microvascular dysfunction is unclear. We used contrast-enhanced ultrasound (CEU) to compare skeletal muscle microvascular perfusion responses to cuff occlusion and leg exercise between healthy young (n = 12, 26 ± 3 years) and older (n = 12, 68 ± 7 years) adults. Test-retest reliability of CEU perfusion parameters was also assessed. Microvascular perfusion (microvascular volume × flow velocity) of the medial gastrocnemius muscle was measured before and immediately after: (a) 5-min of thigh-cuff occlusion, and (b) 5-min of submaximal intermittent isometric plantar-flexion exercise (400 N) using CEU. Whole-leg blood flow was measured using strain-gauge plethysmography. Repeated measures were obtained with a 15-min interval, and averaged responses were used for comparisons between age groups. There were no differences in post-occlusion whole-leg blood flow and muscle microvascular perfusion between young and older participants (p > .05). Similarly, total whole-leg blood flow during exercise and post-exercise peak muscle microvascular perfusion did not differ between groups (p > .05). The overall level of agreement between the test-retest measures of calf muscle perfusion was excellent for measurements taken at rest (intraclass correlation coefficient [ICC] 0.85), and in response to cuff occlusion (ICC 0.89) and exercise (ICC 0.95). Our findings suggest that healthy aging does not affect muscle perfusion responses to cuff-occlusion and submaximal leg exercise. CEU muscle perfusion parameters measured in response to these provocation tests are highly reproducible in both young and older adults.
骨骼肌微血管功能障碍在患有各种心血管代谢疾病的患者中经常被报道，而年龄增长是这些疾病的一个风险因素。然而，衰老本身是否使骨骼肌更容易发生微血管功能障碍尚不清楚。我们使用对比增强超声（CEU）比较了健康的年轻成年人（n=12，年龄 26±3 岁）和老年成年人（n=12，年龄 68±7 岁）在股动脉袖带闭塞和腿部运动时骨骼肌微血管灌注反应。还评估了 CEU 灌注参数的测试-重测可靠性。使用 CEU 测量腓肠肌内侧的微血管灌注（微血管容积×血流速度），在以下情况下测量：（a）大腿袖带闭塞 5 分钟后，和（b）最大间歇性等长跖屈运动（400N）5 分钟后。使用应变计体积描记法测量整个腿部的血流量。在 15 分钟的间隔内获得重复测量，并对年龄组之间的平均反应进行比较。年轻和老年参与者之间的闭塞后整个腿部血流量和肌肉微血管灌注没有差异（p＞.05）。同样，运动期间和运动后峰值肌肉微血管灌注的总整个腿部血流量在组间也没有差异（p＞.05）。在休息时（组内相关系数 [ICC] 0.85）和在袖带闭塞（ICC 0.89）和运动（ICC 0.95）时，小腿肌肉灌注的测试-重测测量之间的总体一致性水平非常好。我们的研究结果表明，健康的衰老不会影响肌肉对袖带闭塞和次最大腿部运动的灌注反应。在年轻和老年成年人中，这些刺激试验引起的 CEU 肌肉灌注参数的测量具有高度可重复性。
