慢性体力活动可减轻老年人中枢性低血容量时的脑灌注不足。
Chronic physical activity mitigates cerebral hypoperfusion during central hypovolemia in elderly humans.
机构信息
Dept. of Integrative Physiology, Univ. of North Texas Health Science Center, Fort Worth, 76107, USA.
出版信息
Am J Physiol Heart Circ Physiol. 2010 Mar;298(3):H1029-37. doi: 10.1152/ajpheart.00662.2009. Epub 2009 Dec 31.
This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O(2) uptake of 10 SED (67.1 +/- 1.4 yr) and 9 ACT (68.0 +/- 1.1 yr) volunteers was determined by a graded cycling exercise test (22.1 +/- 1.2 vs 35.8 +/- 1.3 ml.min(-1).kg(-1), P < 0.01). Baseline mean arterial pressure (MAP; tonometry) and middle cerebral arterial blood flow velocity (V(MCA); transcranial Doppler) were similar between the groups (SED vs. ACT group: 91 +/- 3 vs. 87 +/- 3 mmHg and 54.9 +/- 2.3 vs. 57.8 +/- 3.2 cm/s, respectively), whereas heart rate was higher and stroke volume (bioimpedance) was smaller in the SED group than in the ACT group. Central hypovolemia during graded lower body negative pressure (LBNP) was larger (P < 0.01) in the ACT group than in the SED group. However, the slope of V(MCA)/LBNP was smaller (P < 0.05) in the ACT group (0.159 +/- 0.016 cm/s/Torr) than in the SED group (0.211 +/- 0.008 cm/s/Torr). During LBNP, the SED group had a greater augmentation of cerebral vasomotor tone (P < 0.05) and hypocapnia (P < 0.001) compared with the ACT group. Baseline MAP variability and V(MCA) variability were significantly smaller in the SED group than in the ACT group, i.e., 0.49 +/- 0.07 vs. 1.04 +/- 0.16 (mmHg)(2) and 1.06 +/- 0.19 vs. 4.24 +/- 1.59 (cm/s)(2), respectively. However, transfer function gain, coherence, and phase between MAP and V(MCA) signals (Welch spectral estimator) from 0.08-0.18 Hz were not different between SED (1.41 +/- 0.18 cm.s(-1).mmHg(-1), 0.63 +/- 0.06 units, and 38.03 +/- 6.57 degrees ) and ACT (1.65 +/- 0.44 cm.s(-1).mmHg(-1), 0.56 +/- 0.05 units, and 48.55 +/- 11.84 degrees ) groups. We conclude that a physically active lifestyle improves the intrinsic mechanism of cerebral autoregulation and helps mitigate cerebral hypoperfusion during central hypovolemia in healthy elderly adults.
本研究旨在验证以下假设，即与久坐不动的老年人（SED 组）相比，体力活动活跃的老年人（ACT 组）在直立位诱导的脑灌注不足时，脑灌注不足的情况会较轻。通过分级踏车运动试验确定了 10 名 SED（67.1±1.4 岁）和 9 名 ACT（68.0±1.1 岁）志愿者的最大摄氧量峰值（O2）（22.1±1.2 vs 35.8±1.3 ml.min-1.kg-1，P<0.01）。两组之间的平均动脉压（MAP；测压法）和大脑中动脉血流速度（V（MCA）；经颅多普勒）基线相似（SED 组与 ACT 组：91±3 vs 87±3mmHg 和 54.9±2.3 vs 57.8±3.2cm/s），但 SED 组的心率较高，而心脏射血分数（生物阻抗）较小。在分级下体负压（LBNP）期间，ACT 组的中心性低血容量（P<0.01）大于 SED 组。然而，ACT 组的 V（MCA）/LBNP 斜率较小（P<0.05）（0.159±0.016cm/s/Torr），SED 组（0.211±0.008cm/s/Torr）。在 LBNP 期间，SED 组的脑血管张力增强（P<0.05）和低碳酸血症（P<0.001）均大于 ACT 组。与 ACT 组相比，SED 组的 MAP 变异性和 V（MCA）变异性显著较小，即 0.49±0.07 vs.1.04±0.16（mmHg）（2）和 1.06±0.19 vs.4.24±1.59（cm/s）（2）。然而，从 0.08-0.18Hz 的 MAP 和 V（MCA）信号之间的传递函数增益、相干性和相位（Welch 谱估计器）在 SED（1.41±0.18cm.s-1.mmHg-1、0.63±0.06 单位和 38.03±6.57 度）和 ACT（1.65±0.44cm.s-1.mmHg-1、0.56±0.05 单位和 48.55±11.84 度）组之间没有差异。我们得出结论，积极的生活方式可以改善大脑自动调节的固有机制，并有助于减轻健康老年人中心性低血容量时的脑灌注不足。
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