PDF(Pubmed)
Abstract：
Permanent residence at high-altitude and chronic mountain sickness (CMS) may alter the cerebrovascular homeostasis and orthostatic responses. Healthy male participants living at sea-level (LL; n = 15), 3800 m (HL3800m; n = 13) and 5100 m (HL5100m; n = 17), respectively, and CMS highlanders living at 5100 m (n = 31) were recruited. Middle cerebral artery mean blood flow velocity (MCAv), cerebral oxygen delivery (CDO2), mean blood pressure (MAP), heart rate variability and spontaneuous cardiac baroreflex sensitivity (cBRS) were assessed while sitting, initial 30 s and after 3 min of standing. Cerebral autoregulation index (ARI) was estimated (ΔMCAv%baseline)/ΔMAP%baseline) in response to the orthostatic challenge. Altitude and CMS were associated with hypoxemia and elevated hemoglobin concentration. While sitting, MCAv and LFpower negatively correlated with altitude but were not affected by CMS. CDO2 remained preserved. BRS was comparable across all altitudes, but lower with CMS. Within initial 30 s of standing, altitude and CMS correlated with a lesser ΔMAP while ARI remained unaffected. After 3 min standing, MCAv, CDO2 and cBRS remained preserved across altitudes. The LF/HF ratio increased in HL5100m compared to LL and HL3800m from sitting to standing. In contrary, CMS showed blunted autonomic nervous activation in responses to standing. Despite altitude- and CMS-associated hypoxemia, erythrocytosis and impaired blood pressure regulation (CMS only), cerebral homeostasis remained overall preserved.
摘要：
高海拔和慢性高山病（CMS）的永久居民可能会改变脑血管稳态和体位反应。生活在海平面的健康男性参与者（LL；n=15），3800m(HL3800m;n=13)和5100m(HL5100m;n=17),分别,和居住在5100m（n=31）的CMS高地居民被招募。大脑中动脉平均血流速度(MCAv),脑氧输送（CDO2），平均血压（MAP），在坐着时评估心率变异性和自发性心脏压力反射敏感性（cBRS），最初30s和站立3分钟后。响应于体位挑战,估计脑自动调节指数(ARI)(ΔMCAv%基线)/ΔMAP%基线)。海拔和CMS与低氧血症和血红蛋白浓度升高有关。坐着的时候,MCAv和LFpower与海拔呈负相关，但不受CMS的影响。CDO2仍然保存。BRS在所有海拔高度都相当，但较低的CMS。在站立的最初30秒内，海拔和CMS与较小的ΔMAP相关，而ARI未受影响。站立3分钟后，MCAv,CDO2和cBRS在整个海拔高度仍保留。从坐着到站立，与LL和HL3800m相比，HL5100m的LF/HF比率增加。相反,CMS显示对站立反应的自主神经激活减弱。尽管海拔和CMS相关的低氧血症，红细胞增多和血压调节受损（仅CMS），大脑稳态仍然保持整体。
