关键词: 急进高原; 脑血管反应性; 一氧化氮; 内皮型一氧化氮合酶

Abstract:

【Abstract】 Objective To investigate the cerebrovascular reactivity (CVR) changes of healthy individuals after rapidly ascending to high altitude and its underlying mechanisms. Methods CVR of healthy adults who rapidly ascended from 2200 meters above the sea level to 3800 meters was evaluated by transcranial Doppler ultrasound; The plasma level of nitric oxide (NO) was determined by nitrate reduction method; The plasma level of endothelial nitric oxide synthase (eNOS) was determined by enzyme linked immune absorption methods. Results A total of 46 cases were analyzed in our present study. CVR was significantly increased after rapidly ascending to high altitude than before (before ascending to high altitude CVR 1.43± 0.46, cerebrovascular reserve index [CVRI] 1.82± 0.71; after rapidly ascending to high altitude CVR 2.36 ±0.74, CVRI 2.56± 0.89, P<0.001); Plasmic NO (μmol/L) and eNOS (pg/ml) were significantly increased after rapidly ascending to high altitude than before (before ascending to high altitude NO 34.45± 2.86, eNOS 209.73± 14.34; after rapidly ascending to high altitude NO 44.97± 0.68, eNOS 274.81± 13.68, P<0.001); Mean cerebral blood flow velocity of bilateral middle cerebral artery (MCAv) (cm/s) was significantly increased during regular breathing after rapidly ascending to high altitude than before (before ascending to high altitude MCAv 80.85±11.14, after ascending to high altitude MCAv 93.78± 11.67, P<0.001). Conclusion Our study reveals that CVR, plasmic NO, eNOS, and MCAv in healthy adults are increased after they rapidly ascend to high altitude, which are adaptive strategies of brain in high altitude hypoxic environment

Key words: Rapid ascension to high altitude; Cerebrovascular reactivity; Nitric oxide; Endothelial nitric oxide synthase