Robertson D, Shannon J R, Biaggioni I, Ertl A C, Diedrich A, Carson R, Furlan R, Jacob G, Jordan J
Center for Space Physiology and Medicine, Clinical Research Center, Vanderbilt University, Nashville, TN 37232-2195, USA.
Pflugers Arch. 2000;441(2-3 Suppl):R48-51. doi: 10.1007/s004240000353.
Orthostatic intolerance is a common problem for inbound space travelers. There is usually tachycardia on standing but blood pressure may be normal, low or, rarely, elevated. This condition is analogous to the orthostatic intolerance that occurs on Earth in individuals with orthostatic tachycardia, palpitations, mitral valve prolapse, and light-headedness. Our studies during the Neurolab mission indicated that sympathetic nerve traffic is raised in microgravity and that plasma norepinephrine is higher than baseline supine levels but lower than baseline upright levels. A subgroup of patients with familial orthostatic intolerance differ from inbound space travelers in that they have an alanine-to-to-proline mutation at amino acid position 457 in their norepinephrine transporter gene. This leads to poor clearance of norepinephrine from synapses, with consequent raised heart rate. Clinical features of these syndromes are presented.
体位性不耐受是进入太空的旅行者常见的问题。站立时通常会出现心动过速，但血压可能正常、偏低，或极少情况下升高。这种情况类似于地球上患有体位性心动过速、心悸、二尖瓣脱垂和头晕的个体所出现的体位性不耐受。我们在“神经实验室”任务期间的研究表明，微重力环境下交感神经活动增强，血浆去甲肾上腺素高于仰卧位基线水平，但低于直立位基线水平。患有家族性体位性不耐受的患者亚组与进入太空的旅行者不同，他们的去甲肾上腺素转运体基因第457位氨基酸存在丙氨酸到脯氨酸的突变。这导致去甲肾上腺素从突触的清除不佳，从而使心率升高。本文介绍了这些综合征的临床特征。
