Smith M L
Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
J Clin Pharmacol. 1994 May;34(5):460-5. doi: 10.1002/j.1552-4604.1994.tb04987.x.
Orthostatic intolerance can present a very serious limitation to astronauts attempting any functions requiring the upright position. Vasovagal syncope is a common cause of fainting characterized by paradoxic bradycardia and vasodilation in the presence of decreasing arterial pressure. Several mechanisms have been proposed to mediate vasovagal syncope and it seems likely that redundant mechanisms exist both centrally and peripherally which can mediate these responses. Spaceflight alters reflex control of cardiovascular function in several ways which may influence susceptibility to vasovagal syncope provoked by the Bezold-Jarisch reflex.
直立不耐受对于试图进行任何需要直立姿势的功能的宇航员来说可能是一个非常严重的限制。血管迷走性晕厥是晕厥的常见原因，其特征是在动脉压下降时出现反常性心动过缓和血管扩张。已经提出了几种机制来介导血管迷走性晕厥，并且很可能在中枢和外周都存在冗余机制来介导这些反应。太空飞行以多种方式改变心血管功能的反射控制，这可能会影响对贝佐尔德-雅里什反射诱发的血管迷走性晕厥的易感性。
