Departments of Physiology, Pediatrics and Medicine, New York Medical College, Valhalla, NY, USA. mail:
J Appl Physiol (1985). 2012 Nov;113(10):1659-68. doi: 10.1152/japplphysiol.00266.2012. Epub 2012 Jun 7.
Sympathetic circulatory control is key to the rapid cardiovascular adjustments that occur within seconds of standing upright (orthostasis) and which are required for bipedal stance. Indeed, patients with ineffective sympathetic adrenergic vasoconstriction rapidly develop orthostatic hypotension, prohibiting effective upright activities. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. However, many people experience episodic acute OI as postural faint or chronic OI in the form of orthostatic tachycardia and orthostatic hypotension that significantly reduce the quality of life. Potential mechanisms for OI are discussed including forms of sympathetic hypofunction, forms of sympathetic hyperfunction, and OI that results from regional blood volume redistribution attributable to regional adrenergic hypofunction.
交感循环控制对于在直立（直立位）后几秒钟内发生的快速心血管调整至关重要，这是双足站立所必需的。事实上，交感肾上腺素能血管收缩无效的患者会迅速出现直立性低血压，从而禁止有效的直立活动。当直立时出现低血压和头晕等体征和症状，而躺下时得到缓解时，人们会说存在直立不耐受（OI）。短暂的轻度 OI 是日常生活的一部分。然而，许多人会经历阵发性急性 OI，表现为姿势性晕厥，或慢性 OI 表现为直立性心动过速和直立性低血压，这会显著降低生活质量。OI 的潜在机制包括交感神经功能低下的形式、交感神经功能亢进的形式以及由于区域肾上腺素能功能低下导致的区域性血容量重新分布引起的 OI。
