BAROREFLEXES AND ORTHOSTATISM--FITNESS EFFECT

直立性低血压，涉及调节之间的不平衡， 血管容量、心功能和血管反应性， 据报道，更普遍的耐力（有氧）运动训练 个体这种现象的出现与运动训练有关 引起自主神经系统功能的改变， 离散压力感受器群体（主动脉、颈动脉）的特定作用 和心肺）调节心率和血压， 正射通过使用实验方案，1）选择性抑制 和/或刺激压力感受器或2）干扰颈动脉压力感受器 选择性地在不同水平的中央血量，我们计划， 确定每个压力感受器（主动脉， 颈动脉和心肺）以及它们如何相互作用以改变血液 在硫酸阿托品和酒石酸美托洛尔期间的压力控制，我们 会分离出心脏和颈动脉的血管成分 压力反射这些程序将使用横截面 设计两组指定为训练（最大有氧 容量大于65 m102/kg/min）和未经培训（45 m102/kg/min）。 此外，培训效果将在纵向2最大 通过询问一组受过训练和未经训练的受试者进行调查， 参加为期16周的耐力训练计划， 有氧能力提高20%每个压力感受器的反应性 人口将在培训计划之前和之后确定， 在为期12周的训练计划后， 能力15%。我们预计，这些调查的结果将 使我们能够识别心血管神经控制的变化， 耐力运动训练的结果。而且 结果将使我们能够将变化分类为主要是由于 中心血容量的变化，或心脏效应器的变化， 和血管对压力感受器刺激的反应。的信息 关于压力感受性反射如何在人类中运作和总结， 直立行走为研究压力感受性反射提供了基础 心力衰竭、高血压、衰老和卧床的人的功能 休息或太空飞行不适。

Orthostatic hypotension, involving an imbalance between the regulation of vascular volume, cardiac function and vascular responsiveness, has been reported to be more prevalent in endurance (aerobic) exercise trained individuals. This phenomenon appears related to an exercise training induced alteration in autonomic nervous system unction, which modifies the specific role of discrete baroreceptor populations (aortic, carotid and cardiopulmonary) in regulating heart rate and blood pressure during orthostatism. By using experimental protocols that 1) selectively inhibit and/or stimulate baroreceptors or 2) perturb carotid baroreceptors selectively at various levels of central blood volume, we plan to determine the specific roles played by each of the baroreceptors (aortic, carotid and cardiopulmonary) and how they interact to modify blood pressure control during atropine sulphate and metoprolol tartrate, we will isolate the cardias and vascular components of the carotid baroreflex. these procedures will be carried out using a cross-sectional design on two groups of subject designated as trained (maximal aerobic capacity greater than 65 m102/kg/min) and untrained (45 m102/kg/min). Furthermore, training effects will be determined in a longitudinal 2 max investigation by asking a trained and untrained group of subject to participate in a 16 week endurance exercise training program designed to increase aerobic capacity 20%. Responsiveness of each baroreceptor population will be determined before and after the training program and following a 12 week detraining program designed to decrease aerobic capacity 15%. We expect that the results from these investigations will allow us to identify changes in neural control of the cardiovascular system that result from endurance exercise training. Furthermore, the results will enable us to categorize the changes as being due primarily to changes in central blood volume, or to changes in the effector cardiac and vascular responses to baroreceptor stimulation. The information obtained concerning how baroreflexes operate and summate in humans during orthostatism will provide a base upon which to investigate baroreflex function in people with heart failure, hypertension, senescence and bed rest or space flight deconditioning.