Blood Pressure Control During Exercise in Heart Failure

描述（由申请人提供）：心室功能障碍的一个标志性特征是运动耐量降低。即使在正常人中，动态运动也是对心血管控制的最大挑战之一。在具有大肌肉质量的剧烈动态运动期间，心输出量增加并且到非活动区域的血管传导性降低，以便向活动骨骼肌提供足够的血流量并维持动脉血压。在患有心力衰竭的受试者中，由于心室功能的限制，这些问题变得更加严重，导致对动态运动的心血管反应显著改变。在这种情况下，交感神经系统经常发生深度激活，如高血浆儿茶酚胺和非活动区域（如内脏和肾血管）的强烈血管收缩所证明。即使是活动的骨骼肌，血管也会相对收缩。介导这些反应的机制知之甚少。存在能够在心力衰竭受试者中诱导改变的心血管反应的两种强大反射：肌肉代谢反射和动脉压力反射。本提案中描述的实验旨在测试肌肉代谢反射和动脉压力反射在介导心力衰竭患者对运动的心血管反应改变中的功能重要性。使用我们强大的有意识，长期仪器动物模型，这些研究的重点是确定介导这些反射的机制，这些反射之间的相互作用的程度以及这些机制和相互作用如何在心力衰竭中改变。此外，我们将探讨心力衰竭患者运动期间冠状动脉血流与心室功能之间的关系，以及心力衰竭恢复后是否会出现正常心血管控制机制的恢复。

DESCRIPTION (provided by applicant): A hallmark feature of ventricular dysfunction is decreased exercise tolerance. Even in normal subjects, dynamic exercise presents one of the greatest challenges to cardiovascular control. During strenuous dynamic exercise with a large muscle mass, cardiac output increases and vascular conductance to inactive areas decreases in order to provide both sufficient blood flow to active skeletal muscle and to maintain arterial blood pressure. In subjects with heart failure, these problems become exacerbated due to the limitations in ventricular function resulting in markedly altered cardiovascular responses to dynamic exercise. In this setting profound activation of the sympathetic nervous system often occurs as evidenced by high plasma catecholamines and intense vasoconstriction in inactive areas such as the splanchnic and renal vasculatures. Even active skeletal muscle may be relatively vasoconstricted. The mechanisms mediating these responses are poorly understood. 2 powerful reflexes exist which are capable of inducing the altered cardiovascular responses in subjects with heart failure: the muscle metaboreflex and the arterial baroreflex. Experiments described in this proposal are designed to test the functional importance of the muscle metaboreflex and the arterial baroreflex in mediating the altered cardiovascular responses to exercise in heart failure. Using our powerful conscious, chronically instrumented animal model, these studies are focused on determining the mechanisms of mediating these reflexes, the extent of interaction between these reflexes and how these mechanisms and interactions are altered in heart failure. Furthermore, we will explore the relationships between coronary blood flow and ventricular function during exercise in heart failure and whether recovery of normal cardiovascular control mechanisms can occur with the recovery from heart failure.