Affiliation:
1. Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201
Abstract
Experiments were designed to determine 1) the mechanisms mediating metaboreflex-induced increases in systemic arterial pressure (SAP) in response to total vascular occlusion of hindlimb blood flow [e.g., increases in cardiac output (CO) vs. peripheral vasoconstriction] and 2) whether the individual mechanisms display differential latencies for the onset of the responses. Responses were observed in seven dogs performing steady-state treadmill exercise of mild and moderate workloads (3.2 km/h at 0% grade and 6.4 km/h at 10% grade). Differential latencies were exhibited among CO, nonischemic vascular conductance (NIVC; conductance to all nonischemic vascular beds), and renal vascular conductance (RVC), with peripheral vasoconstriction significantly preceding metaboreflex-mediated increases in CO. In addition, the latencies for SAP were not different from those for NIVC or RVC at either workload. During the lower workload there were small increases and then subsequent decreases in CO before the metaboreflex-induced increase in CO, which did contribute somewhat to the initial increases in SAP. However, the increases in CO mediated by the metaboreflex occurred significantly later than the initial increases in SAP. Therefore, we conclude that the substantial metaboreflex-mediated pressor responses that occur during the initial phase of total vascular occlusion during mild and moderate exercise are primarily caused by peripheral vasoconstriction.
Publisher
American Physiological Society
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine,Physiology
Cited by
41 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献