منابع مشابه
Venous response to orthostatic stress.
Head-up tilt (HUT) induces a reduction in preload, which is thought to be restored through sympathetic venoconstriction, reducing unstressed volume (V(u)) and venous compliance (VeC). In this study, we assessed venous inflow and outflow responses and their reproducibility and determined the relation with autonomic function during HUT. Eight healthy non-pregnant women were subjected to 20 degree...
متن کاملPET(CO(2)) inversely affects MSNA response to orthostatic stress.
Arterial hypocapnia has been associated with orthostatic intolerance. Therefore, we tested the hypothesis that hypocapnia may be detrimental to increases in muscle sympathetic nerve activity (MSNA) and total peripheral resistance (TPR) during head-up tilt (HUT). Ventilation was increased approximately 1.5 times above baseline for each of three conditions, whereas end-tidal PCO(2) (PET(CO(2))) w...
متن کاملAging augments renal vasoconstrictor response to orthostatic stress in humans.
The ability of the human body to maintain arterial blood pressure (BP) during orthostatic stress is determined by several reflex neural mechanisms. Renal vasoconstriction progressively increases during graded elevations in lower body negative pressure (LBNP). This sympathetically mediated response redistributes blood flow to the systemic circulation to maintain BP. However, how healthy aging af...
متن کاملComputational modeling of cardiovascular response to orthostatic stress.
The objective of this study is to develop a model of the cardiovascular system capable of simulating the short-term (< or = 5 min) transient and steady-state hemodynamic responses to head-up tilt and lower body negative pressure. The model consists of a closed-loop lumped-parameter representation of the circulation connected to set-point models of the arterial and cardiopulmonary baroreflexes. ...
متن کاملResponse to creatine kinase and pressor response to orthostatic tolerance.
Response to Creatine Kinase and Pressor Response to Orthostatic Tolerance We thank Karamat et al for their comments on our recent article about sympathetic neural and pressor responses to orthostasis in elderly blacks. It is an interesting hypothesis that racial differences in creatine kinase (CK) levels might be one of the mechanisms for the enhanced pressor response to upright tilt in elderly...
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ژورنال
عنوان ژورنال: American Journal of Physiology-Heart and Circulatory Physiology
سال: 2008
ISSN: 0363-6135,1522-1539
DOI: 10.1152/ajpheart.00571.2008