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Record Details

Record 56 of 13308
Baroreflex-mediated heart rate and vascular resistance responses 24 h after maximal exercise
External Online Source: doi:10.1249/01.MSS.0000069753.92706.DD
Author and Affiliation:
Convertino, Victor A.(U.S. Army Institute of Surgical Research, Fort Sam Houston, TX 78234, United States)
Abstract: INTRODUCTION: Plasma volume, heart rate (HR) variability, and stimulus-response relationships for baroreflex control of forearm vascular resistance (FVR) and HR were studied in eight healthy men after and without performing a bout of maximal exercise to test the hypotheses that acute expansion of plasma volume is associated with 1) reduction in baroreflex-mediated HR response, and 2) altered operational range for central venous pressure (CVP). METHODS: The relationship between stimulus (DeltaCVP) and vasoconstrictive reflex response (DeltaFVR) during unloading of cardiopulmonary baroreceptors was assessed with lower-body negative pressure (LBNP, 0, -5, -10, -15, -20 mm Hg). The relationship between stimulus (Deltamean arterial pressure (MAP)) and cardiac reflex response (DeltaHR) during loading of arterial baroreceptors was assessed with steady-state infusion of phenylephrine (PE) designed to increase MAP by 15 mm Hg alone and during application of LBNP (PE+LBNP) and neck pressure (PE+LBNP+NP). Measurements of vascular volume and autonomic baroreflex responses were conducted on two different test days, each separated by at least 1 wk. On one day, baroreflex response was tested 24 h after graded cycle exercise to volitional exhaustion. On another day, measurement of baroreflex response was repeated with no exercise (control). The order of exercise and control treatments was counterbalanced. RESULTS: Baseline CVP was elevated (P = 0.04) from a control value of 10.5 +/- 0.4 to 12.3 +/- 0.4 mm Hg 24 h after exercise. Average DeltaFVR/DeltaCVP during LBNP was not different (P = 0.942) between the exercise (-1.35 +/- 0.32 pru x mm Hg-1) and control (-1.32 +/- 0.36 pru x mm Hg-1) conditions. However, maximal exercise caused a shift along the reflex response relationship to a higher CVP and lower FVR. HR baroreflex response (DeltaHR/DeltaMAP) to PE+LBNP+NP was lower (P = 0.015) after maximal exercise (-0.43 +/- 0.15 beats x min-1 x mm Hg-1) compared with the control condition (-0.83 +/- 0.14 beats x min-1 x mm Hg-1). CONCLUSION: Expansion of vascular volume after acute exercise is associated with altered operational range for CVP and reduced HR response to arterial baroreceptor stimulation.
Publication Date: Jun 01, 2003
Document ID:
20040087669
(Acquired Sep 07, 2004)
Subject Category: LIFE SCIENCES (GENERAL)
Document Type: Journal Article
Publication Information: Medicine and science in sports and exercise (ISSN 0195-9131); Volume 35; 6; 970-7
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: BAROREFLEXES; BLOOD FLOW; CARDIOVASCULAR SYSTEM; HEART RATE; HEMODYNAMIC RESPONSES; HEMODYNAMICS; PHYSICAL EXERCISE; ADULTS; ARM (ANATOMY); AUTONOMIC NERVOUS SYSTEM; BLOOD PLASMA; BLOOD VOLUME; EXPERIMENT DESIGN; MALES; VASOCONSTRICTION
Other Descriptors: BAROREFLEX/PHYSIOLOGY; EXERCISE/PHYSIOLOGY; HEART RATE/PHYSIOLOGY; VASCULAR RESISTANCE/PHYSIOLOGY; ADULT; ARM/BLOOD SUPPLY; AUTONOMIC NERVOUS SYSTEM/PHYSIOLOGY; HUMAN; MALE; PLASMA VOLUME; RANDOM ALLOCATION; REGIONAL BLOOD FLOW; SUPPORT, U.S. GOV'T, NON-P.H.S; VASOCONSTRICTION; NASA DISCIPLINE CARDIOPULMONARY; NON-NASA CENTER
Availability Source: Other Sources
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