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Record 1 of 1109
Sequential modulation of cardiac autonomic control induced by cardiopulmonary and arterial baroreflex mechanisms
Author and Affiliation:
Furlan, R.(Universita degli Studi di Milano, Medicina Interna II, Ospedale L. Sacco, Dipartimento Scienze Precliniche LITA di Vialba, Italy)
Jacob, G.
Palazzolo, L.
Rimoldi, A.
Diedrich, A.
Harris, P. A.
Porta, A.
Malliani, A.
Mosqueda-Garcia, R.
Robertson, D.
Abstract: BACKGROUND: Nonhypotensive lower body negative pressure (LBNP) induces a reflex increase in forearm vascular resistance and muscle sympathetic neural discharge without affecting mean heart rate. We tested the hypothesis that a reflex change of the autonomic modulation of heartbeat might arise during low intensity LBNP without changes of mean heart rate. METHODS AND RESULTS: Ten healthy volunteers underwent plasma catecholamine evaluation and a continuous recording of ECG, finger blood pressure, respiratory activity, and central venous pressure (CVP) during increasing levels of LBNP up to -40 mm Hg. Spectrum and cross-spectrum analyses assessed the changes in the spontaneous variability of R-R interval, respiration, systolic arterial pressure (SAP), and CVP and in the gain (alpha(LF)) of arterial baroreflex control of heart rate. Baroreceptor sensitivity was also evaluated by the SAP/R-R spontaneous sequences technique. LBNP began decreasing significantly: CVP at -10, R-R interval at -20, SAP at -40, and the indexes alpha(LF) and baroreceptor sensitivity at -30 and -20 mm Hg, compared with baseline conditions. Plasma norepinephrine increased significantly at -20 mm Hg. The normalized low-frequency component of R-R variability (LF(R-R)) progressively increased and was significantly higher than in the control condition at -15 mm Hg. CONCLUSIONS: Nonhypotensive LBNP elicits a reflex increase of cardiac sympathetic modulation, as evaluated by LF(R-R), which precedes the changes in the hemodynamics and in the indexes of arterial baroreflex control.
Publication Date: Dec 11, 2001
Document ID:
20040088609
(Acquired Sep 07, 2004)
Subject Category: AEROSPACE MEDICINE
Document Type: Journal Article
Publication Information: Circulation (ISSN 0009-7322); Volume 104; 24; 2932-7
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ARTERIES; AUTONOMIC NERVOUS SYSTEM; BAROREFLEXES; BREATHING; CONTROLLERS; HEART; HEART FUNCTION; LUNGS; MODULATION; ADULTS; BLOOD PRESSURE; FEMALES; HEART RATE; LOWER BODY NEGATIVE PRESSURE; MALES; RESPIRATION; SUPINE POSITION
Other Descriptors: ARTERIES/PHYSIOLOGY; AUTONOMIC NERVOUS SYSTEM/PHYSIOLOGY; BAROREFLEX/PHYSIOLOGY; HEART/INNERVATION/PHYSIOLOGY; LUNG/PHYSIOLOGY; ADULT; BLOOD PRESSURE/PHYSIOLOGY; FEMALE; HEART RATE/PHYSIOLOGY; HUMAN; LOWER BODY NEGATIVE PRESSURE/METHODS; MALE; RESPIRATORY MECHANICS/PHYSIOLOGY; SUPINE POSITION/PHYSIOLOGY; CLINICAL TRIAL; CONTROLLED CLINICAL TRIAL; NASA DISCIPLINE REGULATORY PHYSIOLOGY; NON-NASA CENTER
Availability Source: Other Sources
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