Positive and negative feedback mechanisms in the neural regulation of cardiovascular function in healthy and spinal cord-injured humans

We tested the hypothesis that in humans, hypertension/tachycardia and hypotension/bradycardia nonbaroreflex sequences that occur within spontaneous arterial pressure (AP) and R-R interval fluctuations are an expression of positive feedback mechanisms neurally regulating the cardiovascular system. We...

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Bibliographic Details
Published in:Circulation (New York, N.Y.) N.Y.), 2001-03, Vol.103 (9), p.1250-1255
Main Authors: LEGRAMANTE, J. M, RAIMONDI, G, MASSARO, M, IELLAMO, F
Format: Article
Language:English
Subjects:
Adult
Baroreflex - physiology
Biological and medical sciences
Blood Pressure - physiology
Cardiovascular Physiological Phenomena
Cardiovascular System - physiopathology
Cerebrospinal fluid. Meninges. Spinal cord
Heart Rate - physiology
Humans
Medical sciences
Nervous system (semeiology, syndromes)
Nervous System - physiopathology
Nervous System Physiological Phenomena
Neurology
Posture - physiology
Spinal Cord Injuries - physiopathology
Supine Position - physiology
Tilt-Table Test
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Summary:We tested the hypothesis that in humans, hypertension/tachycardia and hypotension/bradycardia nonbaroreflex sequences that occur within spontaneous arterial pressure (AP) and R-R interval fluctuations are an expression of positive feedback mechanisms neurally regulating the cardiovascular system. We studied 15 spinal cord-injured (SCI) subjects (8 tetraplegics and 7 paraplegics) and 8 healthy subjects. The occurrence of nonbaroreflex (NBseq) and baroreflex (Bseq) sequences, ie, hypertension-bradycardia and hypotension-tachycardia sequences, was assessed during rest and head-up tilt (HUT). The ratio between Bseq and NBseq (B/NB ratio) was also calculated. In resting conditions, the occurrence of NBseq was significantly lower (P:
ISSN:0009-7322
1524-4539
DOI:10.1161/01.CIR.103.9.1250