Sympathetic nerve activity and simulated diving in healthy humans

Abstract The goal of our study was to develop a simple and practical method for simulating diving in humans using facial cold exposure and apnea stimuli to measure neural and circulatory responses during the stimulated diving reflex. We hypothesized that responses to simultaneous facial cold exposur...

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Bibliographic Details
Published in:Autonomic neuroscience 2014-04, Vol.181, p.74-78
Main Authors: Shamsuzzaman, Abu, Ackerman, Michael J, Kuniyoshi, Fatima Sert, Accurso, Valentina, Davison, Diane, Amin, Raouf S, Somers, Virend K
Format: Article
Language:English
Subjects:
Adult
Advanced Basic Science
Apnea - physiopathology
Arrhythmias
Blood Pressure - physiology
Bradycardia
Bradycardia - etiology
Bradycardia - physiopathology
Cold Temperature
Diving
Diving - physiology
Electrocardiography
Face
Female
Heart Rate - physiology
Humans
Long QT syndrome
Male
Medical Education
Microneurography
Muscle, Skeletal - physiology
Physical Stimulation
Sympathetic nervous system
Sympathetic Nervous System - physiology
Time Factors
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Summary:Abstract The goal of our study was to develop a simple and practical method for simulating diving in humans using facial cold exposure and apnea stimuli to measure neural and circulatory responses during the stimulated diving reflex. We hypothesized that responses to simultaneous facial cold exposure and apnea (simulated diving) would be synergistic, exceeding the sum of responses to individual stimuli. We studied 56 volunteers (24 female and 32 male), average age of 39 years. All subjects were healthy, free of cardiovascular and other diseases, and on no medications. Although muscle sympathetic nerve activity (MSNA), blood pressure, and vascular resistance increased markedly during both early and late phases of simulated diving, significant reductions in heart rate were observed only during the late phase. Total MSNA during simulated diving was greater than combined MSNA responses to the individual stimuli. We found that simulated diving is a powerful stimulus to sympathetic nerve traffic with significant bradycardia evident in the late phase of diving and eliciting synergistic sympathetic and parasympathetic responses. Our data provide insight into autonomic triggers that could help explain catastrophic cardiovascular events that may occur during asphyxia or swimming, such as in patients with obstructive sleep apnea or congenital long QT syndrome.
ISSN:1566-0702
1872-7484
DOI:10.1016/j.autneu.2013.12.001