Changes in the sympathetic nervous system induced by 42 days of head-down bed rest

1998 ◽  
Vol 274 (6) ◽  
pp. H1875-H1884 ◽  
Author(s):  
Dominique Sigaudo ◽  
Jacques-Olivier Fortrat ◽  
Anne-Marie Allevard ◽  
Alain Maillet ◽  
Jean-Marie Cottet-Emard ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Baroreflex Sensitivity ◽  
Bed Rest ◽  
Urinary Catecholamines ◽  
System Activity ◽  
Nervous System Activity ◽  
Sympathetic Nervous

Changes in autonomic nervous system activity could be linked to the orthostatic intolerance (OI) that individuals suffer after a spaceflight or head-down bed rest (HDBR). We examined this possibility by assessing the sympathetic nervous system activity during 42 days of HDBR in seven healthy men. Heart rate variability was studied with the use of power spectral analysis, which provided indicators of the sympathetic (SNSi) and parasympathetic (PNSi) nervous system influences on the heart. Urinary catecholamines and the spontaneous baroreflex sensitivity were measured. Urinary catecholamines decreased by 21.3%, showing a decrease in SNSi. Heart rate variability was greatly reduced during 42 days of HDBR with a drop in PNSi but with no significant changes in SNSi. The baroreflex sensitivity was greatly reduced (30.7%) on day 42 of HDBR. These results suggest a dissociation between the catecholamine response and the SNSi of the heart rate. This dissociation could be the consequence of an increase in β-adrenergic receptor density and/or activity induced by a decrease in catecholamines during HDBR. The subjects who suffered from OI also had a greater sympathetic response and much lower baroreflex sensitivity when supine than those who finished the stand test. However, the mean response of all subjects indicated that the sympathetic activity (catecholamine excretion) was probably slightly inhibited during HDBR and could contribute to OI.

scholarly journals Changes in Short-Term and Ultra-Short Term Heart Rate, Respiratory Rate, and Time-Domain Heart Rate Variability Parameters during Sympathetic Nervous System Activity Stimulation in Elite Modern Pentathlonists—A Pilot Study

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1104
Author(s):  
Jakub S. Gąsior ◽  
Bartosz Hoffmann ◽  
Luiz Eduardo Virgilio Silva ◽  
Łukasz Małek ◽  
Andrew A. Flatt ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Time Domain ◽  
Endurance Athletes ◽  
Sympathetic Nervous System Activity ◽  
Short Term ◽  
Nervous System Activity ◽  
Sympathetic Nervous

Monitoring of markers reflecting cardiac autonomic activity before and during stressful situations may be useful for identifying the physiological state of an athlete and may have medical or performance implications. The study aimed to determine group and individual changes in short-term (5 min) and ultra-short-term (1 min) heart rate (HR), respiratory rate (RespRate), and time-domain heart rate variability (HRV) parameters during sympathetic nervous system activity (SNSa) stimulation among professional endurance athletes. Electrocardiographic recordings were performed in stable measurement conditions (Baseline) and during SNSa stimulation via isometric handgrip in 12 elite modern pentathlonists. Significant increases in short-term HR and decreases in time-domain HRV parameters with no changes in RespRate were observed during SNSa stimulation. Significant differences were observed between Baseline (all minutes) and the last (i.e., 5th) minute of SNSa stimulation for ultra-short-term parameters. Analysis of intra-individual changes revealed some heterogeneity in responses. The study provides baseline responses of HR, RespRate, and time-domain HRV parameters to SNSa stimulation among elite pentathlonists, which may be useful for identifying abnormal responses among fatigued or injured (e.g., concussed) athletes. More attention to individual analysis seems to be necessary when assessing physiological responses to sympathetic stimuli in professional endurance athletes.

scholarly journals Magnesium Dynamics and Sympathetic Nervous System Activity in Patients With Chronic Heart Failure

1999 ◽  
Vol 63 (4) ◽  
pp. 267-273 ◽  
Author(s):  
Hisanori Samejima ◽  
Kazuhiko Tanabe ◽  
Noriyuki Suzuki ◽  
Kazuto Omiya ◽  
Masahiro Murayama
Keyword(s):  
Heart Failure ◽  
Nervous System ◽  
Chronic Heart Failure ◽  
Sympathetic Nervous System ◽  
Sympathetic Nervous System Activity ◽  
System Activity ◽  
Nervous System Activity ◽  
Sympathetic Nervous

scholarly journals Hemodynamic Patterns and Spectral Analysis of Heart Rate Variability during Dialysis Hypotension

1999 ◽  
Vol 10 (12) ◽  
pp. 2577-2584
Author(s):  
MICHEL G. W. BARNAS ◽  
WALTHER H. BOER ◽  
HEIN A. KOOMANS
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Spectral Analysis ◽  
Parasympathetic Nervous System ◽  
Intradialytic Hypotension ◽  
Intravascular Volume ◽  
Autonomic Nervous System Activity ◽  
System Activity ◽  
Nervous System Activity ◽  
Sympathetic Nervous

Abstract. Intradialytic hypotension, a major source of morbidity during hemodialysis and ultrafiltration, is often accompanied by paradoxical bradycardia. Relatively little is known about the sequential changes in autonomic nervous system activity up to and during the hypotensive episode. Continuous, beat-to-beat measurements of BP and heart rate were made during hemodialysis in patients prone (n = 8) and not prone (n = 11) to develop intradialytic hypotension. Off-line spectral analysis of heart rate variability (HRV) was performed to assess changes in autonomic nervous system activity during dialysis sessions both with and without hypotension. The low frequency (LF) component of HRV is thought to correlate with sympathetic nervous system activity, the high frequency (HF) component with that of the parasympathetic nervous system. In the sessions not complicated by symptomatic hypotension (n = 26), mean arterial BP (MAP) hardly fell, whereas heart rate increased from 77 ± 2 to 89 ± 5 bpm (P < 0.05). The LF component of HRV increased from 45.2 ± 5.0 normalized units (nu) to 59.9 ± 4.9 nu (P < 0.05), whereas the HF component fell from 54.8 ± 5.0 to 40.2 ± 4.4 nu (P < 0.05). These changes agree with compensatory baroreflex-mediated activation of the sympathetic nervous system (and suppressed parasympathetic activity) during ultrafiltration-induced intravascular volume depletion. In the sessions complicated by severe symptomatic hypotension (n = 22), the changes in heart rate and the results of spectral analysis of HRV were similar to those reported above up to the moment of sudden symptomatic (nausea, vomiting, dizziness, cramps) hypotension, whereas MAP had already fallen gradually from 94 ± 3 to 85 ± 3 mmHg (P < 0.05). The sudden further reduction in MAP (to 55 ± 2 mmHg, P < 0.02) was invariably accompanied by bradycardia (heart rate directly before hypotension 90 ± 2 bpm, during hypotension 69 ± 3 bpm, P < 0.002). The LF component of HRV fell from 62.8 ± 4.6 nu directly before to 40.0 ± 3.7 nu (P < 0.05) during hypotension, whereas the HF component increased from 37.9 ± 4.7 to 60.3 ± 3.7 nu (P < 0.05). These findings agree with activation of the cardiodepressor reflex, involving decreased sympathetic and increased parasympathetic nervous system activity, respectively. These findings indicate that activation of the sympatho-inhibitory cardiodepressor reflex (Bezold-Jarisch reflex), which is a physiologic response to a critical reduction in intravascular volume and cardiac filling, is the cause of sudden intradialytic hypotension.

scholarly journals Sympathetic nervous system activity after gastric bypass surgery

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Madhuri Somaraju ◽  
Jessica Sawyer ◽  
John Miles ◽  
Michael Joyner ◽  
Nisha Charkoudian ◽  
...  
Keyword(s):  
Gastric Bypass ◽  
Nervous System ◽  
Sympathetic Nervous System ◽  
Bypass Surgery ◽  
Gastric Bypass Surgery ◽  
Sympathetic Nervous System Activity ◽  
System Activity ◽  
Nervous System Activity ◽  
Sympathetic Nervous
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