Arterial pressure oscillation and muscle sympathetic nerve activity after 20days of head-down bed rest

Tanaka, Kunihiko; Nishimura, Naoki; Sato, Maki; Kanikowska, Dominika; Shimizu, Yasuhiko; Ikoma, Yoko; Abe, Chikara; Iwata, Chuzo; Morita, Hironobu; Iwase, Satoshi; Sugenoya, Junichi

doi:10.1016/j.autneu.2013.02.025

Cited by 13 publications

(10 citation statements)

References 25 publications

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“…In our study, sympathetic baroreflex control of MSNA in the supine position was substantially attenuated following HDBR. The response was associated with increased MSNA, a finding already described after bed rest (Tanaka et al, 2013) and during (Ertl et al, 2002) and after weightlessness (Levine et al, 2002). Conversely, other authors found a reduced MSNA burst frequency after 14-day HDBR (Shoemaker et al, 1998).…”

Section: Discussionmentioning

confidence: 51%

Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals

et al. 2019

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Orthostatic intolerance commonly occurs after prolonged bed rest, thus increasing the risk of syncope and falls. Baroreflex-mediated adjustments of heart rate and sympathetic vasomotor activity (muscle sympathetic nerve activity – MSNA) are crucial for orthostatic tolerance. We hypothesized that prolonged bed rest deconditioning alters overall baroreceptor functioning, thereby reducing orthostatic tolerance in healthy volunteers. As part of the European Space Agency Medium-term Bed Rest protocol, 10 volunteers were studied before and after 21 days of −6° head down bed rest (HDBR). In both conditions, subjects underwent ECG, beat-by-beat blood pressure, respiratory activity, and MSNA recordings while supine (REST) and during a 15-min 80° head-up tilt (TILT) followed by a 3-min −10 mmHg stepwise increase of lower body negative pressure to pre-syncope. Cardiac baroreflex sensitivity (cBRS) was obtained in the time (sequence method) and frequency domain (spectrum and cross-spectrum analyses of RR interval and systolic arterial pressure – SAP, variability). Baroreceptor modulation of sympathetic discharge activity to the vessels (sBRS) was estimated by the slope of the regression line between the percentage of MSNA burst occurrence and diastolic arterial pressure. Orthostatic tolerance significantly decreased after HDBR (12 ± 0.6 min) compared to before (21 ± 0.6 min). While supine, heart rate, SAP, and cBRS were unchanged before and after HDBR, sBRS gain was slightly depressed after than before HDBR (sBRS: −6.0 ± 1.1 versus −2.9 ± 1.5 burst% × mmHg −1 , respectively). During TILT, HR was higher after than before HDBR (116 ± 4 b/min versus 100 ± 4 b/min, respectively), SAP was unmodified in both conditions, and cBRS indexes were lower after HDBR ( α index: 3.4 ± 0.7 ms/mmHg; BRS SEQ 4.0 ± 1.0) than before ( α index: 6.4 ± 1.0 ms/mmHg; BRS SEQ 6.8 ± 1.2). sBRS gain was significantly more depressed after HDBR than before (sBRS: −2.3 ± 0.7 versus −4.4 ± 0.4 burst% × mmHg −1 , respectively). Our findings suggest that baroreflex-mediated adjustments in heart rate and MSNA are impaired after prolonged bed rest. The mechanism likely contributes to the decrease in orthostatic tolerance.

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Section: Discussionmentioning

confidence: 51%

Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals

et al. 2019

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“…21,22 Previous findings in bed rest studies support the idea that sympathetic activity is, indeed, increased. [23][24][25] Furthermore, after 21 day bed rest, plasma norepinephrine increased more with orthostasis compared with baseline. 26 We speculate that sympathetic activation may have increased circumferential strain with bed rest.…”

Section: Cardiac Deconditioningmentioning

confidence: 99%

Cardiac adaptations to 60 day head‐down‐tilt bed rest deconditioning. Findings from the AGBRESA study

et al. 2020

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Aims Reduced physical activity increases the risk of heart failure; however, non‐invasive methodologies detecting subclinical changes in myocardial function are not available. We hypothesized that myocardial, left ventricular, systolic strain measurements could capture subtle abnormalities in myocardial function secondary to physical inactivity. Methods and results In the AGBRESA study, which assessed artificial gravity through centrifugation as potential countermeasure for space travel, 24 healthy persons (eight women) were submitted to 60 day strict −6° head‐down‐tilt bed rest. Participants were assigned to three groups of eight subjects: a control group, continuous artificial gravity training on a short‐arm centrifuge (30 min/day), or intermittent centrifugation (6 × 5 min/day). We assessed cardiac morphology, function, strain, and haemodynamics by cardiac magnetic resonance imaging (MRI) and echocardiography. We observed no differences between groups and, therefore, conducted a pooled analysis. Consistent with deconditioning, resting heart rate (∆8.3 ± 6.3 b.p.m., P < 0.0001), orthostatic heart rate responses (∆22.8 ± 19.7 b.p.m., P < 0.0001), and diastolic blood pressure (∆8.8 ± 6.6 mmHg, P < 0.0001) increased, whereas cardiac output (∆−0.56 ± 0.94 L/min, P = 0.0096) decreased during bed rest. Left ventricular mass index obtained by MRI did not change. Echocardiographic left ventricular, systolic, global longitudinal strain (∆1.8 ± 1.83%, P < 0.0001) decreased, whereas left ventricular, systolic, global MRI circumferential strain increased not significantly (∆−0.68 ± 1.85%, P = 0.0843). MRI values rapidly returned to baseline during recovery. Conclusion Prolonged head‐down‐tilt bed rest provokes changes in cardiac function, particularly strain measurements, that appear functional rather than mediated through cardiac remodelling. Thus, strain measurements are of limited utility in assessing influences of physical deconditioning or exercise interventions on cardiac function.

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“…Reported evidence [1,6] supports the satisfactory performance of LFsp as a noninvasive sympathetic activity marker, including its strong correlation with the invasive measure muscular sympathetic nerve activity (MSNA) [3]. Recently, we reported that LFdmAP adequately indicates the sympathetic activity level provoked by different maneuvers [I].…”

Section: Discussionmentioning

confidence: 95%

“…Similarly, increasingly available evidence supports that the LF power of systolic pressure (L F sp) is a satisfactory sympathetic activity index [1,3].…”

Section: Introductionmentioning

confidence: 99%

Beat-to-beat response patterns of spectral sympathetic estimators to the cold face test and their comparison to those of the active orthostatic test

Carrasco-Sosa

Guillen-Mandujano

Mejía-Rodríguez

2015

2015 Computing in Cardiology Conference (CinC)

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We assessed the effects of cold face test (eFT) and active orthostatic test (AOT) on the RR intervals (RR), systolic pressure (SP) and maximal amplitude of arterial pressure first derivative (dmAP) time series of 25 healthy volunteers, and the instantaneous dynamics of their low frequency powers (LF RR, LFsp and LFdmAP), to characterize their time course, and compare their performance as sympathetic markers as well as the magnitude of the sympathetic response evoked by each maneuver. All the variables studied displayed distinct instantaneous response patterns to each maneuver: while in eFT they increased to a plateau, in AOT they presented overshoots at the beginning and end of the test.In both tests, LFdmAP and LFsp dynamics were similar and strongly correlated, and presented a weak correlation with LFRR. Means of LFdmAP and LFsp in eFT were 7 times smaller than in AOT. Our findings support that LFsp and LFdmAP powers exhibit similar performance as noninvasive sympathetic markers and that all variables studied show distinctive beat-to-beat response patterns to each maneuver. Using the sympathetic response produced by AOT as reference, the one evoked by eFT is smaller.

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Arterial pressure oscillation and muscle sympathetic nerve activity after 20days of head-down bed rest

Cited by 13 publications

References 25 publications

Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals

Effects of Prolonged Head-Down Bed Rest on Cardiac and Vascular Baroreceptor Modulation and Orthostatic Tolerance in Healthy Individuals

Cardiac adaptations to 60 day head‐down‐tilt bed rest deconditioning. Findings from the AGBRESA study

Beat-to-beat response patterns of spectral sympathetic estimators to the cold face test and their comparison to those of the active orthostatic test

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