scholarly journals 1 EXERCISE TRAINING AND BLOOD PRESSURE REGULATION DURING ORTHOSTATIC CHALLENGE BY LOWER BODY NEGATIVE PRESSURE !

1990 ◽  
Vol 22 (2) ◽  
pp. S1
Author(s):  
Peter B. Raven
Keyword(s):  
Blood Pressure ◽  
Exercise Training ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Blood Pressure Regulation ◽  
Lower Body ◽  
Pressure Regulation ◽  
Orthostatic Challenge

Hemodynamic Strategies in Blood Pressure Regulation During Orthostatic Challenge in Women

1997 ◽  
Vol 22 (4) ◽  
pp. 351-367
Author(s):  
Tania L. Culham ◽  
Gabrielle K. Savard
Keyword(s):  
Blood Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Peripheral Resistance ◽  
Orthostatic Tolerance ◽  
Lower Body ◽  
Orthostatic Challenge ◽  
Carotid Baroreflex

Several studies indicate that carotid baroreflex responsiveness is a good predictor of orthostatic tolerance. Two groups of healthy women with high (HI) and low (LO) carotid baroreflex responsiveness were studied (a) to determine any differences in the level of orthostatic tolerance of the two groups, and (b) to study the hemodynamic strategies used by HI and LO responders to regulate arterial pressure during the orthostatic challenge of lower body negative pressure (LBNP). Orthostatic tolerance was similar between the two groups, whereas the hemodynamic strategies recruited to maintain blood pressure at −40 mmHg LBNP differed: HI responders exhibited greater LBNP-induced decreases in stroke volume and cardiac output, as well as a greater increase in peripheral resistance compared to LO responders (p < .05). In addition, a significant increase in plasma renin activity during LBNP was found in the HI responders only. No significant between-group differences were found in arterial and cardiopulmonary control of vascular resistance or arterial haroreflex control of heart rate during LBNP. Key words: arterial pressure, carotid baroreceptor, lower body negative pressure, orthostatic tolerance, stroke volume

The impact of menopausal status on cardiac responses to exercise training and lower body negative pressure

Maturitas ◽  
2017 ◽  
Vol 103 ◽  
pp. 91
Author(s):  
Amanda Q.X. Nio ◽  
Eric J. Stöhr ◽  
Samantha Rogers ◽  
Rachel Mynors-Wallis ◽  
Jane M. Black ◽  
...  
Keyword(s):  
Exercise Training ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Menopausal Status ◽  
Lower Body ◽  
Cardiac Responses ◽  
The Impact

Noise-Enhanced Heart Rate and Sympathetic Nerve Responses to Oscillatory Lower Body Negative Pressure in Humans

2001 ◽  
Vol 86 (2) ◽  
pp. 559-564 ◽  
Author(s):  
Ichiro Hidaka ◽  
Shin-Ichi Ando ◽  
Hideaki Shigematsu ◽  
Koji Sakai ◽  
Soko Setoguchi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stochastic Resonance ◽  
Negative Pressure ◽  
Sympathetic Nerve ◽  
Carotid Sinus ◽  
Lower Body Negative Pressure ◽  
Arterial System ◽  
Lower Body ◽  
Cardiopulmonary Baroreceptors

By injecting noise into the carotid sinus baroreceptors, we previously showed that heart rate (HR) responses to weak oscillatory tilt were enhanced via a mechanism known as “stochastic resonance.” It remains unclear, however, whether the same responses would be observed when using oscillatory lower body negative pressure (LBNP), which would unload the cardiopulmonary baroreceptors with physically negligible effects on the arterial system. Also, the vasomotor sympathetic activity directly controlling peripheral resistance against hypotensive stimuli was not observed. We therefore investigated the effects of weak (0 to approximately −10 mmHg) oscillatory (0.03 Hz) LBNP on HR and muscle sympathetic nerve activity (MSNA) while adding incremental noise to the carotid sinus baroreceptors via a pneumatic neck chamber. The signal-to-noise ratio of HR, cardiac interbeat interval, and total MSNA were all significantly improved by increasing noise intensity, while there was no significant change in the arterial blood pressure in synchronized with the oscillatory LBNP. We conclude that the stochastic resonance, affecting both HR and MSNA, results from the interaction of noise with the signal in the brain stem, where the neuronal inputs from the arterial and cardiopulmonary baroreceptors first come together in the nucleus tractus solitarius. Also, these results indicate that the noise could induce functional improvement in human blood pressure regulatory system in overcoming given hypotensive stimuli.

Differential sympathetic nerve and heart rate spectral effects of nonhypotensive lower body negative pressure

2001 ◽  
Vol 281 (2) ◽  
pp. R468-R475 ◽  
Author(s):  
John S. Floras ◽  
Gary C. Butler ◽  
Shin-Ichi Ando ◽  
Steven C. Brooks ◽  
Michael J. Pollard ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stroke Volume ◽  
Negative Pressure ◽  
Sympathetic Nerve ◽  
Lower Body Negative Pressure ◽  
Muscle Sympathetic Nerve Activity ◽  
Venous Pressure ◽  
Harmonic Component ◽  
Lower Body

Lower body negative pressure (LBNP; −5 and −15 mmHg) was applied to 14 men (mean age 44 yr) to test the hypothesis that reductions in preload without effect on stroke volume or blood pressure increase selectively muscle sympathetic nerve activity (MSNA), but not the ratio of low- to high-frequency harmonic component of spectral power (PL/PH), a coarse-graining power spectral estimate of sympathetic heart rate (HR) modulation. LBNP at −5 mmHg lowered central venous pressure and had no effect on stroke volume (Doppler) or systolic blood pressure but reduced vagal HR modulation. This latter finding, a manifestation of arterial baroreceptor unloading, refutes the concept that low levels of LBNP interrogate, selectively, cardiopulmonary reflexes. MSNA increased, whereas PL/PH and HR were unchanged. This discordance is consistent with selectivity of efferent sympathetic responses to nonhypotensive LBNP and with unloading of tonically active sympathoexcitatory atrial reflexes in some subjects. Hypotensive LBNP (−15 mmHg) increased MSNA and PL/PH, but there was no correlation between these changes within subjects. Therefore, HR variability has limited utility as an estimate of the magnitude of orthostatic changes in sympathetic discharge to muscle.

Carotid arterial haemodynamics after mild degrees of lower-body negative pressure in man

1992 ◽  
Vol 83 (5) ◽  
pp. 535-540 ◽  
Author(s):  
P. J. Lacolley ◽  
B. M. Pannier ◽  
M. A. Slama ◽  
J. L. Cuche ◽  
A. P. G. Hoeks ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Weight Bearing ◽  
Normal Subjects ◽  
Lower Body ◽  
Head Up Tilt ◽  
Cardiopulmonary Receptors ◽  
Carotid Arterial

1. Pulsatile changes in the diameter of the common carotid artery were studied transcutaneously using an echo-tracking technique in 15 normal subjects: eight subjects before and during application of graded lower-body negative pressure from −5 to −15 mmHg, and seven subjects before and during weight-bearing head-up tilt at 30 and 60 degrees. 2. In concomitant studies of changes in forearm vascular resistance, it was seen that mild lower-body negative pressure produced deactivation of cardiopulmonary receptors without changes in systemic blood pressure or heart rate. 3. After lower-body negative pressure, a significant decrease in carotid arterial diastolic diameter [from 0.662 ± 0.028 to 0.624 ± 0.033 cm (lower-body negative pressure −10 mmHg) and 0.640 ± 0.030 cm lower-body negative pressure −15 mmHg), P<0.001 and <0.05] was observed. 4. After head-up tilt, carotid arterial diameter was also significantly decreased at 30 and 60 degrees, whereas a significant increase in heart rate occurred only at 60 degrees and mean blood pressure did not change. 5. The study provides evidence that the geometry of the arterial wall is substantially modified by noninvasive manoeuvres such as head-up tilting and lower-body negative pressure. The latter is assumed to selectively deactivate human cardiopulmonary receptors, but the present data suggest that local changes may also influence carotid baroreceptors.

scholarly journals Validity of auscultatory and Penaz blood pressure measurements during profound heat stress alone and with an orthostatic challenge

2011 ◽  
Vol 301 (5) ◽  
pp. R1510-R1516 ◽  
Author(s):  
Matthew S. Ganio ◽  
R. Matthew Brothers ◽  
Rebekah A. I. Lucas ◽  
Jeffrey L. Hastings ◽  
Craig G. Crandall
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Heat Stress ◽  
Brachial Artery ◽  
Lower Body Negative Pressure ◽  
Peripheral Resistance ◽  
Pressure Measurements ◽  
Lower Body ◽  
Dynamic Changes ◽  
Orthostatic Challenge

Despite frequent reporting of blood pressure (BP) during profound passive heat stress, both with and without a hypotensive challenge, the method by which BP is measured often varies between laboratories. It is unknown whether auscultatory and finger BP measures accurately reflect intra-arterial BP during dynamic changes in cardiac output and peripheral resistance associated with the aforementioned conditions. The purpose of this investigation was to test the hypothesis that auscultatory BP measured at the brachial artery, and finger BP measured by the Penaz method, are valid measures of intra-arterial BP during a passive heat stress and a heat-stressed orthostatic challenge, via lower body negative pressure (LBNP). Absolute (specific aim 1) and the change in (specific aim 2) systolic (SBP), diastolic (DBP), and mean BPs (MBP) were compared at normothermia, after a core temperature increase of 1.47 ± 0.09°C, and during subsequent LBNP. Heat stress did not change auscultatory SBP (6 ± 11 mmHg; P = 0.16), but Penaz SBP (−22 ± 16 mmHg; P < 0.001) and intra-arterial SBP (−11 ± 13 mmHg P = 0.017) decreased. In contrast, DBP and MBP did not differ between methods throughout heat stress. Compared with BP before LBNP, the magnitude of the reduction in BP with all three methods was similar throughout LBNP ( P > 0.05). In conclusion, auscultatory SBP and Penaz SBP failed to track the decrease in intra-arterial SBP that occurred during the profound heat stress, while decreases in arterial BP during an orthostatic challenge are comparable between methodologies.

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