Comparison of cardiovascular responses between lower body negative pressure and head-up tilt

2005 ◽  
Vol 98 (6) ◽  
pp. 2081-2086 ◽  
Author(s):  
Asami Kitano ◽  
J. Kevin Shoemaker ◽  
Masashi Ichinose ◽  
Hiroyuki Wada ◽  
Takeshi Nishiyasu
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Upper Limb ◽  
Negative Pressure ◽  
Lower Limb ◽  
Lower Body Negative Pressure ◽  
Cardiovascular Responses ◽  
Left Ventricular ◽  
Lower Body ◽  
Head Up Tilt

To investigate local blood-flow regulation during orthostatic maneuvers, 10 healthy subjects were exposed to −20 and −40 mmHg lower body negative pressure (LBNP; each for 3 min) and to 60° head-up tilt (HUT; for 5 min). Measurements were made of blood flow in the brachial (BFbrachial) and femoral arteries (BFfemoral) (both by the ultrasound Doppler method), heart rate (HR), mean arterial pressure (MAP), cardiac stroke volume (SV; by echocardiography), and left ventricular end-diastolic volume (LVEDV; by echocardiography). Comparable central cardiovascular responses (changes in LVEDV, SV, and MAP) were seen during LBNP and HUT. During −20 mmHg LBNP, −40 mmHg LBNP, and HUT, the following results were observed: 1) BFbrachial decreased by 51, 57, and 41%, and BFfemoral decreased by 40, 53, and 62%, respectively, 2) vascular resistance increased in the upper limb by 110, 147, and 85%, and in the lower limb by 76, 153, and 250%, respectively. The increases in vascular resistance were not different between the upper and lower limbs during LBNP. However, during HUT, the increase in the lower limb was much greater than that in the upper limb. These results suggest that, during orthostatic stimulation, the vascular responses in the limbs due to the cardiopulmonary and arterial baroreflexes can be strongly modulated by local mechanisms (presumably induced by gravitational effects).

scholarly journals The cerebrovascular response to lower-body negative pressure vs. head-up tilt

2017 ◽  
Vol 122 (4) ◽  
pp. 877-883 ◽  
Author(s):  
Anne-Sophie G. T. Bronzwaer ◽  
Jasper Verbree ◽  
Wim J. Stok ◽  
Mat J. A. P. Daemen ◽  
Mark A. van Buchem ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Negative Pressure ◽  
Cerebral Blood Flow Velocity ◽  
Lower Body Negative Pressure ◽  
Orthostatic Stress ◽  
Lower Body ◽  
Head Up Tilt ◽  
End Tidal ◽  
Pronounced Reduction

Lower-body negative pressure (LBNP) has been proposed as a MRI-compatible surrogate for orthostatic stress. Although the effects of LBNP on cerebral hemodynamic behavior have been considered to reflect those of orthostatic stress, a direct comparison with actual orthostasis is lacking. We assessed the effects of LBNP (−50 mmHg) vs. head-up tilt (HUT; at 70°) in 10 healthy subjects (5 female) on transcranial Doppler-determined cerebral blood flow velocity (CBF v) in the middle cerebral artery and cerebral perfusion pressure (CPP) as estimated from the blood pressure signal (finger plethysmography). CPP was maintained during LBNP but decreased after 2 min in response to HUT, leading to an ~15% difference in CPP between LBNP and HUT ( P ≤ 0.020). Mean CBF v initially decreased similarly in response to LBNP and for HUT, but, from minute 3 on, the decline became ~50% smaller ( P ≤ 0.029) during LBNP. The reduction in end-tidal Pco2 partial pressure (PetCO2) was comparable but with an earlier return toward baseline values in response to LBNP but not during HUT ( P = 0.008). We consider the larger decrease in CBF v during HUT vs. LBNP attributable to the pronounced reduction in PetCO2 and to gravitational influences on CPP, and this should be taken into account when applying LBNP as an MRI-compatible orthostatic stress modality. NEW & NOTEWORTHY Lower-body negative pressure (LBNP) has the potential to serve as a MRI-compatible surrogate of orthostatic stress but a comparison with actual orthostasis was lacking. This study showed that the pronounced reduction in end-tidal Pco2 together with gravitational effects on the brain circulation lead to a larger decline in cerebral blood flow velocity in response to head-up tilt than during lower-body negative pressure. This should be taken into account when employing lower-body negative pressure as MRI-compatible alternative to orthostatic stress.

Rodent cardiovascular responses to baroreceptor unloading: Effect of plane of anaesthesia

2011 ◽  
Vol 36 (3) ◽  
pp. 376-381 ◽  
Author(s):  
Charlotte W. Usselman ◽  
Louis Mattar ◽  
Jasna Twynstra ◽  
Ian Welch ◽  
J. Kevin Shoemaker
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Cardiovascular Responses ◽  
Cardiovascular Control ◽  
Noxious Stimulation ◽  
Lower Body

The objective of this study was to determine whether a plane of urethane–α-chloralose anaesthesia that suppresses motor reflexes would affect baroreflex cardiovascular control relative to a plane of anaesthesia that leaves motor reflexes intact. Adult male Sprague–Dawley rats were anaesthetized to either a light (motor reflexes intact) or deep (motor reflexes suppressed) plane of anaesthesia. Animals were exposed to graded (–2 to –10 mm Hg) lower body negative pressure while heart rate, vascular resistance, and mean arterial pressure were assessed. No between-group differences were observed in baseline hemodynamics. Graded lower body negative pressure progressively increased heart rate (p < 0.01) and vascular resistance (p < 0.001) and reduced mean arterial pressure (p < 0.001) similarly in light and deep planes of anaesthesia. Therefore, the deep plane of anaesthesia was not associated with a degradation of the autonomic response to baroreceptor unloading beyond that observed at the light plane. These data support the use of urethane–α-chloralose anaesthesia in studies examining reflex cardiovascular control concomitant with some degree of noxious stimulation.

Bradykinin has no acute effect on the response of forearm blood flow to sympathetic stimulation in man

1990 ◽  
Vol 78 (4) ◽  
pp. 399-401 ◽  
Author(s):  
M. J. Cullen ◽  
J. R. Cockcroft ◽  
D. J. Webb
Keyword(s):  
Blood Flow ◽  
Angiotensin Ii ◽  
Negative Pressure ◽  
Enzyme Inhibitor ◽  
Lower Body Negative Pressure ◽  
Acute Effect ◽  
Acute Administration ◽  
Lower Body ◽  
Resistance Vessels ◽  
Sympathetic Responses

1. Six healthy male subjects received 0.9% (w/v) NaCl (saline) followed by incremental doses of bradykinin (1, 3 and 10 pmol/min), via the left brachial artery. Blood flow and the response of blood flow to lower-body negative pressure were measured in both forearms during infusion of saline and each dose of bradykinin. 2. Bradykinin produced a moderate and dose-dependent increase in blood flow in the infused, but not the non-infused, forearm. Lower-body negative pressure produced an approximately 15–20% reduction in blood flow in both forearms, and this response was unaffected by local infusion of bradykinin. 3. Bradykinin, in contrast to angiotensin II, had no acute effect on peripheral sympathetic responses to lower-body negative pressure. We conclude that, in forearm resistance vessels in man, withdrawal of angiotensin II, rather than accumulation of bradykinin, is likely to account for the attenuation of peripheral sympathetic responses after acute administration of a converting-enzyme inhibitor.

Sustained increases in sympathetic outflow during prolonged lower body negative pressure in humans

1990 ◽  
Vol 68 (3) ◽  
pp. 1004-1009 ◽  
Author(s):  
M. J. Joyner ◽  
J. T. Shepherd ◽  
D. R. Seals
Keyword(s):  
Blood Flow ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Partial Recovery ◽  
Sympathetic Outflow ◽  
Lower Body ◽  
Control Value ◽  
Arterial Blood ◽  
Change In Mean ◽  
Cardiopulmonary Baroreceptors

The purpose of this study was to determine whether prolonged unloading of cardiopulmonary baroreceptors with lower body negative pressure (LBNP) causes constant increases in sympathetic outflow to skeletal muscles. Eight healthy subjects underwent a 20-min control period followed by 20 min of 15-mmHg LBNP. This pressure was selected because it did not cause any significant change in mean arterial blood pressure (sphygmomanometry) or heart rate, suggesting that the cardiopulmonary baroreceptors were selectively unloaded and the activity of the arterial baroreceptors was unchanged. Muscle sympathetic nerve activity in the peroneal nerve (MSNA, microneurography) increased from an average of 21.8 +/- 1.7 bursts/min over the last 5 min of control to 29.0 +/- 2.9 bursts/min during the 1st min of LBNP (P less than 0.05 LBNP vs. control). The increase in MSNA observed during the 1st min was sustained throughout LBNP. Forelimb blood flow (plethysmography) decreased abruptly at the onset of the LBNP from a control value of 4.3 +/- 0.5 ml.min-1.100 ml-1 to 2.5 +/- 0.2 at the 1st min; the flow then increased and remained significantly above this value, but below the control value, throughout LBNP. Similar blood flow findings were obtained in additional studies, when the hand circulation was excluded during the flow measurements. Forearm skin blood flow (laser Doppler) also decreased abruptly at the onset of LBNP and was followed by partial recovery, but these changes were too small to account for all the increases in limb blood flow over the course of LBNP.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of acute hypoxemia on cerebral blood flow velocity control during lower body negative pressure

2018 ◽  
Vol 6 (4) ◽  
pp. e13594 ◽  
Author(s):  
Noud van Helmond ◽  
Blair D. Johnson ◽  
Walter W. Holbein ◽  
Humphrey G. Petersen-Jones ◽  
Ronée E. Harvey ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Negative Pressure ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Lower Body Negative Pressure ◽  
Lower Body ◽  
Velocity Control

scholarly journals Differential Effects of Low- and High-Intensity Lower Body Negative Pressure on Noradrenaline and Adrenaline Kinetics in Humans

1996 ◽  
Vol 90 (5) ◽  
pp. 337-343 ◽  
Author(s):  
Marie-Cecile Jacobs ◽  
David S. Goldstein ◽  
Jacques J. Willemsen ◽  
Paul Smits ◽  
Theo Thien ◽  
...  
Keyword(s):  
Heart Rate ◽  
Vascular Resistance ◽  
Pulse Pressure ◽  
Negative Pressure ◽  
High Intensity ◽  
Lower Body Negative Pressure ◽  
Lower Body ◽  
Total Body ◽  
Noradrenaline And Adrenaline ◽  
Forearm Vascular Resistance

1. Lower body negative pressure provides a means to examine neurocirculatory reflexive responses to decreases in venous return to the heart. We assessed whether the pattern of catecholaminergic responses to lower body negative pressure depends on the intensity of the stimulus (−15 versus −40 mmHg). 2. In 14 healthy subjects, responses of forearm blood flow and noradrenaline spillover and of total body noradrenaline and adrenaline spillover were assessed during infusion of [3H]noradrenaline and [3H]adrenaline during −15 and −40 mmHg of lower body negxative pressure. 3. During lower body negative pressure at −15 mmHg, heart rate and pulse pressure did not change, but forearm vascular resistance increased by 25–50%. Forearm noradrenaline spillover increased by about 50%, from 0.63 ± 0.16 to 0.94 ± 0.23 pmol min−1 100 ml−1 (P<0.05). Total body noradrenaline spillover did not change, and total body adrenaline spillover increased significantly by about 30%. Clearances of noradrenaline and adrenaline were unchanged. 4. During lower body negative pressure at −40 mmHg, heart rate increased and pulse pressure decreased. Forearm vascular resistance increased by about 100%, and forearm noradrenaline spillover increased by 80%, from 0.73 ± 0.19 to 1.32 ± 0.36 pmol min−1 100 ml−1 (P<0.05). Total body noradrenaline spillover increased by 30%, and total body adrenaline spillover increased by about 50%. Clearances of both noradrenaline and adrenaline decreased. 5. The results are consistent with the view that selective deactivation of cardiopulmonary baroreceptors during low-intensity lower body negative pressure increases sympathoneural traffic to forearm skeletal muscle and increases adrenomedullary secretion without a concomitant generalized increase in sympathoneural outflows. Concurrent deactivation of cardiopulmonary and arterial baroreceptors during high-intensity lower body negative pressure evokes a more generalized increase in sympathoneural activity, accompanied by further increased adrenomedullary secretion and decreased plasma clearances of noradrenaline and adrenaline. The findings support differential increases in skeletal sympathoneural and adrenomedullary outflows during orthostasis, with more generalized sympathoneural responses to systemic hypotension.

RECOVERY OF CARDIOVASCULAR RESPONSES TO LOWER BODY NEGATIVE PRESSURE (LBNP) AFTER SPACE FLIGHT 203

1997 ◽  
Vol 29 (Supplement) ◽  
pp. 36
Author(s):  
S. M.C. Lee ◽  
L. Steinmann ◽  
M. Wood ◽  
L. Dussack ◽  
S. M. Fortney
Keyword(s):  
Space Flight ◽  
Negative Pressure ◽  
Lower Body Negative Pressure ◽  
Cardiovascular Responses ◽  
Lower Body
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