scholarly journals Sex differences in limb vasoconstriction responses to increases in transmural pressures

2009 ◽  
Vol 296 (1) ◽  
pp. H186-H194 ◽  
Author(s):  
Mary E. J. Lott ◽  
Cindy Hogeman ◽  
Michael Herr ◽  
Monica Bhagat ◽  
Lawrence I. Sinoway
Keyword(s):  
Sex Differences ◽  
Orthostatic Intolerance ◽  
Transmural Pressure ◽  
Limb Volume ◽  
Percent Change ◽  
Vasoconstrictor Response ◽  
Main Effect ◽  
Dynamic Velocity ◽  
Similar Dynamic ◽  
Leg Pressure

Women compared with men are more likely to have orthostatic intolerance. The purpose of this study was to examine whether sex affects limb vasoconstrictor response to increases in transmural pressure. Brachial and femoral mean blood velocity (MBV) and diameter (Doppler Ultrasound) were measured in 10 women and 10 men as transmural pressure was altered by applying local suction (−25, −50, −75, and −100 mmHg) via pressurized-limb tanks for 1 min to a single arm and leg. With the abrupt application of forearm suction (−75 and −100 mmHg), women compared with men had a greater initial rise in MBV (peak), followed by a quicker dynamic rate of velocity reduction. In the leg, women had a tendency for higher peak MBV but had similar dynamic velocity reductions compared with men. After 60 s of suction, women compared with men had attenuated reductions in brachial flow and conductance (−8.05 ± 1.71 vs. −16.25 ± 1.71 ml/min; −0.12 ± 0.03 vs. −0.20 ± 0.03 ml·min−1·mmHg−1; main effect, P < 0.05), as well as attenuated femoral flow and conductance to sustained leg negative pressure at −100 mmHg ( P < 0.05). When the data were expressed as percent change, women compared with men continued to have attenuated brachial flow responses (−24 ± 2 vs. −36 ± 2%, main effect, P < 0.05), with a trend toward attenuation at the highest leg pressure (−25 ± 11 vs. −46 ± 4%; P = 0.08). These sex differences remained after normalizing the flow responses by limb volume (percent change). Our findings suggest that young women compared with men have attenuated brachial and femoral vasoconstrictor responses to increases in transmural pressure, which may have implications for the greater incidence of orthostatic intolerance in women.

Orthostatic intolerance after spaceflight

1996 ◽  
Vol 81 (1) ◽  
pp. 7-18 ◽  
Author(s):  
J. C. Buckey ◽  
L. D. Lane ◽  
B. D. Levine ◽  
D. E. Watenpaugh ◽  
S. J. Wright ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Space Shuttle ◽  
Orthostatic Intolerance ◽  
Peripheral Resistance ◽  
Systemic Hemodynamic ◽  
Vasoconstrictor Response ◽  
Before And After ◽  
Underlying Mechanisms

Orthostatic intolerance occurs commonly after spaceflight, and important aspects of the underlying mechanisms remain unclear. We studied 14 individuals supine and standing before and after three space shuttle missions of 9-14 days. After spaceflight, 9 of the 14 (64%) crew members could not complete a 10-min stand test that all completed preflight. Pre- and postflight supine hemodynamics were similar in both groups except for slightly higher systolic and mean arterial pressures preflight in the finishers [15 +/- 3.7 and 8 +/- 1.2 (SE) mmHg, respectively; P < 0.05]. Postflight, finishers and nonfinishers had equally large postural reductions in stroke volume (-47 +/- 3.7 and -48 +/- 3.3 ml, respectively) and increases in heart rate (35 +/- 6.6 and 51 +/- 5.2 beats/min, respectively). Cardiac output during standing was also similar (3.6 +/- 0.4 and 4.1 +/- 0.3 l/min, respectively). However, the finishers had a greater postflight vasoconstrictor response with higher total peripheral resistance during standing (22.3 +/- 1.2 units preflight and 29.4 +/- 2.3 units postflight) than did the nonfinishers (20.1 +/- 1.1 units preflight and 19.9 +/- 1.4 units postflight). We conclude that 1) the primary systemic hemodynamic event, i.e., the postural decrease in stroke volume, was similar in finishers and nonfinishers and 2) the heart rate response and cardiac output during standing were not significantly different, but 3) the postural vasoconstrictor response was significantly greater among the finishers (P < 0.01).

scholarly journals Sex differences in blood pressure control during 6° head-down tilt bed rest

2013 ◽  
Vol 304 (8) ◽  
pp. H1114-H1123 ◽  
Author(s):  
Natalia M. Arzeno ◽  
Michael B. Stenger ◽  
Stuart M. C. Lee ◽  
Robert Ploutz-Snyder ◽  
Steven H. Platts
Keyword(s):  
Blood Pressure ◽  
Sex Differences ◽  
Sodium Nitroprusside ◽  
Blood Pressure Control ◽  
High Frequency ◽  
Baroreflex Sensitivity ◽  
Orthostatic Intolerance ◽  
Bed Rest ◽  
Pressure Control ◽  
Sinus Arrhythmia

Spaceflight-induced orthostatic intolerance has been studied for decades. Although ∼22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps.

scholarly journals Sex Differences in Maintaining the Requested Handgrip Force Enhanced by Auditory or Visual Feedback

2020 ◽  
Vol 17 (14) ◽  
pp. 5158
Author(s):  
Jacek Tarnas ◽  
Rafał Stemplewski ◽  
Piotr Krutki
Keyword(s):  
Sex Differences ◽  
Motor Learning ◽  
Visual Feedback ◽  
Motor Task ◽  
Motor Tasks ◽  
Auditory Displays ◽  
Main Effect ◽  
Simple Motor Task ◽  
And Performance ◽  
Mixed Groups

Thus far, the differences in effect of auditory or visual feedback in motor learning have presented results derived from mixed groups and sex differences have not been considered. However, perception and processing of auditory stimuli and performance of visual motor tasks appear to be sex-related. The purpose of this study was to investigate the learning of the simple motor task of maintaining a requested handgrip force in separate male and female groups. A total of 31 volunteers (15 males, 16 females) were randomly assigned to one of four experimental groups with defined sex and training conditions (audio or visual feedback). Participants performed training sessions over a period of six days, for which auditory or visual feedback was provided, and the effectiveness of both types of signals was compared. The evident learning effect was found in all groups, and the main effect of sex was significant among visual groups in favor of the males (p < 0.05). On the other hand, the main effect of feedback conditions was found to be significant among females, beneficially in the case of auditory displays (p < 0.05). The results lead to the conclusion that an equal number of males and females in mixed experimental groups may be supportive to obtain reliable results. Moreover, in motor-learning studies conducted on females only, a design including auditory feedback would be more suitable.

Effect of Visual Detail on Scene Recognition: Some Unexpected Sex Differences

1997 ◽  
Vol 84 (2) ◽  
pp. 619-626 ◽  
Author(s):  
Cheryl J. Hamel ◽  
David L. Ryan-Jones
Keyword(s):  
Sex Differences ◽  
Recognition Test ◽  
Visual Processing ◽  
Scene Recognition ◽  
Urban Scenes ◽  
Visual Detail ◽  
Main Effect ◽  
Learning Trials

30 adults received two learning trials on which they viewed computer images of urban scenes followed by a recognition test to assess the effect of visual detail on scene recognition. The scenes were shown in either high detail (photographic) or reduced detail. Analysis showed no main effect of detail on scene recognition; however, analysis of the interaction for sex X detail indicated that women recognized significantly more scenes in the photographic condition than in the two with reduced detail. Men showed no differences. The unexpected sex differences suggest the relevance of subjects' strategies during visual processing.

scholarly journals Sex differences in forearm vasoconstrictor response to voluntary apnea (1171.1)

2014 ◽  
Vol 28 (S1) ◽  
Author(s):  
Matthew Muller ◽  
Hardikkumar Patel ◽  
Matthew Heffernan ◽  
Amanda Ross
Keyword(s):  
Sex Differences ◽  
Vasoconstrictor Response ◽  
Voluntary Apnea

Sex differences in hemodynamic and sympathetic neural firing patterns during orthostatic challenge in humans

2012 ◽  
Vol 112 (10) ◽  
pp. 1744-1751 ◽  
Author(s):  
Huan Yang ◽  
William H. Cooke ◽  
Kristen S. Reed ◽  
Jason R. Carter
Keyword(s):  
Sex Differences ◽  
Arterial Pressure ◽  
Orthostatic Intolerance ◽  
Muscle Sympathetic Nerve Activity ◽  
Young Men ◽  
Orthostatic Stress ◽  
Neural Firing ◽  
Men And Women ◽  
Firing Patterns ◽  
Arterial Blood

Recent evidence suggests that young men and women may have different strategies for regulating arterial blood pressure, and the purpose of the present study was to determine if sex differences exist in diastolic arterial pressure (DAP) and muscle sympathetic nerve activity (MSNA) relations during simulated orthostatic stress. We hypothesized that young men would demonstrate stronger DAP-MSNA coherence and a greater percentage of “consecutive integrated bursts” during orthostatic stress. Fourteen men and 14 women (age 23 ± 1 yr) were examined at rest and during progressive lower body negative pressure (LBNP; −5 to −40 mmHg). Progressive LBNP did not alter mean arterial pressure (MAP) in either sex. Heart rate increased and stroke volume decreased to a greater extent during LBNP in women (interactions, P < 0.05). DAP-MSNA coherence was strong (i.e., r ≥ 0.5) at rest and increased throughout all LBNP stages in men. In contrast, DAP-MSNA coherence was lower in women, and responses to progressive LBNP were attenuated compared with men (time × sex, P = 0.029). Men demonstrated a higher percentage of consecutive bursts during all stages of LBNP (sex, P < 0.05), although the percentage of consecutive bursts increased similarly during progressive LBNP between sexes. In conclusion, men and women demonstrate different firing patterns of integrated MSNA during LBNP that appear to be related to differences in DAP oscillatory patterns. Men tend to have more consecutive bursts, which likely contribute to a stronger DAP-MSNA coherence. These findings may help explain why young women are more prone to orthostatic intolerance.

scholarly journals Sex differences in forearm vasoconstrictor response to voluntary apnea

2014 ◽  
Vol 306 (3) ◽  
pp. H309-H316 ◽  
Author(s):  
Hardikkumar M. Patel ◽  
Matthew J. Heffernan ◽  
Amanda J. Ross ◽  
Matthew D. Muller
Keyword(s):  
Sex Differences ◽  
Postmenopausal Women ◽  
Young Women ◽  
Young Men ◽  
Breath Hold ◽  
Doppler Flowmetry ◽  
Men And Women ◽  
Female Sex Hormones ◽  
Vasoconstrictor Response ◽  
Obstructive Sleep

Clinical evidence indicates that obstructive sleep apnea is more common and more severe in men compared with women. Sex differences in the vasoconstrictor response to hypoxemia-induced sympathetic activation might contribute to this clinical observation. In the current laboratory study, we determined sex differences in the acute physiological responses to maximal voluntary end-expiratory apnea (MVEEA) during wakefulness in healthy young men and women (26 ± 1 yr) as well as healthy older men and women (64 ± 2 yr). Mean arterial pressure (MAP), heart rate (HR), brachial artery blood flow velocity (BBFV, Doppler ultrasound), and cutaneous vascular conductance (CVC, laser Doppler flowmetry) were measured, and changes in physiological parameters from baseline were compared between groups. The breath-hold duration and oxygen-saturation nadir were similar between groups. In response to MVEEA, young women had significantly less forearm vasoconstriction compared with young men (ΔBBFV: 2 ± 7 vs. −25 ± 6% and ΔCVC: −5 ± 4 vs. −31 ± 4%), whereas ΔMAP (12 ± 2 vs. 16 ± 3 mmHg) and ΔHR (4 ± 2 vs. 6 ± 3 bpm) were comparable between groups. The attenuated forearm vasoconstriction in young women was not observed in postmenopausal women (ΔBBFV −21 ± 5%). We concluded that young women have blunted forearm vasoconstriction in response to MVEEA compared with young men, and this effect is not evident in older postmenopausal women. These data suggest that female sex hormones dampen neurogenic vasoconstriction in response to apnea-induced hypoxemia.

SEX DIFFERENCES IN NEUROPSYCHOLOGICAL FUNCTION AND POST-CONCUSSION SYMPTOMS OF CONCUSSED COLLEGIATE ATHLETES

Neurosurgery ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 345-351 ◽  
Author(s):  
Tracey Covassin ◽  
Philip Schatz ◽  
C. Buz Swanik
Keyword(s):  
Sex Differences ◽  
Visual Memory ◽  
Female Athletes ◽  
Multivariate Analyses ◽  
Neuropsychological Test ◽  
Collegiate Athletes ◽  
Reliable Change ◽  
Main Effect ◽  
Composite Scores ◽  
The Impact

Abstract OBJECTIVE Our purpose was to determine whether sex differences exist with respect to post-concussion symptoms and neurocognitive function in concussed collegiate athletes. METHODS A prospective dependent-sample cohort design was used to compare baseline and post-concussion neuropsychological test scores and endorsed symptoms as functions of serial post-concussion assessment with respect to time and sex. The Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) battery was administered to a multicenter analysis group of 79 concussed athletes. This computerized neuropsychological test was given to the athletes during the preseason and, on average, 2 and 8 days postinjury. RESULTS Multivariate analyses revealed no significant between-group differences on baseline test performance with respect to sex on any of the ImPACT composite scores or on the total symptom score. Multivariate analyses of post-concussion data revealed a significant main effect of time on ImPACT scores, but no main effect of sex was identified, and no time-by-sex interaction existed. Post hoc analysis revealed that concussed female athletes performed significantly worse than concussed male athletes on visual memory tasks (P = 0.001), and analysis of endorsed post-concussion symptoms revealed that concussed men were significantly more likely than concussed women to report post-concussion symptoms of vomiting (P = 0.001) and sadness (P = 0.017). Athletes' scores were examined individually using the reliable-change methodology. At 2 days post-injury, 58% of concussed athletes had one or more reliable incidents of performance decline or increases in symptom reporting. At 8 days post-concussion, 30% of concussed athletes were still showing one or more reliable change from preseason values. CONCLUSIONS College athletes exhibit differences on visual memory composite scores and symptoms post-concussion as a function of sex. These data support the importance of evaluating neuropsychological status and post-concussion symptoms in concussed athletes. In addition, these data illustrate the importance of analyzing an individual athlete's recovery pattern, because individual differences in recovery trajectories may be overshadowed by global norm-group comparisons.

Decreased capillary filtration but maintained venous compliance in the lower limb of aging women

2007 ◽  
Vol 293 (6) ◽  
pp. H3568-H3574 ◽  
Author(s):  
Marcus Lindenberger ◽  
Toste Länne
Keyword(s):  
Young Women ◽  
Elderly Women ◽  
Orthostatic Intolerance ◽  
The Elderly ◽  
Transmural Pressure ◽  
Lower Limbs ◽  
Venous Compliance ◽  
Venous Capacitance ◽  
Capillary Filtration ◽  
Age Related

There are sex-related differences in venous compliance and capillary filtration in the lower limbs, which to some extent can explain the susceptibility to orthostatic intolerance in young women. With age, venous compliance and capacitance are reduced in men. This study was designed to evaluate age-related changes in venous compliance and capillary filtration in the lower limbs of healthy women. Included in this study were 22 young and 12 elderly women (23.1 ± 0.4 and 66.4 ± 1.4 yr). Lower body negative pressure (LBNP) of 11, 22, and 44 mmHg created defined transmural pressure gradients in the lower limbs. A plethysmographic technique was used on the calf to assess venous capacitance and net capillary filtration. Venous compliance was calculated with the aid of a quadratic regression equation. No age-related differences in venous compliance and capacitance were found. Net capillary filtration and capillary filtration coefficient (CFC) were lower in elderly women at a LBNP of 11 and 22 mmHg (0.0032 vs. 0.0044 and 0.0030 vs. 0.0041 ml·100 ml−1·min−1·mmHg−1, P < 0.001). At higher transmural pressure (LBNP, 44 mmHg), CFC increased by ∼1/3 (0.010 ml·100 ml−1·min−1·mmHg−1) in the elderly ( P < 0.001) but remained unchanged in the young women. In conclusion, no age-related decrease in venous compliance and capacitance was seen in women. However, a decreased CFC was found with age, implying reduced capillary function. Increasing transmural pressure increased CFC in the elderly women, indicating an increased capillary susceptibility to transmural pressure load in dependent regions. These findings differ from earlier studies on age-related effects in men, indicating sex-specific vascular aging both in the venous section and microcirculation.

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