Phase of the menstrual cycle does not affect orthostatic tolerance in healthy women

Claydon, Victoria E.; Younis, Nabeela Raheena; Hainsworth, R.

doi:10.1007/s10286-006-0330-y

Cited by 35 publications

(30 citation statements)

References 42 publications

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“…Fu et al (8) reported that 5 of 11 women experienced presyncope during the EF phase, whereas only 3 experienced presyncope during the ML phase. Three recent studies indicate no differences in orthostatic tolerance during high and low hormone phases of the menstrual cycle, but these studies did not assess sympathetic baroreflex sensitivity (2,4,17). Instead, cardiovagal baroreflex sensitivity was assessed and determined to be similar during the various phases of the menstrual cycle (2,4,17).…”

Section: Discussionmentioning

confidence: 99%

“…Three recent studies indicate no differences in orthostatic tolerance during high and low hormone phases of the menstrual cycle, but these studies did not assess sympathetic baroreflex sensitivity (2,4,17). Instead, cardiovagal baroreflex sensitivity was assessed and determined to be similar during the various phases of the menstrual cycle (2,4,17). The influence of menstrual phase on sympathetic baroreflex sensitivities during a maximal orthostatic stress test remains unknown.…”

Section: Discussionmentioning

confidence: 99%

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Menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women

Carter

Lawrence²,

Klein³

2009

American Journal of Physiology-Endocrinology and Metabolism

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Carter JR, Lawrence JE, Klein JC. Menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women. Am J Physiol Endocrinol Metab 297: E85-E91, 2009. First published April 28, 2009 doi:10.1152/ajpendo.00019.2009.-Sympathetic baroreflex sensitivity (BRS) and muscle sympathetic nerve activity (MSNA) responses during early follicular (EF) and midluteal (ML) phases of the menstrual cycle are controversial. We hypothesize an augmented sympathetic BRS and MSNA response to orthostatic stress during the ML phase of the menstrual cycle. MSNA, mean arterial pressure (MAP), and heart rate (HR) were recorded during progressive lower body negative pressure (LBNP) (Ϫ5, Ϫ10, Ϫ15, Ϫ20, Ϫ30, and Ϫ40 mmHg; 3 min/stage) in 13 healthy, eumenorrheic women (age 21 Ϯ 1 yr). Sympathetic BRS was assessed by examining relations between spontaneous fluctuations of diastolic arterial pressure and MSNA at rest and during progressive LBNP. Plasma estradiol (42 Ϯ 6 vs. 112 Ϯ 12 pg/ml; P Ͻ 0.01) and progesterone (2 Ϯ 0 vs. 10 Ϯ 2 ng/ml; P Ͻ 0.04) were elevated during the ML phase. Resting MSNA (8 Ϯ 1 vs. 11 Ϯ 1 bursts/min), MAP (79 Ϯ 2 vs. 78 Ϯ 2 mmHg), and HR (58 Ϯ 2 vs. 60 Ϯ 2 beats/min) were not different during EF and ML phases. MSNA and HR increased during progressive LBNP (P Ͻ 0.001), and the increases in MSNA burst frequency (bursts/min) and HR were similar during both phases. In contrast, increases in total MSNA (arbitrary units) during progressive LBNP were augmented during the ML phase (P Ͻ 0.04), but this response does not appear to be linked to differences in sympathetic BRS. Progressive LBNP did not change MAP during either phase. Our results demonstrate an augmentation of the MSNA response to progressive LBNP during the ML phase of the menstrual cycle. These findings suggest that hormonal fluctuations of eumenorrheic women may influence sympathoexcitation during an orthostatic challenge, but not through sympathetic baroreflex-mediated pathways. muscle sympathetic nerve activity; arterial blood pressure; lower body negative pressure; baroreflex; estrogen EVIDENCE SUGGESTS THAT ORTHOSTATIC intolerance is more prevalent in women compared with men (3,5,7,19,(21)(22)(23). The mechanisms responsible for this apparent sex difference are presently unclear, but altered patterns of sympathoexcitation have been suggested. Shoemaker et al. (22) reported a blunted muscle sympathetic nerve activity (MSNA) response to orthostatic stress in women compared with men, suggesting MSNA responses to an orthostatic challenge may contribute to the higher incidence of orthostatic intolerance in women. In contrast, Fu et al. (9) recently reported that sex did not affect MSNA responses to an orthostatic challenge. The influence of sex on MSNA responses to orthostatic stress remains debatable.Shoemaker et al. (22) and Fu et al. (8) did not control for menstrual phase in their female subjects; thus, it is possible that differences between these two studies were due to hormonal fluctuations associated with the menstrua...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women

Carter

Lawrence²,

Klein³

2009

American Journal of Physiology-Endocrinology and Metabolism

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“…The type of contraceptives was not registered. Cardiovascular responses to LBNP seems to be unaffected by menstrual phase (5,16), and, furthermore, venous compliance and capacitance do not change over the course of the menstrual cycle or with oral contraceptive use (36). Some data from the young women and men have been previously published (29,30).…”

Section: Participantsmentioning

confidence: 99%

“…However, cardiovascular responses to LBNP seem to be unaffected by menstrual phase (5,16). Furthermore, venous compliance and capacitance do not change over the course of the menstrual cycle (36).…”

Section: Limitations Of the Studymentioning

confidence: 99%

Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress

Lindenberger¹,

Olsen²,

Länne³

2008

American Journal of Physiology-Heart and Circulatory Physiology

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Lindenberger M, Olsen H, Lä nne T. Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress. Am J Physiol Heart Circ Physiol 295: H867-H873, 2008; doi:10.1152/ajpheart.00332.2008.-Acute hemorrhage is a leading cause of death in trauma, and women are more susceptible to hypovolemic circulatory stress than men. The mechanisms underlying the susceptibility are not clear, however. The aim of the present study was to examine the compensatory mechanisms to defend central blood volume during experimental hypovolemia in women and men. Twentytwo women (23.1 Ϯ 0.4 yr) and 16 men (23.2 Ϯ 0.5 yr) were included. A lower body negative pressure (LBNP) of 11-44 mmHg induced experimental hypovolemic circulatory stress. The volumetric technique was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as to assess net capillary fluid transfer from tissue to blood in the arm. Plasma norepinephrine (NE) and forearm blood flow were measured before and during hypovolemia, and forearm vascular resistance (FVR) was calculated. LBNP created comparable hypovolemia in women and men. FVR increased less in women during hypovolemic stress, and no association between plasma NE and FVR was seen in women (R 2 ϭ 0.01, not significant), in contrast to men (R 2 ϭ 0.59, P Ͻ 0.05). Women demonstrated a good initial capacitance response, but this was not maintained with time, in contrast to men [e.g., decreased by 24 Ϯ 4% (women) vs. 4 Ϯ 5% (men), LBNP of 44 mmHg, P Ͻ 0.01], and net capillary fluid absorption from tissue to blood was lower in women (0.086 Ϯ 0.007 vs. 0.115 Ϯ 0.011 ml ⅐ 100 ml Ϫ1 ⅐ min Ϫ1 , P Ͻ 0.05). In conclusion, women showed impaired vasoconstriction, reduced capacitance response with time, and reduced capillary fluid absorption during acute hypovolemic circulatory stress, indicating less efficiency to defend central blood volume than men.gender; orthostatic tolerance; baroreceptor sensitivity ACUTE HEMORRHAGE is a leading cause of death in trauma (2, 41). Women are more susceptible to hypovolemic circulatory stress than men (6,13,17,18,48), and clinical studies have found decreased survival in women after penetrating injury as well as burn injuries (19,35). The mechanisms underlying the susceptibility are not entirely clear and are probably multifactorial (17).Lower body negative pressure (LBNP) is an excellent model for acute hemorrhage and hypovolemic circulatory stress, by inducing central hypovolemia and unloading of baroreceptors (8). A decreased baroreceptor sensitivity has been proposed in women by several authors (13,27,42), and women seem to respond with diminished arterial vasoconstriction to the infusion of ␣-receptor agonists (4, 14, 26). Furthermore, a more pronounced decrease in stroke volume and cardiac output has been postulated as the main mechanism for the susceptibility to hypovolemic circulatory stress, due to smaller and functionally stiffer hearts and ...

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“…In female subjects, testing was not carried out at a specific phase of the menstrual cycle, as it has been shown that this does not affect orthostatic tolerance. 21,22 Measurements of CBF velocity, cerebral oxygenation, arterial BP and end-tidal gases During each session, CBF velocity, cerebral oxygenation, arterial BP, end-tidal carbon dioxide (P ET CO 2 ) and electrocardiography were recorded continuously. Blood flow velocity in the right middle cerebral artery was measured using a 2-MHz pulsed Doppler ultrasound system (DWL Doppler, Sterling VA, USA).…”

Section: Experimental Designmentioning

confidence: 99%

Identical pattern of cerebral hypoperfusion during different types of syncope

et al. 2009

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Syncope is caused by insufficient oxygen supply to the brain. There have been attempts to classify syncope on the basis of defects in the venous system, arterial system (that is impaired systemic vascular resistance) or a combination of the two (that is mixed). We examined the hypothesis that a comparable decrease in cerebral perfusion would be evident at pre-syncope irrespective of the category of dysfunction. Young healthy volunteers (N ¼ 37) participated. The protocol consisted of 15 min supine rest, followed by 601 head-up tilt and lower body suction in increments of À10 mm Hg for 5 min each until pre-syncope. Beat-to-beat blood pressure (BP) (Finometer or intra-arterial), cardiac output (Finometer), middle cerebral artery blood velocity (MCAv), end-tidal CO 2 and cerebral oxygenation were monitored continuously. At pre-syncope, mixed dysfunction was common (21 out of 37 participants), followed by venular dysfunction (15 out of 37 participants). In the venular and mixed groups, comparable orthostatic tolerance and declines in BP (À37 vs À43% from baseline, respectively), end-tidal PCO 2 , MCAv (À35 vs À38%) and cerebral oxygenation (À5 vs À7%) were evident despite distinct mechanisms purportedly being responsible for the hypotension. Although different determinants of hypotension do exist, cerebral hypoperfusion occurs to a similar extent.

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Phase of the menstrual cycle does not affect orthostatic tolerance in healthy women

Cited by 35 publications

References 42 publications

Menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women

Menstrual cycle alters sympathetic neural responses to orthostatic stress in young, eumenorrheic women

Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress

Identical pattern of cerebral hypoperfusion during different types of syncope

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