Effects of oral contraceptives on sympathetic nerve activity during orthostatic stress in young, healthy women

Carter, Jason R.; Klein, Jenna C.; Schwartz, Christopher E.

doi:10.1152/ajpregu.00554.2009

Cited by 33 publications

(38 citation statements)

References 18 publications

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“…Therefore, all of the young women in this study would have moderate to high levels of estrogen analog, with low levels of progesterone analog. Carter et al (4) recently reported that there were no cardiovascular or sympathetic repercussions of taking oral contraceptives in young women; thus we anticipated no difference in the cardiovascular responses of women taking oral contraceptives compared with normally cycling women.…”

Section: Discussionmentioning

confidence: 95%

Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men

Edgell

Robertson

Hughson

2012

Journal of Applied Physiology

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Edgell H, Robertson AD, Hughson RL. Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men. J Appl Physiol 112: 1482-1493, 2012. First published February 23, 2012 doi:10.1152/japplphysiol.01204.2011.-Increased incidence of orthostatic hypotension and presyncopal symptoms in young women could be related to hormonal factors that might be isolated by comparing cardiovascular and cerebrovascular responses to postural change in young and older men and women. Seven young women, 11 young men, 10 older women (Ͼ1 yr postmenopausal, no hormone therapy), and 9 older men participated in a supine-to-sit-to-stand test while measuring systemic hemodynamics, end-tidal PCO2, and blood flow velocity of the middle cerebral artery (MCA). Women had a greater reduction in stroke volume index compared with age-matched men (change from supine to standing: young women: Ϫ22.9 Ϯ 1.6 ml/m 2 ; young men: Ϫ14.4 Ϯ 2.4 ml/m 2 ; older women: Ϫ17.4 Ϯ 3.3 ml/m 2 ; older men: Ϫ13.8 Ϯ 2.2 ml/m 2 ). This was accompanied by offsetting changes in heart rate, particularly in young women, resulting in no age or sex differences in cardiac output index. Mean arterial pressure (MAP) was higher in older subjects and increased with movement to upright postures. Younger men and women had higher forearm vascular resistance that increased progressively in the upright posture compared with older men and women. There was no difference between sexes or ages in total peripheral resistance index. Women had higher MCA velocity, but both sexes had reduced MCA velocity while upright, which was a function of reduced blood pressure at the MCA and a significant reduction in end-tidal PCO2. The reductions in stroke volume index suggested impaired venous return in women, but augmented responses of heart rate and forearm vascular resistance protected MAP in younger women. Overall, these results showed significant sex and age-related differences, but compensatory mechanisms preserved MAP and MCA velocity in young women. cerebrovascular; sex; age; orthostatic ORTHOSTATIC HYPOTENSION (a condition that sometimes leads to fainting) is an important and sometimes dangerous condition that particularly affects young women during daily life, as reflected by admission to emergency rooms (51). It has been speculated that female sex hormones might modulate reflex neural or vascular properties, resulting in the greater incidence of orthostatic hypotension in young women (5,14,15,52,69). An additional indication of impaired orthostatic responses in women includes the observation that women have a greater propensity towards postural orthostatic tachycardia syndrome (18, 60).Contrary to observations for young women, clinical evidence supports the concept that orthostatic hypotension occurs less frequently in women ages 40 -60 yr (many of whom could be postmenopausal) (51). Investigations of men and women from 23-77 yr of age indicated that the heart rate response to tilt was reduced with aging, but vascular responses a...

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Section: Discussionmentioning

confidence: 95%

Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men

Edgell

Robertson

Hughson

2012

Journal of Applied Physiology

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“…Simulated orthostatic stress augments MSNA more during the mid-luteal phase (high estrogen and progesterone) than in the early follicular phase (low estrogen and progesterone) of the menstrual cycle. 23,24 Combined oral hormonal contraceptives in premenopausal women 25 and transdermal estrogen therapy in postmenopausal women 26 are reported not to influence the magnitude of MSNA increases elicited by orthostatic stress. The reason for such conflicting findings has yet to be resolved but difference in the mode of orthostatic challenge, the comparison of endogenous versus exogenous estrogen preparations, and confounding effects of progesterone 20 are plausible candidates.…”

Section: Discussionmentioning

confidence: 99%

Discordant Orthostatic Reflex Renin–Angiotensin and Sympathoneural Responses in Premenopausal Exercising-Hypoestrogenic Women

et al. 2015

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Its prevalence is markedly higher in recreationally and competitively exercising women and women with physically demanding jobs (≈1% to 44%) than in sedentary women (≈2% to 5%).2,3 Hypothalamic-pituitary-ovarian suppression in physically active women with FHA (ExFHA) has been related causally to energy deficiency (ie, caloric deficit) in association with high energy expenditure and insufficient energy intake (ie, low caloric intake). 4Circulating estradiol concentrations in women with ExFHA are chronically low and resemble those observed in postmenopausal women and in men. 5,6 In postmenopausal women, estrogen deficiency is associated with increases in blood pressure (BP) and a marked acceleration in the development and progression of atherosclerosis.7 Cardiovascular consequences of premenopausal hypoestrogenemia in ExFHA women are not yet known, but disruption of the menstrual cycle during the reproductive years is also associated with the premature development and progression of coronary artery disease. 8,9 However, in contrast to postmenopausal women, ExFHA women have lower resting systolic blood pressure (SBP) and heart rate (HR) than age-and fitness-matched estrogen-replete physically active women.10,11 The presence of low arterial BP, despite hypoestrogenemia, suggests that estrogen deficiency may have different consequences for BP regulation in premenopausal and postmenopausal women.The sympathetic nervous system and the renin-angiotensinaldosterone system (RAAS) are cornerstones of BP regulation. Estrogen modulates both. In estrogen-deficient Abstract-Our prior observations in normotensive postmenopausal women stimulated the hypotheses that compared with eumenorrheic women, active hypoestrogenic premenopausal women with functional hypothalamic amenorrhea would demonstrate attenuated reflex renin-angiotensin-aldosterone system responses to an orthostatic challenge, whereas to defend blood pressure reflex increases in muscle, sympathetic nerve activity would be augmented. To test these hypotheses, we assessed, in recreationally active women, 12 with amenorrhea (ExFHA; aged 25±1 years; body mass index 20.7±0.7 kg/m 2 ; mean±SEM) and 17 with eumenorrhea (ExOv; 24±1 years; 20.9±0.5 kg/m 2 ), blood pressure, heart rate, plasma renin, angiotensin II, aldosterone, and muscle sympathetic nerve activity at supine rest and during graded lower body negative pressure (−10, −20, and −40 mm Hg). At baseline, heart rate and systolic blood pressure were lower (P<0.05) in ExFHA (47±2 beats/min and 94±2 mm Hg) compared with ExOv (56±2 beats/min and 105±2 mm Hg), but muscle sympathetic nerve activity and renin-angiotensin-aldosterone system constituents were similar (P>0.05). In response to graded lower body negative pressure, heart rate increased (P<0.05) and systolic blood pressure decreased (P<0.05) in both groups, but these remained consistently lower in ExFHA (P<0.05). Lower body negative pressure elicited increases (P<0.05) in renin, angiotensin II, and aldosterone in ExOv, but not in ExFHA (P>0.05). Muscle sympatheti...

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“…The mechanisms underlying the lack of the normal fluctuation in SNA in OCP users, particularly the potential role of the baroreflex and non-baroreflex-mediated mechanisms, remain unclear. The effects of endogenous and exogenous hormones on baroreflex control of MSNA in humans have been studied, and the results have been variable and inconclusive (2,4,12,27,28).The purpose of this study was to investigate the effects of the ovarian cycle and OCPs on resting SNA, baroreflex-mediated deactivation and activation of MSNA, and non-baroreflexmediated [cold pressor test (CPT)] activation of MSNA in otherwise healthy, nonsmoking premenopausal females. Furthermore, because OCP use may increase the risk of hypertension through a sympathetically mediated mechanism, an additional purpose of this study was to assess 24-h ambulatory blood pressure (ABP) during each hormone phase in non-OCP and OCP users.…”

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confidence: 99%

“…Premenopausal female smokers, at higher cardiovascular risk than nonsmoking counterparts, have been shown to lack the cyclical fall in MSNA during the EF phase (31). Similarly, this cyclical pattern of SNA with the ovarian cycle has been reported to be absent in premenopausal women treated with OCPs (2,28). The mechanisms underlying the lack of the normal fluctuation in SNA in OCP users, particularly the potential role of the baroreflex and non-baroreflex-mediated mechanisms, remain unclear.…”

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confidence: 99%

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Lack of effect of ovarian cycle and oral contraceptives on baroreceptor and nonbaroreceptor control of sympathetic nerve activity in healthy women

Middlekauff

Park²,

Gornbein

2012

American Journal of Physiology-Heart and Circulatory Physiology

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Middlekauff HR, Park J, Gornbein JA. Lack of effect of ovarian cycle and oral contraceptives on baroreceptor and nonbaroreceptor control of sympathetic nerve activity in healthy women. Am J Physiol Heart Circ Physiol 302: H2560 -H2566, 2012. First published April 27, 2012 doi:10.1152/ajpheart.00579.2011.-Endogenous and exogenous female hormones regulate sympathetic nerve activity (SNA) in animal models, but their impact in humans is controversial. The purpose of this study is to investigate the effects of the ovarian cycle and oral contraceptive pills (OCPs) on SNA. We hypothesized that the effects of endogenous hormones were baroreflex (BR)-mediated and that these cyclical changes in BR control were blunted by OCPs. Furthermore, we hypothesized that the nocturnal fall in blood pressure (BP) ("dipping"), which is sympathetically mediated, also varied with the ovarian cycle. In 23 healthy females (13 OCP users, 10 agematched, no OCPs), SNA was recorded (microneurography) at rest, during BR activation/deactivation, and cold pressor test (CPT) during low and high hormonal phases. Furthermore, 24-h BP monitoring was performed during low and high hormonal phases. SNA was lower during the low vs. high hormone phase in non-OCP users (17.3 Ϯ 2.4 vs. 25.4 Ϯ 3.2 bursts/min, P Ͻ 0.001) but was not different between phases in OCP users [15.5 Ϯ 1.7 vs. 16.6 Ϯ 2.0 bursts/min, P ϭ not significant (NS)]. BR control of SNA was not different during the hormone phases in either group [SNA (total activity/min) mean slope %change from baseline, no OCP users, low vs. high hormone phase 35.4 Ϯ 6.2 vs. 29.6 Ϯ 3.4%, P ϭ NS and OCP users, low vs. high hormone phase 35.7 Ϯ 3.9 vs. 33.5 Ϯ 3.5%, P ϭ NS]. SNA activation during CPT was not impacted by hormonal phase or OCP use. Finally, nondipping was not different between OCP users and nonusers, although there was a trend for nondipping to occur more frequently in the OCP users. SNA varies during the ovarian cycle in women in the absence of OCPs. This modulation cannot be attributed to cyclical changes in the BR sensitivity. baroreflex control; estrogen; progesterone; ambulatory blood pressure; autonomic nervous system; cold pressor test CARDIOVASCULAR DISEASE, INCLUDING coronary artery disease and hypertension, is relatively rare in premenopausal women but increases dramatically following menopause. This low incidence of cardiovascular disease in premenopausal women has been attributed to the protective effects of endogenous female hormones, specifically estrogen (8). The female hormones fluctuate monthly with the ovarian cycle in premenopausal women: estrogen and progesterone levels are low during the early follicular (EF) phase and reach their peak during the midluteal (ML) phase. Concomitantly, basal sympathetic nerve activity (SNA) has been shown to follow a cyclical pattern with the ovarian cycle in premenopausal women. Some (27, 31), but not all (3,4,10,12,20,22,23), investigators have previously reported that resting SNA directed to the vascular bed of muscle displays a cyclical pat...

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Effects of oral contraceptives on sympathetic nerve activity during orthostatic stress in young, healthy women

Cited by 33 publications

References 18 publications

Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men

Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men

Discordant Orthostatic Reflex Renin–Angiotensin and Sympathoneural Responses in Premenopausal Exercising-Hypoestrogenic Women

Lack of effect of ovarian cycle and oral contraceptives on baroreceptor and nonbaroreceptor control of sympathetic nerve activity in healthy women

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