Women Have Lower Tonic Autonomic Support of Arterial Blood Pressure and Less Effective Baroreflex Buffering Than Men

Christou, Demetra D.; Jones, P. P.; Jordan, Jens; Diedrich, André; Robertson, David; Seals, Douglas R.

doi:10.1161/01.cir.0000153864.24034.a6

Cited by 167 publications

(140 citation statements)

References 33 publications

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“…Indeed, there have been reports using indirect indices of sympathetic nerve activity showing that men have a predominance of sympathetic effects on the heart interval using spectral analysis, 39,40 and higher circulating catecholamine levels than women. 41 These reported findings are consistent with our results of an existing difference in the sympathetic drive between women and men.…”

Section: For Hypertensive Women (F-eht) and Men (M-eht) Normotensivesupporting

confidence: 93%

“…48 In that report, the baroreceptor reflex sensitivity controlling MSNA was found to be increased in relation to increased plasma levels of oestrogen and progesterone. 48 Although we did not examine the mechanisms underlying the observed gender-related differences, taking the above considerations together with previously published reports, 20,41,49,50 it is reasonable to raise the possibility that the lower sympathetic activity in women could be related to their greater sympatho-inhibitory baroreceptor reflexes than those in men. This normal genderrelated difference would then affect the level of the central sympathetic hyperactivity attained in women and men with hypertension.…”

Section: For Hypertensive Women (F-eht) and Men (M-eht) Normotensivementioning

confidence: 94%

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The effect of gender on the sympathetic nerve hyperactivity of essential hypertension

2006

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We planned to determine whether or not there is a difference in the level of muscle sympathetic nerve activity (MSNA) between hypertensive women and hypertensive men. Sympathetic activation of essential hypertension (EHT) has been associated with increased cardiovascular events, which are known to be less likely to occur in women than in men. Normal women have been reported to have less sympathetic nerve activity than men, but no reported data are available regarding gender differences in sympathetic activity in hypertensive subjects. We examined 36 patients with untreated and uncomplicated EHT comprising 18 women and 18 men, and 36 normal controls comprising 18 women and 18 men. MSNA was quantified as the mean frequency of single units and as multiunit bursts using the technique of microneurography. The hypertensive groups had greater sympathetic nerve activity than the control groups. Female hypertensives had lower (Po0.001) single unit hyperactivity (5671.7 impulses/100 cardiac beats) than male hypertensives (7271.7 impulses/100 cardiac beats). Normotensive females had lower (Po0.01) single unit activity (4273.6 impulses/100 cardiac beats) than normotensive males (5674.6 impulses/100 cardiac beats). Similar results were obtained for the frequency of multiunit burst activity. Hypertension in women is associated with a lower level of central sympathetic hyperactivity than in men. It is suggested that this may at least partly explain the observed lower hypertension-related cardiovascular events in women than in men. In addition, the findings may have implications for gender-specific management of hypertension.

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Section: For Hypertensive Women (F-eht) and Men (M-eht) Normotensivesupporting

confidence: 93%

Section: For Hypertensive Women (F-eht) and Men (M-eht) Normotensivementioning

confidence: 94%

The effect of gender on the sympathetic nerve hyperactivity of essential hypertension

2006

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“…Indeed, forearm vasoconstrictor responses to norepinephrine were observed to be blunted in young women compared with men (34,35). In agreement, recent studies (11,25,54) have suggested that young women exhibit lower tonic autonomic nervous system support of arterial BP compared with young men due to their lower basal sympathetic nerve activity and attenuated ␣-adrenergic sensitivity. Furthermore, a positive relationship between sympathetic nerve activity and total peripheral resistance has been reported in young men but not young women (9,27).…”

supporting

confidence: 76%

Sex differences in carotid baroreflex control of arterial blood pressure in humans: relative contribution of cardiac output and total vascular conductance

Kim

Deo²,

Vianna³

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

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Kim A, Deo SH, Vianna LC, Balanos GM, Hartwich D, Fisher JP, Fadel PJ. Sex differences in carotid baroreflex control of arterial blood pressure in humans: relative contribution of cardiac output and total vascular conductance. Am J Physiol Heart Circ Physiol 301: H2454 -H2465, 2011. First published September 30, 2011 doi:10.1152/ajpheart.00772.2011.-It is presently unknown whether there are sex differences in the magnitude of blood pressure (BP) responses to baroreceptor perturbation or if the relative contribution of cardiac output (CO) and total vascular conductance (TVC) to baroreflex-mediated changes in BP differs in young women and men. Since sympathetic vasoconstrictor tone is attenuated in women, we hypothesized that carotid baroreflex-mediated BP responses would be attenuated in women by virtue of a blunted vascular response (i.e., an attenuated TVC response). BP, heart rate (HR), and stroke volume were continuously recorded during the application of 5-s pulses of neck pressure (NP; carotid hypotension) and neck suction (NS; carotid hypertension) ranging from ϩ40 to Ϫ80 Torr in women (n ϭ 20, 21 Ϯ 0.5 yr) and men (n ϭ 20, 21 Ϯ 0.4 yr). CO and TVC were calculated on a beat-to-beat basis. Women demonstrated greater depressor responses to NS (e.g., Ϫ60 Torr, Ϫ17 Ϯ 1%baseline in women vs. Ϫ11 Ϯ 1%baseline in men, P Ͻ 0.05), which were driven by augmented decreases in HR that, in turn, contributed to larger reductions in CO (Ϫ60 Torr, Ϫ15 Ϯ 2%baseline in women vs. Ϫ6 Ϯ 2%baseline in men, P Ͻ 0.05). In contrast, pressor responses to NP were similar in women and men (e.g., ϩ40 Torr, ϩ14 Ϯ 2%baseline in women vs. ϩ10 Ϯ 1%baseline in men, P Ͼ 0.05), with TVC being the primary mediating factor in both groups. Our findings indicate that sex differences in the baroreflex control of BP are evident during carotid hypertension but not carotid hypotension. Furthermore, in contrast to our hypothesis, young women exhibited greater BP responses to carotid hypertension by virtue of a greater cardiac responsiveness. arterial baroreceptors; gender; heart rate; stroke volume; total peripheral resistance THE ARTERIAL BAROREFLEX plays an important role in the beatto-beat regulation of arterial blood pressure (BP). These rapid baroreflex adjustments are mediated by alterations in autonomic neural activity to the heart and vasculature, which modulates cardiac output (CO) and total vascular conductance (TVC), respectively (19,48). Studies (7, 10) in animals have demonstrated that baroreflex-mediated heart rate (HR) responses are greater in female rodents compared with male rodents. However, limited studies have been performed in humans, and equivocal results have been reported. Indeed, compared with young men, young women have been reported to exhibit similar, increased, or decreased cardiac baroreflex control (1, 8, 13, 59). In addition, the majority of these studies used pharmacological approaches to examine arterial baroreflex function, which do not permit an assessment of BP responses to baroreflex perturbation. Thus, to date,...

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“…In a previous study, we compared responses to phenylephrine before and during near-complete ganglionic blockade to estimate baroreflex blood pressure function in women and men. 11 Baroreflex blood pressure buffering was less effective in healthy young women compared with healthy young men. The phenomenon could be related to a gender difference in baroreflex heart rate or MSNA regulation.…”

Section: Discussionmentioning

confidence: 97%

“…Previous studies suggest that baroreflex blood pressure buffering is less effective in women than in men. 11 The balance between baroreflex-mediated heart rate and muscle sympathetic nerve activity (MSNA) changes may also be influenced by gender. The idea is supported by the observation that resting sympathetic vasomotor tone tends to be decreased in women, 12,13 whereas resting heart rate is increased.…”

mentioning

confidence: 99%

Baroreflex Regulation of Heart Rate and Sympathetic Vasomotor Tone in Women and Men

et al. 2005

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Abstract-Gender has been reported to influence baroreflex heart rate regulation and baroreflex blood pressure buffering.We tested the hypothesis that gender influences baroreflex regulation of heart rate and sympathetic vasomotor tone. We recruited 32 normal-weight healthy subjects (17 men and 15 women). ECGs for heart rate, brachial and finger blood pressure, and muscle sympathetic nerve activity (MSNA) were measured. Baroreflex heart rate and MSNA regulation were assessed using incremental phenylephrine and nitroprusside infusions. Baseline blood pressure was similar in men and women. MSNA was 21Ϯ2.5 bursts/min in women and 19Ϯ2.8 bursts/min in men (NS). The gain of the baroreflex MSNA curves was similar in women and men (Ϫ1.9Ϯ0.2 bursts/min per mm Hg in men and Ϫ2.0Ϯ0.3 bursts/min per mm Hg in women). Baroreflex gain for heart rate regulation was 17Ϯ3.2 ms/mm Hg in women and 19Ϯ1.9 ms/mm Hg in men (NS). We conclude that baroreflex gains for heart rate and sympathetic MSNA regulation are similar in women and men. However, the probability for congruence between men and women in terms of the MSNA baroreflex curves was 0.06% for burst rate, 0.4% for burst incidence, and 0.01% for burst area. In women, the MSNA baroreflex curve may be shifted to slightly lower blood pressure such that at a given blood pressure MSNA tends to be lower. Key Words: autonomic nervous system Ⅲ baroreflex Ⅲ gender Ⅲ nervous system, sympathetic T he autonomic nervous system influences blood pressure and heart rate through adjustments in parasympathetic and sympathetic activity. Parasympathetic and sympathetic activities are tightly regulated through baroreflex mechanisms. Therefore, baroreflexes have a pivotal role in shortterm cardiovascular regulation and buffer-excessive blood pressure swings. 1,2 Among numerous other variables, baroreflexes are also involved in long-term blood pressure maintenance. [3][4][5] Even when overall blood pressure regulation is functioning properly, the balance between baroreflex regulation of heart rate and vascular tone may be perturbed. Imbalance between sympathetic activation of the heart and the vasculature has been described in heart failure patients, 6 postural tachycardia syndrome patients, 7,8 and in healthy subjects treated with norepinephrine transporter inhibitors. 9,10 Factors influencing baroreflex function may have an important bearing on human cardiovascular disease. Gender may be such a variable. Previous studies suggest that baroreflex blood pressure buffering is less effective in women than in men. 11 The balance between baroreflex-mediated heart rate and muscle sympathetic nerve activity (MSNA) changes may also be influenced by gender. The idea is supported by the observation that resting sympathetic vasomotor tone tends to be decreased in women, 12,13 whereas resting heart rate is increased. 14 -16 Furthermore, with standing, women showed an exaggerated heart rate and an attenuated sympathetic vasomotor response. 17 Moreover, previous studies suggested that baroreflex heart rate regulati...

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Women Have Lower Tonic Autonomic Support of Arterial Blood Pressure and Less Effective Baroreflex Buffering Than Men

Abstract: Background-Short-term and tonic regulation of arterial blood pressure (BP) differ in premenopausal women and men of similar age. The autonomic nervous system (ANS) plays a critical role in BP regulation. Methods and Results-To

Cited by 167 publications

References 33 publications

The effect of gender on the sympathetic nerve hyperactivity of essential hypertension

The effect of gender on the sympathetic nerve hyperactivity of essential hypertension

Sex differences in carotid baroreflex control of arterial blood pressure in humans: relative contribution of cardiac output and total vascular conductance

Baroreflex Regulation of Heart Rate and Sympathetic Vasomotor Tone in Women and Men

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