Postural influences on the mechanical and neural components of the cardiovagal baroreflex

Taylor, Chloe E.; Willie, Christopher K.; Atkinson, Greg; Jones, Helen; Tzeng, Yu‐Chieh

doi:10.1111/apha.12087

Cited by 14 publications

(21 citation statements)

References 35 publications

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“…We have previously shown that posture significantly affects cardiac BRS (Taylor et al. ). Furthermore, resting MSNA is lower in the supine position (Ray et al.…”

Section: Discussionmentioning

confidence: 96%

“…It is possible that the methods used may explain the discrepancy with the current findings; in the study by Dutoit et al (2010) participants lay in the supine position, whereas in the current study participants were in an upright seated position. We have previously shown that posture significantly affects cardiac BRS (Taylor et al 2013). Furthermore, resting MSNA is lower in the supine position (Ray et al 1993), which may reduce the number of MSNA bursts with which to produce a sympathetic baroreflex slope.…”

Section: Relationship Between Cardiac and Sympathetic Baroreflex Sensmentioning

confidence: 99%

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Relationship between spontaneous sympathetic baroreflex sensitivity and cardiac baroreflex sensitivity in healthy young individuals

et al. 2015

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Low baroreflex sensitivity (BRS) is associated with elevated cardiovascular risk. However, the evidence is based primarily on measurements of cardiac BRS. It cannot be assumed that cardiac or sympathetic BRS alone represent a true reflection of baroreflex control of blood pressure. The aim of this study was to examine the relationship between spontaneous sympathetic and cardiac BRS in healthy, young individuals. Continuous measurements of blood pressure, heart rate, and muscle sympathetic nerve activity (MSNA) were made under resting conditions in 50 healthy individuals (18–28 years). Sympathetic BRS was quantified by plotting MSNA burst incidence against diastolic pressure (sympathetic BRSinc), and by plotting total MSNA against diastolic pressure (sympathetic BRStotal). Cardiac BRS was quantified by plotting R-R interval against systolic pressure using the sequence method. Significant sympathetic BRSinc and cardiac BRS slopes were obtained for 42 participants. A significant positive correlation was found between sympathetic BRSinc and cardiac BRS (r = 0.31, P = 0.049). Among this group, significant sympathetic baroreflex slopes were obtained for 39 participants when plotting total MSNA against diastolic pressure. In this subset, a significant positive correlation was observed between sympathetic BRStotal and cardiac BRS (r = 0.40, P = 0.012). When males and females were assessed separately, these modest relationships only remained significant in females. Analysis by gender revealed correlations in the females between sympathetic BRSinc and cardiac BRS (r = 0.49, P = 0.062), and between sympathetic BRStotal and cardiac BRS (r = 0.57, P = 0.025). These findings suggest that gender interactions exist in baroreflex control of blood pressure, and that cardiac BRS is not appropriate for estimating overall baroreflex function in healthy, young populations. This relationship warrants investigation in aging and clinical populations.

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“…We have previously shown that posture significantly affects cardiac BRS (Taylor et al. ). Furthermore, resting MSNA is lower in the supine position (Ray et al.…”

Section: Discussionmentioning

confidence: 96%

Section: Relationship Between Cardiac and Sympathetic Baroreflex Sensmentioning

confidence: 99%

Relationship between spontaneous sympathetic baroreflex sensitivity and cardiac baroreflex sensitivity in healthy young individuals

et al. 2015

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“…However, we recently used the modified Oxford method to examine the mechanical and neural components of the cardiac baroreflex in supine and standing postures (Taylor et al . ). Our results indicate that the assumption of an upright posture is associated with significant reductions in cardiac BRS in response to rising pressures due to an attenuation of the neural component.…”

Section: Postural Influences On Baroreflex Functionmentioning

confidence: 97%

“…Integrated, mechanical and neural baroreflex sensitivity for rising pressures whilst supine (●) and standing (○) for one subject (Taylor et al . ).…”

Section: Postural Influences On Baroreflex Functionmentioning

confidence: 97%

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Assessment of human baroreflex function using carotid ultrasonography: what have we learnt?

et al. 2014

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The arterial baroreflex is critical to both short- and long-term regulation of blood pressure. However, human baroreflex research has been largely limited to the association between blood pressure and cardiac period (or heart rate) or indices of vascular sympathetic function. Over the past decade, emerging techniques based on carotid ultrasound imaging have allowed new means of understanding and measuring the baroreflex. In this review, we describe the assessment of the mechanical and neural components of the baroreflex through the use of carotid ultrasound imaging. The mechanical component refers to the change in carotid artery diameter in response to changes in arterial pressure, and the neural component refers to the change in R-R interval (cardiac baroreflex) or muscle sympathetic nerve activity (sympathetic baroreflex) in response to this barosensory vessel stretch. The key analytical concepts and techniques are discussed, with a focus on the assessment of baroreflex sensitivity via the modified Oxford method. We illustrate how the application of carotid ultrasound imaging has contributed to a greater understanding of baroreflex physiology in humans, covering topics such as ageing and diurnal variation, and physiological challenges including exercise, postural changes and mental stress.

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A comparison of four common mathematical models to assess baroreflex sensitivity

Filogonio

Leite

2023

J Exp Zool Pt A

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Different methods have been used to assess baroreflex gain in experiments where changes in the carotid sinus pressure or the arterial blood pressure using different techniques provoke a baroreflex response, usually a rapid variation of heart rate. Four mathematical models are most used in the literature: the linear regression, the piecewise regression, and two different four‐parameter logistic equations: equation 1, Y = (A1–D1)/[1 + eB1(X – C1)] + D1; equation 2, Y = (A2–D2)/[1 + (X/C2)B2] + D2. We compared the four models regarding the best fit to previously published data in all vertebrate classes. The linear regression had the worst fit in all cases. The piecewise regression generally exhibited a better fit than the linear regression, though it returned a similar fit when no breakpoints were found. The logistic equations showed the best fit among the tested models and were similar to each other. We demonstrate that equation 2 is asymmetric and the level of asymmetry is accentuated according to B2. This means that the baroreflex gain calculated when X = C2 is different from the actual maximum gain. Alternatively, the symmetric equation 1 returns the maximum gain when X = C1. Furthermore, the calculation of baroreflex gain using equation 2 disregards that baroreceptors may reset when individuals experience different mean arterial pressures. Finally, the asymmetry from equation 2 is a mathematical artifact inherently skewed to the left of C2, thus bearing no biological meaning. Therefore, we suggest that equation 1 should be used instead of equation 2.

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Postural influences on the mechanical and neural components of the cardiovagal baroreflex

Abstract: Cardiovagal baroreflex sensitivity in response to rising pressures is reduced in young individuals during postural stress. Our data suggest that the mechanical component is unaffected by standing, and the reduction in baroreflex sensitivity is driven by the neural component.

Cited by 14 publications

References 35 publications

Relationship between spontaneous sympathetic baroreflex sensitivity and cardiac baroreflex sensitivity in healthy young individuals

Relationship between spontaneous sympathetic baroreflex sensitivity and cardiac baroreflex sensitivity in healthy young individuals

Assessment of human baroreflex function using carotid ultrasonography: what have we learnt?

A comparison of four common mathematical models to assess baroreflex sensitivity

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