Nocturnal variation in human sympathetic baroreflex sensitivity

Nakazato, Takashi; Shikama, Takeshi; Toma, Shinobu; Nakajima, Yoshio; Masuda, Yoshiaki

doi:10.1016/s0165-1838(98)00024-1

Cited by 43 publications

(40 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, Tochikubo et al 12 found the circadian variation to be bimodal with a secondary peak in baroreflex sensitivity at 7:00 PM and trough at 11:00 PM. Although these findings support those of Nakazato et al, 33 who reported no difference in sensitivity between morning (7:00 AM) and evening (11:00 PM), earlier research reported a peak at 11:00 PM. 10 Although baroreflex sensitivity was not investigated in the evening in the present study, it is possible that the greater afternoon sensitivity that we have reported may continue to rise later into the day.…”

Section: Comparison With Previous Studiessupporting

confidence: 89%

“…35 Studies using spontaneous baroreflex indices have consistently shown that the highest sensitivities occur during the night, with reduced sensitivities in the morning after waking. 10,12,13,33 However, the variations during the daytime have not been consistent between studies. For example, Tochikubo et al 12 found the circadian variation to be bimodal with a secondary peak in baroreflex sensitivity at 7:00 PM and trough at 11:00 PM.…”

Section: Comparison With Previous Studiesmentioning

confidence: 88%

“…10,12,33,34 Hossmann et al 14 were the first to investigate baroreflex sensitivity changes over a full 24-hour period, which was examined at 3-hour intervals using l-noradrenaline infusions to perturb BP. Although the times of the trials do not coincide precisely with those of this study, our 7:00 AM trial is broadly comparable with their 9:00 AM trial, a time in which they also reported low baroreflex sensitivity.…”

Section: Comparison With Previous Studiesmentioning

confidence: 99%

See 2 more Smart Citations

Diurnal Variation in the Mechanical and Neural Components of the Baroreflex

et al. 2011

View full text Add to dashboard Cite

Abstract-Diminished baroreflex sensitivity in the morning negatively influences morning coronary blood flow and blood pressure control in hypertensive patients. Our aim was to determine the contribution of the mechanical and neural components of the cardiac baroreflex to diurnal variation in blood pressure control. In 12 healthy participants, we used the modified Oxford method to quantify baroreflex sensitivity for rising (G up ) and falling (G down ) pressures in the morning (7:00 AM) and afternoon (4:00 PM). Beat-to-beat blood pressure, R-R intervals, and carotid artery diameter measurements were recorded. Integrated sensitivity was determined by plotting R-R intervals against systolic blood pressure. The mechanical component was carotid artery diameter plotted against systolic blood pressure, and the neural component was R-R intervals plotted against carotid artery diameter. Linear mixed models were used to compare the integrated, mechanical, and neural sensitivities between morning and afternoon. We found significant diurnal variation in integrated sensitivity, with an attenuated response in the morning (G up ϭ13.0Ϯ0.6; G down ϭ6.3Ϯ0.4 ms/mm Hg) when compared with the afternoon (G up ϭ15.1Ϯ0.6; G down ϭ12.6Ϯ0.4 ms/mm Hg). For rising pressures, the diminished integrated sensitivity in the morning was caused by a reduction in mechanical sensitivity, whereas for falling pressures it was caused by a reduction in neural sensitivity. Our findings explicate the mechanisms underlying diurnal variation in baroreflex function. Pharmacological and lifestyle interventions targeted specifically at the diminished component of the cardiac baroreflex in the morning may lead to better management of hypertension. (Hypertension. 2011;58:51-56.)Key Words: circadian rhythms Ⅲ baroreflex Ⅲ blood pressure Ⅲ heart rate Ⅲ carotid artery B lood pressure (BP) exhibits a circadian rhythm, with the lowest pressures occurring during nocturnal sleep and a rapid "morning surge" after waking. 1 BP is most reactive to a given level of physical activity in the morning, 2 and risk of orthostatic intolerance is also greater at this time compared with the afternoon. 3 In a number of prospective studies (reviewed by Kario 4 ), the morning surge in BP has been found to be an independent risk factor for cardiovascular and cerebrovascular events, which also peak between 6:00 AM and 12:00 PM. 5,6 There is a wealth of evidence that BP control varies significantly over a 24-hour period, with studies in the frequency domain indicating the presence of a circadian rhythm in sympathovagal balance. 7,8 However, investigations directed at unraveling the autonomic mechanisms governing these time-of-day differences are lacking.The arterial baroreflex control of vagal neural outflow is quantified by the responses in R-R interval to changes in systolic BP. 9 Previous studies have identified diurnal variation in baroreflex sensitivity in both normotensive and hypertensive people, with reduced sensitivities after waking compared with during sleep. 10 -13 Moreover,...

show abstract

Section: Comparison With Previous Studiessupporting

confidence: 89%

Section: Comparison With Previous Studiesmentioning

confidence: 88%

Section: Comparison With Previous Studiesmentioning

confidence: 99%

See 1 more Smart Citation

Diurnal Variation in the Mechanical and Neural Components of the Baroreflex

et al. 2011

View full text Add to dashboard Cite

show abstract

“…[56][57][58] This further highlights the baroreflex dysfunction in high-level SCI. [59][60][61] In support of this notion, baroreflex function (assessed using spectral analysis of oscillations in heart period and blood pressure) during orthostatic stress was found to be abnormal in SCI patients with lesions at T3 or above. 62 Furthermore, individuals with tetraplegia are also reported to have impaired baroreceptor responses to discrete stimulation of the carotid sinus using neck suction or neck pressure, whereby both the baroreceptor sensitivity and range of operation were reduced.…”

Section: Predisposing Factorsmentioning

confidence: 84%

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

2005

View full text Add to dashboard Cite

Motor and sensory deficits are well-known consequences of spinal cord injury (SCI). During the last decade, a significant number of experimental and clinical studies have focused on the investigation of autonomic dysfunction and cardiovascular control following SCI. Numerous clinical reports have suggested that unstable blood pressure control in individuals with SCI could be responsible for their increased cardiovascular mortality. The aim of this review is to outline the incidence and pathophysiological mechanisms underlying the orthostatic hypotension that commonly occurs following SCI. We describe the clinical abnormalities of blood pressure control following SCI, with particular emphasis upon orthostatic hypotension. Possible mechanisms underlying orthostatic hypotension in SCI, such as changes in sympathetic activity, altered baroreflex function, the lack of skeletal muscle pumping activity, cardiovascular deconditioning and altered salt and water balance will be discussed. Possible alterations in cerebral autoregulation following SCI, and the impact of these changes upon cerebral perfusion are also examined. Finally, the management of orthostatic hypotension will be considered.

show abstract

“…However, the Valsalva method has also been reported to be a feasible and reproducible method for measuring BRS (41). Third, because BRS was reported to show circadian variation (42), the assessment of BRS should have been done twice: in the morning and in the afternoon. Fourth, there were no associations between the parameters of BP variability and the two measures of BRS.…”

Section: Limitations Of This Studymentioning

confidence: 99%

Factors Associated with Baroreflex Sensitivity: Association with Morning Blood Pressure

et al. 2007

View full text Add to dashboard Cite

Baroreflex sensitivity (BRS) is a primary mechanism for acute and chronic control of blood pressure (BP).However, there are few data showing the relationship between BRS and ambulatory BP (ABP). We assessed the hypothesis that BRS specifically contributes to some specific parameters of ABP in never-treated hypertensive/normotensive subjects. We studied 128 subjects (mean age: 54.5 ± 13 years, 60% male) consisting of 92 untreated hypertensive and 36 normotensive subjects. Radial tonometric BP and simultaneous RR interval were recorded for 10 min, and the Valsalva maneuver was performed 3 times for each subject. BRS was calculated in two ways: the spontaneous-BRS by the spectral method, and the Valsalva-BRS by the slope method, using commercial software. ABP monitoring was performed on the same day as the BRS test.

show abstract

Nocturnal variation in human sympathetic baroreflex sensitivity

Cited by 43 publications

References 23 publications

Diurnal Variation in the Mechanical and Neural Components of the Baroreflex

Diurnal Variation in the Mechanical and Neural Components of the Baroreflex

Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology

Factors Associated with Baroreflex Sensitivity: Association with Morning Blood Pressure

Contact Info

Product

Resources

About