The effects of the adrenergic transmission change on low frequency (LF) and very low frequency (VLF) components of heart rate and blood pressure fluctuation in conscious rats. -Studies with wavelet analysis-

This study extends our previous work by examining the effects of alpha2-adrenoceptors under cold stimulation involving the increase of myogenic vascular oscillations as increases of very-low-frequency and low-frequency of the blood pressure variability. Forty-eight adult male Sprague-Dawley rats were randomly divided into four groups: vehicle; yohimbine; hexamethonium+yohimbine; guanethidine+yohimbine. Systolic blood pressure, heart rate, power spectral analysis of spontaneous blood pressure and heart rate variability and spectral coherence at very-low-frequency (0.02 to 0.2 Hz), low-frequency (0.2 to 0.6 Hz), and high-frequency (0.6 to 3.0 Hz) regions were monitored using telemetry. Key findings are as follows: 1) Cooling-induced pressor response was attenuated by yohimbine and further attenuated by hexamethonium+yohimbine and guanethidine+yohimbine, 2) Cooling-induced tachycardia response of yohimbine was attenuated by hexame-thonium+yohimbine and guanethidine+yohimbine, 3) Different patterns of power spectrum reaction and coherence value compared hexamethonium+yohimbine and guanethi-dine+yohimbine to yohimbine alone under cold stimulation. The results suggest that sympathetic activation of the postsynaptic alpha2-adrenoceptors causes vasoconstriction and heightening myogenic vascular oscillations, in turn, may increase blood flow to prevent tissue damage under stressful cooling challenge.

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Frequency-dependent Response of Arterial Baroreceptors in Heart Failure: Predominance of Modulation of Heart Rate and Blood Pressure in the Very Low Frequency Bands

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(97)83921-6 ◽

1998 ◽

Vol 31 (2) ◽

pp. 48A

Author(s):

A Mortara

Keyword(s):

Heart Failure ◽

Blood Pressure ◽

Heart Rate ◽

Low Frequency ◽

Frequency Dependent ◽

Frequency Bands ◽

Very Low Frequency ◽

Arterial Baroreceptors

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A common origin of the very low frequency heart rate and blood pressure variability—a new insight into an old debate

Autonomic Neuroscience ◽

10.1016/s1566-0702(01)00392-7 ◽

2002 ◽

Vol 96 (2) ◽

pp. 140-148 ◽

Cited By ~ 3

Author(s):

Ron J Leor-Librach ◽

Ben-Zion Bobrovsky ◽

Sarah Eliash ◽

Elieser Kaplinsky

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Blood Pressure Variability ◽

Low Frequency ◽

Common Origin ◽

Very Low Frequency ◽

Insight Into

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Chemoreceptor dependence of very low frequency rhythms in advanced chronic heart failure

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1997.272.1.h438 ◽

1997 ◽

Vol 272 (1) ◽

pp. H438-H447 ◽

Cited By ~ 5

Author(s):

P. Ponikowski ◽

T. P. Chua ◽

M. Piepoli ◽

A. A. Amadi ◽

D. Harrington ◽

...

Keyword(s):

Heart Failure ◽

Blood Pressure ◽

Heart Rate ◽

Chronic Heart Failure ◽

Low Frequency ◽

Peripheral Chemoreceptor ◽

Very Low Frequency ◽

Oscillatory Power ◽

Male Patients ◽

Frequency Power

Factors responsible for very low frequency oscillations (VLF; cycle > 30 s) in the cardiovascular system remain obscure. We tested the hypothesis that increased peripheral chemosensitivity is important in the pathogenesis of VLF oscillations in patients with chronic heart failure (CHF). Fourteen male patients with stable, moderate to severe CHF (age 60 +/- 1.1 yr, ejection fraction 23 +/- 11%) and reproducible VLF oscillations in heart rate underwent a protocol consisting of three consecutive 20-min phases during which they breathed air, hyperoxia (O2 via mask, 60% O2 concn), and air again. Autoregressive spectral analysis of R-R intervals, blood pressure, and respiration was used to quantify total oscillatory power (TP), VLF, low (0.04-0.15 Hz)- and high (0.15-0.40Hz)-frequency power, and the coherence between these signals. Peripheral chemosensitivity was studied by assessing the ventilatory response to hypoxia using transient inhalations of pure N2. Discrete VLF rhythms were seen in R-R intervals in all 14 patients, in blood pressure in 7 of 14, and in respiration in 8 of 14 patients. A significant coherence (> 0.5) between heart rate and systolic blood pressure within the VLF band with mean phase value of -140 degrees, suggesting an antibaroreflex relationship, was seen in six subjects. Transient hyperoxia abolished the VLF oscillations in most subjects (12 of 14 in R-R intervals) and decreased R-R variability power within the VLF band. This response significantly correlated with peripheral chemoreceptor sensitivity (r = 0.77, P = 0.014). This study suggests that in CHF, enhanced peripheral chemoreceptor activity may facilitate slow oscillations in the cardiorespiratory signals.

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Myogenic vascular function affects very low frequency blood pressure variability in conscious rats and dogs

The FASEB Journal ◽

10.1096/fasebj.21.6.a877-b ◽

2007 ◽

Vol 21 (6) ◽

Author(s):

Harald M Stauss ◽

Brett J. Wong ◽

Don D. Sheriff

Keyword(s):

Blood Pressure ◽

Vascular Function ◽

Blood Pressure Variability ◽

Low Frequency ◽

Very Low Frequency ◽

Conscious Rats

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Very-low-frequency oscillations in heart rate and blood pressure in periodic breathing: role of the cardiovascular limb of the hypoxic chemoreflex

Clinical Science ◽

10.1042/cs0990125 ◽

2000 ◽

Vol 99 (2) ◽

pp. 125-132 ◽

Cited By ~ 13

Author(s):

Darrel P. FRANCIS ◽

L. Ceri DAVIES ◽

Keith WILLSON ◽

Piotr PONIKOWSKI ◽

Andrew J. S. COATS ◽

...

Keyword(s):

Heart Failure ◽

Blood Pressure ◽

Heart Rate ◽

Chronic Heart Failure ◽

Spectral Power ◽

Low Frequency ◽

Periodic Breathing ◽

Free Breathing ◽

Very Low Frequency ◽

Rr Interval

In chronic heart failure, very-low-frequency (VLF) oscillations (0.01–0.04 Hz) in heart rate and blood pressure may be related to periodic breathing, although the mechanism has not been fully characterized. Groups of ten patients with chronic heart failure and ten healthy controls performed voluntary periodic breathing with computer guidance, while ventilation, oxygen saturation, non-invasive blood pressure and RR interval were measured. In air, voluntary periodic breathing induced periodic desaturation and prominent VLF oscillations when compared with free breathing in both patients [RR interval spectral power from 179 to 358 ms2 (P < 0.05); systolic blood pressure (SBP) spectral power from 3.44 to 6.25 mmHg2 (P < 0.05)] and controls [RR spectral power from 1040 to 2307 ms2 (P < 0.05); SBP spectral power from 3.40 to 9.38 mmHg2 (P < 0.05)]. The peak in RR interval occurred 16–26 s before that in SBP, an anti-baroreflex pattern. When the patients followed an identical breathing pattern in hyperoxic conditions to prevent desaturation, the VLF RR interval spectral power was 50% lower (179.0±51.7 ms2; P < 0.01) and the VLF SBP spectral power was 44% lower (3.51±0.77 mmHg2; P < 0.01); similar effects were seen in controls (VLF RR power 20% lower, at 1847±899 ms2, P < 0.05; VLF SBP power 61% lower, at 3.68±0.92 mmHg2, P = 0.01). Low- and high-frequency spectral powers were not significantly affected. Thus periodic breathing causes oxygen-sensitive (and by implication chemoreflex-related) anti-baroreflex VLF oscillations in RR interval and blood pressure in both patients with chronic heart failure and normal controls.

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