Frequency response characteristics of whole body autoregulation of blood flow in rats

Stauss, Harald M.; Rarick, Kevin R.; Deklotz, Richard J.; Sheriff, Don D.

doi:10.1152/ajpheart.01262.2008

Cited by 7 publications

(5 citation statements)

References 35 publications

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“…This is in accordance with previous studies that concluded that this VLF BP variability is largely mediated by L-type Ca(2+) channel-dependent mechanisms [6] and that the frequency response characteristic of whole-body autoregulation of blood flow and/or myogenic vascular function is consistent with the frequency range of VLF BP variability (0.02-0.2 Hz) in rats [12]. Another study also concluded that dynamic autoregulation of cerebral blood flow is restricted to VLF (<0.1 Hz) in rats [30].…”

Section: Discussionsupporting

confidence: 93%

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Myogenic Oscillations in Rabbit Ocular Vasculature Are Very Low Frequency

Delgado

Marques-Neves²,

Rocha³

et al. 2013

Ophthalmic Res

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Background/Aims: In a previously described model of isolated rabbit eye, we detected myogenic intrinsic vascular tone of unknown origin in the ophthalmic artery. In order to better understand the origin of these low frequency oscillations, we analyzed their spectral characteristics using fast Fourier. Methods: Hybrid New Zealand rabbits of either sex (n = 24) were used; they were divided into 2 groups according to age. The spectral characteristics of the myogenic behaviour of the rabbit external ophthalmic artery were analyzed using the fast Fourier algorithm. Results: The frequency of the oscillations of the myogenic activity seen in the rabbit external ophthalmic artery varied between 0.033 and 0.066 Hz (mean 0.045 ± 0.012 Hz), all in the region of very low frequency (VLF) oscillations (VLF <0.07 Hz for the rabbit). The frequency of spontaneous oscillations was higher in younger animals. Conclusion: Fast Fourier analysis proved to be an adequate mathematical tool to analyze the myogenic tone oscillations, which were all in the range of VLF in the model we used. These results indicate that myogenic vascular function of ocular blood flow is composed of VLF oscillations, and they provide a new explanation for the origin of VLF in arterial spectra. They also suggest that the ocular local myogenic vascular function observed is more efficient in younger animals.

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Section: Discussionsupporting

confidence: 93%

“…However, the origin of VLF oscillations in the cardiovascular physiological variables is still controversial [3,5,6,7,8], with possible mechanisms involving thermoregulation [9], parasympathetic influences [10], peripheral chemosensitivity [11], or myogenic vascular function [12]. …”

Section: Introductionmentioning

confidence: 99%

Myogenic Oscillations in Rabbit Ocular Vasculature Are Very Low Frequency

Delgado

Marques-Neves²,

Rocha³

et al. 2013

Ophthalmic Res

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“…It would be of interest to explore in future whether spectral measures in PPGV could track short term changes in SVR, hence providing a real time measure of sympathetic vascular function. While the current study focused on LF and HF fluctuations, future studies could also incorporate information from the VLF band, which has been associated with adrenergic as well as autoregulation mechanisms [19,30], thus may provide potentially useful indication of peripheral circulatory impairment in patients.…”

Section: Discussionmentioning

confidence: 99%

Fingertip photoplethysmographic waveform variability and systemic vascular resistance in intensive care unit patients

Middleton

Grace

Steel

et al. 2011

Med Biol Eng Comput

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Low frequency variability in the fingertip photoplethysmogram (PPG) waveform has been utilized for inferring sympathetic vascular control, but its relationship with a quantitative measure of vascular tone has not been established. In this study, we examined the association between fingertip PPG waveform variability (PPGV) and systemic vascular resistance (SVR) obtained from thermodilution cardiac output (CO) and intra-arterial pressure measurements in 48 post cardiac surgery intensive care unit patients. Among the hemodynamic measurements, both CO (P < 0.05) and SVR (P < 0.0001) had statistically significant relationships with the normalized low frequency power (LF(nu)) of PPGV. The LF(nu) of baseline PPGV had moderate but significant positive correlation with SVR (r = 0.54, P < 0.0001), and a value below 52.5 nu was able to identify SVR < 900 dyn s cm⁻⁵ with sensitivity of 59% and specificity of 95%. The results have provided quantitative evidence to confirm the link between fingertip PPGV and sympathetic vascular control. Suppression of LF vasomotor waves leading to dominance of respiration-related HF fluctuations in the fingertip circulation was a specific (though not sensitive) marker of systemic vasodilatation, which could be potentially utilized for the assessment of critical care patients.

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“…They are created by multiple mechanisms acting in concert and opposition. Oscillation at ∼0.1 Hz in rat originates from spontaneous myogenic activity of blood vessels (Stauss et al ., ), these can be enhanced by activation of the rennin‐angiotensin system (Ponchon and Elghozi, ) and counteracted by the baroreceptor reflex, as suggested from results obtained in experiments where the baroreceptor reflex loop has been surgically or pharmacologically compromised (Japundzic et al ., ; Cerutti et al ., ). Therefore, in our experiments, the reduction of VLF variability could be related to the enhanced BRS.…”

Section: Discussionmentioning

confidence: 90%

Overexpression of oxytocin receptors in the hypothalamic PVN increases baroreceptor reflex sensitivity and buffers BP variability in conscious rats

Lozić

Greenwood

Šarenac

et al. 2014

British J Pharmacology

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Experiments were performed in conscious male Wistar rats equipped with a radiotelemetric device. The PVN was unilaterally co-transfected with an adenoviral vector (Ad), engineered to overexpress OT receptors, and an enhanced green fluorescent protein (eGFP) tag. Control groups: PVN was transfected with an Ad expressing eGFP alone or untransfected, sham rats (Wt). Recordings were obtained without and with selective blockade of OT receptors (OTX), during both baseline and stressful conditions. Baroreceptor reflex sensitivity (BRS) and cardiovascular short-term variability were evaluated using the sequence method and spectral methodology respectively. KEY RESULTSUnder baseline conditions, rats overexpressing OT receptors (OTR) exhibited enhanced BRS and reduced BP variability compared to control groups. Exposure to stress increased BP, BP variability and HR in all rats. In control groups, but not in OTR rats, BRS decreased during stress. Pretreatment of OTR rats with OTX reduced BRS and enhanced BP and HR variability under baseline and stressful conditions. Pretreatment of Wt rats with OTX, reduced BRS and increased BP variability under baseline and stressful conditions, but only increased HR variability during stress. CONCLUSIONS AND IMPLICATIONSOT receptors in PVN are involved in tonic neural control of BRS and cardiovascular short-term variability. The failure of this mechanism could critically contribute to the loss of autonomic control in cardiovascular disease.

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Frequency response characteristics of whole body autoregulation of blood flow in rats

Cited by 7 publications

References 35 publications

Myogenic Oscillations in Rabbit Ocular Vasculature Are Very Low Frequency

Myogenic Oscillations in Rabbit Ocular Vasculature Are Very Low Frequency

Fingertip photoplethysmographic waveform variability and systemic vascular resistance in intensive care unit patients

Overexpression of oxytocin receptors in the hypothalamic PVN increases baroreceptor reflex sensitivity and buffers BP variability in conscious rats

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