| Frequency response characteristics of whole body autoregulation of blood flow in rats. | |
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MedLine Citation:
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PMID: 19252087 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Previously, we demonstrated that very low-frequency (VLF) blood pressure variability (BPV) depends on voltage-gated L-type Ca(2+)-channels, suggesting that autoregulation of blood flow and/or myogenic vascular function significantly contributes to VLF BPV. To further substantiate this possibility, we tested the hypothesis that the frequency response characteristic of whole body autoregulation of blood flow is consistent with the frequency range of VLF BPV (0.02-0.2 Hz) in rats. In anesthetized rats (n = 11), BPV (0.016-0.5 Hz) was induced by computer-regulated cardiac pacing while blood pressure, heart rate, and cardiac output (CO) were recorded during control conditions (NaCl, 1 ml/h iv) and during alpha(1)-adrenergic receptor stimulation (phenylephrine, 1 mg.ml(-1).h(-1) iv) that has been reported to facilitate myogenic vascular function. Baroreceptor-heart rate reflex responses were elicited to confirm a functional baroreflex despite anesthesia. During control conditions, transfer function analyses between mean arterial pressure (MAP) and CO, and between MAP and total vascular conductance (CO/MAP) indicated autoregulation of blood flow at 0.016 Hz, passive vascular responses between 0.033 and 0.2 Hz, and vascular responses compatible with baroreflex-mediated mechanisms at 0.333 and 0.5 Hz. Stimulation of alpha(1)-adrenergic receptors extended the frequency range of autoregulation of blood flow to frequencies up to 0.033 Hz. In conclusion, depending on sympathetic vascular tone, whole body autoregulation of blood flow operates most effectively at frequencies below 0.05 Hz. This frequency range overlaps with the lower end of the frequency band of VLF BPV in rats. Baroreceptor reflex-like mechanisms contribute to LF (0.2-0.6 Hz) but not VLF BPV-induced vascular responses. |
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Authors:
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Harald M Stauss; Kevin R Rarick; Richard J Deklotz; Don D Sheriff |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-02-27 |
Journal Detail:
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Title: American journal of physiology. Heart and circulatory physiology Volume: 296 ISSN: 0363-6135 ISO Abbreviation: Am. J. Physiol. Heart Circ. Physiol. Publication Date: 2009 May |
Date Detail:
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Created Date: 2009-05-04 Completed Date: 2009-06-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901228 Medline TA: Am J Physiol Heart Circ Physiol Country: United States |
Other Details:
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Languages: eng Pagination: H1607-16 Citation Subset: IM |
Affiliation:
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Dept. of Integrative Physiology, The Univ. of Iowa, 410 Field House, Iowa City, IA 52242, USA. harald-stauss@uiowa.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-Agonists
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administration & dosage Animals Baroreflex* / drug effects Blood Flow Velocity Blood Pressure* / drug effects Cardiac Output Cardiac Pacing, Artificial Fourier Analysis Heart Rate Homeostasis Infusions, Intravenous Laser-Doppler Flowmetry Male Muscle, Smooth, Vascular / innervation* Oscillometry Phenylephrine / administration & dosage Rats Rats, Sprague-Dawley Regional Blood Flow Sympathetic Nervous System / drug effects, physiology* Time Factors |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-Agonists; 59-42-7/Phenylephrine |
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