Faculty Collaboration Database

Frequency response characteristics of whole body autoregulation of blood flow in rats. Am J Physiol Heart Circ Physiol 2009 May;296(5):H1607-16

Date

03/03/2009

Pubmed ID

19252087

DOI

10.1152/ajpheart.01262.2008

Scopus ID

2-s2.0-66149150494 (requires institutional sign-in at Scopus site)   8 Citations

Abstract

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.

Author List

Stauss HM, Rarick KR, Deklotz RJ, Sheriff DD

Author

Kevin Richard Rarick PhD Assistant Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adrenergic alpha-Agonists
Animals
Baroreflex
Blood Flow Velocity
Blood Pressure
Cardiac Output
Cardiac Pacing, Artificial
Fourier Analysis
Heart Rate
Homeostasis
Infusions, Intravenous
Laser-Doppler Flowmetry
Male
Muscle, Smooth, Vascular
Oscillometry
Phenylephrine
Rats
Rats, Sprague-Dawley
Regional Blood Flow
Sympathetic Nervous System
Time Factors