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Comparison of aortic and carotid baroreflex stimulus-response characteristics in humansIn order to characterize the stimulus-response relationships of the arterial, aortic, and carotid baroreflexes in mediating cardiac chronotropic function, we measured heart rate (HR) responses elicited by acute changes in mean arterial pressure (MAP) and carotid sinus pressure (CSP) in 11 healthy individuals. Arterial (aortic + carotid) baroreflex control of HR was quantified using ramped changes in MAP induced by bolus injection of phenylephrine (PE) and sodium nitroprusside (SN). To assess aortic-cardiac responses, neck pressure (NP) and suction (NS) were applied during PE and SN administration, respectively, to counter alterations in CSP thereby isolating the aortic baroreflex. Graded levels of NP and NS were delivered to the carotid sinus using a customized neck collar device to assess the carotid-cardiac baroreflex, independent of drug infusion. The operating characteristics of each reflex were determined from the logistic function of the elicited HR response to the induced change in MAP. The arterial pressures at which the threshold was located on the stimulus-response curves determined for the arterial, aortic and carotid baroreflexes were not significantly different (72+/-4, 67+/-3, and 72+/-4 mm Hg, respectively, P > 0.05). Similarly, the MAP at which the saturation of the reflex responses were elicited did not differ among the baroreflex arcs examined (98+/-3, 99+/-2, and 102+/-3 mm Hg, respectively). These data suggest that the baroreceptor populations studied operate over the same range of arterial pressures. This finding indicates each baroreflex functions as both an important anti-hypotensive and anti-hypertensive mechanism. In addition, this investigation describes a model of aortic baroreflex function in normal healthy humans, which may prove useful in identifying the origin of baroreflex dysfunction in disease- and training-induced conditions.
Document ID
20040112348
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Smith, S. A.
(University of North Texas Health Science Center Fort Worth 76107, United States)
Querry, R. G.
Fadel, P. J.
Weiss, M. W.
Olivencia-Yurvati, A.
Shi, X.
Raven, P. B.
Date Acquired
August 21, 2013
Publication Date
April 12, 2001
Publication Information
Publication: Autonomic neuroscience : basic & clinical
Volume: 88
Issue: 2-Jan
ISSN: 1566-0702
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: HL 45547
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cardiopulmonary

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