title: Baroreflex variability and "resetting": a new perspective.
abstract: A new framework is proposed for the interpretation of spontaneous cardiac baroreflex sensitivity data and the general concept of baroreflex resetting. The framework is used to explore baroreflex function along two separate lines of inquiry: one following a direct intervention in baroreflex function in individual subjects, another in a group of subjects where baroreflex function may have been compromised by coronary artery disease or aging. It is found that under baseline conditions the baroreflex is in a "free-floating" state in which the gain or "sensitivity" is highly variable, while under orthostatic stress or in the absence of or reduced vagal input the gain is more tightly controlled with an expected decline in sensitivity but a very large decline in the variability of that sensitivity. It is concluded that baroreflex "resetting" is better viewed not simply as a change in baroreflex sensitivity but rather as a change in the "focus" or "attention" of the baroreflex as expressed by an observed decline in the variability of the measured gain. The results do not support the interpretation of baroreflex "resetting" as a departure from or return to a universal "set point" as in homeostasis or open loop models.
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada N6A 3K7; Department of Applied Mathematics, Western University, London, Ontario, Canada N6A 3K7; Department of Medical Biophysics, Western University, London, Ontario, Canada N6A 3K7. Electronic address: zamir@uwo.ca.
authors.forename: M
authors.initials: M
authors.lastname: Zamir
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada N6A 3K7.
authors.forename: N S
authors.initials: NS
authors.lastname: Coverdale
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada N6A 3K7.
authors.forename: C C
authors.initials: CC
authors.lastname: Barron
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada N6A 3K7.
authors.forename: C P
authors.initials: CP
authors.lastname: Sawicki
authors.affiliation: Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada N6A 3K7; Department of Physiology and Pharmacology, Western University, London, Ontario, Canada N6A 3K7.
authors.forename: J K
authors.initials: JK
authors.lastname: Shoemaker
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D017704:Baroreflex; D001794:Blood Pressure; D003324:Coronary Artery Disease / Q000503:physiopathology; D005260:Female; D006706:Homeostasis; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011187:Posture
keywords: Baroreflex; Baroreflex resetting; Baroreflex sensitivity; Logistic response curve