title: High-cut characteristics of the baroreflex neural arc preserve baroreflex gain against pulsatile pressure.
abstract: A transfer function from baroreceptor pressure input to sympathetic nerve activity (SNA) shows derivative characteristics in the frequency range below 0.8 Hz in rabbits. These derivative characteristics contribute to a quick and stable arterial pressure (AP) regulation. However, if the derivative characteristics hold up to heart rate frequency, the pulsatile pressure input will yield a markedly augmented SNA signal. Such a signal would saturate the baroreflex signal transduction, thereby disabling the baroreflex regulation of AP. We hypothesized that the transfer gain at heart rate frequency would be much smaller than that predicted from extrapolating the derivative characteristics. In anesthetized rabbits (n = 6), we estimated the neural arc transfer function in the frequency range up to 10 Hz. The transfer gain was lost at a rate of -20 dB/decade when the input frequency exceeded 0.8 Hz. A numerical simulation indicated that the high-cut characteristics above 0.8 Hz were effective to attenuate the pulsatile signal and preserve the open-loop gain when the baroreflex dynamic range was finite.
authors.affiliation: Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Osaka 565-8565, Japan. torukawa@res.ncvc.go.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Kawada
authors.forename: Can
authors.initials: C
authors.lastname: Zheng
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yanagiya
authors.forename: Kazunori
authors.initials: K
authors.lastname: Uemura
authors.forename: Tadayoshi
authors.initials: T
authors.lastname: Miyamoto
authors.forename: Masashi
authors.initials: M
authors.lastname: Inagaki
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shishido
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002346:Carotid Sinus / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D008955:Models, Cardiovascular; D011311:Pressoreceptors / Q000502:physiology*; D011674:Pulse; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000502:physiology*