title: Dynamic characteristics of carotid sinus pressure-nerve activity transduction in rabbits.
abstract: The dynamic characteristics of the baroreflex neural arc from pressure input to efferent sympathetic nerve activity (SNA) reveal derivative characteristics in the frequency range of 0.01 to 0.8 Hz (i.e., the baroreflex gain augments with increasing frequency) and high-cut characteristics in the frequency range above 0.8 Hz (i.e., the baroreflex gain decreases with increasing frequency) in rabbits. The derivative characteristics accelerate the arterial pressure regulation via the baroreflex. The high-cut characteristics preserve the baroreflex gain against pulsatile pressure by attenuating the high-frequency components less necessary for arterial pressure regulation. However, to what extent the carotid sinus baroreceptor transduction from pressure input to afferent baroreceptor nerve activity (BNA) contributes to these characteristics remains unanswered. To test the hypothesis that the carotid sinus pressure-BNA transduction partly explains the derivative characteristics but not the highcut characteristics, we examined the dynamic BNA response to pressure input in the frequency range from 0.01 to 3 Hz by using a white noise analysis in 7 anesthetized rabbits. The transfer function from pressure input to BNA showed slight derivative characteristics in the frequency range from 0.01 to 0.3 Hz with approximately a 1.7-fold increase in dynamic gain, but it showed no high-cut characteristics. In conclusion, the carotid sinus baroreceptor transduction partly explained the derivative characteristics but not the high-cut characteristics of the baroreflex neural arc. The present results suggest the importance of the central processing from BNA to efferent SNA to account for the overall dynamic characteristics of the baroreflex neural arc.
authors.affiliation: Department of Cardiovascular Dynamics, Advanced Medical Engineering Center, 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: Kenta
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Atsunori
authors.initials: A
authors.lastname: Kamiya
authors.forename: Hideto
authors.initials: H
authors.lastname: Ariumi
authors.forename: Daisaku
authors.initials: D
authors.lastname: Michikami
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shishido
authors.forename: Kenji
authors.initials: K
authors.lastname: Sunagawa
authors.forename: Masaru
authors.initials: M
authors.lastname: Sugimachi
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002346:Carotid Sinus / Q000294:innervation*; D009475:Neurons, Afferent / Q000502:physiology; D009476:Neurons, Efferent / Q000502:physiology; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors