title: Low-order chaos in sympathetic nerve activity and scaling of heartbeat intervals.
abstract: The mechanism of 1/f scaling of heartbeat intervals remains unknown. We recorded heartbeat intervals, sympathetic nerve activity, and blood pressure in conscious rats with normal or high blood pressure. Using nonlinear analyses, we demonstrate that the dynamics of this system of three variables is low-order chaos, and that sympathetic nerve activity leads to heartbeat interval and blood pressure changes. It is suggested that impaired regulation of blood pressure by sympathetic nerve activity is likely to cause experimentally observable steeper scaling of heartbeat intervals in hypertensive (high blood pressure) rats.
authors.affiliation: Department of Life Information Sciences, Institute of Gerontology, Nippon Medical School, 1-396 Kosugi, Nakahara-ku, Kawasaki 211-8533, Japan. osaka@nms.ac.jp
authors.forename: Motohisa
authors.initials: M
authors.lastname: Osaka
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kumagai
authors.forename: Katsufumi
authors.initials: K
authors.lastname: Sakata
authors.forename: Toshiko
authors.initials: T
authors.lastname: Onami
authors.forename: Ki H
authors.initials: KH
authors.lastname: Chon
authors.forename: Mari A
authors.initials: MA
authors.lastname: Watanabe
authors.forename: Takao
authors.initials: T
authors.lastname: Saruta
mesh_terms: D000465:Algorithms; D000818:Animals; D001794:Blood Pressure; D006321:Heart / Q000502:physiology*; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D051381:Rats; D011918:Rats, Inbred SHR; D013564:Sympathetic Nervous System / Q000502:physiology*; D013997:Time Factors