Muscle mechanoreflex augments arterial baroreflex-mediated dynamic sympathetic response to carotid sinus pressure

Kenta Yamamoto, Toru Kawada, Atsunori Kamiya, Hiroshi Takaki, Toshiaki Shishido, Kenji Sunagawa, Masaru Sugimachi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Although the muscle mechanoreflex is one of the pressor reflexes during exercise, its interaction with dynamic characteristics of the arterial baroreflex remains to be quantitatively analyzed. In anesthetized, vagotomized, and aortic-denervated rabbits (n = 7), we randomly perturbed isolated carotid sinus pressure (CSP) using binary white noise while recording renal sympathetic nerve activity (SNA) and arterial pressure (AP). We estimated the transfer functions of the baroreflex neural arc (CSP to SNA) and peripheral arc (SNA to AP) under conditions of control and muscle stretch of the hindlimb (5 kg of tension). The muscle stretch increased the dynamic gain of the neural arc while maintaining the derivative characteristics [gain at 0.01 Hz: 1.0 ± 0.2 vs. 1.4 ± 0.6 arbitrary units (au)/mmHg, gain at 1 Hz: 1.7 ± 0.6 vs. 2.7 ± 1.4 au/mmHg; P < 0.05, control vs. stretch]. In contrast, muscle stretch did not affect the peripheral arc. In the time domain, muscle stretch augmented the steady-state response at 50 s (-1.1 ± 0.3 vs. -1.7 ± 0.7 au; P < 0.05, control vs. stretch) and negative peak response (-2.1 ± 0.5 vs. -3.1 ± 1.5 au; P < 0.05, control vs. stretch) in the SNA step response. A simulation experiment using the results indicated that the muscle mechanoreflex would accelerate the closed-loop AP regulation via the arterial baroreflex.

Original languageEnglish
Pages (from-to)H1081-H1089
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume295
Issue number3
DOIs
Publication statusPublished - Sep 1 2008
Externally publishedYes

Keywords

  • Arterial pressure
  • Exercise
  • Exercise pressor reflex
  • Muscle stretch
  • Transfer function

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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