Muscle mechanoreflex induces the pressor response by resetting the arterial baroreflex neural arc

Kenta Yamamoto, Toru Kawada, Atsunori Kamiya, Hiroshi Takaki, Tadayoshi Miyamoto, Masaru Sugimachi, Kenji Sunagawa

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The effects of the muscle mechanoreflex on the arterial baroreflex neural control have not previously been analyzed over the entire operating range of the arterial baroreflex. In anesthetized, vagotomized, and aortic-denervated rabbits (n = 8), we isolated carotid sinuses and changed intracarotid sinus pressure (CSP) from 40 to 160 mmHg in increments of 20 mmHg every minute while recording renal sympathetic nerve activity (SNA) and arterial pressure (AP). Muscle mechanoreflex was induced by passive muscle stretch (5 kg of tension) of the hindlimb. Muscle stretch shifted the CSP-SNA relationship (neural arc) to a higher SNA, whereas it did not affect the SNA-AP relationship (peripheral arc). SNA was almost doubled [from 63 ± 15 to 118 ± 14 arbitrary units (au), P < 0.05] at the CSP level of 93 ± 8 mmHg, and AP was increased ∼50% by muscle stretch. When the baroreflex negative feedback loop was closed, muscle stretch increased SNA from 63 ± 15 to 81 ± 21 au (P < 0.05) and AP from 93 ± 8 to 109 ± 12 mmHg (P < 0.05). In conclusion, the muscle mechanoreflex resets the neural arc to a higher SNA, which moves the operating point towards a higher SNA and AP under baroreflex closed-loop conditions. Analysis of the baroreflex equilibrium diagram indicated that changes in the neural arc induced by the muscle mechanoreflex might compensate for pressure falls resulting from exercise-induced vasodilatation.

Original languageEnglish
Pages (from-to)H1382-H1388
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume286
Issue number4 55-4
DOIs
Publication statusPublished - Apr 1 2004
Externally publishedYes

Keywords

  • Arterial pressure
  • Baroreflex equilibrium diagram
  • Exercise
  • Exercise pressor reflex
  • Sympathetic nerve activity

ASJC Scopus subject areas

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

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