Differential sympathetic outflow and vasoconstriction responses at kidney and skeletal muscles during fictive locomotion

Satoshi Koba, Takayoshi Yoshida, Naoyuki Hayashi

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

We compared sympathetic and circulatory responses between kidney and skeletal muscles during fictive locomotion evoked by electrical stimulation of the mesencephalic locomotor region (MLR) in decerebrate and paralyzed rats (n = 8). Stimulation of the MLR for 30 s at 40-μA current intensity significantly increased arterial pressure (+38 ± 6 mmHg), triceps surae muscle blood flow (+17 ± 3%), and both renal and lumbar sympathetic nerve activities (RSNA +113 ± 16%, LSNA +31 ± 7%). The stimulation also significantly decreased renal cortical blood flow (-18 ± 6%) and both renal cortical and triceps surae muscle vascular conductances (RCVC -38 ± 5%, TSMVC -17 ± 3%). The sympathetic and vascular conductance changes were significantly dependent on current intensity for stimulation at 20, 30, and 40 μA. The changes in LSNA and TSMVC were significantly less than those in RSNA and RCVC, respectively, at all current intensities. At the early stage of stimulation (0-10 s), decreases in RCVC and TSMVC were significantly correlated with increases in RSNA and LSNA, respectively. These data demonstrate that fictive locomotion induces less vasoconstriction in skeletal muscles than in kidney because of less sympathetic activation. This suggests that a neural mechanism mediated by central command contributes to blood flow distribution by evoking differential sympathetic outflow during exercise.

Original languageEnglish
Pages (from-to)H861-H868
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume290
Issue number2
DOIs
Publication statusPublished - 2006 Feb
Externally publishedYes

Keywords

  • Central command
  • Mesencephalic locomotor region
  • Muscle blood flow
  • Renal blood flow
  • Sympathetic nervous system

ASJC Scopus subject areas

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

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