Reflex responses of renal nerve activity during isometric muscle contraction in cats

K. Matsukawa, P. T. Wall, L. B. Wilson, J. H. Mitchell

Research output: Contribution to journalArticle

61 Scopus citations

Abstract

Renal sympathetic nerve activity (RSNA), arterial blood pressure (AP), and heart rate (HR) were measured during isometric muscle contraction of a hindlimb in chloralose-anesthetized cats. In 14 cats RSNA, AP, and HR increased during a 1-min contraction by 45%, 39 mmHg, and 11 beats/min, respectively; however, in three cats there was a brief initial decrease in RSNA followed by an increase. In 11 cats isometric contraction was maintained for 5 min by alternate stimulation of the L7 and S1 ventral roots. In the first 1 min of sustained contraction, there was a positive correlation (γ = 0.58, P < 0.005) between RSNA and tension development. Thereafter RSNA remained elevated despite a tension decrease, and there was no significant correlation between these changes. The RSNA response to contraction of both hindlimbs was greater than that to contraction of either hindlimb alone. Passive stretch of the hindlimb muscle significantly increased RSNA. Thus the initial increase in RSNA during sustained contraction is likely due to activation of muscle mechanoreceptors, whereas the later increase is probably caused by activation of the muscle metaboreceptors.

Original languageEnglish (US)
Pages (from-to)H1380-H1388
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume259
Issue number5 28-5
StatePublished - Jan 1 1990

Keywords

  • Arterial blood pressure
  • Heart rate
  • Passive mechanical stretch of muscle
  • Sympathetic nerve activity

ASJC Scopus subject areas

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

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