Document Detail

Altered firing pattern of single-unit muscle sympathetic nerve activity during handgrip exercise in chronic heart failure.
MedLine Citation:
PMID:  19403612     Owner:  NLM     Status:  MEDLINE    
Sympathetic activation in chronic heart failure (CHF) is greatly augmented at rest but the response to exercise remains controversial. We previously demonstrated that single-unit muscle sympathetic nerve activity (MSNA) provides a more detailed description of the sympathetic response to physiological stress than multi-unit nerve recordings. The purpose of this study was to determine whether the reflex response and discharge properties of single-unit MSNA are altered during handgrip exercise (HG, 30% of maximum voluntary contraction for 3 min) in CHF patients (New York Heart Association functional class II or III, n = 16) compared with age-matched healthy control subjects (n = 13). At rest, both single-unit and multi-unit indices of sympathetic outflow were augmented in CHF compared with controls (P < 0.05). However, the percentage of cardiac intervals that contained one, two, three or four single-unit spikes were not different between the groups. Compared to the control group, HG elicited a larger increase in multi-unit total MSNA (Delta1002 +/- 50 compared with Delta636 +/- 76 units min(-1), P < 0.05) and single-unit MSNA spike incidence (Delta27 +/- 5 compared with Delta8 +/- 2 spikes (100 heart beats)(-1)), P < 0.01) in the CHF patients. More importantly, the percentage of cardiac intervals that contained two or three single-unit spikes was increased (P < 0.05) during exercise in the CHF group only (Delta8 +/- 2% and Delta5 +/- 1% for two and three spikes, respectively). These results suggest that the larger multi-unit total MSNA response observed during HG in CHF is brought about in part by an increase in the probability of multiple firing of single-unit sympathetic neurones.
Hisayoshi Murai; Masayuki Takamura; Michirou Maruyama; Manabu Nakano; Tatsunori Ikeda; Daisuke Kobayashi; Kan-ichi Otowa; Hiroshi Ootsuji; Masaki Okajima; Hiroshi Furusho; Shigeo Takata; Shuichi Kaneko
Publication Detail:
Type:  Journal Article     Date:  2009-04-29
Journal Detail:
Title:  The Journal of physiology     Volume:  587     ISSN:  1469-7793     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-06-01     Completed Date:  2009-08-03     Revised Date:  2013-06-02    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  2613-22     Citation Subset:  IM    
Disease Control and Homeostasis, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
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MeSH Terms
Action Potentials
Blood Pressure
Case-Control Studies
Chronic Disease
Exercise Tolerance
Hand Strength*
Heart Failure / physiopathology*
Heart Rate
Middle Aged
Muscle Contraction*
Muscle, Skeletal / blood supply,  innervation*
Peroneal Nerve / physiopathology
Recruitment, Neurophysiological
Sympathetic Nervous System / physiopathology*
Comment In:
J Physiol. 2009 Jun 1;587(Pt 11):2421   [PMID:  19483249 ]

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