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Group III muscle afferents are sensitized in rats with heart failure
Author(s) -
Hayes Shawn G.
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.952.15
Subject(s) - heart failure , reflex , medicine , stimulus (psychology) , endocrinology , contraction (grammar) , afferent , sympathetic nervous system , microneurography , cardiology , anesthesia , heart rate , baroreflex , blood pressure , psychology , psychotherapist
The mechanisms responsible for exaggerated sympathoexcitation of heart failure are unknown, but research suggests that it may be the result of an exaggerated exercise pressor reflex caused by sensitized muscle mechanoreceptors (group III afferents). The afferent arm of this reflex is composed of metabolically sensitive and mechanically sensitive afferents that when stimulated by exercise reflexly increases sympathetic function. To determine the role played by group III afferents in the exaggerated sympathoexcitation of heart failure, I compared the responses of single group III afferents in decerebrate rats with heart failure to those of their healthy counterparts. Group III afferents of heart failure rats had a significantly higher discharge in response to the same stimulus as compared to healthy rats. For example, tendon stretch in healthy rats increased the discharge of group III afferents from a baseline activity 0.17±0.1 to 0.73±0.2 impulses/sec (n=6) whereas tendon stretch in heart failure rats increased the discharge of group III afferents from 0.2 ±0.2 to 2.3±0.7 imp/sec (n=6, p<0.05). Likewise, the responses of group III muscle afferents to static contraction were significantly greater in rats with heart failure rats compared to healthy rats (p<0.05). These sensitized group III afferents may be responsible for the exaggerated sympathetic responses to exercise in heart failure.