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Muscle sympathetic nerve activity responses to dynamic passive muscle stretch.
Author(s) -
Cui Jian,
Blaha Cheryl,
Moradkhan Raman,
Gray Kristen S.,
Sinoway Lawrence I.
Publication year - 2006
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.20.4.a768-c
Subject(s) - blood pressure , reflex , medicine , heart rate , beat (acoustics) , stimulation , microneurography , contraction (grammar) , muscle contraction , cardiology , anatomy , baroreflex , physics , acoustics
It is suggested that mechanoreceptors in muscle play an important role in the exercise pressor reflex, however, it has not been verified whether isolated stimulation of the mechanoreceptors can induce responses in muscle sympathetic nerve activity (MSNA) in young healthy individuals. The purpose of present study was to test the hypothesis that passive stretch of muscle can evoke an increase in MSNA in healthy individuals. In 7 young subjects, calf muscles in a leg were passively stretched, or actively contracted for 5 sec followed by a 15–25 sec (random) relaxation period. Stretch and contraction were each repeated 25 times. MSNA, ECG, heart rate, and blood pressure were recorded, analyzed, and averaged according to the onset of the force on a beat‐by‐beat basis. At the 1 st and/or the 2 nd heart beat from the onset of stretch, MSNA increased transiently but significantly (7.27±1.87 units/beat) from the prior stretching baseline (4.80±1.43 units/beat, P <0.01), followed (at 3 rd to 5 th beat from the onset of stretching) by a transient increase in mean blood pressure from the baseline (change 2.48±0.68 mmHg, P <0.05). After end of stretch, another MSNA increase was observed when blood pressure fell. Similar responses were observed during active muscle contractions. The present data can be considered as evidence to support the concept that isolated stimulation of mechanoreceptors can evoke MSNA responses in young healthy humans. Supported by P01 HL077670 and M01 RR010732.