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Human muscle sympathetic action potential patterns during graded lower body negative pressure
Author(s) -
Liu Yinchun,
Shoemaker J. Kevin
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.740.1
Subject(s) - baroreflex , baroreceptor , medicine , heart rate , blood pressure , spike (software development) , microneurography , cardiology , orthostatic vital signs , anesthesia , lower body , management , economics
This study assessed baroreflex modulation of within‐burst neural action potential (spike) discharge in muscle sympathetic nerve activity (MSNA). Spike rate and inter‐spike interval were exposed from raw MSNA recorded from 6 healthy individuals during graded lower body negative pressure (LBNP) (baseline, −10, −40, −60 mmHg). The first 30s raw MSNA of the 4 th min for each LBNP level was analyzed after applying a spike detection method ( Autonomic neuroscience: Basic & Clinical 143(2007) 92–105 ). Spikes/30 sec increased progressively with LBNP beginning at −10 mmHg (P<0.05), with a doubling of spike rate (range = 40 – 290%) at −60 mmHg. Mean inter‐spike interval decreased progressively from 0.175±0.045 s at Baseline to 0.087±0.028 s at −60 LBNP (P<0.05) reflecting increases in average discharge frequencies from 5 to 10 Hz. In probability distributions, progressive increases in the proportion of spikes occurred only within the shortest inter‐spike interval bin (ranging 0.04 (25 Hz) – 0.1 (10 Hz) s across participants). Thus, the increment in MSNA with baroreceptor unloading is focused at high‐frequency discharge patterns and reflects progressive increments in action potential content with evidence for a doubling of neurons recruited between baseline and high levels of orthostatic stress. Supported by NSERC‐CHRP