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Characterization of adult mouse muscle spindle afferents in an in vitro isolated muscle nerve preparation
Author(s) -
Wilkinson Katherine,
Kloefkorn Heidi,
Hochman Shawn
Publication year - 2011
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.25.1_supplement.1051.29
Subject(s) - isometric exercise , anatomy , muscle spindle , contraction (grammar) , afferent , tonic (physiology) , chemistry , medicine , biology , neuroscience
Changes in muscle spindle afferent activity has been demonstrated in models of muscle pain and diabetes and may also be altered in Restless Legs Syndrome. Here we describe a novel in vitro adult mouse muscle nerve preparation ideally suited to measure plasticity in muscle afferent activity. Briefly, we removed the Extensor Digitorum Longus (EDL) and its nerve from adult (2‐month old) male C57Bl/6 mice. The isolated muscle was attached to a force and length controller (Aurora). The length at which the highest force following twitch contraction occurred was set as the resting length (L o ). Muscle afferent activity was recorded using a suction electrode and individual units discriminated using WaveClus (Quiroga, 2004). A battery of stretches and vibrations were performed at L o , L o + 5%, and L o ‐5%. We collected the responses of at least 2 stretch sensitive units in 12 muscles at room temperature. Group Ia afferents were found to have clear dynamic sensitivity and showed entrainment to vibration with amplitudes as low 5 μM. Muscles were stretched 2.5%, 5%, and 7.5% L o and increased firing frequency by a constant number of impulses per mm stretch, similar to that reported in vivo for rats and cats. Health of the preparation was confirmed following stretch in a subset of animals by determining the maximal isometric tension (23.4 ± 2.5 N/cm 2 , n = 6). This research was supported by K12 GM000680 NIH/NIGMS More Division (KAW) and Pfizer (SH).