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Duration of intermittent total tracheal occlusion (ITTO) sessions influences fiber CSA in parasternal muscle fibers
Author(s) -
Smith Barbara K,
Martin Daniel,
Davenport Paul W
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.653.6
Respiratory mechanical overloads can elicit intercostal fiber remodeling. The purpose of this study was to determine whether the duration of ITTO sessions influenced parasternal muscle fiber CSA. Thirteen male rats underwent surgical placement of a cuff that was intermittently inflated to occlude the trachea and assigned to either 10 or 20 minutes of ITTO (n=8), or SHAM (n=5) conditioning. Animals completed 10 sessions over 2 weeks. Daily ITTO trials consisted of 3–5 seconds of occlusion, followed by 10–12 seconds of unobstructed breathing, for 10 or 20‐minutes. Following the last session, 3rd parasternal intercostals muscles were extracted and quick‐frozen, then sectioned. Myosin heavy chain (MHC) isoforms were detected with immunohistochemistry. There was a significant (2‐way ANOVA) phenotype and CSA group‐MHC interaction for CSA. Type IIx/b fibers were significantly larger in both ITTO groups, compared to SHAM (3602±219 μm) animals, but ITTO‐20 type IIx/b fibers (5384±219 μm) were larger than ITTO‐10 (4525±219 μm, p<.05). In conclusion, longer durations of ITTO facilitate parasternal intercostal fiber CSA hypertrophy, at high conditioning intensities. Research support: none.