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Respiratory muscle conditioning intensity is a greater factor than trial duration for eliciting diaphragm fiber hypertrophy
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.653.5
Our laboratory recently demonstrated that intrinsic transient tracheal occlusion (ITTO) conditioning elicited significant increases in diaphragm (DIA) motor drive. The objective of this project was to determine whether ITTO was as effective in facilitating DIA fiber hypertrophy. Seventeen male rats underwent surgical placement of a cuff that was transiently inflated to occlude the trachea. Rats were assigned to either ITTO (n=7), partial obstruction (IPTO) (n=5), or SHAM (n=5) conditioning. Animals completed 10 sessions in 2 weeks. TO consisted of 3–5 seconds of occlusion, followed by 10–12 seconds of recovery, for 10 to 20 minutes. Upon completion of conditioning, DIA muscles were extracted and quick‐frozen, then sectioned. Myosin heavy chain (MHC) isoforms were detected with immunohistochemistry. Phenotype and CSA showed a significant (2‐way ANOVA) group‐MHC interaction for CSA. Type IIx/b fibers were larger in the ITTO animals (4058±472 μm), compared to IPTO (2698±289 μm) and SHAM (3194±606 μm) groups (p<.05). ITTO for 10 minutes was as effective as 20 minutes (p=.19). In conclusion, training intensity was more critical than trial length for promoting DIA fiber hypertrophy. Research support: none.