Details

Autor(en) / Beteiligte

• Geiger, Paige C
• Cody, Mark J
• Macken, Rebecca L
• Bayrd, Megan E
• Sieck, Gary C

Titel

Effect of unilateral denervation on maximum specific force in rat diaphragm muscle fibers

Ist Teil von

• Journal of applied physiology (1985), 2001-04, Vol.90 (4), p.1196-1204

Ort / Verlag

Bethesda, MD: Am Physiological Soc

Erscheinungsjahr

2001

Quelle

MEDLINE

Beschreibungen/Notizen

• Departments of 1  Anesthesiology and 2  Physiology and Biophysics, Mayo Clinic and Foundation, Rochester, Minnesota 55905 We hypothesize that 1 ) the effect of denervation (DNV) is more pronounced in fibers expressing fast myosin heavy chain (MHC) isoforms and 2 ) the effect of DNV on maximum specific force reflects a reduction in MHC content per half sarcomere or the number of cross bridges in parallel. Studies were performed on single Triton X-100-permeabilized fibers activated at a pCa ( log Ca 2+ concentration) of 4.0. MHC content per half sarcomere was determined by densitometric analysis of SDS-PAGE gels and comparison to a standard curve of known MHC concentrations. After 2 of wk DNV, the maximum specific force of fibers expressing MHC 2X was reduced by ~40% (MHC 2B expression was absent), whereas the maximum specific force of fibers expressing MHC 2A and MHC slow decreased by only ~20%. DNV also reduced the MHC content in fibers expressing MHC 2X, with no effect on fibers expressing MHC 2A and MHC slow . When normalized for MHC content per half sarcomere, force generated by DNV fibers expressing MHC 2X and MHC 2A was decreased compared with control fibers. These results suggest the force per cross bridge is also affected by DNV. inactivity; skinned fibers; myosin heavy chain content; force per cross bridge