Limits...
Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus

Stretch speed‐dependent damage of muscle fibers. Representative triple immunofluorescent images of sections from tibialis anterior (TA) 2 days after lengthening contraction (LC) at different angular velocities: 50 deg/sec (A), 100 deg/sec (B), 200 deg/sec (C), and 400 deg/sec (D). Red: damaged myofibers stained with Evans blue dye (EBD), green: muscle cell membrane labeled with anti‐laminin antibody, blue: nuclei of muscle cells stained with 4′,6‐diamidino‐2‐phenylindole (DAPI). Scale bar: 1 mm. Anterior side of TA; left and medial side; upper. Enlarged image shown in each inset (scale bar: 50 μm). The number of EBD‐positive fibers increases with the angular velocity of LC and larger‐diameter fibers are preferentially labeled in an all‐or‐none fashion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4255819&req=5

fig02: Stretch speed‐dependent damage of muscle fibers. Representative triple immunofluorescent images of sections from tibialis anterior (TA) 2 days after lengthening contraction (LC) at different angular velocities: 50 deg/sec (A), 100 deg/sec (B), 200 deg/sec (C), and 400 deg/sec (D). Red: damaged myofibers stained with Evans blue dye (EBD), green: muscle cell membrane labeled with anti‐laminin antibody, blue: nuclei of muscle cells stained with 4′,6‐diamidino‐2‐phenylindole (DAPI). Scale bar: 1 mm. Anterior side of TA; left and medial side; upper. Enlarged image shown in each inset (scale bar: 50 μm). The number of EBD‐positive fibers increases with the angular velocity of LC and larger‐diameter fibers are preferentially labeled in an all‐or‐none fashion.

Mentions: To examine whether stretch speed affects the severity of LC‐induced muscle damage, rats were subjected to varying LC angular velocities (50, 100, 200, and 400 deg/sec) during electrically evoked ankle extensor muscle contraction. This was followed by in vivo EBD staining and subsequent analysis of EBD‐positive myofiber numbers (as an index of muscle damage or increased sarcolemma permeability) in triple immunofluorescence‐labeled sections of TA. The number of EBD‐positive fibers appeared to increase with LC stretch speed (Fig. 2), and dye labeling was observed preferentially in relatively large‐diameter cells in a roughly all‐or‐none fashion. In contrast, there were no EBD‐positive cells in TA sections from untreated rats (n = 6, photograph not shown).


Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Stretch speed‐dependent damage of muscle fibers. Representative triple immunofluorescent images of sections from tibialis anterior (TA) 2 days after lengthening contraction (LC) at different angular velocities: 50 deg/sec (A), 100 deg/sec (B), 200 deg/sec (C), and 400 deg/sec (D). Red: damaged myofibers stained with Evans blue dye (EBD), green: muscle cell membrane labeled with anti‐laminin antibody, blue: nuclei of muscle cells stained with 4′,6‐diamidino‐2‐phenylindole (DAPI). Scale bar: 1 mm. Anterior side of TA; left and medial side; upper. Enlarged image shown in each inset (scale bar: 50 μm). The number of EBD‐positive fibers increases with the angular velocity of LC and larger‐diameter fibers are preferentially labeled in an all‐or‐none fashion.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255819&req=5

fig02: Stretch speed‐dependent damage of muscle fibers. Representative triple immunofluorescent images of sections from tibialis anterior (TA) 2 days after lengthening contraction (LC) at different angular velocities: 50 deg/sec (A), 100 deg/sec (B), 200 deg/sec (C), and 400 deg/sec (D). Red: damaged myofibers stained with Evans blue dye (EBD), green: muscle cell membrane labeled with anti‐laminin antibody, blue: nuclei of muscle cells stained with 4′,6‐diamidino‐2‐phenylindole (DAPI). Scale bar: 1 mm. Anterior side of TA; left and medial side; upper. Enlarged image shown in each inset (scale bar: 50 μm). The number of EBD‐positive fibers increases with the angular velocity of LC and larger‐diameter fibers are preferentially labeled in an all‐or‐none fashion.
Mentions: To examine whether stretch speed affects the severity of LC‐induced muscle damage, rats were subjected to varying LC angular velocities (50, 100, 200, and 400 deg/sec) during electrically evoked ankle extensor muscle contraction. This was followed by in vivo EBD staining and subsequent analysis of EBD‐positive myofiber numbers (as an index of muscle damage or increased sarcolemma permeability) in triple immunofluorescence‐labeled sections of TA. The number of EBD‐positive fibers appeared to increase with LC stretch speed (Fig. 2), and dye labeling was observed preferentially in relatively large‐diameter cells in a roughly all‐or‐none fashion. In contrast, there were no EBD‐positive cells in TA sections from untreated rats (n = 6, photograph not shown).

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus