title: Mild eccentric stretch injury in skeletal muscle causes transient effects on tensile load and cell proliferation.
abstract: The biomechanical and regenerative responses in rabbit tibialis anterior muscle following a single eccentric stretch injury were investigated 1, 3 and 7 days after traumatization. The stretch injury produced a transient biomechanical effect. On day 1, the load at failure was decreased in the injured muscles compared with the uninjured controls (P<0.05), but on days 3 and 7 significant biomechanical differences were no longer recorded between the injured and control muscles. In immunohistochemical analyses, no overt myonecrosis or connective tissue disruption was observed in any of the stretch-injured muscles. Yet satellite cells were activated to incorporate a thymidine analogue, bromodeoxyuridine indicating mitotic activity. They did not, however, produce muscle-specific proteins, i.e., they did not differentiate further. Furthermore, the intact appearing but mildly injured myofibers of the stretched muscles expressed both neonatal myosin and vimentin near the myotendinous junctions. Collectively, these results suggest that a single mild eccentric stretch of skeletal muscle which does not cause gross structural alterations results in a short-term decrease in tensile load and induces transient proliferation of satellite cells and fibroblasts together with expression of primitive proteins in myofibers.
authors.affiliation: Department of Surgery, Turku University Hospital, Turku, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Aärimaa
authors.forename: Jussi
authors.initials: J
authors.lastname: Rantanen
authors.forename: Thomas
authors.initials: T
authors.lastname: Best
authors.forename: Edward
authors.initials: E
authors.lastname: Schultz
authors.forename: David
authors.initials: D
authors.lastname: Corr
authors.forename: Hannu
authors.initials: H
authors.lastname: Kalimo
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D049109:Cell Proliferation; D004548:Elasticity; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology*; D011817:Rabbits; D018709:Statistics, Nonparametric; D013718:Tensile Strength