کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10432235 910241 2012 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Overextended sarcomeres regain filament overlap following stretch
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی پزشکی
پیش نمایش صفحه اول مقاله
Overextended sarcomeres regain filament overlap following stretch
چکیده انگلیسی
Sarcomere overextension has been widely implicated in stretch-induced muscle injury. Yet, sarcomere overextensions are typically inferred based on indirect evidence obtained in muscle and fibre preparations, where individual sarcomeres cannot be observed during dynamic contractions. Therefore, it remains unclear whether sarcomere overextensions are permanent following injury-inducing stretch-shortening cycles, and thus, if they can explain stretch-induced force loss. We tested the hypothesis that overextended sarcomeres can regain filament overlap in isolated myofibrils from rabbit psoas muscles. Maximally activated myofibrils (n=13) were stretched from an average sarcomere length of 2.6±0.04 μm by 0.9 μm sarcomere−1 at a speed of 0.1 μm sarcomere−1 s−1 and immediately returned to the starting lengths at the same speed (sarcomere strain=34.1±2.3%). Myofibrils were then allowed to contract isometrically at the starting lengths (2.6 μm) for ∼30 s before relaxing. Force and individual sarcomere lengths were measured continuously. Out of the 182 sarcomeres, 35 sarcomeres were overextended at the peak of stretch, out of which 26 regained filament overlap in the shortening phase while 9 (∼5%) remained overextended. About 35% of the sarcomeres with initial lengths on the descending limb of the force-length relationship and ∼2% of the sarcomeres with shorter initial lengths were overextended. These findings provide first ever direct evidence that overextended sarcomeres can regain filament overlap in the shortening phase following stretch, and that the likelihood of overextension is higher for sarcomeres residing initially on the descending limb.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Biomechanics - Volume 45, Issue 14, 21 September 2012, Pages 2387-2391
نویسندگان
, ,