1. The focal nature of contraction‐induced injury to skeletal muscle fibres may arise from heterogeneities in sarcomere length that develop during contractions. We tested the hypothesis that when a maximally activated single permeabilized fibre segment is stretched and a deficit in maximum isometric force (force deficit) is produced, the regions of sarcomeres with the longest lengths of prior to the stretch contain the majority of the damaged sarcomeres when the fibre is returned to optimum length (Lo) after the stretch. 2. Single fibre segments (n = 16) were obtained from soleus muscles of rats. Average sarcomere length at five discrete positions along the length of each fibre was determined by lateral deflection of a diode laser spot. Diffraction patterns were obtained while fibres were relaxed and immediately before, during and after a single stretch of 40% strain relative to Lo. Following the stretch, the regions of each fibre that potentially contained damaged sarcomeres were identified by an increased scatter of the first‐order diffraction patterns. The damage was confirmed by light and electron microscopy. 3. While single fibre segments were in relaxing solution, the mean value for all of the average sarcomere lengths sampled (n = 80) was 2.53 +/‐ 0.01 microns (range, 2.40‐2.68 microns). During the maximum isometric contraction before each stretch, the mean sarcomere length decreased to 2.42 +/‐ 0.02 microns and the range increased to 2.12‐3.01 microns. 4. During the stretch of 40% strain, all regions of sarcomeres were stretched onto the descending limb of the length‐force curve, but sarcomere lengthening was non‐uniform. After the stretch, when the maximally activated fibres were returned to Lo, the force deficit was 10 +/‐ 1%. Microscopic evaluation confirmed that the regions with the longest sarcomere lengths before the stretch contained the majority of the damaged sarcomeres after the stretch. We conclude that when heterogeneities in sarcomere length develop in single permeabilized fibre segments during a maximum isometric contraction, the sarcomeres in the regions with the longest lengths are the most susceptible to contraction‐induced injury.
The Journal of Physiology – Wiley
Published: Apr 15, 1997
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera