Are titin properties reflected in single myofibrils?

Herzog, Jens A.; Leonard, Timothy R.; Jinha, Azim; Herzog, Walter

Are titin properties reflected in single myofibrils?

dc.contributor.author	Herzog, Jens A.
dc.contributor.author	Leonard, Timothy R.
dc.contributor.author	Jinha, Azim
dc.contributor.author	Herzog, Walter
dc.date.accessioned	2018-09-26T18:05:11Z
dc.date.available	2018-09-26T18:05:11Z
dc.date.issued	2012-07-26
dc.description.abstract	Titin is a structural protein in muscle that spans the half sarcomere from Z-band to M-line. Although there are selected studies on titin's mechanical properties from tests on isolated molecules or titin fragments, little is known about its behavior within the structural confines of a sarcomere. Here, we tested the hypothesis that titin properties might be reflected well in single myofibrils. Single myofibrils from rabbit psoas were prepared for measurement of passive stretch-shortening cycles at lengths where passive titin forces occur. Three repeat stretch-shortening cycles with magnitudes between 1.0 and 3.0μm/sarcomere were performed at a speed of 0.1μm/s·sarcomere and repeated after a ten minute rest at zero force. These tests were performed in a relaxation solution (passive) and an activation solution (active) where cross-bridge attachment was inhibited with 2,3 butanedionemonoxime. Myofibrils behaved viscoelastically producing an increased efficiency with repeat stretch-shortening cycles, but a decreased efficiency with increasing stretch magnitudes. Furthermore, we observed a first distinct inflection point in the force-elongation curve at an average sarcomere length of 3.5μm that was associated with an average force of 68±5nN/mm. This inflection point was thought to reflect the onset of Ig domain unfolding and was missing after a ten minute rest at zero force, suggesting a lack of spontaneous Ig domain refolding. These passive myofibrillar properties observed here are consistent with those observed in isolated titin molecules, suggesting that the mechanics of titin are well preserved in isolated myofibrils, and thus, can be studied readily in myofibrils, rather than in the extremely difficult and labile single titin preparations.	en_US
dc.description.grantingagency	Canadian Institutes of Health Research - Other Programs	en_US
dc.description.grantingagency	Natural Sciences and Engineering Research Council - Discovery Grant	en_US
dc.identifier.citation	Herzog, J. A., Leonard, T. R., Jinha, A., & Herzog, W. (2012). Are titin properties reflected in single myofibrils? Journal of Biomechanics, 45(11), 1893–1899. https://doi.org/10.1016/j.jbiomech.2012.05.021	en_US
dc.identifier.doi	http://dx.doi.org/10.1016/j.jbiomech.2012.05.021	en_US
dc.identifier.issn	1873-2380
dc.identifier.uri	http://hdl.handle.net/1880/108053
dc.language.iso	en	en_US
dc.publisher	Journal of Biomechanics	en_US
dc.publisher.department	Human Performance Lab	en_US
dc.publisher.faculty	Kinesiology	en_US
dc.publisher.hasversion	Post-print	en_US
dc.publisher.institution	University of Calgary	en_US
dc.publisher.policy	https://www.jbiomech.com/content/authorinfo?code=bm-site	en_US
dc.rights	Unless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.	en_US
dc.rights.uri	https://creativecommons.org/licenses/by/4.0	en_US
dc.subject	muscle	en_US
dc.subject	titin	en_US
dc.subject	myofibril	en_US
dc.subject	sarcomere	en_US
dc.subject	contraction	en_US
dc.title	Are titin properties reflected in single myofibrils?	en_US
dc.type	journal article	en_US