Calcium sensitivity of residual force enhancement in rabbit skinned fibers

Joumaa, Venus; Herzog, Walter

Calcium sensitivity of residual force enhancement in rabbit skinned fibers

dc.contributor.author	Joumaa, Venus
dc.contributor.author	Herzog, Walter
dc.date.accessioned	2018-10-09T20:24:40Z
dc.date.available	2018-10-09T20:24:40Z
dc.date.issued	2014-08-15
dc.description.abstract	Isometric force after active stretch of muscles is higher than the purely isometric force at the corresponding length. This property is termed residual force enhancement. Active force in skeletal muscle depends on calcium attachment characteristics to the regulatory proteins. Passive force has been shown to influence calcium attachment characteristics, specifically the sarcomere length dependence of calcium sensitivity. Since one of the mechanisms proposed to explain residual force enhancement is the increase in passive force that results from engagement of titin upon activation and stretch, our aim was to test if calcium sensitivity of residual force enhancement was different from that of its corresponding purely isometric contraction and if such a difference was related to the molecular spring titin. Force-pCa curves were established in rabbit psoas skinned fibers for reference and residual force-enhanced states at a sarcomere length of 3.0 μm 1) in a titin-intact condition, 2) after treatment with trypsin to partially eliminate titin, and 3) after treatment with trypsin and osmotic compression with dextran T-500 to decrease the lattice spacing in the absence of titin. The force-pCa curves of residual force enhancement were shifted to the left compared with their corresponding controls in titin-intact fibers, indicating increased calcium sensitivity. No difference in calcium sensitivity was observed between reference and residual force-enhanced contractions in trypsin-treated and osmotically compressed trypsin-treated fibers. Furthermore, calcium sensitivity after osmotic compression was lower than that observed for residual force enhancement in titin-intact skinned fibers. These results suggest that titin-based passive force regulates the increase in calcium sensitivity of residual force enhancement by a mechanism other than reduction of the myofilament lattice spacing.	en_US
dc.description.grantingagency	Canadian Institutes of Health Research - Foundation Scheme	en_US
dc.description.grantingagency	Natural Sciences and Engineering Research Council - Discovery Grant	en_US
dc.description.grantingagency	Other	en_US
dc.identifier.citation	Joumaa, V., & Herzog, W. (2014). Calcium sensitivity of residual force enhancement in rabbit skinned fibers. American Journal of Physiology. Cell Physiology, 307(4), C395–C401. https://doi.org/10.1152/ajpcell.00052.2014	en_US
dc.identifier.doi	http://dx.doi.org/10.1152/ajpcell.00052.2014	en_US
dc.identifier.issn	1522-1563
dc.identifier.uri	http://hdl.handle.net/1880/108809
dc.identifier.uri	https://doi.org/10.11575/PRISM/43918
dc.language.iso	en	en_US
dc.publisher	American Journal of Physiology	en_US
dc.publisher.department	Human Performance Lab	en_US
dc.publisher.faculty	Kinesiology	en_US
dc.publisher.institution	University of Calgary	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	calcium	en_US
dc.subject	signaling	en_US
dc.subject	cross-brdiges	en_US
dc.subject	muscle	en_US
dc.subject	titin	en_US
dc.subject	myofibrils	en_US
dc.title	Calcium sensitivity of residual force enhancement in rabbit skinned fibers	en_US
dc.type	unknown