Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/84027
Title: A post-MI power struggle: adaptations in cardiac power occur at the sarcomere level alongside MyBP-C and RLC phosphorylation
Authors: Toepfer, Christopher N.
Sikkel, Markus B.
Caorsi, Valentina
Vydyanath, Anupama
Torre, Iratxe
Copeland, O'Neal
Lyon, Alexander R.
Marston, Steven B.
Luther, Pradeep K.
Macleod, Kenneth T.
West, Timothy G.
Ferenczi, Michael Alan
Keywords: contractile function
infarction
Issue Date: 2016
Source: Toepfer, C. N., Sikkel, M. B., Caorsi, V., Vydyanath, A., Torre, I., Copeland, O., et al. (2016). A post-MI power struggle: adaptations in cardiac power occur at the sarcomere level alongside MyBP-C and RLC phosphorylation. American Journal of Physiology - Heart and Circulatory Physiology, 311(2), H465-H475.
Series/Report no.: American Journal of Physiology - Heart and Circulatory Physiology
Abstract: Myocardial remodeling in response to chronic myocardial infarction (CMI) progresses through two phases, hypertrophic "compensation" and congestive "decompensation." Nothing is known about the ability of uninfarcted myocardium to produce force, velocity, and power during these clinical phases, even though adaptation in these regions likely drives progression of compensation. We hypothesized that enhanced cross-bridge-level contractility underlies mechanical compensation and is controlled in part by changes in the phosphorylation states of myosin regulatory proteins. We induced CMI in rats by left anterior descending coronary artery ligation. We then measured mechanical performance in permeabilized ventricular trabecula taken distant from the infarct zone and assayed myosin regulatory protein phosphorylation in each individual trabecula. During full activation, the compensated myocardium produced twice as much power and 31% greater isometric force compared with noninfarcted controls. Isometric force during submaximal activations was raised >2.4-fold, while power was 2-fold greater. Electron and confocal microscopy demonstrated that these mechanical changes were not a result of increased density of contractile protein and therefore not an effect of tissue hypertrophy. Hence, sarcomere-level contractile adaptations are key determinants of enhanced trabecular mechanics and of the overall cardiac compensatory response. Phosphorylation of myosin regulatory light chain (RLC) increased and remained elevated post-MI, while phosphorylation of myosin binding protein-C (MyBP-C) was initially depressed but then increased as the hearts became decompensated. These sensitivities to CMI are in accordance with phosphorylation-dependent regulatory roles for RLC and MyBP-C in crossbridge function and with compensatory adaptation in force and power that we observed in post-CMI trabeculae.
URI: https://hdl.handle.net/10356/84027
http://hdl.handle.net/10220/41594
ISSN: 0363-6135
DOI: 10.1152/ajpheart.00899.2015
Rights: © 2016 The American Physiological Society. This is the author created version of a work that has been peer reviewed and accepted for publication by American Journal of Physiology - Heart and Circulatory Physiology, The American Physiological Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1152/ajpheart.00899.2015].
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:LKCMedicine Journal Articles

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