Myofilament length-dependent activation develops within 5 ms in guinea-pig myocardium Journal Article

Authors: Mateja, R. D.; de Tombe, P. P.
Article Title: Myofilament length-dependent activation develops within 5 ms in guinea-pig myocardium
Abstract: Myofilament length-dependent activation is a universal property of striated muscle, yet the molecular mechanisms that underlie this phenomenon are incompletely understood. Additionally, the rate by which sarcomere length (SL) is sensed and then transduced to form length-dependent activation is unknown. Here, using isolated guinea-pig myocardium, we employed a rapid solution-switch single myofibril technique that allows for the study of contractile action/relaxation dynamics in the virtual absence of diffusion delays. We compared contraction kinetics obtained at submaximal activation at steady-state SL with contractions observed after rapid SL ramps to that same SL just before activation. Neither the activation and relaxation kinetics nor the final submaximal force development differed significantly between the two contraction modes for SL ramps as fast as 5 ms. We conclude that the transduction of the length signal by the cardiac sarcomere to modulate thin filament activation levels occurs virtually instantaneously, possibly resulting from structural rearrangements of the contractile proteins.
Journal Title: Biophysical journal
Volume: 103
Issue: 1
ISSN: 1542-0086; 0006-3495
Publisher: Unknown  
Journal Place: United States
Date Published: 2012
Start Page: L13
End Page: 5
Language: eng
Notes: LR: 20131115; CI: Copyright (c) 2012; GR: HL075494/HL/NHLBI NIH HHS/United States; GR: HL07692/HL/NHLBI NIH HHS/United States; GR: HL62426/HL/NHLBI NIH HHS/United States; JID: 0370626; OID: NLM: PMC3388202; 2012/04/19 [received]; 2012/05/15 [revised]; 2012/05/18 [accepted]; ppublish