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_name
Biophys Jjournal_title
Biophysical journalauthors
Mateja RD,de Tombe PPdoi
10.1016/j.bpj.2012.05.034subject
Has Abstractpub_date
2012-07-03 00:00:00pages
L13-5issue
1eissn
0006-3495issn
1542-0086pii
S0006-3495(12)00614-5journal_volume
103pub_type
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