The proposed experiments are designed to continue to explore the dynamics of sarcomeres in the heart. The specific plans are built largely around a recent discovery: sarcomeres that shorten by 1-2% of their initial length generate substantially more isometric tension than sarcomeres that remain at their initial length throughout contraction. The phenomenon has been labelled shortening-induced force enhancement. The plan is to study the phenomenon in detail, to explore several hypotheses concerning the underlying mechanism, and to determine the impact, if any, on contraction of the heart. Three classes of preparation will be used, each at a different level of organization. At the highest level, single fibers and isolated cardiac trabeculae will be used. At the next level down, sarcomere dynamics will be studied at the level of the single myofibril. Finally, at the most basic level, an in vitro motility assay will be used to study interactions among molecules and filaments. The primary aim in these multi-level experiments is to determine whether the mechanism lies at the molecular level, or at some higher level of organization. Time permitting, a secondary goal is to study additional mechanical phenomena with this unique combination of experimental-approaches. The ability to explore well known features such as the force-velocity relation, the length-tension relation, etc., at the fiber-, myofibril-, and myofilament-level offers an unusual opportunity to approach the mechanisms underlying these features.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL018676-18
Application #
3335666
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Project Start
1979-04-01
Project End
1994-03-31
Budget Start
1993-04-01
Budget End
1994-03-31
Support Year
18
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Washington
Department
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
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Kellermayer Jr, M S; Hinds, T R; Pollack, G H (1995) Persisting in vitro actin motility at nanomolar adenosine triphosphate levels: comparison of skeletal and cardiac myosins. Physiol Chem Phys Med NMR 27:167-78
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Trombitas, K; Pollack, G H; Wright, J et al. (1993) Elastic properties of titin filaments demonstrated using a ""freeze-break"" technique. Cell Motil Cytoskeleton 24:274-83
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