Abstract

Our aim is to continue studies of the mechanics of the heart. We have been interested in the dynamics of contraction, the long-term goal being to relate properties at the sarcomere and molecular level to contraction in the myocardium. The present experiments, in particular, are designed to explore the implications of stepwise shortening. We have found that shortening occurs in discrete steps, synchronized over a large region of space and punctuated by pauses. This is unexpected according to current ideas about the contractile process; yet we have now confirmed it by four independent methods. Among the questions we wish to answer are: (1) Do steps occur in single myofibrillar sarcomers? (2) Is myosin critical for the presence of stepwise shortening? (3) Is step size quantized? (4) What is the mechanism of synchrony? (5) Does the pause precede the step, or vice-versa? (6) What is the role of activation? These questions will be answered using state of the art sensors to measure sarcomere and segment dynamics.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL018676-12
Application #
3335662
Study Section
Cardiovascular Study Section (CVA)
Project Start
1979-04-01
Project End
1988-03-31
Budget Start
1987-04-01
Budget End
1988-03-31
Support Year
12
Fiscal Year
1987
Total Cost
Indirect Cost

  Institution

Name
University of Washington
Department
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195

  Publications

Trombitas, K; Pollack, G H; Greaser, M L (1999) Adaptation of a super-sensitive epitope detection technique for the immunoelectron microscopy of titin filaments in vertebrate striated muscle. J Microsc 196:299-304
Fauver, M E; Dunaway, D L; Lilienfeld, D H et al. (1998) Microfabricated cantilevers for measurement of subcellular and molecular forces. IEEE Trans Biomed Eng 45:891-8
deBeer, E L; Sontrop, A M; Kellermayer, M S et al. (1997) Actin-filament motion in the in vitro motility assay has a periodic component. Cell Motil Cytoskeleton 38:341-50
Kellermayer, M S; Pollack, G H (1996) Rescue of in vitro actin motility halted at high ionic strength by reduction of ATP to submicromolar levels. Biochim Biophys Acta 1277:107-14
Trombitas, K; Pollack, G H (1995) Visualization of the transverse cytoskeletal network in insect-flight muscle by scanning-electron microscopy. Cell Motil Cytoskeleton 32:226-32
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
Trombitas, K; Pollack, G H (1995) Actin filaments in honeybee-flight muscle move collectively. Cell Motil Cytoskeleton 32:145-50
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
Bartoo, M L; Popov, V I; Fearn, L A et al. (1993) Active tension generation in isolated skeletal myofibrils. J Muscle Res Cell Motil 14:498-510
Alevriadou, B R; McIntire, L V; Lasslo, A (1992) Inhibition of platelet adhesion and thrombus formation on a collagen-coated surface by novel carbamoylpiperidine antiplatelet agents. Biochim Biophys Acta 1137:279-86

Showing the most recent 10 out of 18 publications