The general objective of this research is to investigate the mechanism of control of contraction of striated muscle in both normal and diseased states at the cellular and molecular level. There are several specific aims in this research. The first is to estimate the Ca bound to the filaments and determine whether this binding depends on cross-bridge interaction. These studies utilize aequorin luminescence to measure Ca in barnacle single muscle fibers under controlled stimulation and mechanical conditions.
The second aim i s to investigate the mechanism of hystersis in Ca sensitivity in muscles whereby muscles are more sensitive to calcium when the Ca concentration is being decreased as in relaxation than when it is being increased as at the beginning of contraction. Experiments will be done to test the hypothesis that hysteresis is caused by a cross-bridge dependent increase in Ca binding to the activating sites, and not by phosphorylation. Skinned barnacle frog, rabbit, and rat muscles will be used in this study.
Our third aim i s to understand better how Ca activates muscles from the giant barnacle, Balanus nubilus, the muscle preparation we use extensively.
Our fourth aim i s to develop a technique of measuring Ca bound to various sites of Tn-C in skinned mammalian skeletal muscle using selective extraction, fluorescent labeling and reintroduction of labeled Tn-C into skinned muscle fibers and measuring the fluorescence that accompanies Ca activation. This technique will be used to study Ca binding to the Ca specific and Ca-Mg sites on Tn-C to correlate this binding with contraction and with factors which change cross-bridge interaction such as sarcomere length, MgATP, hysteresis, rigor, and step changes in length. Using this same technique, we will attach a fluorescent label to measure thin filament activation to test its relationship to cross-bridge interaction. Finally, we will measure the relative time courses of the sequential events in activation from Ca binding, to thin filament activation, to cross-bridge interaction, to force production during Ca activation of contraction and relaxation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS008384-19
Application #
3393760
Study Section
Physiology Study Section (PHY)
Project Start
1978-08-01
Project End
1991-07-31
Budget Start
1987-08-01
Budget End
1988-07-31
Support Year
19
Fiscal Year
1987
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
Martyn, D A; Chase, P B (1995) Faster force transient kinetics at submaximal Ca2+ activation of skinned psoas fibers from rabbit. Biophys J 68:235-42
Chase, P B; Martyn, D A; Hannon, J D (1994) Isometric force redevelopment of skinned muscle fibers from rabbit activated with and without Ca2+. Biophys J 67:1994-2001
Chase, P B; Martyn, D A; Hannon, J D (1994) Activation dependence and kinetics of force and stiffness inhibition by aluminiofluoride, a slowly dissociating analogue of inorganic phosphate, in chemically skinned fibres from rabbit psoas muscle. J Muscle Res Cell Motil 15:119-29
Martyn, D A; Chase, P B; Hannon, J D et al. (1994) Unloaded shortening of skinned muscle fibers from rabbit activated with and without Ca2+. Biophys J 67:1984-93
Martyn, D A; Coby, R; Huntsman, L L et al. (1993) Force-calcium relations in skinned twitch and slow-tonic frog muscle fibres have similar sarcomere length dependencies. J Muscle Res Cell Motil 14:65-75
Yates, L D; Coby, R L; Luo, Z et al. (1993) Filament overlap affects TnC extraction from skinned muscle fibres. J Muscle Res Cell Motil 14:392-400
Bond, E F; Gordon, A M (1993) Insulin-induced membrane changes in K(+)-depleted rat skeletal muscle. Am J Physiol 265:C257-65
Gordon, A M; Ridgway, E B (1993) Cross-bridges affect both TnC structure and calcium affinity in muscle fibers. Adv Exp Med Biol 332:183-92;discussion 192-4
Hannon, J D; Chase, P B; Martyn, D A et al. (1993) Calcium-independent activation of skeletal muscle fibers by a modified form of cardiac troponin C. Biophys J 64:1632-7
Allen, T S; Yates, L D; Gordon, A M (1992) Ca(2+)-dependence of structural changes in troponin-C in demembranated fibers of rabbit psoas muscle. Biophys J 61:399-409

Showing the most recent 10 out of 19 publications