scholarly journals The effect of tropomyosin on force and elementary steps of the cross-bridge cycle in reconstituted bovine myocardium

2004 ◽  
Vol 556 (2) ◽  
pp. 637-649 ◽  
Author(s):  
Hideaki Fujita ◽  
Xiaoying Lu ◽  
Madoka Suzuki ◽  
Shin'ichi Ishiwata ◽  
Masataka Kawai
Keyword(s):  
Elementary Steps ◽  
Cross Bridge ◽  
The Cross ◽  
Bovine Myocardium

scholarly journals Elementary Steps of the Cross-Bridge Cycle in Bovine Myocardium with and without Regulatory Proteins

2002 ◽  
Vol 82 (2) ◽  
pp. 915-928 ◽  
Author(s):  
Hideaki Fujita ◽  
Daisuke Sasaki ◽  
Shin’ichi Ishiwata ◽  
Masataka Kawai
Keyword(s):  
Regulatory Proteins ◽  
Elementary Steps ◽  
Cross Bridge ◽  
The Cross ◽  
Bovine Myocardium

Inotropic agent EMD-53998 weakens nucleotide and phosphate binding to cross bridges in porcine myocardium

1996 ◽  
Vol 271 (4) ◽  
pp. H1394-H1406 ◽  
Author(s):  
Y. Zhao ◽  
M. Kawai
Keyword(s):  
Equilibrium Constant ◽  
Isometric Tension ◽  
Association Constants ◽  
Phosphate Binding ◽  
Sinusoidal Analysis ◽  
Elementary Steps ◽  
Cross Bridge ◽  
The Cross ◽  
Cross Bridges ◽  
Emd 53998

The effect of EMD-53998 (EMD) on elementary steps of the cross-bridge cycle in skinned porcine myocardium was studied to understand the positive inotropic mechanisms of EMD. The kinetic constants of the elementary steps were obtained by sinusoidal analysis and compared in the presence and absence of 50 microM EMD. In the presence of 50 microM EMD, the equilibrium constant of the cross-bridge detachment step decreases three times, and the equilibrium constant of the cross-bridge attachment (force generation) step increases two times. Our results further show that, in the presence of 50 microM EMD, the association constants of MgATP and MgADP decrease to one-ninth and one-third, respectively, and the association constant of phosphate decreases to one-third. These results indicate that EMD suppresses the nucleotide binding to cross bridges and increases cross-bridge resistance to phosphate accumulation in myocardium. These results predict that EMD decreases the number of detached cross bridges and increases the number of attached cross bridges. This prediction is consistent with the twofold increase of isometric tension with 50 microM EMD.

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