|
|
|
|
|
|
|
||
The Journal of General Physiology, Vol 83, 563-588, Copyright © 1984 by The Rockefeller University Press
ARTICLES |
HC Hartzell
The molecular mechanisms by which neurotransmitters modulate the force of contraction of cardiac muscle are incompletely understood. Hartzell and Titus (1982. J. Biol. Chem. 257:2111-2120) have recently reported that C-protein, an integral component of the thick filament, is reversibly phosphorylated in response to ionotropic agents. In this communication, C-protein phosphorylation (as measured by isotopic labeling with 32P) is correlated with changes in the rate of relaxation of twitch tension. On the average, isoproterenol simultaneously increases peak systolic tension twofold, decreases twitch relaxation time from a control value of approximately 450 to approximately 300 ms, and increases C-protein phosphorylation two- to threefold, with a maximum effect occurring less than 60 s after addition of 1 microM isoproterenol. Carbamylcholine, in contrast, decreases peak systolic tension more rapidly than it affects relaxation or C-protein phosphorylation. The maximum decrease in peak tension (60%) occurs within 1 min of addition of 0.5 microM carbamylcholine, but relaxation time increases slowly to 800 ms over approximately 6 min. The increase in relaxation time correlates well with the decrease in 32P incorporation into C-protein (r = 0.94). Changing beat frequency between 0.2 and 1/s has no effect on C-protein phosphorylation but does alter relaxation time (relaxation time decreases approximately 100 ms when beat frequency is changed from 0.5 to 1/s) and thus alters the quantitative relationship between C-protein phosphorylation and relaxation rate. These results suggest that two separate processes affect relaxation. It is proposed that the level of C-protein phosphorylation sets the boundaries over which relaxation is regulated by a second process that is dependent upon beat frequency and probably involves changes in intracellular Ca.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  S. P. Harris, E. Rostkova, M. Gautel, and R. L. Moss Binding of Myosin Binding Protein-C to Myosin Subfragment S2 Affects Contractility Independent of a Tether Mechanism Circ. Res., October 29, 2004; 95(9): 930 - 936. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Kulikovskaya, G. McClellan, J. Flavigny, L. Carrier, and S. Winegrad Effect of MyBP-C Binding to Actin on Contractility in Heart Muscle J. Gen. Physiol., November 24, 2003; 122(6): 761 - 774. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. M. Wolska, G. M. Arteaga, J. R. Pena, G. Nowak, R. M. Phillips, S. Sahai, P. P. de Tombe, A. F. Martin, E. G. Kranias, and R. J. Solaro Expression of Slow Skeletal Troponin I in Hearts of Phospholamban Knockout Mice Alters the Relaxant Effect of {beta}-Adrenergic Stimulation Circ. Res., May 3, 2002; 90(8): 882 - 888. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Li, J. Desantiago, G. Chu, E. G. Kranias, and D. M. Bers Phosphorylation of phospholamban and troponin I in beta -adrenergic-induced acceleration of cardiac relaxation Am J Physiol Heart Circ Physiol, March 1, 2000; 278(3): H769 - H779. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. C Fentzke, S. H Buck, J. R Patel, H. Lin, B. M Wolska, M. O Stojanovic, A. F Martin, R J. Solaro, R. L Moss, and J. M Leiden Impaired cardiomyocyte relaxation and diastolic function in transgenic mice expressing slow skeletal troponin I in the heart J. Physiol., May 15, 1999; 517(1): 143 - 157. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Weisberg and S. Winegrad Relation Between Crossbridge Structure and Actomyosin ATPase Activity in Rat Heart Circ. Res., July 13, 1998; 83(1): 60 - 72. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R Gilbert, M. Kelly, T Mikawa, and D. Fischman The carboxyl terminus of myosin binding protein C (MyBP-C, C-protein) specifies incorporation into the A-band of striated muscle J. Cell Sci., January 1, 1996; 109(1): 101 - 111. [Abstract] [PDF]
|
|
|
|
|
|
R. Zhang, J. Zhao, A. Mandveno, and J. D. Potter Cardiac Troponin I Phosphorylation Increases the Rate of Cardiac Muscle Relaxation Circ. Res., June 1, 1995; 76(6): 1028 - 1035. [Abstract] [Full Text]
|
|
|
|
|
|
B. M. Wolska, G. M. Arteaga, J. R. Pena, G. Nowak, R. M. Phillips, S. Sahai, P. P. de Tombe, A. F. Martin, E. G. Kranias, and R. J. Solaro Expression of Slow Skeletal Troponin I in Hearts of Phospholamban Knockout Mice Alters the Relaxant Effect of {beta}-Adrenergic Stimulation Circ. Res., May 3, 2002; 90(8): 882 - 888. [Abstract] [Full Text] [PDF]
|
|
|
|
