| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Section on Cardiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
We tested the hypotheses that Ca2+ concentration ([Ca2+]) and sarcomere length (SL) modulate force development via graded effects on cross-bridge kinetics in chemically permeabilized rat cardiac trabeculae. Using sinusoidal length perturbations, we derived the transfer functions of stiffness over a range of [Ca2+] at a constant SL of 2.1 µm (n = 8) and at SL of 2.0, 2.1, and 2.2 µm (n = 4). We found that changes in SL affected only the magnitude of stiffness, whereas [Ca2+] affected the magnitude and phase-frequency relations. The data were fit to complex functions of two exponential processes. The characteristic frequencies (b and c) of these processes are indexes of cross-bridge kinetics, with b relating to cross-bridge attachment to and c to detachment from certain non-force-generating states. Both were significantly affected by [Ca2+], with an increase in b and c of 140 and 44%, respectively, over the range of [Ca2+] studied (P < 0.01). In contrast, SL had no effect on the characteristic frequencies (P > 0.6). We conclude that Ca2+ activation modulates force development in rat myocardium, at least in part, via a graded effect on cross-bridge kinetics, whereas SL effects are mediated mainly by recruitment of cross bridges.
sinusoidal perturbation; dynamic transfer function of stiffness; myocardial cross-bridge mechanics; skinned fibers
This article has been cited by other articles:
|
|
 |
|
  M. Chandra, M. L. Tschirgi, S. J. Ford, B. K. Slinker, and K. B. Campbell Interaction between myosin heavy chain and troponin isoforms modulate cardiac myofiber contractile dynamics Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2007; 293(4): R1595 - R1607. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. F. Edes, D. Czuriga, G. Csanyi, S. Chlopicki, F. A. Recchia, A. Borbely, Z. Galajda, I. Edes, J. van der Velden, G. J. M. Stienen, et al. Rate of tension redevelopment is not modulated by sarcomere length in permeabilized human, murine, and porcine cardiomyocytes Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R20 - R29. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. D. Gao, T. Dai, and D. Nyhan Increased cross-bridge cycling rate in stunned myocardium Am J Physiol Heart Circ Physiol, February 1, 2006; 290(2): H886 - H893. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. B. Campbell, Y. Wu, A. M. Simpson, R. D. Kirkpatrick, S. G. Shroff, H. L. Granzier, and B. K. Slinker Dynamic myocardial contractile parameters from left ventricular pressure-volume measurements Am J Physiol Heart Circ Physiol, July 1, 2005; 289(1): H114 - H130. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Yaniv, R. Sivan, and A. Landesberg Analysis of hystereses in force length and force calcium relations Am J Physiol Heart Circ Physiol, January 1, 2005; 288(1): H389 - H399. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. B. Campbell, M. Chandra, R. D. Kirkpatrick, B. K. Slinker, and W. C. Hunter Interpreting cardiac muscle force-length dynamics using a novel functional model Am J Physiol Heart Circ Physiol, April 1, 2004; 286(4): H1535 - H1545. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Levy and A. Landesberg Hystereses in the force-length relation and regulation of cross-bridge recruitment in tetanized rat trabeculae Am J Physiol Heart Circ Physiol, January 1, 2004; 286(1): H434 - H441. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 X. Lu, L. S Tobacman, and M. Kawai Effects of tropomyosin internal deletion {Delta}23Tm on isometric tension and the cross-bridge kinetics in bovine myocardium J. Physiol., December 1, 2003; 553(2): 457 - 471. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Fatkin and R. M. Graham Molecular Mechanisms of Inherited Cardiomyopathies Physiol Rev, October 1, 2002; 82(4): 945 - 980. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. P Konhilas, T. C Irving, and P. P de Tombe Length-dependent activation in three striated muscle types of the rat J. Physiol., October 1, 2002; 544(1): 225 - 236. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. E. Bartunek, V. A. Claes, and P. R. Housmans Effects of volatile anesthetics on elastic stiffness in isometrically contracting ferret ventricular myocardium J Appl Physiol, June 1, 2002; 92(6): 2491 - 2500. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Fujita and M. Kawai Temperature effect on isometric tension is mediated by regulatory proteins tropomyosin and troponin in bovine myocardium J. Physiol., February 15, 2002; 539(1): 267 - 276. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
