| First Author | Janssen PM | Year | 2010 |
| Journal | Am J Physiol Heart Circ Physiol | Volume | 299 |
| Issue | 4 | Pages | H1092-9 |
| PubMed ID | 20656885 | Mgi Jnum | J:165683 |
| Mgi Id | MGI:4838000 | Doi | 10.1152/ajpheart.00417.2010 |
| Citation | Janssen PM (2010) Kinetics of cardiac muscle contraction and relaxation are linked and determined by properties of the cardiac sarcomere. Am J Physiol Heart Circ Physiol 299(4):H1092-9 |
| abstractText | The regulation of myocardial contraction and relaxation kinetics is currently incompletely understood. When the amplitude of contraction is increased via the Frank-Starling mechanism, the kinetics of the contraction slow down, but when the amplitude of contraction is increased with either an increase in heart rate or via beta-adrenergic stimulation, the kinetics speed up. It is also unknown how physiological mechanisms affect the kinetics of contraction versus those of relaxation. We investigated contraction-relaxation coupling in isolated trabeculae from the mouse and rat and stimulated them to contract at various temperatures, frequencies, preloads, and in the absence and presence of beta-adrenergic stimulation. In each muscle at least 16 different conditions were assessed, and the correlation coefficient of the speed of contraction and relaxation was very close (generally >0.98). Moreover, in all but one of the analyzed murine strains, the ratio of the minimum rate of the derivative of force development (dF/dt) over maximum dF/dt was not significantly different. Only in trabeculae isolated from myosin-binding protein-C mutant mice was this ratio significantly lower (0.61 +/- 0.07 vs. 0.84 +/- 0.02 in 11 other strains of mice). Within each strain, this ratio was unaffected by modulation of length, frequency, or beta-adrenergic stimulation. Rat trabeculae showed identical results; the balance between kinetics of contraction and relaxation was generally constant (0.85 +/- 0.04). Because of the great variety in underlying excitation-contraction coupling in the assessed strains, we concluded that contraction-relation coupling is a property residing in the cardiac sarcomere. |
