Regulation of cardiomyocyte mechanotransduction by the cardiac cycle.
BACKGROUND
Overloading the left ventricle in systole (pressure overload) is associated with a distinct morphological response compared with overload in diastole (volume overload).


RESULTS
We designed a novel computer-controlled experimental system that interfaces biaxially uniform strain with electrical pacing, so that cellular deformation can be imposed during a specified phase of the cardiac cycle. Cardiomyocytes were exposed to strain (4%) during either the first third (systolic phase) or last third (diastolic phase) of the cardiac cycle. Strain imposed during the systolic phase selectively activated p44/42 mitogen-activated protein kinase (MAPK) and MAPK/extracellular signal-regulated protein kinase kinase (MEK1/2, an activator of p44/42 MAPK) compared with strain imposed during the diastolic phase. In contrast, there was no difference in activation of p38 and c-Jun NH(2)-terminal kinases induced by strain imposed during the systolic phase (5.8- and 3.3-fold versus control, n=4) compared with the diastolic phase (5.5- and 3.1-fold). Induction of both brain natriuretic peptide (5.8-fold versus control, P:<0.05, n=3) and tenascin-C (7.0-fold, P:<0.02) mRNA expression by strain imposed during the systolic phase was greater than during the diastolic phase (3.9- and 3.6-fold, respectively). [(3)H]leucine incorporation induced by strain imposed during the systolic phase (4.0-fold versus control) was greater than during the diastolic phase (2.7-fold, P:<0.02, n=4); a selective inhibitor of MEK1/2 inhibited this difference.


CONCLUSIONS
Mechanical activation of p44/42 MAPK and MEK1/2, gene expression, and protein synthesis is regulated by the cardiac cycle, suggesting that mechanotransduction at the cellular level may underlie differences between pressure and volume overload of the heart.
Yamamoto
K
K
Cardiovascular Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Dang
Q N
QN
Maeda
Y
Y
Huang
H
H
Kelly
R A
RA
Lee
R T
RT
D000818:Animals; D001696:Biomechanical Phenomena; D015870:Gene Expression; D006321:Heart / Q000502:physiology; D066298:In Vitro Techniques; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D020097:Natriuretic Peptide, Brain / Q000096:biosynthesis / Q000235:genetics; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017725:Ventricular Pressure / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases
D020097:Natriuretic Peptide, Brain; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases