Mechanisms of favorable effects of Rho kinase inhibition on myocardial remodeling and systolic function after experimental myocardial infarction in the rat.
OBJECTIVE
The objective of this study was to determine the molecular mechanisms by which cardiac Rho-associated coiled-coil containing protein kinase (ROCK) activation after myocardial infarction (MI) does intervene in cardiac systolic function decline and remodeling.


METHODS
Simultaneous measurement of different cardiac ROCK target proteins levels, in vivo left ventricular (LV) systolic function, myocardial fibrosis and hypertrophy in rats with MI under ROCK inhibition with fasudil.


RESULTS
Seven days after MI, the ventricular mass increased significantly by 5.6% in the MI group and was reduced with fasudil. LV systolic dysfunction improved significantly with fasudil whereas cardiac ROCK activation was reduced to sham levels. The ROCK inhibitor also reduced increased cardiac levels of both ROCK1 and ROCK2 isoforms, cardiomyocyte ROCK2 fluorescence levels and β-myosin heavy chain (MHC) levels in addition to myocardial collagen volume fraction decline. Compared with sham rats, troponin phosphorylation levels after MI were similar and ROCK inhibition reduced them. MI significantly increased phosphorylation levels of extracellular-signal-regulated kinase (ERK) 42 and ERK 44 by twofold and 63%, respectively, whereas in the fasudil-treated MI group these levels were similar to those in the sham group. MI significantly increased phosphorylated levels of the transcription factor GATA-4 and the ROCK inhibitor normalized them.


CONCLUSIONS
LV systolic dysfunction after MI was strongly associated with cardiac ROCK activation and subsequent phosphorylation of ROCK target proteins that promote ventricular remodeling such as β-MHC and the ERK/GATA-4 pathway. ROCK inhibition with fasudil significantly improved systolic function, diminished myocardial fibrosis and normalized β-MHC and ERK/GATA-4 phosphorylation levels.
Pontificia Universidad Católica de Chile, School of Medicine, Division of Cardiovascular Diseases, Laboratory of Molecular Cardiology, Santiago, Chile.
Claudia
C
Mera
Pontificia Universidad Católica de Chile, School of Medicine, Division of Cardiovascular Diseases, Laboratory of Molecular Cardiology, Santiago, Chile.
Iván
I
Godoy
Pontificia Universidad Católica de Chile, School of Medicine, Division of Cardiovascular Diseases, Laboratory of Molecular Cardiology, Santiago, Chile.
Renato
R
Ramírez
Pontificia Universidad Católica de Chile, School of Medicine, Division of Cardiovascular Diseases, Laboratory of Molecular Cardiology, Santiago, Chile.
Jackeline
J
Moya
Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, ChileDivision of Cardiovascular Diseases, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
María Paz
MP
Ocaranza
Pontificia Universidad Católica de Chile, School of Medicine, Division of Cardiovascular Diseases, Marcoleta 367 Piso 8, Santiago, Chile jjalil@med.puc.cl.
Jorge E
JE
Jalil
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D004195:Disease Models, Animal; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D050991:GATA4 Transcription Factor / Q000378:metabolism; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy* / Q000503:physiopathology; D018995:Myosin Heavy Chains / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018487:Ventricular Dysfunction, Left / Q000188:drug therapy / Q000503:physiopathology; D020257:Ventricular Remodeling / Q000187:drug effects*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D050991:GATA4 Transcription Factor; C084365:Gata4 protein, rat; C000594638:MYH7 protein, rat; D047428:Protein Kinase Inhibitors; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C578418:ROCK1 protein, rat; C515852:ROCK2 protein, human; D054460:rho-Associated Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D018995:Myosin Heavy Chains; C049347:fasudil
ERM; Rho kinase; contractility; fasudil; heart failure; remodeling