Objectives: The normal expression of Ca2+-handling protein is critical for efficient myocardial function. The present study was designed to test the hypothesis that beta-blocker treatment may attenuate left ventricular (LV) remodeling and cardiac contractile dysfunction in the failing heart, which may be associated with alterations of Ca2+-handling protein
Methods: We investigated the change of LV remodeling and function in a rat model of heart failure due to myocardial infarction (MI) with or without carvedilol (30 mg/kg/d) or metoprolol (60 mg/kg/d) treatment for 6 weeks (n = 9 in the MI plus carvedilol group, and n = 8 in every other group). The expression of messenger RNA and proteins of sarcoplasmic reticulum Ca2+-adenosine triphosphatase (SERCA) and phospholamban in cardiomyocytes of all rats were also measured
Results: There was significant LV remodeling and cardiac contractile dysfunction in MI rats. The messenger RNA and protein expression of SERCA were down-regulated (p < 0.01), but the expression of phospholamban messenger RNA and protein were up-regulated (p < 0.01) in MI rats compared to sham-operated rats. After the treatment with beta-blockers, LV remodeling and function were clearly improved. Carvedilol was better in attenuating the weight of the LV and the relative weight of the right ventricle than metoprolol (p < 0.05). beta-Blockers restored the low expression of SERCA (p < 0.05) but showed no effect on phospholamban expression (p > 0.05). Moreover, carvedilol induced a more significant improvement of SERCA expression than metoprolol (p < 0.05)
Conclusions: Beta-blockers are effective in preventing LV remodeling and cardiac contractile dysfunction in the failing heart. The molecular mechanism may be related to normalization of SERCA expression.