Right ventricle dysfunction in heart failure rats following myocardial infarction involves the increment of phospholamban to phosphorilated‐phospholamban ratio

Abstract

The aim of this study was to assess right ventricle (RV) contractility and proteins involving in calcium transient early (1 week) and late phase (8 weeks) in rats with or without heart failure (HF) after myocardial infarction (MI). The Increment of left ventricle end diastolic pressure, lung weight and body weight ratio and right ventricle to body weight ratio was used to divide MI rats with (HF) and without HF (Inf). The scar size was not different between groups neither was correlated to signals of HF. Strips from RV were superfused with Krebs in an isometric apparatus. The inotropic response to Ca2+ and Isoproterenol were preserved early and reduced late after MI. Inversely, in the Inf group, the positive intropic response was reduced only in the early phase. The SERCA‐2a, phospholamban (PLB total), PLB phosphorylated and Na+/Ca2+ exchange proteins were not different among groups in the early phase. In the late phase there was a SERCA‐2a overexpression only in the Inf group (Sham=0.79±0.05; Inf=1.81±0.06*; HF=0,88±0.1; *P<0.05). There was an increment on SERCA/PLB ratio also in Inf group (Sham=0.8±0.08; Inf=1.33±0.12*; HF=0.87±0.09; *P<0.05). The PLB/PLBPratio was increased only in the HF animals at 8 weeks (Sham=1.19±0.19; Inf=1.72±0.24; HF=3.51±1.04* P<0.05). These results suggest that increased SERCA‐2a expression contribute to maintain RV contractility in Inf group. The reduced RV contractility in the HF group at 8 weeks could be related to the increment on PLB/PLBP ratio.