Strain Related Regional Alterations of Calcium Handling Proteins in Heart Failure
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Objective: The purpose of this study is to quantify the deterministic link between changes in calcium handling protein expressions and the amount of regional myocardial strain during ischemic heart failure.
Methods: Sixteen sonomicrometry transducers were placed into the mid-myocardium of the LV free wall to assess remodeling by an end systolic regional strain map in an ovine model of heart failure (n=7). Regional myocardial tissue underwent Western blotting and phosphorimager quantification for sarcoplasmic reticulum Ca2+ adenosine triphosphatase subtype 2a (SERCA2a), Na+/ Ca2+ exchanger (NCX-1) and phospholamban (PLB). The regional samples were compared with normal, non-instrumented sheep myocardium (n=3).
Results: The end systolic strain map showed dilatation of the infarct with a strain of 3.52 % ± 1.89. The adjacent region showed shortening with a strain of -4.74 ± 1.75 (p ≤ 0.05) and the remote region had a strain of -5.37 % ± 1.87 (p ≤ 0.001). The relative abundance of protein is summarized (table). A negative relationship between SERCA2a expression and strain (r = -0.46, p ≤ 0.05), a positive relationship between NCX-1 and strain (r = 0.49, p ≤ 0.05) and no relationship between PLB and strain was observed.
Conclusions: Regional strain during cardiac remodeling may be the initial and continous driving force behind regional protein changes expressed in ischemic HF. 
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