Figure 5. Calcium handling proteins and cardiac angiotensin-II.

Western blots of calcium handling proteins were quantified relative to GAPDH. A) SERCA2 protein was significantly reduced in aged WT heart, and better preserved in old mCAT heart; B) NCX protein was significantly increased in aged heart, and lower in old mCAT compared with old WT; C) Linear regression demonstrates an inverse correlation between SERCA2 and NCX protein levels (all ages: β= −0.61, R²=0.49, p<0.01; old mice only: β= −0.82, R²=0.52, p=0.001). D) Cardiac angiotensin II concentration (fmol/mg total protein) measured by mass spectrometry was significantly increased with age in both WT and mCAT mice. E) Phosphorylated and total protein levels of phospholamban did not change significantly with age or mCAT expression.