ATP2A2 and congestive heart failure: Consistent with the qPCR results, the protein expression levels of RyR2 and SERCA2 were significantly lower in the CHF-SS group compared with the SO-SS group (P=0.001 and P<0.000, respectively), and were higher in the CHF-VNS group compared with the CHF-SS group (P=0.011 and P=0.001, respectively).