Although expression and phosphorylation of the SR Ca<sup>2+</sup>-ATPase type-2a (SERCA2a) regulator phospholamban were unchanged in HFrEF and HFrEF-cAF patients, protein levels of SERCA2a were increased in HFrEF-cAF and sarcolipin expression was decreased in both HFrEF and HFrEF-cAF, likely increasing SR Ca<sup>2+</sup> uptake and load.
The selective downregulation of SLN and enhanced SR Ca(2+) uptake in human AF suggest that SLN downregulation could play an important role in abnormal intracellular Ca(2+) cycling in atrial pathology.
Chronic electrical and mechanical overload decreased the expression of sarcolipin mRNA in the right atrial myocardium in patients with chronic atrial fibrillation.